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The objective of this study was to quantify the effects of supplementing early-lactation cows with a dry pure glycerol product, delivered through the automated milking system (AMS) concentrate, in the first 21 DIM on metabolic markers, milking behavior, and milk production. In 5 commercial AMS dairy herds, 389 dairy cows were randomly assigned, controlling for parity, 21 d before expected calving to 1 of 2 treatments, within farm: (1) the control group (CON) which received the standard AMS pellet (n = 213) from 1 to 150 DIM; or (2) the glycerol group (GLY), which received the treatment AMS pellet (n = 176) formulated to additionally deliver 250 as fed g/d of glycerol product from 1 to 21 DIM, followed by the standard AMS pellet from 22 to 150 DIM. Across all farms, cows were fed partial mixed rations that were similar in ingredient and nutrient composition. One prepartum blood sample and 5 postpartum blood samples were collected from each cow to determine serum nonesterified fatty acids (NEFA), blood BHB, and blood glucose concentrations. Cow BCS was recorded every 21 d from -21 to 63 DIM. Data were collected and analyzed for the treatment period (1-21 DIM) and a follow-up period (22-150 DIM). We detected no treatment effect on serum NEFA concentrations in the first week of lactation. We detected a treatment by time interaction for blood BHB and blood glucose, where GLY cows tended to have increased BHB concentrations at 5 DIM and had decreased glucose concentrations at 9 and 12 DIM. We detected an interaction of BCS with treatment on the incidence of BHB ≥1.2 mmol/L, whereby over-conditioned CON cows (BCS ≥3.5) were 3.5 times more likely to have a high BHB test than CON cows with normal prepartum BCS. During the treatment period, GLY cows had 0.1 ± 0.05 more successful milkings per day, were delivered 0.27 ± 0.05 DM kg/d more AMS concentrate, and tended to yield 0.8 ± 0.47 kg/d more milk. During the follow-up period, GLY cows had 0.1 ± 0.04 more successful milkings per day, were delivered 0.18 ± 0.06 DM kg/d more AMS concentrate, and yielded 1.5 ± 0.53 kg/d more milk than CON cows. Glycerol supplementation allowed cows to maintain better BCS, as GLY cows lost less BCS from calving to 63 DIM than CON cows. Overall, the results of this study demonstrate that supplementing pure glycerol through the AMS concentrate for the first 21 DIM can reduce BCS loss in early lactation, improve milking behavior, and increase milk yield to mid-lactation., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this study was to better understand current management practices for down cows in Ontario, Canada, and to identify factors associated with the adoption of acceptable practices. An online survey was distributed to all dairy producers in Ontario, Canada (n = 3,367) and was available from November 2020 to March 2021, inclusive. Dairy producers were identified through their provincial dairy organization and contacted via email, and the survey was also promoted via social media. The survey was comprised of 134 questions, 31 of which were related to down cow management. Descriptive statistics were evaluated, and 2 logistic regression models were generated using Stata 17, exploring factors associated with 1) relocating down cows with hip lifters and 2) assisting cows to stand within an hour after discovering a down cow. A total of 226 producers responded (7.4%). Participants were predominantly male (68%), farm owners (78%), and 30-39 years old (29%). Producers reported relocating down cows with a boat or sled (32.6%), front-end loader bucket (31.4%), hip lifters (28.0%), or 'other' (with a text box to further describe) (8.0%). The median time to relocating a down cow after identifying her was 1 h (range 0 - 17h). Farms that relocated a down cow sooner after identifying her as down, were more likely to use appropriate methods to move the cow. However, we also found that farms that provided feed and water sooner to down cows, were more likely to use an inappropriate method (hip lifters) to move her. Farms that used hip lifters to move cows had higher odds of assisting a cow to stand within an hour following the discovery of recumbency. Additionally, producers who waited longer to relocate a down cow were less likely to assist the cow to stand within one hour of finding them down. Research has identified effective management practices for down cows, yet there remains a gap in understanding the implementation and the decision-making process of producers. Data from this study will be helpful in designing future research that further explores the barriers and motivations of producers when implementing evidence-based management plans to care for down dairy cows and may help inform current industry extension efforts., (© 2024, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objectives of this study were to determine the farm-level hyperketolactia (HKL) prevalence, as diagnosed from the milk BHB concentration, on dairy farms milking with an automated milking system (AMS) and to describe the farm-level housing, management, and nutritional risk factors associated with increased farm-average milk BHB and the within-herd HKL prevalence in the first 45 DIM. Canadian AMS farms (n = 162; eastern Canada, n = 8; Quebec, n = 24; Ontario, n = 75; western Canada n = 55) were visited once between April and September 2019 to record housing and herd management practices. The first test milk data for each cow under 45 DIM were collected, along with the final test of the previous lactations for all multiparous cows, from April 1, 2019, to September 30, 2020. The first test milk BHB was then used to classify each individual cow as having or not having HKL (milk BHB ≥0.15 mmol/L) at the time of testing. Milk fat and protein content, milk BHB, and HKL prevalence were summarized by farm and lactation group (all, primiparous, and multiparous). During this same time period, formulated diets for dry and lactating cows, including ingredients and nutrient composition, and AMS milking data were collected. Data from the AMS were used to determine milking behaviors and milk production of each herd during the first 45 DIM. Multivariable regression models were used to associate herd-level housing, feeding management practices, and formulated nutrient composition with first test milk BHB concentrations and within-herd HKL levels separately for primiparous and multiparous cows. The within-herd HKL prevalence for all cows was 21.8%, with primiparous cows having a lower mean prevalence (12.2 ± 9.2%) than multiparous cows (26.6 ± 11.3%). Milk BHB concentration (0.095 ± 0.018 mmol/L) and HKL prevalence for primiparous cows were positively associated with formulated prepartum DMI and forage content of the dry cow diet; however, they were negatively associated with formulated postpartum DMI, the major ingredient in the concentrate supplemented through the AMS, and the partially mixed ration to AMS concentrate ratio. Multiparous cows' milk BHB concentration (0.12 ± 0.023 mmol/L) and HKL prevalence were positively associated with the length of the previous lactation, milk BHB at dry-off, prepartum diet nonfiber carbohydrate content, and the major forage fed on farm, while tending to be negatively associated with feed bunk space during lactation. This study is the first to determine the farm-level risk factors associated with herd-level prevalence of HKL in AMS dairy herds. The results may help to optimize management and guide diet formulation and thus promote the reduction of HKL prevalence., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The welfare of cull cows during transport to slaughter is a current concern in the Canadian dairy industry. Cull cows sold through auction often have a high prevalence of lameness, low BCS, hock lesions, and udder engorgement. To evaluate whether drying off and feeding cull dairy cows before transport can mitigate these challenges, 45 cows designated for culling were randomly assigned to either be fed for 60 d after being dried off (fed group; n = 24) or to serve as controls by being sent directly to slaughter (direct group; n = 21). Two fed group cows were removed for health reasons before completing the feeding period. Both fed group and direct group cows were assessed for locomotion (5-point scale), BCS (5-point scale), hock lesions (3-point scale), udder engorgement (3-point scale), and BW at the time of enrollment. Fed group cows, locomotion, BCS, hock, and udder engorgement scores were assessed weekly until slaughter. Weights of the fed group cows were measured again the day before slaughter. Mixed linear regression models were used to assess continuous outcomes BCS and weight. Mixed logistic regression models were used to assess dichotomous outcomes presence of hock lesions and lameness. Fed group cows gained an average of 116.9 kg over the feeding period (SE ± 8.20). Fed group cows had an average weight at slaughter of 834.2 kg, whereas direct group cows' average weight was 767.3 kg (SE ± 26.8). The fed group cows' average BCS at the start of the trial was 2.4, and at slaughter was 3.6, with an average gain of 1.2 BCS points. At slaughter, the proportion of udders involuted in the fed group was 45.1% (10/22) and in the direct group cows, was 0% (0/21). No differences were found in locomotion or hock lesions between the fed group and direct groups. It is important to weigh potential benefits for the fed group cows with the fact that direct group cows did not endure a drying off procedure, nor were they placed at risk of potential adverse health events. However, despite these potential limitations, due to the improved BCS and udder engorgement scores, cows fed for 60 d may be better prepared for the transportation to slaughter, as well as sell for a higher price due to increased BW and body condition., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Despite a high volume of market (cull) dairy cows entering the food chain every year, beef from market dairy cows is largely considered insignificant when compared with beef from beef cattle in the market and is widely thought to be used for ground beef only. Our study aimed to evaluate the effects of feeding dairy market cows on a lactating TMR diet before slaughter on carcass and beef quality traits. Forty-three Holstein market cows were randomly assigned into 2 treatments: Fed or Direct. Fed cows (n = 22) were dried off, then fed a lactating cow TMR ration for approximately 60 d whereas Direct cows (n = 21) were sent directly to slaughter. Hot carcass weight (HCW) was used to calculate the dressing percentage (DP) together with the animals' body weight recorded when animals left the farm to go to the abattoir. At 24h post-mortem, the rib fat thickness (RFT) and rib eye area (REA) were measured by a certified grader. Afterward, rib samples were collected between the 12th -10th ribs from one side of the carcass and divided into 5 ribeye steaks. The first steak was used for intramuscular fat (IMF) content analysis by NIRS. The other 4 steaks were then aged for 7, 14, 21, or 28 d. Following aging, the steaks available were assessed for tenderness using the Warner-Bratzler Shear Force protocol. Data were analyzed by mixed linear regression to compare experimental groups for continuous outcomes. HCW of the Fed cows was higher than the Direct cows, with a mean HCW of 408.3 kg and 326.1 kg, respectively (SE ± 9.0). Average DP in Fed cows was 49.1%, compared with 42.5% in Direct cows (SE ± 0.69). The average percentage of IMF in Fed cows was 8.1% and in Direct cows was 5.0% (SE ± 0.43). Fed cows had a mean REA of 68.1 cm 2 and Direct cows had a mean of 57.7 cm 2 (SE ± 11.9). No differences were found for RFT. The steaks aged for 14 d resulted in meat with a mean shear force (SF) of 4.19 kg in Fed cows, while Direct cows had a mean SF of 6.28 kg (SE ± 0.29) Feeding market dairy cows for 60 d before slaughter enhanced carcass weight and yield, IMF content, and tenderness. These results indicate that approximately 60 d of feeding can improve the quality of market dairy cow meat and may help improve market cow value., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Objective: The objective of this prospective observational research project was to have dairy producers use and assess the utility of a cull cow evaluation form., Animals: Cull dairy cows., Procedure: Veterinarians were recruited to enrol a purposively selected group of dairy producers into a project to evaluate a cull cow evaluation form. Producers were provided with evaluation forms and asked to complete a form for every cow they culled from their herd from January to June 2017, inclusive., Results: A total of 44 producers used the form to record information on 323 cows prior to transport., Conclusion and Clinical Relevance: Despite the completion of 323 forms, only ~1/3 were completed fully, with compliance highest for body condition score, lameness, and temperature recordings (> 90% of forms). A cull cow evaluation form may improve the thoroughness and consistency of dairy producer assessment of cull dairy cows for fitness for transport., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

The objective of this study was to describe the nutritional strategies used on Canadian dairy farms with automated milking systems (AMS), both at the feed bunk and the concentrate offered at the AMS, as well as to determine what dietary components and nutrients, as formulated, were associated with milk production and milking behaviors on those farms. Formulated diets (including ingredients and nutrient content) and AMS data were collected from April 1, 2019, until September 30, 2020, on 160 AMS farms (eastern Canada [East] = 8, Ontario [ON] = 76, Quebec [QC] = 22, and western Canada [West] = 54). Both partial mixed ration (PMR) and AMS concentrate samples were collected from May 1 to September 30, 2019, on 169 farms (East = 12, ON = 63, QC = 42, West = 52). We collected AMS milking data for 154 herds. For each farm (n = 161), milk recording data were collected and summarized by farm to calculate average milk yield and components. Multivariable regression models were used to associate herd-level formulated nutrient composition and feeding management practices with milk production and milking behavior. Milk yield (mean ± SD = 37.0 ± 0.3 kg/d) was positively associated with the PMR ether extract (EE) concentration (+0.97 kg/d per percentage point [p.p.] increase) and with farms that fed barley silage as their major forage source (n = 16; +2.18 kg/d) as compared with haylage (n = 42), whereas farms that fed corn silage (n = 96; +1.23 kg/d) tended to produce more milk than farms that fed haylage. Greater milk fat content (4.09 ± 0.28%) was associated with a greater PMR-to-AMS concentrate ratio (+0.02 p.p. per unit increase) and total diet net energy for lactation (+0.046 p.p. per 0.1 Mcal/kg increase), but a lesser percentage of NFC of the PMR (-0.016 p.p. per p.p. increase of NFC percentage). Milk protein content (3.38 ± 0.14%) was positively associated with the forage percentage of the PMR (+0.003 p.p. per p.p. increase of forage percentage) and the total diet starch percentage (+0.009 p.p. per p.p. increase of starch percentage), but was negatively associated with farms feeding corn silage (-0.1 p.p. compared with haylage) as their major forage. Greater milking frequency (2.77 ± 0.40 milkings/d) was observed on farms with free-flow cow traffic systems (+0.62 milkings/d) and was positively associated with feed push-up frequency (+0.013 milkings/d per additional feed push-up), but negatively associated with PMR NFC content and forage percentage of the total ration (-0.017 milkings/d per p.p. increase of forage percentage). Lastly, greater milking refusal frequency (1.49 ± 0.82 refusals/d) was observed on farms with free-flow cow traffic systems (+0.84 refusals/d) and farms feeding barley silage (+0.58 refusals/d) than with guided flow and farms feeding either corn silage or haylage, respectively. These data give insight into the ingredients, nutrient formulations and type of diets fed on AMS dairy farms across Canada and the association of those factors with milk production and milking behaviors., (The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this study was to quantify the effects of supplementing a low level of dry glycerol product pre- and postpartum on the feeding behavior, lying behavior, and reticulorumen pH of dairy cows. Multiparous Holstein dairy cows (n = 60) were enrolled in a 2 × 2 factorial design study. Twenty-one days before expected parturition, cows individually received a dry cow diet with (1) 250 g/d glycerol supplementation (GLY; 66% pure glycerol, United States Pharmacopeia grade), or (2) no supplementation (CON). Following parturition, cows were individually assigned to either (1) 250 g/d glycerol product (GLY; 66% pure glycerol), or (2) no supplementation (CON) to their partial mixed ration (PMR) for the first 21 d in milk (DIM). All cows were milked by an automated milking system and offered a target of 5.4 kg/d pellet (23% of target total dry matter intake [DMI]). For both treatment periods, cows were individually assigned to automated feed bins to measure PMR feeding behavior. Rumination time and lying behavior were monitored with electronic sensors for the whole study (-21 to 21 DIM). Reticulorumen pH boluses were administered to a subset of cows (n = 40) where pH was recorded every 10 min from 21 d prepartum to 21 d postpartum. Prepartum, cows fed GLY had fewer, larger meals and spent 20.2% more time feeding than CON while consuming feed at a similar rate. Cows on the CON diet prepartum spent more time lying down in more frequent bouts in the 21 d before calving. Following parturition, cows that received GLY prepartum continued to devote more time to eating, while tending to spend less time ruminating per kilogram of DMI. Cows receiving CON postpartum had larger meals with longer intervals between meals. In the first 21 DIM, cows receiving CON prepartum tended to have shorter, but significantly more frequent, lying bouts than cows fed GLY prepartum. Glycerol supplementation pre- and postpartum resulted in less time spent lying down following parturition. Minimal differences between treatments were observed for pre- and postpartum sorting behavior or reticulorumen pH. Overall, supplementation of glycerol pre- and postpartum altered cow time budgets, with cows spending more time eating pre- and postpartum, less time lying pre- and postpartum, and having fewer, larger meals prepartum when receiving glycerol prepartum, and with cows having slower feeding rates and smaller meals following parturition with postpartum glycerol supplementation., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this study was to quantify the effects of supplementing transition dairy cows with a low inclusion dry glycerol product in the pre- and postpartum periods on feed intake, metabolic markers, and milk yield and components. Multiparous Holstein dairy cows (n = 60) were enrolled in a 2-by-2 factorial design study. Starting 21 d before expected parturition, cows individually received a dry cow diet with (1) 250 g/d glycerol product supplementation [66% pure glycerol (United States Pharmacopeia grade); GLY], or (2) no supplementation (CON) mixed to their total mixed ration. After parturition, cows, again, were individually assigned to either GLY, or (2) no supplementation (CON) to their partial mixed ration for the first 21 d in milk (DIM). Cows were milked by an automated milking system and offered a target of 5.4 kg DM/d pellet (23% of target total dry matter intake, DMI) in the automated milking system and followed for 42 d into lactation. Blood samples were collected 6.3 ± 3.47 d before calving for all blood measures and 3, 7, 10, and 14 DIM for analysis of glucose and β-hydroxybutyrate, as well as 3 and 7 DIM for nonesterified fatty acids (NEFA) and haptoglobin. Initial dry cow body weight (BW), calf birth weight, previous 305-d milk, and month of parturition were used as covariates in the statistical model. Cows supplemented with GLY prepartum lost less BW and consumed more DMI pre- and postpartum, as well as had lower postpartum blood β-hydroxybutyrate and NEFA concentrations compared with those fed the CON treatment prepartum. Cows supplemented with GLY postpartum had lesser DMI in the first 42 DIM than cows fed CON postpartum, but also had reduced blood NEFA concentrations, odds of a high haptoglobin test, odds of a low blood glucose test, and lesser preformed fatty acid concentrations and yields in their milk. Cows supplemented glycerol both pre- and postpartum lost the least total BW from -21 to 21 DIM. No treatment effects were detected for milk yield; however, cows receiving GLY postpartum had lower milk fat. Overall, glycerol supplementation during the transition period, particularly during the 21 d before calving, was associated with markers of improved metabolic status., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this observational study was to assess the relationship between herd-level prevalence of hyperketolactia (HPH) with management practices of the transition period and herd milk production. Dairy herds (n = 71) were selected based on their inclusion in a herd management risk assessment study (August 2014-March 2018) using a Vital 90 (Elanco) Risk Assessment tool (one assessment per farm). Data from multiple milk recording test-days (Dairy Herd Improvement, DHI; Lactanet) were included in the analysis. Tests performed within ±6 mo relative to each farm's risk assessment date were included (10 ± 2 SD tests per farm). The majority of the farms were located in Ontario (83%). For each farm DHI test, the data set included herd average milk yield (kg/cow per day), average milk fat and protein (%), average somatic cell count (cells/mL), average days in milk (DIM), number of cows tested for ketosis, number of ketosis-positive tests (milk β-hydroxybutyrate ≥0.15 mmol/L), and proportion of cows by parity groups. Overall HPH (5-21 DIM) was calculated based on data available per farm (sum of all positive tests within 5-21 DIM/sum of all cows tested within 5-21 DIM). Each farm average was obtained by considering all test-days. A logit-transformation was applied to hyperketolactia prevalence. Linear regression models (PROC GLM and MIXED of SAS, Version 9.4) were used to predict herd HPH (milk β-hydroxybutyrate ≥0.15 mmol/L within 5 to 21 DIM; the outcome of interest). Four initial models (far-off, close-up, and fresh periods, and DHI) were separately built to assess associations between their variables and HPH; a final model considered variables selected in the initial models. Univariable (liberal P < 0.25) followed by multivariable models were used to build specific models for each period of the risk assessment. Herd prevalence of hyperketolactia was 27 ± 14%, with an average herd size of 141 ± 110 cows. The final HPH model (R 2 = 24.8%) included weighted milk yield, the proportion of primiparous cows, water access in the close-up period, and access to rest areas or stall access in the fresh period. Herd prevalence of hyperketolactia was negatively associated with milk yield [odds ratio, OR = 0.96 (95% confidence interval 0.92-0.99)] and proportion of primiparous cows [OR = 0.98 (0.96-0.99)]. The odds of hyperketolactia were greater with poor water access and quality (<5 cm of linear access per cow; dirty water; only 1 water location in pen) than with ≥10.2 cm of linear access per cow; clean water; >2 water locations in pen [1.23 (1.11-2.39)] in the close-up period. The odds of hyperketolactia were greater in farms providing limited access to rest areas in the fresh period than in farms providing constant access to rest areas, without dead-ends [1.64 (1.03-2.80)]. In Canadian dairy herds, HPH in early lactation was associated with certain transition-period management practices and was negatively associated with herd productivity., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The removal (culling) of dairy cows from the farm is a regular and required management practice. The main objectives of this study were to describe the involvement of bovine veterinarians in Ontario, Canada, in dairy cull cow management decisions, their expectations of current producer practices, and their perspectives on welfare issues and best management practices for cull dairy cows. Between February and May 2021, a province-wide survey was conducted among all members of the Ontario Association of Bovine Practitioners (OABP), with questions addressing veterinarians' background and demographics, veterinary clinic characteristics, cull cow management, down cow management, and learning preferences. The response rate for the survey was 25.1%, with 45 responses meeting all eligibility criteria. Dairy veterinarians would like to have greater involvement in cull cow management; when asked for desired involvement in culling decisions, 57.5% of veterinarians would like to be involved in culling decisions most of the time or always. Most (70.0%) veterinarians believed that cull cow welfare has improved over the last decade. However, most respondents also identified at least one area of management (farm of origin, transportation, auction, slaughter) as currently being a high risk to cull cow welfare. Given the frequency of their visits, trust by dairy producers, and knowledge, herd veterinarians are among those in the best position to improve the care of cull dairy cows. Information generated from this survey can be used to inform the development of improved decision-making tools for culling cows, and this, along with increased veterinarians' involvement in cull cow management, could improve the economic and welfare outcomes of culling decisions for dairy producers., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Ketosis in dairy cattle is primarily diagnosed based on the concentrations of ketone bodies in the blood, milk, or urine. Cow-side tests using these fluids are available for rapid detection of elevated concentrations of ketone bodies. Although these tests have been extensively validated, the performance of different tests has not been compared over time. Our objectives were to investigate the relationship between point-of-care diagnostic tests measuring the concentrations of β-hydroxybutyrate (BHB) in blood (BT; Precision Xtra, Abbott Laboratories), BHB in milk (MT; Keto-Test, Elanco), and acetoacetate (AcAc) in urine (UT; Ketostix, Bayer Corporation) through cases of ketosis. Holstein cows (n = 148) were screened daily for hyperketonemia (HYK; blood BHB ≥1.2 mmol/L) from 3 to 16 d in milk (DIM); moreover, milk and urine samples were collected concomitantly and tested for ketones (ketosis thresholds: 100 µmol/L milk BHB and 5 mg/dL urine AcAc). Of the animals screened (n = 148), 74% were diagnosed with HYK. When diagnosed with HYK, cows were treated with propylene glycol orally once daily for 5 d. After the day of diagnosis (d 0), hyperketonemic cows were retested with BT, MT, and UT for 3 d (d 1, 2, and 3). We assessed the diagnostic test performance and time to ketosis (survival analyses and Cox proportional hazards models) of MT and UT compared with BT. Considering all paired samples (before and after diagnosis of HYK), MT had 61% sensitivity and 91% specificity, whereas the UT had 77% sensitivity and 94% specificity compared with BT. The specificity of MT and UT increased from d 0 to d 1, decreased on d 2, and increased on d 3. The median time to diagnosis of ketosis in blood was 5 DIM (95% CI 5 to 7 DIM); moreover, MT and UT had 2 d greater median time to diagnosis of ketosis compared with the BT [7 DIM (6 to 11 d); and 7 DIM (6 to 13 d), respectively]. We concluded that the UT is a more sensitive predictor of blood BHB concentration than the MT. The UT and MT tests diagnosed ketotic cows approximately 2 d later than the BT. The possible consequences of delay in detection of ketosis in milk and urine should be investigated., (© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objectives of this study were (1) to describe navel healing in male and female neonatal Holstein calves over a 14-d observation period, and (2) to determine the associations of dam parity, calving factors, and calf factors with navel measurements and time to healing. A total of 68 Holstein calves (43 female and 25 male) were enrolled. Navel healing outcomes (cessation of navel discharge, navel cord remnant drying, navel cord remnant drop-off) and navel stump measurement outcomes (proximal diameter, distal diameter, length) were recorded every 24 ± 1 h for a 14-d observation period. Data were also collected for dam parity, calving factors (time of birth, calving ease), and calf factors (calf sex, calf vitality at birth, birth weight, average daily gain, serum total protein, and medical treatment or treatments). The mean time to navel cord remnant drying was 2 d, and all calves had dry navels by d 5. A total of 56% of calves retained their navel cord remnant beyond the end of the observation period, and calves began to shed their navel cord remnants as early as d 2. In addition, at least once during the observation period, 85% of calves had a proximal navel diameter measurement over a 13-mm threshold recently proposed to identify navel infections. For distal navel diameter measurements, 72% of calves had a diameter over the 13-mm threshold at least once during the observation period. No associations were identified between navel healing outcomes and dam, calving, and calf factors. Navel measurement outcomes were associated with calving and calf factors. Specifically, proximal navel stump diameter was associated with the day of observation (decreased from d 5 to 14), calf sex (smaller in female calves), time of birth (larger in calves born overnight or unobserved, compared with the morning), and birth weight (larger in birth weights >44.1 kg compared with <38.5 kg). Distal navel stump diameter was associated with calf sex, medical treatment, and day of observation; however, we observed an interaction between sex and day of observation (larger in male calves on d 3 to 7, d 9, and d 12, compared with female calves), and sex and medical treatment (larger in untreated male calves, no difference between treated male and female calves). Navel stump length was associated with time of birth (longer in calves born overnight or unobserved compared with any other time) and the interaction of birth weight and day of observation (longer in birth weights >44.1 kg compared with 38.6-41.5 kg on d 3, 8-10, and 13, and 41.6-44.0 kg on d 3, 5, 7-8, and 13). The wide range in time to navel cord remnant drying and drop-off suggest that these measures may not be adequate indicators of calf age on their own. More research on navel healing is required to improve our understanding of factors that influence navel measurements and time to healing, as well as how this information could be used in an objective assessment of navel health., (© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Removal of cows from dairy cattle production is a routine and unavoidable practice of the dairy industry and is often referred to as culling. The objectives of this study were to use a survey to describe current on-farm cull cow management, farmers' perception of cull cows' journeys to slaughter, and the adoption of current recommendations and regulations by Ontario dairy farmers. All Ontario dairy farmers were invited to complete a cull cow management survey between December 2020 and March 2021 that included 44 questions covering farmer demographic information, farm characteristics, and cull cow management. The survey response rate was 7.4% ( n = 248); a total of 226 of the responses were included in this study for analysis. Most respondents indicated they have a written standard operating procedure (SOP) for cull cows (62%), and 48, 13, and 15% of those identified they use their cull cow SOP "always," "sometimes," and "never," respectively. The more confident respondents were that cull cows arrived at slaughter in the condition they left the farm the less likely they were to have a cull cow SOP [odds ratio (OR) 0.83]. The most important sources of information for the management of cull cows were the herd veterinarian (64%) and members of the marketing/regulatory organization the Dairy Farmers of Ontario (44%). Drug withdrawal time was the only factor most respondents (73%) considered "very important" for the assessment of cull cows prior to transport. Most farmers believe cull cows journey from the farm to slaughter is three or less days (55%), and the confidence of farmers that cull cows arrive at slaughter in the condition they left their farm was generally high. Lastly, most farmers (66%) identified they were familiar with recent regulatory changes around the fitness, duration of transport, and lactation status for cull cows. These results highlight farmers' perceptions of the impacts and durations of the journey of cull cows differs from reality, and there are misunderstandings of the requirements for cull cow management. Further research should investigate how different strategies for training farmers may lead to improved cull cow welfare and regulatory compliance., Competing Interests: Author SR was employed by ACER Consulting Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Marshall, Haley, Levison, Kelton, Miltenburg, Roche and Duffield.)

This review synthesizes research findings on the pain and welfare of dairy calves undergoing disbudding procedures. We describe disbudding practices in North America as well as the use and perceptions of pain control for these procedures. Governing bodies across Canada and the United States, including each country's veterinary medical association and nationwide initiatives such as proAction and Farmers Assuring Responsible Management (FARM), recommend or require the use of a local anesthetic, a nonsteroidal anti-inflammatory drug (NSAID), and a sedative for disbudding procedures. Although the use of pain relief for disbudding has increased over the past decade or so, some in the dairy industry still do not believe that pain control for disbudding is necessary. As a painful procedure, disbudding has numerous welfare impacts on the calf both during and following the procedure that can be categorized under all 3 principles of animal welfare: natural living, biological functioning, and affective state. The use of pain control for disbudding; namely, a local anesthetic and NSAID, can improve welfare outcomes such as procedure-induced pain behavior, cortisol concentrations, mechanical nociceptive threshold, emotional states, and so on, compared with no pain control for the procedure. Although extensive research exists on pain control practices for disbudding, this review identified further gaps in knowledge and areas for future research. Mechanical nociceptive threshold can be evaluated around the disbudding wounds and is a reliable test in older calves; however, this outcome in very young calves after caustic paste disbudding has been reported to be inconclusive compared with that in older calves. As well, research evaluating xylazine sedation for disbudding has reported both potentially positive and negative results that are difficult to interpret or base suggestions on for the use of this drug. Finally, wounds caused by disbudding take a long time to heal (up to 13 wk) and have increased sensitivity for the entire healing process. Therefore, future research should aim to (1) determine accurate behavioral tests for calves under 1 wk of age undergoing disbudding to better understand their experience, (2) further attempt to understand the effects of xylazine sedation for disbudding and potential impacts of providing this medication, and (3) determine more ways to reduce the healing time and pain experienced by the calf after disbudding procedures., (© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this study was to determine the effect of a biologically normal plane of nutrition compared with a limited plane on the primary outcome wound healing, and one dose of nonsteroidal anti-inflammatory drug (NSAID) compared with 2 on the secondary outcomes: lying behavior, haptoglobin concentrations, and mechanical nociceptive threshold (MNT) in calves disbudded via cautery iron. Eighty female Holstein calves were enrolled at birth, individually housed, and fed via a Calf Rail system (Förster Technik). A 2 × 2 factorial design was used to assess the effect of plane of nutrition and an additional NSAID. Calves were randomly assigned to a biologically normal plane of nutrition (BN; offered up to 15 L/d) or a limited plane (LP; offered up to 6 L/d) and to receive one or 2 doses of meloxicam. All calves received a lidocaine cornual nerve block and a subcutaneous injection of meloxicam 15 min before cautery disbudding at 18 to 25 d of age, and half the calves received an additional injection of meloxicam (0.5 mg/kg) 3 d after disbudding. Tissue type present, wound diameter, and wound depth were evaluated 2 times per week for 7 to 8 wk as measures of wound healing, lying behavior was recorded beginning 1 to 2 wk before disbudding until 7 to 8 wk after as a behavioral indicator of pain, haptoglobin concentrations were measured once per day for 7 d after disbudding, and MNT was evaluated 2 times/wk for 3 wk. Survival analyses were analyzed using Cox regression models (wound healing) and continuous data were analyzed using mixed-effect linear regression models. Only 12% of horn buds were completely healed by 7 to 8 wk after disbudding and 54% had re-epithelized at this time. At any time, wounds from BN calves were more likely to have had re-epithelization occur compared with wounds from LP calves (hazard ratio: 1.93, 95% CI: 1.18-3.14). Wounds from calves that received only one dose of NSAID were more likely to have re-epithelization occur, compared with wounds from calves given 2 doses (hazard ratio: 1.87, 95% CI: 1.15-3.05). Wounds from BN calves had smaller diameters and depths over time beginning on wk 3 compared with LP calves. Wounds from calves that received an additional NSAID had larger diameters and depths over time beginning on wk 4 and 3 respectively, compared with calves that only received one dose of NSAID. Calves that received an extra NSAID tended to be less sensitive 7, 10, and 17 d after disbudding compared with calves that only received one dose and spent less time lying in the week after disbudding. Calves on the BN milk program were more active compared with LP calves with lower lying times, fewer lying bouts per day, and longer average lying bouts. Our results indicate that a BN milk feeding program for calves can result in faster healing times and more activity, and that providing an extra NSAID 3 d after disbudding appears to slow the healing process but may result in less pain experienced by the calf 1 to 2 wk after the procedure. This study is also among the first to demonstrate that after the complete removal of the horn bud, wounds can take more than 8 weeks to re-epithelize and fully heal., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this randomized clinical trial was to evaluate the effectiveness of a single application of 7% iodine tincture-based umbilical dip for preventing infection of the external umbilical structures in dairy calves. Five dairy farms in southern Ontario were visited twice weekly from September 2020 through June 2021. Female (n = 244) and male (n = 40) Holstein calves were randomly assigned at birth to receive either a 7% iodine tincture-based umbilical dip (n = 140) or no treatment (n = 144). Calves in the 7% iodine tincture umbilical dip group had the product administered once by the producer shortly after birth. For each newborn calf, the experimental group, calving difficulty, volume and timing of colostrum administration, time of birth, calving pen cleanliness, and the dam ID were recorded. Calf body weight was recorded during the first visit after birth, and a blood sample was collected for measurement of serum IgG concentration. Calves were health scored twice weekly from enrollment until approximately 30 d of age for assessment of external umbilical infection, joint inflammation, respiratory disease, and diarrhea. The primary outcome of the study was external umbilical infection, which was defined as an enlarged umbilicus with pain, heat, or a malodorous discharge. Calves were also weighed at 30 and 60 d to determine average daily gain. Serum IgG concentration and birth weight did not differ significantly between groups. Twenty-nine calves (20%) in the umbilical dip group developed an external umbilical infections, compared with 31 calves (22%) in the control group. A mixed logistic regression model, accounting for farm as a random effect, showed no effect of treatment on the incidence of an external umbilical infection. However, for every additional hour that calves received colostrum after birth, the odds of developing an external umbilical infection increased during the first month of life (odds ratio = 1.15; 95% confidence interval: 1.04-1.26). Additionally, treatment had no effect on respiratory disease, joint inflammation, diarrhea, average daily gain, or mortality, compared with the untreated control. These findings suggest that administering a single application of 7% iodine tincture dip to the umbilicus around the time of birth may not be effective for preventing external umbilical infections. Farm-level management factors, including colostrum management, appear to have more influence on risk of this disease., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The objective of this scoping review was to describe and characterize the existing literature regarding umbilical health and identify gaps in knowledge. Six databases were searched for studies examining umbilical health in an intensively raised cattle population. There were 4249 articles initially identified; from these, 723 full text articles were then screened, with 150 articles included in the review. Studies were conducted in the USA ( n = 41), Brazil ( n = 24), Canada ( n = 13), UK ( n = 10), and 37 additional countries. Seventeen were classified as descriptive, 24 were clinical trials, and 109 were analytical observational studies. Umbilical outcomes evaluated in descriptive studies were infection ( n = 11), parasitic infection ( n = 5), and hernias ( n = 2). Of the clinical trials, only one examined treatment of navel infections; the remainder evaluated preventative management factors for navel health outcomes (including infections ( n = 17), myiasis ( n = 3), measurements ( n = 5), hernias ( n = 1), and edema ( n = 1)). Analytical observational studies examined risk factors for umbilical health ( n = 60) and umbilical health as a risk factor ( n = 60). Studies examining risk factors for umbilical health included navel health outcomes of infections ( n = 28; 11 of which were not further defined), hernias ( n = 8), scoring the navel sheath/flap size ( n = 16), myiasis ( n = 2), and measurements ( n = 6). Studies examining umbilical health as a risk factor defined these risk factors as infection ( n = 39; of which 13 were not further defined), hernias ( n = 8; of which 4 were not further defined), navel dipping ( n = 12), navel/sheath scores as part of conformation classification for breeding ( n = 2), measurements ( n = 3), and umbilical cord drying times ( n = 2). This review highlights the areas in need of future umbilical health research such as clinical trials evaluating the efficacy of different treatments for umbilical infection. It also emphasizes the importance for future studies to clearly define umbilical health outcomes of interest, and consider standardization of these measures, including time at risk.

Nonambulatory dairy cattle pose a complex problem due to the challenges associated with prevention, appropriate treatment and management, and arriving at an accurate prognosis. There is a breadth of literature regarding this topic, of which there is currently no formal synthesis. The objective of this scoping review was to describe and characterize the literature investigating risk factors, sequela, preventions, treatments, and prognostic factors for nonambulatory conditions in dairy cattle, with the intent of qualitatively synthesizing knowledge of the topic and identifying gaps in the literature. A literature search was conducted in 6 databases and 2 conference proceeding archives, which returned 7,568 unique articles. Initial screening of abstracts resulted in 1,544 articles reviewed at the full-text stage, of which 379 were included for data extraction. Over 75% of the included literature was published after 1980, and the most common countries in which these studies took place were the United States (n = 72), Canada (18), Sweden (17), and Germany (17). Common eligibility criteria used for inclusion were geographic region (97) and parity (92). Of the 379 studies included in this review, 144 were randomized controlled trials and 235 were observational studies. The majority of the controlled trials assessed prevention of nonambulatory conditions (116), most commonly through supplementation of vitamin D (27) and calcium (25) or the provision of anionic salts (22). Of the 28 studies focusing on treatment of nonambulatory conditions, 26 focused on calcium administration. Becoming nonambulatory was evaluated as an outcome in 165 of the observational studies. Frequently measured risk factors for becoming nonambulatory included hematological variables, such as blood calcium (73), phosphorus (53) and magnesium (42), and other factors such as parity (35) and breed (22). Recovery from a nonambulatory condition was the outcome in 31 of the observational studies, with commonly measured prognostic indicators being calcium (9), phosphorus (9), and duration of recumbency (7). Nonambulatory disorders were measured as risk factors in 53 of the observational studies, with the most commonly assessed outcomes including disorders of the transition period (11), and death or euthanasia (11). The most common terms used to describe nonambulatory conditions were "milk fever" (199) and "parturient paresis" (147). These terms were only further defined with explicit symptomatic criteria in 193 of the 379 studies in this review. Recumbency was the most commonly used of these criteria (144), followed by inability to rise (55). Potential gaps in the literature concerning nonambulatory dairy cattle that were identified in the present review included investigation of prognostic indicators for recovery from nonambulatory conditions that are applicable on farm, treatment alternatives to calcium administration, and guidance regarding the appropriate usage of terms meant to categorize nonambulatory dairy cattle., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

This randomized controlled trial investigated the effects of temporarily reducing milking frequency (MF) on the resolution of ketosis and milk production in dairy cows in early lactation. To detect ketosis [blood β-hydroxybutyrate (BHB) ≥1.2 mmol/L], Holstein cows were screened daily from 3 to 16 d in milk using a cow-side meter. Cows diagnosed with ketosis (n = 104) were randomly assigned to twice-daily milking (TDM) or reduced to once-daily milking (ODM) for 2 wk, then returned to twice-daily milking. Both treatment groups received a 5-d treatment of an oral propylene glycol drench (PG; 300 g) beginning on the afternoon of the diagnosis; cows received additional 5-d PG treatments if they had a ketotic test result (blood BHB ≥1.2 mmol/L) at least 4 d after finishing the first PG treatment. Blood BHB tests were conducted for the first 3 d after ketosis diagnosis, and then once every 3 d for 21 d of trial (DOT). Milk and milk component data were collected weekly for 15 wk following trial enrollment. The ODM group showed rapidly and markedly decreased blood BHB concentrations (primiparous cows: 1 DOT, 0.92 ODM vs. 1.22 TDM, 15 DOT, 0.55 vs. 0.81 mmol/L; multiparous cows: 1 DOT, 1.01 vs. 1.40, 15 DOT, 0.78 vs. 1.65 mmol/L). In addition, a logistic regression model indicated that ODM cows were less likely to have blood BHB concentrations ≥1.2 mmol/L [primiparous cows: 3 DOT: ODM 1% (95% confidence interval: 0-10%) vs. TDM 43% (30-58%), 15 DOT ODM 0% (0-0.2%) vs. TDM 22% (13-36%); multiparous cows: 3 DOT: ODM 33% (24-44%) vs. TDM 59% (48-69%), 15 DOT ODM 20.9% (13-31%) vs. TDM 64% (53-74%)]. The proportion of ODM cows that required additional treatments of PG were substantially lower than the TDM group (ODM: 39%; TDM: 64%) than the TDM cows during the initial 21-d period. However, during the 2-wk treatment period, cows in the ODM group produced 26% less milk and 25% less energy-corrected milk than the TDM cows. During wk 3 to 15, when all cows were milked twice daily, ODM cows produced less milk (-14%) and energy-corrected milk (-12%) compared with the TDM group. Milk protein percentage was greater, and milk fat percentage and linear score tended to be greater in the ODM group over 15 wk. In conclusion, a 2-wk reduction of MF in ketotic cows from twice to once daily with treatment with PG resolved ketosis and decreased blood BHB concentrations more effectively than treating TDM cows with PG alone. However, the 2-wk MF reduction had immediate and long-term (up to 13 wk after cessation of MF reduction) negative effects on milk production., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

The complex and interrelated management components of dairy farming are associated with health, production, and profitability of the herd, yet there is limited objective data on current management practices of the far-off, close-up, and fresh periods across Canadian dairy farms. We aimed to describe management practices of Canadian dairy farms by using a pre-existing risk assessment tool and outline potential management opportunities. Upon veterinarians' or producers' request, a transition management risk assessment (The Vital 90, Elanco) was performed by trained observers (n = 10) during farm visits (n = 78) between August 2014 and March 2018. Most farms were in Ontario (n = 64), whereas the remaining were in Alberta (n = 5), British Columbia (n = 4), Manitoba (n = 1), Prince Edward Island (n = 2), Newfoundland (n = 1), and Saskatchewan (n = 1). The study included 79 questions about nutrition, pen management, and cow comfort of the dry (approximate ranges: far-off, -60 to -20 d in milk; close-up, -20 to 0 d in milk) and fresh (0-30 d in milk) periods. The herds averaged 125 milking cows, and most had 2 defined dry groups (81%). Freestall (FS; 54%) and straw-bedded loose pack (BP; 81%) were the most common housing systems observed in the far-off and close-up periods, respectively. Heifers and cows were housed together in 56, 80, and 59% of the far-off, close-up, and fresh pens, respectively. A large proportion of the far-off (FS: >100% stocking density; BP: <9.3 m 2 /cow; 41%), close-up, and fresh pens (FS: >80% stocking density; BP: <13.9 m 2 /cow; 52 and 49%, respectively) were overstocked. Poor water access was observed across all periods (65, 58, and 24% of the far-off, close-up, and fresh, respectively). Only a few farms had proper heat abatement systems in place (absence of properly functioning soakers or fans; <10% in the dry and 15% in the fresh periods). Cows were able to sort their ration in 60% of the dry period pens and 31% of the fresh pens. In 73% of the farms, fresh cow health monitoring protocols were not in place. Colostrum cows and sick cows were housed together in 40% of the farms; 59% separated the newborn from the dam within 2 to 12 h of birth with colostrum harvested immediately thereafter. This work describes prevalent management practices in the dry and fresh periods and highlights areas for potential improvement. Future research should focus on the associations between management choices and health performance of dairy farms., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Understanding how downer cattle are managed allows for the evaluation of strengths and weaknesses in these practices, which is an important step toward improving the care these animals receive. The objective of this cross-sectional study was to analyze factors associated with the care and management of downer cattle by Canadian dairy producers. Data were obtained from the 2015 National Dairy Study, and analysis was limited to the 371 respondents completing the downer cow scenario. The scenario described a downer cow that the producer wanted to keep in their herd but must be moved, and was followed by questions addressing the cow's care and management. Using multivariable logistic regression models, associations between respondent demographics and farm characteristics, and the presence of downer cow protocols, we assessed decisions regarding euthanasia and use of behavioral prognostic indicators. Written downer cow protocols were reported by 18.2% of respondents, 67% indicated that they had a nonwritten protocol, and 14.8% reported that they did not have a protocol (either written or nonwritten). Respondents from western provinces were more likely to have a written protocol than those from Ontario. Nineteen percent of the respondents with a written or unwritten protocol reported veterinary involvement in developing their downer cow protocol, which occurred more commonly on farms with more frequent herd health visits and a good producer-veterinarian relationship. An area to move a downer cow to was present on 88% of farms, with respondents who were farm staff being less likely to report having knowledge of a designated area than respondents who were the farm owner. In addition, approximately half (45%) of respondents reported moving downer cattle with hip lifters as their most common method. Behavioral prognostic indicators chosen by respondents were associated with the respondent's geographic region, age, farm size, and education. Most notably, older respondents were more likely to use appetite, and less likely to use attitude, as a prognostic indicator compared with younger respondents. Using perceived pain as a prognostic indicator was more common among respondents from western and Atlantic provinces compared with respondents from Ontario, and more common among respondents with a college or university education. These results highlighted herd and farmer demographics that were associated with how Canadian dairy producers managed downer cattle in 2015 and could be used as a benchmark for evaluating how these management practices compare with those currently implemented., (© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Impaired locomotion (lameness) may negatively affect the ability and desire of cows to milk voluntarily, which is a key factor in success of automated milking systems (AMS). The objective of this study was to identify factors associated with herd-level lameness prevalence and associations of lameness and other farm-level factors with milking activity, milk yield, and milk quality in herds with AMS. From April to September 2019, 75 herds with AMS in Ontario, Canada, were visited, and data on barn design and farm management practices were collected. Data from AMS were collected, along with milk recording data, for the 6-mo period before farm visits. Farms averaged 98 ± 71 lactating cows, 2.3 ± 1.5 robot units/farm, 43.6 ± 9.4 cows/robot, 36.4 ± 4.9 kg/d of milk, a milking frequency of 3.01 ± 0.33 milkings/d, and a herd average geometric mean SCC of 179.3 ± 74.6 (× 1,000) cells/mL. Thirty percent of cows/farm (minimum of 30 cows/farm) were scored for body condition (1 = underconditioned to 5 = over conditioned) and locomotion (1 = sound to 5 = lame; clinically lame ≥3 out of 5 = 28.3 ± 11.7%, and severely lame ≥4 out of 5 = 3.0 ± 3.2%). Clinical lameness (locomotion score ≥3) was less prevalent on farms with sand bedding, with increased feed bunk space per cow, and on farms with non-Holstein breeds versus Holsteins, and tended to be less prevalent with lesser proportion of underconditioned cows (with body condition score ≤2.5). Severe lameness occurrence (farms with any cows with locomotion score ≥4) was associated with a greater proportion of underconditioned cows and in farms with stalls with greater curb heights. Herd average milk yield/cow per day increased with lesser prevalence of clinical lameness (each 10-percentage-point decrease in clinical lameness prevalence was associated with 2.0 kg/cow per day greater milk yield) and greater milking visit frequency per day, and tended to be greater with increased feed push-up frequency. Lesser herd average somatic cell count was associated with lesser clinical lameness prevalence, herd average days in milk, and proportion of overconditioned cows, and somatic cell count tended to be lesser for farms with sand bedding versus those with organic bedding substrates. The results highlight the importance of minimizing lameness prevalence, using of sand bedding, ensuring adequate feed access and feed bunk space, and maintaining proper cow body condition to optimize herd-level productivity and milk quality in AMS herds., (© 2022, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Calfhood morbidity is an important issue on commercial dairy operations, with substantial production and welfare impacts. The objective of this observational study was to evaluate potential risk factors for morbidity, including disbudding, disbudding pain control, serum total protein (STP) concentrations, and haptoglobin concentrations in young dairy calves. A total of 140 heifer calves from a commercial dairy farm in southwestern Ontario, Canada, were enrolled at 1 to 9 d of age and followed for 1 wk. Calves were scored at enrollment for several health parameters using a scale from 0 to 3, with 0 representing normal and 3 representing severely abnormal. Calves were only included if they were considered healthy enough to participate using cut points of <3 for rectal temperature and fecal score; ≤2 for nasal discharge, ocular discharge, and cough score; and 1 for ear position, navel score, and joint score. To ensure that only calves that were considered healthy on the baseline day were included, 17 calves were excluded from analysis, resulting in a total of 123 calves. These calves were a part of a disbudding trial, with 100 disbudded using a commercial caustic paste and 23 sham disbudded with a placebo paste. The disbudding paste (commercial or sham) was applied to calves on enrollment day (baseline) with health scoring at baseline and 3 and 7 d later. The following health outcomes were analyzed: diarrhea (a fecal consistency score of ≥2), respiratory disease (a total respiratory score of ≥5), and general sickness [suffering from either diarrhea, respiratory disease, or a navel or joint infection (joint or navel score of ≥2)]. The following variables were assessed for association with the outcomes: STP, inadequate transfer of passive immunity (<5.2 g/dL STP), pain control treatment for disbudding (lidocaine nerve block alone, meloxicam alone, lidocaine nerve block and meloxicam, no pain control, sham), disbudding (disbudded or sham), and haptoglobin concentrations (taken on the baseline day, +3 d and +7 d). We did not detect any relationship between the development of a health outcome of interest (diarrhea, respiratory, or sick) and disbudding or pain control on any of the days following disbudding. However, for every 1 g/dL increase in STP concentration, calves had 0.24 and 0.33 times the odds of suffering from diarrhea or any sickness event, respectively, 3 d after disbudding. At 3 d after disbudding, for every 0.1 mg/mL increase in haptoglobin concentration on that day, calves had 1.34 and 1.20 times the odds of having diarrhea or a general sickness, respectively. These findings suggest that disbudding itself or the pain control method does not appear to influence health after the procedure when healthy calves are disbudded. Calves developing an illness 3 d after disbudding were more likely to have had lower STP concentrations and increased haptoglobin concentrations., (© 2021.)

The objective of this randomized, double-blind, controlled trial was to evaluate the effect of pegbovigrastim (pegylated recombinant bovine granulocyte colony-stimulating factor) on early-lactation disease, milk yield, and reproduction on commercial dairy farms. A total of 1,607 Holstein cows from 6 farms in Ontario and Québec, Canada, were randomly assigned to receive two 2.7-mL subcutaneous injections of either 15 mg of pegbovigrastim (n = 798; Imrestor, Elanco) or sterile physiological saline (placebo; n = 809). The first injection was administered by investigators 1 wk before expected calving, and the second by farm personnel within 24 h after calving, according to the product label. Producers inspected cows daily and using standardized disease definitions, recorded cases of retained placenta, metritis, displaced abomasum, and clinical mastitis until 63 d in milk. Progesterone concentration was measured in serum at wk 3, 5, 7, and 9 postpartum. Cows were examined for purulent vaginal discharge using the Metricheck (Simcro) device and endometritis using the cytobrush method at wk 5 postpartum. Milk production and reproduction data were obtained from farm management software and the national milk recording database. Disease and culling outcomes were assessed with logistic regression, milk production with linear regression, and time-to-event outcomes with proportional hazards regression. All analyses considered parity and pre-treatment body condition score and their interaction with treatment, and accounted for clustering of cows within farm. In a subset of 246 cows, the effect of treatment on metabolic markers (serum concentrations of glucose, β-hydroxybutyrate, nonesterified fatty acids, cholesterol, haptoglobin, albumin, and calcium) was assessed in wk 1 and 2 postpartum. Pegbovigrastim had no significant effects on the incidence of retained placenta, metritis, displaced abomasum, clinical or subclinical mastitis, purulent vaginal discharge, or endometritis. Treatment reduced the serum concentration of glucose, slightly reduced the concentration of albumin, and slightly increased concentrations of β-hydroxybutyrate and nonesterified fatty acids, with no effect on the other markers. There were no differences between treatments in culling risk, time to first insemination, pregnancy at first insemination, or time to pregnancy. Milk yield over the first 3 test days of lactation was 1.0 kg per day lower in the pegbovigrastim group, although a mechanism for that effect could not be explained through analysis of our data., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The objective of this study was to benchmark the herd-level housing and management strategies of automated milking system (AMS) farms across Canada and assess the associations of these herd-level housing factors and management practices with milk production and quality. Canadian AMS farms (n = 197; Western Canada: n = 50, Ontario: n = 77, Quebec: n = 59, Atlantic Canada: n = 11) were each visited once from April to September 2019, and details were collected related to barn design and herd management practices. Milk-recording data for the 6 mo before farm visits were collected. Farms averaged (± standard deviation) 110 ± 102 lactating cows, 2.4 ± 1.9 AMS units/farm, 47.5 ± 14.9 cows/AMS, 36.7 ± 5.0 kg/d of milk, 4.13 ± 0.34% fat, 3.40 ± 0.16% protein, and a herd-average somatic cell count of 186,400 ± 80,800 cells/mL. Farms mainly used freestall housing systems (92.5%), organic bedding substrates (73.6%), and free flow cow traffic systems (87.8%); farms predominantly milked Holsteins (90.4%). Multivariable regression models were used to associate herd-level housing factors and management practices with milk production and quality. At the herd level, feed push-up frequency (mean = 12.8 ± 8.3 times per day) and feed bunk space (mean = 64 ± 21.5 cm/cow) were positively associated with milk yield. Greater milk yield was associated with herds using inorganic (sand) versus organic bedding, milking Holsteins versus non-Holsteins, and using a form of mechanical ventilation versus natural ventilation alone. Milk fat and milk protein content were only associated with breed. Herds with lower somatic cell counts had more frequent alley cleaning (mean = 12.1 ± 7.5 times per day), wider lying alleys (mean = 304.5 ± 40.0 cm), and sand bedding. The results highlight the importance of using sand bedding, using mechanical ventilation, keeping feed pushed up, ensuring alleys are clean, and ensuring adequate space at the feed bunk for maintaining herd-level productivity and milk quality in farms with AMS., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The objective of this study was to assess the effects of feeding negative dietary cation-anion difference (DCAD) dry cow diets on postpartum health. Cows from 4 commercial dairy farms in Ontario, Canada, were enrolled in a pen-level controlled trial from November 2017 to April 2019. Close-up pens (1 per farm), with cows 3 wk before expected calving, were randomly assigned to a negative DCAD [TRT; -108 mEq/kg of dry matter (DM); target urine pH 6.0-6.5] or a control diet (CON; +105 mEq/kg of DM with a placebo supplement). Each pen was fed TRT or CON for 3 mo (1 period) then switched to the other treatment for the next period, with 4 periods per farm. Urine pH was measured weekly until calving, and body condition score (BCS) was measured at enrollment and at 5 wk postpartum. Data from 15 experimental units [8 TRT and 7 CON, with 1,086 (TRT: n = 681; CON: n = 405) observational units (cows)] that received the assigned diet for >1 wk were included. The incidence of milk fever (MF), retained placenta (RP), metritis, hyperketonemia (blood β-hydroxybutyrate >1.2 mmol/L, measured weekly in wk 1 and 2), clinical mastitis within 30 DIM (MAST), displaced abomasum (DA) within 30 d in milk (DIM), purulent vaginal discharge (PVD, assessed once at wk 5), and number of disease events (≥1 or ≥2) were analyzed with logistic regression models with treatment, parity, BCS, and their interactions, accounting for pen-level randomization and clustering of animals within farm with random effects, giving 10 degrees of freedom to test treatment effects. Multiparous cows fed TRT had greater blood calcium between 1 and 4 DIM than multiparous cows fed CON, and the prevalence of subclinical hypocalcemia (total Ca ≤2.14 mmol/L) was lesser when fed TRT compared with CON (d 1: 73 ± 6% vs. 93 ± 4%; d 2: 65 ± 7% vs. 90 ± 5%), with no differences between treatments detected in primiparous cows. We detected interactions of treatment and BCS at enrollment for MF in multiparous cows and of treatment and parity for ≥2 disease events. Overconditioned (BCS ≥3.75) multiparous cows had reduced incidence of MF when fed TRT (TRT: 2 ± 1%, vs. CON: 13 ± 8%). We detected no treatment effects on RP, metritis, hyperketonemia, or PVD incidence. Cows fed TRT had lesser incidence of DA (1.7 ± 0.7% vs. 3.6 ± 1.6%) and tended to have lesser incidence of MAST compared with CON (1.8% ± 0.6% vs. 4.4 ± 1.4%). No treatment effect was detected on ≥1 disease events (TRT: 38 ± 7%, vs. CON: 42 ± 8%); however, multiparous cows on TRT were less likely to have ≥2 disease events than cows on CON (14 ± 4% vs. 23 ± 6%). Under commercial herd conditions, feeding prepartum diets with negative DCAD improved several measures of postpartum health., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Our objective was to assess the effects of feeding negative dietary cation-anion difference (DCAD) prepartum diets on milk production, reproductive performance, and culling. Cows from 4 commercial farms in Ontario, Canada were enrolled in a pen-level controlled trial from November 2017 to April 2019. Close-up pens (1 per farm) with cows 3 wk before calving were randomly assigned to a negative DCAD (TRT; -108 mEq/kg of dry matter; target urine pH 6.0-6.5) or a control diet (CON; +105 mEq/kg of dry matter with a placebo supplement). Each pen was fed TRT or CON for 3 mo (1 period), and then switched to the other treatment for the next period (4 periods per farm). Data from 15 experimental units (8 pen treatments in TRT and 7 in CON), with a total of 1,086 observational units (cows), were included. The effect of treatment on milk yield at the first 3 milk recording tests of lactation was assessed with linear regression models accounting for repeated measures. The risk of pregnancy at first artificial insemination and culling by 30, 60, and 305 d in milk (DIM) were analyzed with logistic regression models, and effects on time to first AI, pregnancy, and culling were assessed with Cox proportional hazards models. All models included treatment, parity, and their interactions, accounting for pen-level randomization and clustering of animals within farm with random effects, giving 10 degrees of freedom for treatment effects. Multiparous cows fed TRT produced more milk at the first (42.0 vs. 38.8 ± 1.2 kg/d) and second (44.2 vs. 41.7 ± 1.3 kg/d) milk tests. However, multiparous cows fed TRT tended to have 0.2 percentage units less milk fat content at these tests. Although multiparous cows fed TRT tended to have greater energy-corrected milk at the first test (least squares means ± standard error: TRT = 46.1 ± 0.9 vs. CON = 43.8 ± 1 kg/d), there were no differences observed in energy-corrected milk at the second or third tests. In primiparous cows, there was no effect of treatment on milk production. Multiparous cows fed TRT had greater pregnancy to first insemination (TRT = 42 ± 3 vs. CON = 32 ± 4%) and tended to have shorter time to pregnancy [hazard ratio (HR) = 1.20; 95% CI: 0.96-1.49]. In primiparous cows fed TRT, time to pregnancy was increased (HR = 0.76; 95% CI: 0.59-0.99). Culling by 30 DIM tended to be less in TRT (3.3 ± 1.1%) than CON (5.5 ± 1.8%). No effect of treatment on culling by 305 DIM was detected in primiparous cows, but in multiparous cows, the TRT diets decreased the odds of culling (21.3 ± 1.9 vs. 31.7 ± 2.8%) and daily risk of culling to 305 DIM (HR = 0.64; 95% CI: 0.46 to 0.89). Under commercial herd conditions, prepartum negative DCAD diets improved milk production and reproductive performance, and reduced culling risk in multiparous cows. In primiparous cows, TRT diets had no effect on milk yield or culling, but increased the time to pregnancy. Our results suggest that negative DCAD diets should be targeted to multiparous cows., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The use of local anesthesia and a nonsteroidal anti-inflammatory drug (NSAID) can reduce indicators of pain and inflammation and encourage self-rewarding behavior in calves following disbudding. Although the use of sedation may be recommended as a best practice for disbudding, there is little research in this area. The objective of this study was to evaluate the effects of xylazine sedation in conjunction with a local anesthetic and an NSAID in calves undergoing cautery disbudding. One hundred twenty-two group-housed female and male Holstein calves fed milk with automated feeders, aged 13 to 44 d, were enrolled over 9 replicates and randomly allocated to 1 of 2 treatments: (1) sedated: lidocaine cornual nerve block, 0.5 mg/kg meloxicam (administered subcutaneously) and 0.2 mg/kg xylazine (administered intramuscularly), or (2) nonsedated: lidocaine cornual nerve block and meloxicam. Outcomes collected consisted of feeding behavior (collected using automated milk feeders), latency to drink milk following disbudding, play behavior (induced by adding bedding), lying behavior, mechanical nociceptive threshold (MNT, measured using a pressure force algometer), struggling behavior during disbudding, length of time to administer the nerve block, length of time to disbud, and serum haptoglobin concentrations. Data were analyzed using mixed models with a fixed effect for baseline values and a random effect for trial replicate. Linear regression was used to assess continuous outcomes, logistic regression for binary outcomes, and Poisson and negative binomial models for count data with negative binomial models used if the over dispersion term was significant. There were no detected differences between the treatment groups in mean daily milk consumption in the 72-h following disbudding. Sedated calves had reduced average milk drinking speed from 0 to 24 h and 24 to 48 h following disbudding compared with nonsedated calves, but no difference was detected from 48 to 72 h. Sedated calves had reduced MNT at 0, 60, and 240 min after disbudding, but no differences were detected between groups at 24 h after disbudding. Nonsedated calves had 4.5 times the odds (95% CI: 1.5-13.2) of struggling more than twice during the disbudding procedure compared with sedated calves, and it took less time to administer a nerve block to sedated calves compared with nonsedated. At +3 h, nonsedated calves were 79 times (95% CI: 22.4 to 279.2) more likely to play compared with sedated calves, and 24 h after disbudding, sedated calves were 2 times more likely to play compared with nonsedated calves (95% CI: 0.93-4.3). The results indicate that calves sedated with xylazine for cautery disbudding responded less to painful stimuli (disbudding and MNT) both during and following the procedure and had a higher rate of play behavior 24 h following sedation compared with the nonsedated calves, but xylazine may also have a prolonged carryover effect that affects suckling behavior for 48 h following sedation., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)

This narrative literature review summarizes findings regarding the associations of clinical and subclinical hypocalcemia with postpartum health, reproduction, and milk production. To better understand the effects of hypocalcemia, we reviewed clinical and subclinical presentations of the condition and the dynamics of blood Ca concentration in the early postpartum period. We summarize and discuss the associations between hypocalcemia and performance of dairy cows. Up to 50% of dairy cows suffer from at least one disease event in the transition period. The important roles of calcium in muscle contraction and immune function make it a key component of metabolism, inflammation, and defense against infection. Although the effect of clinical hypocalcemia (milk fever) on health and performance is clear, the definition of subclinical hypocalcemia (SCH) and its consequences for health and performance are still ambiguous. Differences in study designs, sampling protocols, Ca concentration thresholds, and sample sizes that may be underpowered for health and reproduction outcomes lead to inconsistent conclusions on the effects of SCH. On current evidence, classification of SCH should be based on at least 2 measurements of blood calcium, using cutpoints supported with relevant data, which may vary depending on the outcome of interest. Arbitrary or poorly supported interpretative thresholds for blood Ca concentrations should be abandoned. Transient SCH appears to be associated with greater milk yield, whereas SCH that is present several days after calving is associated with lesser production and greater disease risk. However, when blood calcium is measured days after calving, primary effects of calcium metabolism may be confounded by feed intake, inflammation, or disease, which might either contribute to or be a consequence of hypocalcemia. Additional research is needed to refine sampling schemes to classify SCH, and to better inform the goals and means of prevention of SCH., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Our objective was to validate a point-of-care handheld blood total calcium analyzer (Ca meter, CM; TD-5220 Vet Ca 2+ , TaiDoc, New Taipei, Taiwan) to estimate circulating Ca concentrations in postpartum dairy cows. Whole blood was collected from 251 multiparous cows between 1 and 4 d in milk from 2 commercial dairy herds in Ontario, Canada. Blood total calcium concentration (tCa) was analyzed in whole blood, fresh plasma, and thawed plasma, and compared with tCa results from thawed serum analyzed in a diagnostic laboratory (using a Cobas Calcium Gen 2 kit, Roche Diagnostics, Indianapolis, IN) as the reference test (RT). Lin's concordance correlation coefficient (βrho;) and Bland-Altman (B-A) plots were assessed to evaluate the agreement between the RT and CM results in each type of sample. Receiver operating characteristic curve analyses were used to describe the accuracy of each test against the categorized RT results (at a cut-point of ≤2.14 mmol/L). Samples where the meter gave a nonquantitative result ("high" or "low"; thawed plasma: 3/247; fresh plasma: 6/100; and whole blood: 20/98) were not included in the βrho; and B-A analyses. Lin's correlation coefficients demonstrated poor agreement between tests (thawed plasma: βrho; = 0.16; fresh plasma: βrho; = 0.21; and whole blood: βrho; = 0.23). Fresh plasma (using a cut-point of 2.55 mmol/L as measured on the CM) had the greatest diagnostic sensitivity (72%), specificity (86%), and accuracy (77%) for determining subclinical hypocalcemia, but that would still misclassify 23% of samples. In addition to substantial variability, the B-A plots revealed bias with changing concentrations of calcium. Because of low sensitivity on whole blood (58%) or thawed plasma (56%), measurement with the CM is not recommended on these types of samples. This rapid and low-cost meter was not sufficiently accurate to quantify blood Ca concentration, but when used with fresh plasma it might be useful as a screening tool for subclinical hypocalcemia., (© 2020.)

Selective antimicrobial treatment strategies present a means to reduce antimicrobial use at the time of arrival at a veal or dairy beef operation. On-farm machine leukocyte differential cell counts (DCC) that can be acquired quickly may be useful to augment calf risk identification protocols. The objective of this study was to assess the utility of DCC taken at the time of arrival at a grain-fed veal facility and 72 h postarrival for determining morbidity risk, mortality risk, and growth during the production cycle. Data were collected between June and October 2018 from 240 calves upon arrival and from a subset of 160 calves 72 h postarrival at a commercial grain-fed veal facility in Ontario, Canada. Blood samples were evaluated using the QScout BLD test for leukocyte DCC (Advanced Animal Diagnostic, Morrisville, NC). All calves were screened using a standardized health examination, and a blood sample was collected to evaluate serum total protein and DCC. Cox proportional hazards models were constructed for both morbidity and mortality outcomes. Mixed linear regression models were constructed to evaluate average daily gain. Results from data collected at the time of arrival suggest that total protein values ≥5.2 g/dL reduced the hazard of mortality and that a rectal temperature >39.6°C was associated with an increased hazard of morbidity. Calves that were dehydrated gained less, whereas calves with an increased lymphocyte count had a higher rate of growth. Results from DCC collected 72 h postarrival suggest that lymphocyte counts between 4.8 and 5.8 × 10 9 cells/L decreased the hazard of mortality and counts >7.0 × 10 9 cells/L decreased the hazard of morbidity, whereas neutrophil counts >6.0 × 10 9 cells/L increased the hazard of mortality. This study demonstrates that machine DCC at the time of arrival and 72 h after arrival has potential for use in identifying high-risk calves that might require treatment, as part of selective antimicrobial therapy protocols, with the purpose of reducing antimicrobial use without sacrificing animal health in veal facilities., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Disbudding is a common procedure practiced in the dairy industry and is known to cause pain when performed without pain control. Dairy producers who disbud calves with caustic paste are less likely to provide pain control than those using cautery. Little research has been conducted on pain control for caustic paste disbudding and no studies have specifically examined calves under 9 d of age. The objective of this study was to evaluate the efficacy of local anesthesia and nonsteroidal anti-inflammatory drug analgesia on indicators of pain and inflammation in dairy calves disbudded using caustic paste. One hundred forty Holstein heifer calves 1 to 9 d of age were enrolled in 28 blocks and randomly allocated to 1 of 5 treatments: sham control (SH); positive control (POS); lidocaine cornual nerve block (LC); meloxicam (MEL); and lidocaine cornual nerve block plus meloxicam (LCM). We measured outcomes including serum cortisol and haptoglobin, pressure sensitivity, and lying behavior. Data were analyzed using mixed linear regression models with treatment as a fixed effect, baseline values as a covariate, and trial block as a random effect. Compared with the POS group, the LCM group had reduced serum cortisol at 15, 30, 45, and 60 min post-disbudding; cortisol values were not different between LC, LCM, and SH calves at these time points. At 60, 90, 120, and 180 min post-disbudding, LCM calves had reduced cortisol compared with LC calves, whereas, values did not differ between LCM and SH calves at these time points. At 3 to 4 d post-disbudding, the LCM group tended to have reduced haptoglobin, but no differences were found between groups at 180 min and 7 d post-disbudding. At 60, 90, and 120 min post-disbudding, LC and LCM treated calves had decreased pressure sensitivity compared with other groups. No differences were seen in pressure sensitivity between groups at 180 min, 3 to 4 or 7 d post-disbudding. No differences in lying behavior were found between treatment groups on any of the 7 d following disbudding. These findings demonstrate that the combination of a local anesthetic with a nonsteroidal anti-inflammatory drug is beneficial for reducing indicators of pain and inflammation in young calves disbudded with caustic paste., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)

Our objectives were to assess the effects of a diet with a negative dietary cation-anion difference (DCAD) before calving on phagocytosis (Pc) and oxidative burst (OB) function of circulating neutrophils, and to determine the associations of serum ionized (iCa) and total calcium (tCa) concentrations with Pc and OB in transition dairy cows. We hypothesized that multiparous cows fed a negative DCAD diet prepartum would have greater iCa and tCa, and thus improved Pc and OB. From 3 wk before expected parturition until calving, 38 healthy multiparous cows from 3 farms were assigned to negative DCAD treatment (TRT; -100 mEq/kg of diet dry matter; n = 21) or a control (CON; 95 mEq/kg of dry matter; n = 17) diet. Each farm was on one treatment or the other at a time, but all farms contributed cows to both groups. Urine pH was measured weekly and in TRT was 6.1 ± 0.8 with 80% of 50 samples <7 and 74% ≤ 6.5. Phagocytosis, OB, iCa, and tCa were measured at d -7, 1, and 4 relative to calving. Median fluorescence intensity for Pc (MFIP) and OB (MFIOB), and the shift of percentage of cells active for Pc (PPc) and OB (POB) were measured in isolated, stimulated neutrophils via flow cytometry. Outcomes were assessed with mixed linear regression models accounting for repeated measures. There were no differences between treatments in the 4 neutrophil function outcomes. Although MFIOB varied over time, there were no interactions of treatment with time for any outcome. Serum ionized and tCa did not differ between TRT and CON. The least squares means ± standard deviation for iCa were: d -7, 1.23 ± 0.12 vs. 1.21 ± 0.12; d 1, 1.07 ± 0.12 vs. 1.02 ± 0.12; d 4, 1.16 ± 0.12 vs. 1.17 ± 0.12 mmol/L for TRT and CON, respectively; and for tCa: d -7 2.39 ± 0.25 vs 2.44 ± 0.31; d 1, 2.01 ± 0.25 vs 1.97 ± 0.31; d 4, 2.33 ± 0.25 vs 2.32 ± 0.31 mmol/L, respectively. The proportion of blood samples with tCa <2.15mmol/L at d -7, 1 and 4 was 5, 76, and 13%, respectively, with no differences between TRT and CON. Correlations of iCa or tCa with each of the 4 polymorphonuclear leukocyte (PMN) function outcomes were weak (r < |0.3|). We did not observe the hypothesized differences in aspects of innate immunity in clinically healthy multiparous cows fed a negative DCAD. We underline that cows that experienced clinical disease were excluded from this study, which is important for interpretation of the results., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The objective of this study was to determine the effects of adding molasses-based liquid feed to a high-straw dry cow diet on intake, behavior, health, and performance of dairy cows across the transition period. Holstein cows (n = 40) entering their second lactation or greater were enrolled at dry-off (∼45 d before expected calving) and assigned to 1 of 2 treatments: a high-straw dry cow total mixed ration (TMR) with either (1) no molasses [CON; n = 20; 10.7% crude protein (CP), 1.45 Mcal/kg of net energy for lactation (NE L )] or (2) supplemented with 1 kg/cow daily [dry matter (DM) basis] of molasses-based liquid feed (LF; n = 20; 11.2% CP, 1.49 Mcal/kg of NE L ). At calving all cows were fed the same lactating TMR (14.9% CP, 1.68 Mcal/kg of NE L ) and followed for 28 d. During the dry period, cows fed the LF diet had greater DM intake (15.3 ± 0.24 vs. 13.4 ± 0.24 kg/d) and tended to have a shorter interval between meals (192.8 ± 8.38 vs. 216.5 ± 7.97 min) and more frequent meals (6.3 ± 0.27 vs. 5.6 ± 0.27 meals/d), while consuming their feed faster (0.09 ± 0.001 vs. 0.08 ± 0.001 kg of DM/min) compared with cows fed the CON diet. Regardless of treatment, cows sorted [100% × (actual intake/predicted intake)] against the longest ration particles (>19 mm), with cows fed the CON diet sorting more against these (81.1 ± 2.6 vs. 93.9 ± 2.6%). Cows fed the CON diet did not sort for or against short particles (<8, >4 mm; 100.2 ± 0.31%), but cows fed the LF diet tended to sort against these (99.2 ± 0.31%). Post-calving, cows fed the LF diet did not sort for long particles (98.5 ± 1.1%), but cows fed the CON diet continued to sort against these (96.3 ± 1.1%). Cows fed the LF diet had higher mean reticulorumen pH in the dry period (6.4 ± 0.05 vs. 6.2 ± 0.06 pH), in the first week after calving (CON = 5.7 ± 0.06 pH, LF = 5.8 ± 0.06 pH), and tended to have higher mean reticulorumen pH in the second week after calving (CON = 5.7 ± 0.06 pH, LF = 5.9 ± 0.06 pH). The results suggest that supplementing a molasses-based liquid feed in high-straw dry cow diets may improve intake and consistency in nutrients consumed during the dry period and in early lactation, as well as possibly promoting better rumen health across the transition period., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

This retrospective cross-sectional study was designed to identify risk factors associated with failed transfer of passive immunity (FTPI) and to determine differences in colostrum management between male and female dairy calves. Research technicians visited a total of 16 commercial dairy farms weekly. For each calf born on these farms, the farm personnel completed a birth record to document the colostrum management practices provided, level of calving assistance, calf sex, and time of birth. On the weekly visits to the farms, the technicians collected blood from calves that were 1 to 7 d of age. Serum was separated via centrifugation and the concentration of serum total protein (STP) was determined using a digital refractometer. Failed transfer of passive immunity was defined as calves having an STP of <5.2 g/dL. Data were available for 1,778 calves aged 1 to 7 d. Several differences were observed with respect to how male and female calves were managed. Male calves were more likely to receive a lower volume of colostrum, have colostrum delivered using a nipple bottle followed by an esophageal tube feeder, be fed pooled colostrum, and receive fresh colostrum rather than frozen colostrum relative to female calves. Serum total protein (STP) ranged from 3.6 to 9.7 g/dL with a mean of 5.7 g/dL (standard deviation, 0.7 g/dL) and 21.1% of the calves had FTPI. Using a mixed linear regression model, we identified that a calf being male (-0.14 g/dL), being delivered by a hard pull (-0.23 g/dL), and receiving the first feeding colostrum from a combination of a nipple bottle followed by an esophageal tube feeder (-0.12 g/dL) were associated with a lower concentration of STP. Feeding 6 L or more of colostrum in the first 24 h of life was associated with a 0.14 g/dL higher concentration of STP compared with feeding <3.9 L of colostrum. For FTPI, being delivered by a hard pull [odds ratio (OR) 2.21] and receiving the first feeding colostrum from a nipple bottle followed by an esophageal tube feeder (OR 1.83) were associated with higher odds of FTPI. Feeding >6 L of colostrum in the first 24 h of life was associated with a reduced odds (OR 0.65) of FTPI compared with feeding <3.9 L of colostrum. This study highlights the importance of certain management practices in reducing FTPI incidence and identifies discrepancies in colostrum management between male and female dairy calves., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The objective of this study was to determine the effect of adding water to a high-straw dry cow diet on feeding behavior, health, and performance of dairy cows. Holstein cows (n = 40) entering their second or greater lactation were enrolled at dry off (∼45 d before expected calving) and assigned to 1 of 2 dietary treatments, consisting of a high-straw dry cow total mixed ration [TMR; 36% wheat straw, 41% corn silage, 23% pellet, on a dry matter (DM) basis, formulated for 11.6% crude protein, 1.35 Mcal/kg net energy for lactation] with (1) no water (CON; n = 20; DM = 53.4%) or (2) water added to decrease the DM by ∼10 percentage points (wet diet, WD; n = 20; DM = 45.4%). Upon calving, all cows were fed the same lactating TMR (45.2% DM, 14.9% crude protein, 1.68 Mcal/kg net energy for lactation) and followed for 28 d. Dry matter intake, feeding behavior, and rumination activity were recorded automatically. Fresh TMR and orts samples were collected 2×/wk to determine differences in sorting. A particle separator was used to separate feed samples into 4 fractions: long (>19 mm), medium (<19, >8 mm), short (<8, >4 mm), and fine (<4 mm) particles. Feed sorting was calculated as actual intake of each particle fraction expressed as a % of predicted intake. Cows fed WD had greater DM intake during the dry period than cows fed CON (CON = 13.4 ± 0.24, WD = 14.2 ± 0.24 kg/d), but rumination did not differ (CON = 522.2 ± 8.48, WD = 518.5 ± 8.69 min/d) between treatments. Cows fed WD tended to consume their feed faster (CON = 0.08 ± 0.001, WD = 0.09 ± 0.001 kg of DM/min) compared with CON cows. Regardless of treatment, cows sorted against the longest ration particles, with cows fed CON sorting more against these (CON = 81.1 ± 2.51%, WD = 94.9 ± 2.58%). Cows fed CON tended to sort more in favor of the medium particles than those fed WD (CON = 105.0 ± 0.36%, WD = 104.2 ± 0.37%). Postcalving DM intake and feeding behavior were not affected by dry diet treatment. Cows fed WD experienced a less rapid daily decline in rumen pH during the first 7 d after calving compared with those fed the CON diet. The results suggest that increasing the moisture content of high-straw dry cow diets, by adding water, may improve intake and reduce sorting against the longest ration particles, which may help promote consistency in targeted nutrients consumed during the dry period and greater rumen health in early lactation., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The primary objective of this prospective cohort study was to identify factors evaluated upon arrival at a grain-fed veal facility that were associated with increased growth. A secondary objective was to determine if the factors associated with average daily gain (ADG) varied between the pre- and postweaning periods. Calves were visually assessed and scored using a standardized health scoring system immediately upon arrival. They were also weighed and vaccinated, and had blood drawn from their jugular vein to determine their serum total protein level. Weights were taken on d 49 and 78 after arrival and were used to calculate ADG. Three mixed linear regression models were created to determine factors associated with ADG from 0 to 49 d after arrival, 0 to 78 d after arrival, and 49 to 78 d after arrival. A total of 998 calves were evaluated and weighed upon arrival; 636 and 915 of those calves were weighed at d 49 and d 78, respectively. Mean ADG were 610 g/d from 0 to 49 d after arrival, 860 g/d from 0 to 78 d after arrival, and 1,240 g/d from 49 to 78 d after arrival. In the model evaluating growth from 0 to 49 d, calves arriving at the facility with a higher body mass index (BMI) gained more weight per day than calves that arrived with a lower BMI. If calves arrived in the spring, they gained 201 g/d more than calves that arrived in the winter. For the period following weaning (d 49 to 78), BMI was also associated with growth. For every additional 1 g/cm 2 increase in BMI at arrival, calves gained an additional 1.55 g/d from d 49 to 78. Growth from arrival to d 78 was affected solely by BMI. For every 1 g/cm 2 increase in BMI at arrival, calves gained 1.23 g/d more during the entire observation period. Body mass index and season at arrival affected growth through the initial period at a grain-fed veal facility. Producers should consider these factors, especially BMI, when purchasing calves to maximize the calves' growth potential., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The study investigated the effect of chop length of wheat straw in a high-straw dry cow diet on the feeding behavior, health, and performance of Holstein dairy cows across the transition period. Forty cows were enrolled at dry off, approximately 45 d before expected calving, and assigned to 1 of 2 dietary treatments containing (on a dry matter basis) 36% corn silage, 35% dry cow pellet, and 29% wheat straw. Diets were formulated to target an energy consumption of 19 Mcal/d of net energy for lactation per cow. The diets differed in the chop length of wheat straw: (1) long straw chopped with a 10.16-cm screen (LDD; n = 20), or (2) short straw chopped with a 2.54-cm screen (SDD; n = 20). Dietary treatments were fed throughout the dry period. Feeding behavior, rumination time, and reticulorumen pH were monitored electronically, and feed samples were collected to determine feed sorting. Blood samples were taken weekly, and body condition scores and body weights were taken every 2 wk. Postcalving, all cows were fed the same lactating cow total mixed ration for 28 d; the same measurements were recorded with the addition of daily milk yield and twice weekly milk components. During the dry period, cows fed the SDD treatment consumed more dry matter (15.6 vs. 15.0 kg/d), had more consistent dry matter intake in the week leading up to calving, had a faster feeding rate, consumed 0.4 kg/meal more, and had 0.6 fewer meals per day. No differences were observed in rumination time or mean reticulorumen pH between treatments in both the dry and lactating period. Regardless of treatment during the dry period, cows sorted against the long particles (>19 mm) and in favor of the short particles (<8, >4 mm), but cows fed the LDD treatment sorted to a greater extent than cows fed the SDD treatment. Dietary treatment in the dry period did not influence feed sorting behavior postcalving. Cows fed the LDD treatment had a greater daily change (decline) in rumen pH in the first week postcalving and had a greater blood β-hydroxybutyrate concentration in the third week postcalving. Overall, the results from this study indicate that feeding shorter chopped wheat straw in a high-straw dry cow diet improved intake, reduced sorting during the dry period, and resulted in greater metabolic health and rumen stability in early lactation., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

A systematic review and network meta-analysis were conducted to assess the relative efficacy of antimicrobial therapy given to dairy cows at dry-off. Eligible studies were controlled trials assessing the use of antimicrobials compared to no treatment or an alternative treatment, and assessed one or more of the following outcomes: incidence of intramammary infection (IMI) at calving, incidence of IMI during the first 30 days in milk (DIM), or incidence of clinical mastitis during the first 30 DIM. Databases and conference proceedings were searched for relevant articles. The potential for bias was assessed using the Cochrane Risk of Bias 2.0 algorithm. From 3480 initially identified records, 45 trials had data extracted for one or more outcomes. Network meta-analysis was conducted for IMI at calving. The use of cephalosporins, cloxacillin, or penicillin with aminoglycoside significantly reduced the risk of new IMI at calving compared to non-treated controls (cephalosporins, RR = 0.37, 95% CI 0.23-0.65; cloxacillin, RR = 0.55, 95% CI 0.38-0.79; penicillin with aminoglycoside, RR = 0.42, 95% CI 0.26-0.72). Synthesis revealed challenges with a comparability of outcomes, replication of interventions, definitions of outcomes, and quality of reporting. The use of reporting guidelines, replication among interventions, and standardization of outcome definitions would increase the utility of primary research in this area.

A systematic review and meta-analysis were conducted to determine the efficacy of selective dry-cow antimicrobial therapy compared to blanket therapy (all quarters/all cows). Controlled trials were eligible if any of the following were assessed: incidence of clinical mastitis during the first 30 DIM, frequency of intramammary infection (IMI) at calving, or frequency of IMI during the first 30 DIM. From 3480 identified records, nine trials were data extracted for IMI at calving. There was an insufficient number of trials to conduct meta-analysis for the other outcomes. Risk of IMI at calving in selectively treated cows was higher than blanket therapy (RR = 1.34, 95% CI = 1.13, 1.16), but substantial heterogeneity was present (I2 = 58%). Subgroup analysis showed that, for trials using internal teat sealants, there was no difference in IMI risk at calving between groups, and no heterogeneity was present. For trials not using internal teat sealants, there was an increased risk in cows assigned to a selective dry-cow therapy protocol, compared to blanket treatment, with substantial heterogeneity in this subgroup. However, the small number of trials and heterogeneity in the subgroup without internal teat sealants suggests that the relative risk between treatments may differ from the determined point estimates based on other unmeasured factors.

A systematic review and network meta-analysis were conducted to assess the relative efficacy of internal or external teat sealants given at dry-off in dairy cattle. Controlled trials were eligible if they assessed the use of internal or external teat sealants, with or without concurrent antimicrobial therapy, compared to no treatment or an alternative treatment, and measured one or more of the following outcomes: incidence of intramammary infection (IMI) at calving, IMI during the first 30 days in milk (DIM), or clinical mastitis during the first 30 DIM. Risk of bias was based on the Cochrane Risk of Bias 2.0 tool with modified signaling questions. From 2280 initially identified records, 32 trials had data extracted for one or more outcomes. Network meta-analysis was conducted for IMI at calving. Use of an internal teat sealant (bismuth subnitrate) significantly reduced the risk of new IMI at calving compared to non-treated controls (RR = 0.36, 95% CI 0.25-0.72). For comparisons between antimicrobial and teat sealant groups, concerns regarding precision were seen. Synthesis of the primary research identified important challenges related to the comparability of outcomes, replication and connection of interventions, and quality of reporting of study conduct.

Mycobacterium avium ssp. paratuberculosis (MAP) is the causative agent of Johne's disease, an enteric infection of ruminants that causes significant economic burden for dairy and beef producers. Efforts to control MAP in endemic herds typically focus on herd management practices such as limiting exposure or early culling of infected animals and, occasionally, vaccination. The ionophore monensin sodium may have protective effects against MAP both in vivo and in vitro; however, this has not been thoroughly evaluated experimentally. Using a direct intestinal MAP challenge model, we have observed similarities regarding persistence of MAP in tissues and apparent resilience to infection compared with experimental oral infection or natural disease. Here we sought to investigate the effects of oral monensin supplementation in experimentally MAP-infected calves. We examined the persistence of MAP in the intestinal tissues, MAP-induced intestinal inflammation, fecal MAP shedding, and seroconversion using a commercial serologic assay. Monensin-supplemented MAP-infected calves demonstrated evidence for resilience to MAP infection earlier in this study compared with monensin-free MAP-infected calves. However, statistical modeling did not identify a significant effect of monensin on outcomes of infection, and more work is required to understand how monensin affects early tissue colonization of MAP in calves., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

High levels of morbidity, mortality, and antimicrobial use are common in the veal industry. For the sustainability of the industry, it is important to address these challenges and determine factors that can be used to improve animal health and welfare. The objectives of this prospective observational cohort study were to describe the health status of calves on arrival at a grain-fed veal facility and determine characteristics that were associated with morbidity and mortality. On arrival, the calves were assessed for health abnormalities, weighed, measured for hip height and length from withers to lumbosacral junction, and had blood collected to determine serum total protein level. Body mass index (BMI) was calculated using weight on arrival divided by the sum of the calf's length from withers to lumbosacral junction and hip height. The calves were observed for 77 d after arrival, during which the producer was responsible for recording all antibiotic treatments and mortality. We built Cox proportional hazard models for morbidity and mortality variables. We created 2 morbidity models: 1 for calves that were treated <21 d after arrival at the facility, and 1 for calves that were treated during the 11 wk at the facility. From January to December 2017, 998 calves were evaluated on arrival at the veal rearing facility. A large proportion (68%) were treated with antibiotics in the first 21 d after arrival. The only explanatory variable in the final <21 d morbidity model was BMI: calves with a higher BMI had a lower hazard of being treated for disease in the first 21 d after arrival. A total of 872 calves (87%) were treated at least once over the 11-wk housing period. A calf arriving with a BMI >371.46 g/cm or a serum total protein between 5.8 and 6.2 g/dL had a lower level of morbidity during the observation period. Over the 11-wk housing period, 74 calves (7.5%) died. Calves that arrived at the facility with a fecal score of 2 or a rectal temperature between 38.9 and 39.1°C had a higher hazard of dying; calves that had a BMI of >371 g/cm were less likely to die than calves that had a BMI <330 g/cm. These results point to the importance of assessing calves on arrival at a veal facility as a measure of identifying those at high risk for morbidity and mortality., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The objective of this study was to evaluate the accuracy of inline milk fat-to-protein (F:P) data to detect hyperketonemia (HYK) in herds with automated milking systems (AMS). The F:P ratio has been investigated as a tool for detecting HYK with moderate accuracy in past studies, but inline F:P data in AMS may also be useful for HYK screening. To assess the accuracy of these data in commercial settings, we monitored 484 cows from 9 AMS herds for their first 3 wk of lactation, taking blood samples once per week (n = 1,427). Positive cases of HYK were defined by whole-blood β-hydroxybutyrate (BHB) concentrations ≥1.2 or ≥1.4 mmol/L. Milk data were collected from the AMS software on each farm for each cow and converted into 4 different F:P values: (1) value from the same day as the BHB test; (2) 5-d centered-moving average (CMA); (3) 5-d backward-moving average (BMA); (4) 5-d forward-moving average (FMA). In linear regression models, all 4 values were associated with BHB, but slope estimates varied and R 2 were low: same day (slope = 0.95, R 2 = 0.07), CMA (slope = 1.05, R 2 = 0.07), BMA (slope = 0.65, R 2 = 0.04), and FMA (slope = 1.23, R 2 = 0.09). In logistic regression models, the odds of having HYK (BHB ≥1.2 mmol/L) increased with every 0.1-unit increase from the mean F:P ratio (1.16) using same-day values (odds ratio = 1.35, 95% confidence interval = 1.25-1.47) and CMA (odds ratio = 1.39, 95% confidence interval = 1.27-1.51). The same increase in F:P from mean BMA (1.14) and FMA (1.17) was associated with 1.22 and 1.49 times the odds of HYK, respectively. For all 4 F:P variations, we evaluated the sensitivity, specificity, positive predictive value, and negative predictive value of different F:P thresholds with HYK status. As the F:P threshold increased from 1.17 to 1.50, sensitivity decreased (range: 77 to 9%) but specificity increased (range: 58 to 96%). Same-day and CMA F:P cutoffs at which a balance was reached between sensitivity and specificity ranged from 1.18 to 1.22; however, even at these values we found high rates of false positives and negatives (range: 31-39%). These results suggest that inline milk F:P data from inconsistently calibrated sensors should not be used alone to detect HYK in AMS herds., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Male calves are purchased from the dairy industry in North America to produce red meat. The price paid for male calves varies widely, and it is unclear which variables influence the price paid for each calf. The objective of this study was to assess how the health traits of calves at the time of arrival and demographic variables affect the breakeven purchase price of a male calf entering the veal industry. A financial model was constructed using the prevalence of health abnormalities, weight at arrival, source of the calf, number of days in the barn, base carcass price, days to mortality, feed costs, season at arrival, interest rate, housing location, carcass dressing percentage, and costs associated with housing, labor, utilities, trucking, and health to calculate the breakeven purchase price and an estimate of profit. Sensitivity analysis was conducted using health variables measured at arrival and demographic variables, including season at arrival and housing location, to identify the factors with the largest impact on the predicted average daily gain, early and late mortality risk, breakeven purchase price, and profit. At the baseline inputs, the average calculated profit was -$5.36 per calf and it was most sensitive to the location of housing where calves were fed and the body weight of the arriving calf. The mortality risk in the first 21 d after arrival (early) was calculated to be 2.2%, whereas the risk of mortality after 21 d (late) was 3.7%. The risks of early and late mortality were most sensitive to the level of dehydration measured at arrival and the season at arrival for the purchased calves, respectively. The calculated average daily gain was 1.12 kg/d and it was most sensitive to housing location. The breakeven purchase price was calculated to be $242.49 per calf, which was most sensitive to the housing location where the calves were fed. The results of this analysis demonstrate that veal producers need to consider many variables before purchasing calves. In addition to overall market conditions, veal producers should factor health characteristics and the expected performance of the calves they purchase into what they are willing to pay for them., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Recent advances in the understanding of risk factors and biomarkers in calves entering rearing facilities show promise for identifying high-risk calves on arrival at veal and dairy beef operations. Rapid automated leukocyte differential cell counts may be a good addition for augmenting or refining calf risk identification on-farm. The objective of this study was to validate an automated leukocyte cell counter, the QScout BLD test (Advanced Animal Diagnostics, Morrisville, NC), for its ability to determine leukocyte differential cell counts in neonatal Holstein calves. From June to July 2018, blood samples collected in EDTA anticoagulant from 235 calves upon arrival at an independent veal research facility in Ontario, Canada, were evaluated using the QScout BLD test and manually by microscopy. We compared these leukocyte differential counts using Lin's concordance correlation coefficient (ρ) and found very good agreement between tests for neutrophil counts (ρ = 0.83); fair agreement for lymphocyte counts (ρ = 0.32); fair agreement for the ratio of neutrophils to lymphocytes (ρ = 0.36); slight agreement for monocyte counts (ρ = 0.14); and slight agreement for eosinophil counts (ρ = 0.20). We further examined test results to determine if they differed in their classification of samples as being above, within, or below reported 95% reference intervals for neonatal Holstein calves. Classification between tests resulted in very good agreement for neutrophils and lymphocytes, with only 4.2% and 5.8% disagreement in classification, respectively. We observed moderate agreement for monocytes, with 23.3% classified differently, and poor agreement for eosinophils, with 70.3% classified differently. Further study is required to determine the role of leukocyte profiling in the risk assessment of calves arriving at calf-rearing facilities., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The objectives of this randomized clinical trial were to determine whether the utilization of a multispecies probiotic bolus (MSP) in dairy calves with diarrhea led to a rapid resolution of diarrhea and improved average daily gain (ADG). Calves, from a convenience sample of dairy farms with diarrhea challenges, having fecal scores of ≥2 were randomly assigned to receive MSP or a placebo (PLB). The MSP bolus contained Pediococcus acidilactici, Enterococcus faecium, Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, peptide extract, an enzyme blend, killed yeast extract, dried whey, and natural flavors (Revive, Partnar Animal Health, Ilderton, ON, Canada). The enrolled calves were fecal scored daily for 7 consecutive days and resolution of diarrhea was defined as having 2 consecutive days with a fecal score ≤1. Calves were also weighed at enrollment, 7, and 14 d following enrollment and ADG was calculated. A Cox proportional hazards model was built to investigate time to resolution of an abnormal fecal score. Two mixed linear regression models were created to evaluate the effect of treatment group on ADG in the first and second weeks following enrollment. A total of 148 calves were enrolled in the experiment and no differences were observed between the groups with respect to the age or weight at enrollment. The mean time to resolution of abnormal fecal score was 5.1 and 5.9 d in the MSP and PLB groups, respectively. In the Cox proportional hazards model, the calves in the MSP group had faster resolution of diarrhea when compared with the PLB group; however, an interaction between time from enrollment of the first calf and treatment group was present. No differences were found between the 2 groups with respect to ADG. This study demonstrates a multispecies probiotic and yeast bolus administered to calves at the onset of diarrhea reduced the duration of diarrhea; however, the clinical and economic relevance of this reduction requires further exploration., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)