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Dairy goat’s lactation persistence forces farmers at limiting nutrient supply to reduce yield at dry-off. Omitting dry period could be a solution, but metabolic effects of this practice have never been tested. Eight Alpine (AL) and 12 Saanen (SA) goats approaching their second kidding blocked by breed and number of kids carried (single - SIN - or double - DOU) were allocated to one out of two groups (4 AL and 6 SA; 5 SIN and 5 DOU in each group). At −42 ± 7 days from kidding (DFK), they were either dried off (DR) or milked continuously until kidding (CL). Body condition score (BCS) was assessed, and blood samples were collected at −10, −3, 5, 12, and 29 DFK to determine metabolic profile. Milk yield and composition were assessed at −56, 7, 31, 62, and 97 DFK. Compared with DR, CL had higher plasma reactive oxygen metabolites and liver enzymes. Compared with DR counterparts, AL-CL had higher nonesterified fatty acids (NEFA) at −10, whereas SA-CL had lower NEFA at −3 DFK. CL goats had lower BCS, higher plasma beta-hydroxybutyrate (BHB) and urea before kidding, but higher glucose at −3 and 5, lower NEFA at 5 and 12, and higher BCS at 29 DFK. CL goats had lower haptoglobin and myeloperoxidase at −3 and 5 DFK, paired with higher albumin, cholesterol, and paraoxonase at 12 DFK. Omitting dry period mitigated the inflammatory condition around kidding in dairy goats, possibly accounting for an improved energy balance in early lactation, despite body reserve mobilisation prepartum was greater under continuous lactation.

This study used 16S rRNA sequencing to evaluate the effects of dry cow antimicrobial therapy on the udder milk microbiota by comparing the microbial populations in milk at dry-off (DRY) (~60 days before calving) and post-partum (FRESH) (4-11 days after calving) from cows receiving an intramammary antibiotic infusion prior to dry-off (IMT) and cows that did not receive treatment (CTL). Milk was collected from 23 cows from the IMT group and 27 cows from the CTL group. IMT and DRY samples had a greater correlation with the genera Brevibacterium and Amaricoccus, and the family Micrococcaceae, when compared to IMT and FRESH samples. CTL group samples collected at DRY had a greater correlation with the genera Akkermansia and Syntrophus, when compared to FRESH samples; no bacterial taxa were observed to have a significant correlation with FRESH samples in the CTL group. DRY samples collected from the CTL group had a greater correlation with the genus Mogibacterium when compared to IMT and CTL samples. For DRY samples collected from the IMT group, a greater correlation with the genus Alkalibacterium when compared to DRY and CTL samples, was observed. The lack of a correlation for FRESH samples between the CTL and IMT treatment groups indicated that intramammary antimicrobial dry cow therapy had no significant effect on the udder milk microbiota post-partum.

The objective of this study was to characterize changes in the serum metabolome and various indicators of oxidative balance in dairy cows starting 2 wk before dry-off and continuing until wk 16 of lactation. Twelve Holstein dairy cows (body weight 745 ± 71 kg, body condition score 3.43 ± 0.66; mean ± SD) were housed in a tiestall barn from 10 wk before to 16 wk after parturition. Cows were dried off 6 wk before the expected calving date (mean dry period length = 42 d). From 8 wk before calving to 16 wk after calving, blood samples were taken weekly to study redox metabolism by determining antioxidant capacity, measured as the ferric-reducing ability of plasma, reactive oxidative metabolites, oxidative stress index, oxidative damage of lipids, measured as thiobarbituric acid reactive substances, and glutathione peroxidase activity. According to these results, dairy cows had the lowest serum antioxidant capacity and greater levels of oxidative stress during the dry-off period and the early postpartum period. For metabolomics, a subset of serum samples including wk −7 (before dry-off), −5 (after dry-off), −1, 1, 5, 10, and 15 relative to calving were used. A targeted metabolomics approach was performed using liquid chromatography and flow injection with electrospray ionization triple quadrupole mass spectrometry using the MxP Quant 500 kit (Biocrates Life Sciences AG). A total of 240 metabolites in serum were used in the final data analysis. Principal component analysis revealed a clear separation by days of sampling, indicating a remarkable shift in metabolic phenotype between the dry period and late and early lactation. Changes in many non-lipid metabolites associated with one-carbon metabolism, the tricarboxylic acid cycle, the urea cycle, and AA catabolism were observed in the study, with changes in AA serum concentrations likely related to factors such as energy and nitrogen balance, digestive efficiency, and changing diets. The study confirmed an extensive remodeling of the serum lipidome in peripartum dairy cows, highlighting the importance of changes in acylcarnitine (acylCN), phosphatidylcholines (PC), and triacylglycerols (TG), as they play a crucial role in lipid metabolism. Results showed that short-chain acylCN increased after dry-off and decreased thereafter, whereas lipid-derived acylCN increased around parturition, suggesting that more fatty acids could enter mitochondria. Phospholipids and sphingolipids in serum showed changes during lactation. In particular, concentrations of sphingomyelins, PC, and lysoPC decreased around calving but increased in mid- and late lactation. In contrast, concentrations of TG remained consistently low after parturition. The serum concentrations of bile acids fluctuated during the dry period and lactation, with glycocholic acid, cholic acid, glycodeoxycholic acid, and taurocholic acid showing the greatest concentrations. These changes are likely due to the interplay of diet, liver function, and the ability of the gut microbiota to convert primary to secondary bile acids. Overall, these descriptive results may aid in hypothesis generation and in the design and interpretation of future metabolite-based studies in dairy cows. Furthermore, they contribute to our understanding of the physiological ranges in serum metabolites relative to the lactation cycle of the dairy cow. [ABSTRACT FROM AUTHOR]

ABSTRACT: Use of selective dry cow antimicrobial therapy requires to precisely differentiate cows with an intramammary infection (IMI) from uninfected cows close to drying-off to enable treatment allocation. Milk somatic cell count (SCC) is an indicator of an inflammatory response in the mammary gland and is usually associated with IMI. However, SCC can also be influenced by cow-level variables such as milk yield, lactation number and stage of lactation. In recent years, predictive algorithms have been developed to differentiate cows with IMI from cows without IMI based on SCC data. The objective of this observational study was to explore the association between SCC and subclinical IMI, taking cognizance of cow-level predictors on Irish seasonal spring calving, pasture-based systems. Additionally, the optimal test-day SCC cut-point (maximized sensitivity and specificity) for IMI diagnosis was determined. A total of 2,074 cows, across 21 spring calving dairy herds with an average monthly milk weighted bulk tank SCC of ≤200,000 cells/mL were enrolled in the study. Quarter-level milk sampling was carried out on all cows in late lactation (interquartile range = 240–261 d in milk) for bacteriological culturing. Bacteriological results were used to define cows with IMI, when ≥1 quarter sample resulted in bacterial growth. Cow-level test-day SCC records were provided by the herd owners. The ability of the average, maximum and last test-day SCC to predict infection were compared using receiver operator curves. Predictive logistic regression models tested included parity (primiparous or multiparous), yield at last test-day and a standardized count of high SCC test-days. In total, 18.7% of cows were classified as having an IMI, with first parity cows having a higher proportion of IMI (29.3%) compared with multiparous cows (16.1%). Staphylococcus aureus accounted for the majority of these infections. The last test-day SCC was the best predictor of infection with the highest area under the curve. The inclusions of parity, yield at last test-day, and a standardized count of high SCC test-days as predictors did not significantly improve the ability of last test-day SCC to predict IMI. The cut-point for last test-day SCC which maximized sensitivity and specificity was 64,975 cells/mL. This study indicates that in Irish seasonal pasture-based dairy herds, with low bulk tank SCC control programs, the last test-day SCC (interquartile range days in milk = 221–240) is the best predictor of IMI in late lactation.

ABSTRACT: The objectives were to compare the effects of an intermittent milking schedule with a thrice daily milking schedule during the final week of lactation on the well-being, udder health, milk production, and risk of culling of dairy cows. We hypothesized that cows subjected to an intermittent milking schedule would experience less udder engorgement and pain, lower concentrations of fecal glucocorticoid metabolites (11,17-dioxoandrostanes; 11,17-DOA concentration) after dry-off, lower risk of an intramammary infection during the dry period, higher milk production and lower somatic cell count in the subsequent lactation, and lower culling risk compared with herd mates milked 3 times daily and dried off by abrupt cessation. In a randomized controlled field study, Holstein cows (n = 398) with a thrice daily milking schedule were assigned to treatment and control groups. The treatment consisted of an intermittent milking schedule for 7 d before dry-off (gradual cessation of milking, GRAD). Gradual-cessation cows were milked once daily until the day of dry-off, whereas cows in the control group (abrupt cessation of milking, APT) were milked 3 times daily until the day of dry-off. Udder firmness and pain responses of the udder 3 d after dry-off, as well as the percentage change in fecal 11,17-DOA concentration (3 d after dry-off compared with the dry-off day), were used to assess the well-being of the animals. Compared with cows in the GRAD group, the odds [95% confidence interval (CI)] of udder firmness were 1.55 (0.99–2.42) for cows in the APT group, and the odds of a pain response were 1.48 (0.89–2.44) for cows in the APT group. The least squares means (95% CI) of the percentage change in 11,17-DOA concentration were 129.3% (111.1–150.4) for the APT group and 113.6% (97.5–132.4) for the GRAD group. Quarter-level culture results from the periods before dry-off and after calving were compared, to assess the likelihoods of microbiological cure and new infection. Cows in the APT group had lower odds of a new intramammary infection in the dry period [odds ratio, 95% CI: 0.63 (0.37–1.05)], whereas we observed no meaningful differences in the microbiological cure likelihood among groups. The least squares means (95% CI) for somatic cell counts (log10-transformed) were 4.9 (4.8–5.0) in the APT group and 4.9 (4.8–5.0) in the GRAD group. The odds (95% CI) of clinical mastitis in the first 30 d postcalving were 1.32 (0.53–3.30) in the APT group compared with the GRAD group. We observed no meaningful differences in milk production at the first test date postcalving or the culling risk among groups. We conclude that the gradual-cessation protocol tested herein failed to significantly improve animal well-being, udder health, milk production, and survival in the tested study cohort. However, the observed differences in udder firmness, as well as the numerical differences in udder pain and the percentage change in fecal 11,17-DOA concentrations suggest that this line of research may be useful. Future research is needed to develop drying-off strategies that are appropriate for lowering milk production at the end of the lactation and improve animal well-being without compromising udder health.

Use of selective dry cow antimicrobial therapy requires to precisely differentiate cows with an intramammary infection (IMI) from uninfected cows close to drying-off to enable treatment allocation. Milk somatic cell count (SCC) is an indicator of an inflammatory response in the mammary gland and is usually associated with IMI. However, SCC can also be influenced by cow-level variables such as milk yield, lactation number and stage of lactation. In recent years, predictive algorithms have been developed to differentiate cows with IMI from cows without IMI based on SCC data. The objective of this observational study was to explore the association between SCC and subclinical IMI, taking cognizance of cow-level predictors on Irish seasonal spring calving, pasture-based systems. Additionally, the optimal test-day SCC cut-point (maximized sensitivity and specificity) for IMI diagnosis was determined. A total of 2,074 cows, across 21 spring calving dairy herds with an average monthly milk weighted bulk tank SCC of ≤200,000 cells/mL were enrolled in the study. Quarter-level milk sampling was carried out on all cows in late lactation (interquartile range = 240–261 d in milk) for bacteriological culturing. Bacteriological results were used to define cows with IMI, when ≥1 quarter sample resulted in bacterial growth. Cow-level test-day SCC records were provided by the herd owners. The ability of the average, maximum and last test-day SCC to predict infection were compared using receiver operator curves. Predictive logistic regression models tested included parity (primiparous or multiparous), yield at last test-day and a standardized count of high SCC test-days. In total, 18.7% of cows were classified as having an IMI, with first parity cows having a higher proportion of IMI (29.3%) compared with multiparous cows (16.1%). Staphylococcus aureus accounted for the majority of these infections. The last test-day SCC was the best predictor of infection with the highest area under the curve. The inclusions of parity, yield at last test-day, and a standardized count of high SCC test-days as predictors did not significantly improve the ability of last test-day SCC to predict IMI. The cut-point for last test-day SCC which maximized sensitivity and specificity was 64,975 cells/mL. This study indicates that in Irish seasonal pasture-based dairy herds, with low bulk tank SCC control programs, the last test-day SCC (interquartile range days in milk = 221–240) is the best predictor of IMI in late lactation. [ABSTRACT FROM AUTHOR]

ABSTRACT: The objective of this study was to characterize total-tract nutrient digestibility, energy balance, and N balance in the critical dietary and metabolic transitions of the lactation cycle. Twelve dairy cows were housed in tiestalls from 10 wk before to 16 wk after parturition. After 2 wk of adaptation to the facility and diet, digestibility of organic matter (OM), neutral detergent fiber (NDF), starch, and N were measured, and energy and N balances determined at weekly intervals by total collection of feces, urine, and milk over 48 h. Cows were individually fed ad libitum a grass silage- and corn silage-based total mixed ration during lactation and a corn silage- and barley straw-based total mixed ration during the dry period. Effects of stage of lactation were evaluated by clustering week in 5 groups: late lactation (wk −8 to −7), dry period (wk −6 to −1), and 3 early lactation periods (wk 1 to 5, wk 6 to 10, and wk 11 to 16). In lactation, apparent total-tract digestibility of OM, NDF, and starch was lowest in the first 5 wk of lactation. From wk 2 to 16 after parturition, apparent nutrient digestibility of all nutrients increased linearly, but with a negative quadratic component for dry matter, OM, and NDF, to levels comparable to those reported in last 2 wk of the previous lactation. However, differences in digestibility across lactation stage were moderate, illustrated by the difference between OM digestibility in late lactation (last 2 wk, 74.8%) and early lactation (first 5 wk, 72.5%). Cows were in negative energy balance for the first 8 wk after calving, and in negative N balance for the first 4 wk after calving. Based on energy and N balance, we predicted that 36.5 kg of body fat and 3.5 kg of body protein were gained in the last 8 wk before calving, and that 47.5 kg of body fat and 7.6 kg of body protein were mobilized in the first weeks of lactation. These predicted changes in body mass, both the gain before calving and loss after calving, were greater by 37% and 10%, respectively, than fluctuations in measured body weight (corrected for predicted gut fill and fetus weights). At wk 1 and 2 postpartum, body N loss corresponded to 25 and 29%, respectively, of total N excretion in milk, and body energy loss corresponded to 64% and 44%, respectively, of the energy exported to milk, illustrating the important contribution of N and energy from body stores to milk production in early lactation. Metabolic N efficiency, measured as total N output (milk and body) over digestible N input (from diet and body), averaged 54.4% in the last 2 wk of lactation, increased to 65.9% 2 wk after calving, and decreased linearly as lactation advanced to 61.9% by wk 16. Short (48 h) but weekly repetition of total collection of feces and urine appears to be a suitable approach to evaluate temporal changes in nutrient digestibility, energy balance, and N balance across lactation and the dry period.

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The objectives were to compare the effects of an intermittent milking schedule with a thrice daily milking schedule during the final week of lactation on the well-being, udder health, milk production, and risk of culling of dairy cows. We hypothesized that cows subjected to an intermittent milking schedule would experience less udder engorgement and pain, lower concentrations of fecal glucocorticoid metabolites (11,17-dioxoandrostanes; 11,17-DOA concentration) after dry-off, lower risk of an intramammary infection during the dry period, higher milk production and lower somatic cell count in the subsequent lactation, and lower culling risk compared with herd mates milked 3 times daily and dried off by abrupt cessation. In a randomized controlled field study, Holstein cows (n = 398) with a thrice daily milking schedule were assigned to treatment and control groups. The treatment consisted of an intermittent milking schedule for 7 d before dry-off (gradual cessation of milking, GRAD). Gradual-cessation cows were milked once daily until the day of dry-off, whereas cows in the control group (abrupt cessation of milking, APT) were milked 3 times daily until the day of dry-off. Udder firmness and pain responses of the udder 3 d after dry-off, as well as the percentage change in fecal 11,17-DOA concentration (3 d after dry-off compared with the dry-off day), were used to assess the well-being of the animals. Compared with cows in the GRAD group, the odds [95% confidence interval (CI)] of udder firmness were 1.55 (0.99–2.42) for cows in the APT group, and the odds of a pain response were 1.48 (0.89–2.44) for cows in the APT group. The least squares means (95% CI) of the percentage change in 11,17-DOA concentration were 129.3% (111.1–150.4) for the APT group and 113.6% (97.5–132.4) for the GRAD group. Quarter-level culture results from the periods before dry-off and after calving were compared, to assess the likelihoods of microbiological cure and new infection. Cows in the APT group had lower odds of a new intramammary infection in the dry period [odds ratio, 95% CI: 0.63 (0.37–1.05)], whereas we observed no meaningful differences in the microbiological cure likelihood among groups. The least squares means (95% CI) for somatic cell counts (log 10 -transformed) were 4.9 (4.8–5.0) in the APT group and 4.9 (4.8–5.0) in the GRAD group. The odds (95% CI) of clinical mastitis in the first 30 d postcalving were 1.32 (0.53–3.30) in the APT group compared with the GRAD group. We observed no meaningful differences in milk production at the first test date postcalving or the culling risk among groups. We conclude that the gradual-cessation protocol tested herein failed to significantly improve animal well-being, udder health, milk production, and survival in the tested study cohort. However, the observed differences in udder firmness, as well as the numerical differences in udder pain and the percentage change in fecal 11,17-DOA concentrations suggest that this line of research may be useful. Future research is needed to develop drying-off strategies that are appropriate for lowering milk production at the end of the lactation and improve animal well-being without compromising udder health. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize total-tract nutrient digestibility, energy balance, and N balance in the critical dietary and metabolic transitions of the lactation cycle. Twelve dairy cows were housed in tiestalls from 10 wk before to 16 wk after parturition. After 2 wk of adaptation to the facility and diet, digestibility of organic matter (OM), neutral detergent fiber (NDF), starch, and N were measured, and energy and N balances determined at weekly intervals by total collection of feces, urine, and milk over 48 h. Cows were individually fed ad libitum a grass silage- and corn silage-based total mixed ration during lactation and a corn silage- and barley straw-based total mixed ration during the dry period. Effects of stage of lactation were evaluated by clustering week in 5 groups: late lactation (wk −8 to −7), dry period (wk −6 to −1), and 3 early lactation periods (wk 1 to 5, wk 6 to 10, and wk 11 to 16). In lactation, apparent total-tract digestibility of OM, NDF, and starch was lowest in the first 5 wk of lactation. From wk 2 to 16 after parturition, apparent nutrient digestibility of all nutrients increased linearly, but with a negative quadratic component for dry matter, OM, and NDF, to levels comparable to those reported in last 2 wk of the previous lactation. However, differences in digestibility across lactation stage were moderate, illustrated by the difference between OM digestibility in late lactation (last 2 wk, 74.8%) and early lactation (first 5 wk, 72.5%). Cows were in negative energy balance for the first 8 wk after calving, and in negative N balance for the first 4 wk after calving. Based on energy and N balance, we predicted that 36.5 kg of body fat and 3.5 kg of body protein were gained in the last 8 wk before calving, and that 47.5 kg of body fat and 7.6 kg of body protein were mobilized in the first weeks of lactation. These predicted changes in body mass, both the gain before calving and loss after calving, were greater by 37% and 10%, respectively, than fluctuations in measured body weight (corrected for predicted gut fill and fetus weights). At wk 1 and 2 postpartum, body N loss corresponded to 25 and 29%, respectively, of total N excretion in milk, and body energy loss corresponded to 64% and 44%, respectively, of the energy exported to milk, illustrating the important contribution of N and energy from body stores to milk production in early lactation. Metabolic N efficiency, measured as total N output (milk and body) over digestible N input (from diet and body), averaged 54.4% in the last 2 wk of lactation, increased to 65.9% 2 wk after calving, and decreased linearly as lactation advanced to 61.9% by wk 16. Short (48 h) but weekly repetition of total collection of feces and urine appears to be a suitable approach to evaluate temporal changes in nutrient digestibility, energy balance, and N balance across lactation and the dry period. [ABSTRACT FROM AUTHOR]

ABSTRACT: Concentrate withdrawal and feed restriction are commonly used to reduce milk production and to facilitate dry-off, but may impair immune function in dairy cows. We investigated the effect of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses, as well as on leukocyte function before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dry-off (56 d before scheduled calving). Cows were fed experimental concentrates rich in crude protein (nitrogenic, n = 14), glucogenic precursors (glucogenic, n = 14), or lipids (lipogenic, n = 15). On d 3 before dry-off, total feed allowance was restricted to 50% in half of the animals of each dietary group, whereas feed allowance remained unchanged in the other animals. Performance parameters (milk yield, milk composition, and dry matter intake) were recorded, and daily blood and milk samples were taken and analyzed for various metabolic and endocrine parameters. Additionally, activity and mRNA abundance of several genes in leukocytes were measured at selected time points before and after feed restriction and dry-off, respectively. Feed restriction immediately resulted in a negative energy balance and decreased milk production. Concomitantly, concentrations of nonesterified fatty acids increased, whereas insulin, insulin-like growth factor-1, and glucagon decreased. After dry-off, energy balance turned positive and plasma nonesterified fatty acids decreased. Plasma glucose, insulin, and insulin-like growth factor-1 concentrations increased in all groups after dry-off. Glucose, insulin, and glucagon concentrations in plasma were higher in nonrestricted compared with restricted animals after dry-off. The experimental concentrate types marginally affected the investigated metabolic and endocrine factors, with the exception of elevated milk and plasma urea concentrations in cows fed the nitrogenic concentrate. Chemotactic and phagocytic activity of leukocytes were not affected by diets, feed restriction, or dry-off. Likewise, blood leukocyte mRNA abundance encoding for tumor necrosis factor α (TNF), heat shock protein family A (HSP70), and the glucose transporters (GLUT) 1 and 3 remained unchanged throughout the study period. Overall, the short-term negative energy balance induced by feed restriction was temporarily accompanied by metabolic adaptations, but did not alter the studied factors related to the immune system. Metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood.

ABSTRACT: Milk production may be reduced before dry-off to decrease the risk of cows developing intramammary infections during the dry period. Such reductions in milk may be possible in automated milking systems (AMS) where milking frequency and feed allocation at the AMS can be controlled at the cow level. This study investigated the effect of dry-off management of cows milked in AMS on milk yield, milking behavior, and somatic cell count (SCC). Using a 2 × 2 factorial arrangement of treatments, applied from d 14 to 1 before dry-off, 445 cows from 5 commercial dairy farms in Quebec, Canada, were assigned within farm to either (1) reduced feed [RF; allowed a maximum of 0.75 kg/d of AMS pellet for the first week (14 to 8 d before dry-off) of treatment, and 0.50 kg/d for the second week (7 to 1 d before dry-off) of treatment], or (2) nonreduced feed (NF; allowed up to 2 kg/d of AMS pellet), and either (1) reduced milking (RM; reduced to 2 milkings/d or as many times as required to yield 17 kg/milking), or (2) nonreduced milking (NM; allowed up to 6 AMS milkings/d) and no maximum production. Feed and milking behavior data, as well as milk yield and SCC were collected from the AMS software. The RF cows had lower AMS feed delivered during the treatment period, as per the experimental design. Across the treatment period, the NF-NM cows had the highest milking frequency (2.7 times/d), followed by the RF-NM cows (2.4 times/d), and then both of the RM groups (1.8 times/d), which did not differ from each other. All cows, except the NF-NM cows, were gradually milked less frequently as dry-off approached. Across the entire 2-wk treatment period before dry-off, cows with RM allowance experienced a higher reduction in milk yield compared with the cows with no milking allowance restrictions (−4.8 vs. −3.6 kg). Similarly, cows with a RF allocation tended to have a higher reduction in milk yield than cows with NF (−4.6 vs. −3.7 kg). As result, those cows with both reduced milking permissions and feed allocation at the AMS experienced the greatest drop in milk production before dry-off. There were no differences between treatments for milking frequency or yield in the next lactation. Somatic cell score (calculated from SCC) was not different between treatments in the 2-wk or day before dry-off, nor in the first month after calving. Overall, these data suggest that reducing both milking frequency and feed quantity in the AMS is the most efficient method to decrease milk yield before dry-off, without negatively influencing milking frequency or yield in the next lactation, as well as without affecting milk quality.

Concentrate withdrawal and feed restriction are commonly used to reduce milk production and to facilitate dry-off, but may impair immune function in dairy cows. We investigated the effect of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses, as well as on leukocyte function before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dry-off (56 d before scheduled calving). Cows were fed experimental concentrates rich in crude protein (nitrogenic, n = 14), glucogenic precursors (glucogenic, n = 14), or lipids (lipogenic, n = 15). On d 3 before dry-off, total feed allowance was restricted to 50% in half of the animals of each dietary group, whereas feed allowance remained unchanged in the other animals. Performance parameters (milk yield, milk composition, and dry matter intake) were recorded, and daily blood and milk samples were taken and analyzed for various metabolic and endocrine parameters. Additionally, activity and mRNA abundance of several genes in leukocytes were measured at selected time points before and after feed restriction and dry-off, respectively. Feed restriction immediately resulted in a negative energy balance and decreased milk production. Concomitantly, concentrations of nonesterified fatty acids increased, whereas insulin, insulin-like growth factor-1, and glucagon decreased. After dry-off, energy balance turned positive and plasma nonesterified fatty acids decreased. Plasma glucose, insulin, and insulin-like growth factor-1 concentrations increased in all groups after dry-off. Glucose, insulin, and glucagon concentrations in plasma were higher in nonrestricted compared with restricted animals after dry-off. The experimental concentrate types marginally affected the investigated metabolic and endocrine factors, with the exception of elevated milk and plasma urea concentrations in cows fed the nitrogenic concentrate. Chemotactic and phagocytic activity of leukocytes were not affected by diets, feed restriction, or dry-off. Likewise, blood leukocyte mRNA abundance encoding for tumor necrosis factor α (TNF), heat shock protein family A (HSP70), and the glucose transporters (GLUT) 1 and 3 remained unchanged throughout the study period. Overall, the short-term negative energy balance induced by feed restriction was temporarily accompanied by metabolic adaptations, but did not alter the studied factors related to the immune system. Metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood. [ABSTRACT FROM AUTHOR]

Milk production may be reduced before dry-off to decrease the risk of cows developing intramammary infections during the dry period. Such reductions in milk may be possible in automated milking systems (AMS) where milking frequency and feed allocation at the AMS can be controlled at the cow level. This study investigated the effect of dry-off management of cows milked in AMS on milk yield, milking behavior, and somatic cell count (SCC). Using a 2 × 2 factorial arrangement of treatments, applied from d 14 to 1 before dry-off, 445 cows from 5 commercial dairy farms in Quebec, Canada, were assigned within farm to either (1) reduced feed [RF; allowed a maximum of 0.75 kg/d of AMS pellet for the first week (14 to 8 d before dry-off) of treatment, and 0.50 kg/d for the second week (7 to 1 d before dry-off) of treatment], or (2) nonreduced feed (NF; allowed up to 2 kg/d of AMS pellet), and either (1) reduced milking (RM; reduced to 2 milkings/d or as many times as required to yield 17 kg/milking), or (2) nonreduced milking (NM; allowed up to 6 AMS milkings/d) and no maximum production. Feed and milking behavior data, as well as milk yield and SCC were collected from the AMS software. The RF cows had lower AMS feed delivered during the treatment period, as per the experimental design. Across the treatment period, the NF-NM cows had the highest milking frequency (2.7 times/d), followed by the RF-NM cows (2.4 times/d), and then both of the RM groups (1.8 times/d), which did not differ from each other. All cows, except the NF-NM cows, were gradually milked less frequently as dry-off approached. Across the entire 2-wk treatment period before dry-off, cows with RM allowance experienced a higher reduction in milk yield compared with the cows with no milking allowance restrictions (−4.8 vs. −3.6 kg). Similarly, cows with a RF allocation tended to have a higher reduction in milk yield than cows with NF (−4.6 vs. −3.7 kg). As result, those cows with both reduced milking permissions and feed allocation at the AMS experienced the greatest drop in milk production before dry-off. There were no differences between treatments for milking frequency or yield in the next lactation. Somatic cell score (calculated from SCC) was not different between treatments in the 2-wk or day before dry-off, nor in the first month after calving. Overall, these data suggest that reducing both milking frequency and feed quantity in the AMS is the most efficient method to decrease milk yield before dry-off, without negatively influencing milking frequency or yield in the next lactation, as well as without affecting milk quality. [ABSTRACT FROM AUTHOR]

Abrupt and gradual dry-off strategies by reducing feeding level (normal vs. reduced energy density), reducing milking frequency (twice vs. once daily), and administration of a dopamine agonist after last milking (i.m. saline vs. cabergoline injection) were investigated (2 × 2 × 2 factorial arrangement) for their effects on feed intake, milk yield, energy balance, milk leakage, and clinical udder characteristics in 119 Holstein cows. In the last week before dry-off, cows were assigned to 1 of 4 combinations of feeding level and milking frequency. Within 3 h after last milking, cows were injected with either saline or a dopamine agonist (cabergoline; Velactis, Ceva Santé Animale; labeled for use only with abrupt dry-off, i.e., no preceding reduction in feeding level or milking frequency before last milking). After dry-off, all cows were fed the same diet for dry cows, and data collection continued for a week. Dry matter intake (DMI) was recorded in automated feed bins and milk yield in an automatic milking system where additional concentrate was fed. Clinical udder characteristics and milk leakage were scored 10 times during the week before and the week after dry-off. Before dry-off, total DMI decreased with reduced feeding level compared with normal feeding level, but did not differ between milking frequencies. The combined effect of reduced DMI and diet energy concentration resulted in a 47% lower net energy intake with reduced feeding level compared with normal feeding level during the week before dry-off. Milk yield was approximately 30% lower during the week before dry-off when either feeding level or milking frequency was reduced compared with no change in feeding level or milking frequency, whereas milk yield was 45% lower when both feeding level and milking frequency were reduced. The net energy balance during the week before dry-off was negative with reduced feeding level and more negative when combined with twice-daily milking. After dry-off, udder engorgement was reduced in the 3 gradual dry-off treatments compared with abrupt dry-off. Cabergoline injection after last milking resulted in least udder engorgement and signs of milk leakage for 48 h, but also resulted in abrupt reduction of DMI lasting approximately 24 h irrespective of treatment before dry-off. In conclusion, gradual cessation of lactation by reducing milking frequency to once daily without reducing the feeding level decreased milk yield before dry-off in high-yielding dairy cows and reduced udder engorgement after dry-off without inducing negative energy balance during the period of dry-off. In contrast, reduced feeding level induced negative energy balance, which may compromise welfare due to metabolic stress and hunger. No clear differences in risk of milk leakage after dry-off were observed between abrupt and gradual dry-off management strategies. Use of cabergoline led to fewer signs of milk leakage and reduced udder engorgement during the first days after dry-off, which may positively affect welfare at dry-off. However, the mechanism behind and the welfare consequences of the concomitant abrupt decrease in DMI lasting approximately 24 h needs further investigation to complete our understanding of dopamine agonist use for dry-off. [ABSTRACT FROM AUTHOR]

We investigated the single and combined effects of 2 feeding levels (normal lactation diet vs. energy-reduced diet, both fed for ad libitum intake) and 2 daily milking frequencies (twice vs. once) during 1 wk before the dry-off day (d 0), as well as an intramuscular injection of either a dopamine agonist (cabergoline; Velactis, Ceva Santé Animale; labeled for use only with abrupt dry-off, e.g., no reduction in feeding level or milking frequency before the last milking) or saline after the last milking on d 0 on the feeding motivation of clinically healthy, loose-housed, pregnant, lactating Holstein cows. From d 0, all cows were fed the same dry-cow diet for ad libitum intake. Cows were subjected to 2 feed-thwarting tests, a test in the home pen using their diets (test A: d −6, −1, and 1; during 35 min when the feed bins were filled, but locked) and another test carried out in an adjacent pen in which access to concentrate provided in a familiar plastic box was blocked by a wire-mesh lid (test B: d −5 and 2). In test A, we recorded how often cows attempted to feed per 35 min, whether cows vocalized during the 35-min period, and latency to feed within 300 s after feed bins were unlocked. In test B, we recorded latency to approach either of 2 familiar boxes (the wire-mesh box and an identical open box with a small portion of concentrate) within 600 s and how often cows directed behaviors toward the wire-mesh box (number of occurences/5 min). On d −6 (test A), no clear differences in feeding motivation among treatments were found. On d −5 and −1, cows fed the energy-reduced diet displayed a higher probability of vocalizing (test A), were more than 50% quicker to feed (test A), were approximately 5× quicker to approach a box (test B), and directed 60% more behavior toward the wire-mesh box (test B) than cows fed the normal diet. Moreover, cows fed the energy-reduced diet attempted to feed approximately 75% more on d −1 compared with d −6 (test A). On d 2 (test B), cows previously fed the normal diet directed 40% more behavior toward the wire-mesh box than cows previously fed the energy-reduced diet. Reducing feeding level, either before or on the dry-off day, resulted in consistently increased feeding motivation, interpreted as a sign of hunger. No clear effects of change in milking frequency, singly or combined with reduced diet energy density, on feeding motivation were found before d 0. Whereas, on d 2, cows previously milked twice daily were quicker to approach a box than cows previously milked once daily. Cows injected with cabergoline attempted to feed more, but showed lower probability of vocalizing compared with saline-injected cows (d 1; test A), irrespective of treatment before d 0. The effects of cabergoline on feeding motivation are not easily interpreted and warrant further investigation. From a hunger perspective, reducing milking frequency rather than diet energy density seems to be a less negative management to reduce milk production before dry-off. [ABSTRACT FROM AUTHOR]

The dry-off of dairy cows represents an important phase of the lactation cycle, influencing the outcome of the next lactation. Among the physiological changes, the severity of the inflammatory response can vary after the dry-off, and this response might have consequences on cow adaptation in the transition period. The plasma protein profile is a diagnostic tool widely used in humans and animals to assess the inflammatory status and predict the outcome of severe diseases. The albumin-to-globulin ratio (AG) can represent a simple and useful proxy for the inflammatory condition. In this study, we investigated the relationship between AG before dry-off and inflammation, metabolic profile, and performance of 75 Holstein dairy cows. Blood samples were collected from −62 (7 d before dry-off) to 28 d relative to calving (DFC) to measure metabolic profile biomarkers, inflammatory variables, and liver function. Daily milk yield in the first month of lactation was recorded. Milk composition, body condition score, fertility, and health status were also assessed. The AG calculated 1 wk before dry-off (−62 DFC) was used to retrospectively group cows into tertiles (1.06 ± 0.09 for HI, 0.88 ± 0.04 for IN, and 0.72 ± 0.08 for LO). Data were subjected to ANOVA using the PROC MIXED program in SAS software. Differences among groups observed at −62 DFC were almost maintained throughout the period of interest, but AG peaked before calving. According to the level of acute-phase proteins (haptoglobin, ceruloplasmin, albumin, cholesterol, retinol-binding protein), bilirubin, and paraoxonase, a generally overall lower inflammatory condition was found in HI and IN than in the LO group immediately after the dry-off but also after calving. The HI cows had greater milk yield than LO cows, but no differences were observed in milk composition. The somatic cell count reflected the AG ratio trend, with higher values in LO than IN and HI either before dry-off or after calving. Fertility was better in HI cows, with fewer days open and services per pregnancy than IN and LO cows. Overall, cows with high AG before dry-off showed an improved adaptation to the new lactation, as demonstrated by a reduced systemic inflammatory response and increased milk yield than cows with low AG. In conclusion, the AG ratio before dry-off might represent a rapid and useful proxy to evaluate the innate immune status and likely the ability to adapt while switching from the late lactation to the nonlactating phase and during the transition period with emphasis on early lactation. [ABSTRACT FROM AUTHOR]

This study used 16S rRNA sequencing to evaluate the effects of dry cow antimicrobial therapy on the udder milk microbiota by comparing the microbial populations in milk at dry-off (DRY) (~60 days before calving) and post-partum (FRESH) (4–11 days after calving) from cows receiving an intramammary antibiotic infusion prior to dry-off (IMT) and cows that did not receive treatment (CTL). Milk was collected from 23 cows from the IMT group and 27 cows from the CTL group. IMT and DRY samples had a greater correlation with the genera Brevibacterium and Amaricoccus, and the family Micrococcaceae, when compared to IMT and FRESH samples. CTL group samples collected at DRY had a greater correlation with the genera Akkermansia and Syntrophus, when compared to FRESH samples; no bacterial taxa were observed to have a significant correlation with FRESH samples in the CTL group. DRY samples collected from the CTL group had a greater correlation with the genus Mogibacterium when compared to IMT and CTL samples. For DRY samples collected from the IMT group, a greater correlation with the genus Alkalibacterium when compared to DRY and CTL samples, was observed. The lack of a correlation for FRESH samples between the CTL and IMT treatment groups indicated that intramammary antimicrobial dry cow therapy had no significant effect on the udder milk microbiota post-partum.

We used spontaneous behaviours to assess response to dry-off involving abrupt dietary and milking frequency changes, followed by regrouping, after the last milking in 15 clinically healthy Holstein-Frisian cows kept outdoors. Moreover, we explored the potential of infrared thermography to detect eye temperature variations possibly induced by dry-off. On days − 1, 0, 1 and 2 relative to dry-off, we recorded whether cows vocalised during feed delivery; ate fresh feed within 5 min; and mean maximum eye temperature at approximately 1 h after feed delivery. On days 1 and 2, cows were more likely to eat fresh feed compared to days − 1 and 0. No difference in likelihood of vocalising was found. Compared to day − 1, eye temperature was substantially higher on days 0 and 2. Collectively, the results suggest that cows responded, both behaviourally and physiologically, to the abrupt dry-off management. The interpretation of the current findings deserves further investigation using larger sample sizes, more controlled environments and further behavioural, physiological, cognitive and clinical measures. [ABSTRACT FROM AUTHOR]

The incidence of milk leakage (ML) after dry-off (DO) and related risk factors was studied in 1,175 dairy cows from 41 commercial herds in 8 European countries: Belgium, Czech Republic, Denmark, France, Germany, Italy, the Netherlands, and Spain. Milk leakage was assessed twice for 30 s each during 3 visits at 20 to 24 h, 30 to 34 h, and 48 to 52 h after DO. Information related to dry-cow management and udder health was collected at herd and cow level, including individual somatic cell count (ISCC) from test-day controls and occurrence of clinical mastitis cases from DO until 30 d in lactation. Mixed-effect logistic regression analyses were used to identify possible risk factors for ML and to study the association between ML and new intramammary infections. Intramammary infections were defined as clinical mastitis cases during the dry period and in the first 30 d in lactation or a rise in ISCC from before to after the dry period (threshold: 200,000 cells/mL) or both. Milk leakage was observed in 24.5% of the cows between 20 and 52 h after DO, where the herd incidence varied between 0.0 and 77.8%. The reduction in number of milkings in the weeks before DO had statistically significant effect on the ML incidence. When the milking frequency was reduced from 3 times/d to 2 or maintained at twice a day, cows had 11 (95% CI = 3.43–35.46) or 9 (95% CI = 1.85–48.22) times higher odds of leaking milk, respectively, compared with cows where the milking frequency was reduced from twice to once a day. Also, the milk production 24 h before DO was associated with ML incidence. Hence, cows with a milk production between 13 and 21 L or above 21 L had 2.3 (95% CI = 1.48–3.53) and 3.1 (95% CI = 1.79–5.3) times higher odds of leaking milk, respectively, compared with cows with a milk production below 13 L. A higher ML incidence was present in the group of cows with an average ISCC in the last 3 mo before DO ≥200,000 cells/mL (odds ratio = 1.7; 95% CI = 1.13–2.41) compared with cows with an average ISCC <100,000 cells/mL. Quarters with ML tended to have 2.0 times higher odds of developing clinical mastitis compared with quarters not leaking milk. Cows with ML tended to have 1.5 times higher odds of intramammary infections (i.e., an increase of ISCC or clinical mastitis) compared with cows without ML. [ABSTRACT FROM AUTHOR]

The abrupt cessation of milking at dry-off may induce milk leakage, which may increase the risk of new intramammary infections (IMI). This study assessed the efficacy of 1 i.m. injection of 5.6 mg of cabergoline (Velactis, Ceva Santé Animale, Libourne, France) at drying-off on milk leakage after dry-off and new IMI across the dry period and postcalving compared with a placebo (negative control) and an intramammary antibiotic treatment (positive control) under field conditions. The study was a double-blind, randomized, 3-arm, multicenter, clinical trial performed under Good Clinical Practice conditions. Data from 900 dairy cows of various breeds from 63 farms in France, Germany, and Hungary were analyzed. Only quarters with no bacterial growth at drying-off and a cow somatic cell count ≤200,000 cells/mL were included. Quarters infected with major or minor pathogens or cows with high somatic cell count at time of inclusion were excluded. Cows that qualified for the study were visited 7 times in total before and after drying-off and after calving. Presence (yes/no) of milk leakage was recorded on the day after dry-off. A new infected quarter (new IMI) was defined as one with a major pathogen present in any one of the 2 postcalving samples. Two mixed logistic regression models were fitted to the data to evaluate the efficacy of cabergoline in the reduction of milk leakage and new IMI. One i.m. injection of cabergoline at drying-off significantly reduced the incidence of milk leakage the day after dry-off compared with both placebo and antibiotic treatment. Cabergoline-treated cows significantly reduced the risk of new IMI by major pathogens across the dry period and postcalving by 21% when compared with placebo cows (20.5 vs. 26.0%, respectively). However, when milk leakage was added to the model, the significance of cabergoline was reduced. We interpreted this to show that milk leakage is an intervening variable between treatment with cabergoline and lower risk of new IMI. The antibiotic treatment significantly decreased the odds of new IMI compared with both cabergoline and placebo. However, because several countries are currently disallowing the preventive use of antibiotics at dry-off in noninfected quarters, the dry-off facilitator cabergoline may therefore be of particular value to reduce the risk of new IMI across the dry period. [ABSTRACT FROM AUTHOR]

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 (I 2 = 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The goal of the present study was to quantify the increase of intramammary pressure (IMP) in dry-off during an extended milking interval of 72 h. In particular, we tested the hypothesis that feed restriction (no concentrate and roughage with reduced energy) causes earlier cessation of milk secretion and a lower IMP than continued feeding of the lactational diet. In addition to repeated IMP measurements, we tested a noninvasive method that records udder firmness (UF) via external application of pressure on the udder. Two experimental groups consisted of 10 Holstein cows each, with a daily milk yield of 20 to 25 kg. The restricted group (RG) was changed to restricted feeding on the afternoon of the final milking (0 h), whereas late-lactation feeding was continued in the control group (CG). Both IMP and UF were measured before and after the final milking immediately before milking was stopped for 72 h. These measurements represented IMP and UF levels at 10 h and 0 h milking intervals, respectively. Further measurements were performed at 18, 24, 30, 36, 42, 48, and 72 h after final milking. Milk samples (2 mL) were taken through the IMP catheter at each sampling event, for analysis of somatic cell count (SCC) and serum albumin (SA). Both IMP and UF increased with time, and both parameters peaked at 30 h in CG and at 24 h in RG. The mean IMP from 18 to 72 h, compared with the 10-h IMP (normal milking interval) was higher in CG than in RG. The duration of elevated IMP and UF was prolonged in CG compared with RG (>36 h vs. 12 h). The Pearson correlation between IMP and UF was r = 0.67. Thus, the noninvasive measurement of UF is suitable to replace invasive IMP measurements. However, due to individual differences in udder shape, the correlation between UF and IMP was too low to predict exact IMP levels using UF. Both SCC (presented as logSCC) and SA increased after the final milking until the end of the experiment. The mean increase from 18 to 72 h, compared with levels immediately after final milking, was higher in CG than in RG for SCC but did not differ between treatments for SA. In conclusion, feed restriction causes a faster cessation of milk secretion and therefore limits the increase of IMP at dry-off. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the effect of treating cows with teat sealant only compared with antibiotic plus teat sealant at drying off on weekly somatic cell count, potential intramammary infection, and milk production across the entire subsequent lactation. In 3 research herds in the south of Ireland, cows with SCC that did not exceed 200,000 cells/mL in the previous lactation (LowSCC) were randomly assigned to 1 of 2 treatments at drying off: internal teat sealant alone (ITS) or antibiotic plus teat sealant (AB+ITS). Cows with SCC that exceeded 200,000 cells/mL in the previous lactation were treated with AB+ITS and included in the analyses as a separate group (HighSCC). Weekly individual animal composite SCC records were available for 654 cow lactations and were transformed to somatic cell scores (SCS) for the purpose of analysis. Data were divided into 3 data sets to represent records obtained (1) up to 35 DIM, (2) up to 120 DIM, and (3) across the lactation. Foremilk secretions were taken from all quarters at drying off, at calving, 2 wk after calving, and in mid-lactation and were cultured to detect the presence of bacteria. The LowSCC cows treated with ITS alone had higher daily milk yield (0.67 kg/d) across lactation compared with LowSCC cows treated with AB+ITS. The LowSCC cows treated with ITS alone had higher SCS in early, up to mid, and across lactation compared with LowSCC cows treated with AB+ITS. We detected no difference in weekly SCS of LowSCC cows treated with ITS alone and SCS of HighSCC cows. The least squares means back-transformed SCC across lactation of the LowSCC cows treated with ITS alone, LowSCC cows treated with AB+ITS, and HighSCC cows were 41,523, 34,001, and 38,939 cells/mL respectively. The odds of LowSCC cows treated with ITS alone having bacteria present in their foremilk across lactation was 2.7 (95% confidence interval: 1.91 to 3.85) and 1.6 (1.22 to 2.03) times the odds of LowSCC cows treated with AB+ITS and of HighSCC cows treated with AB+ITS, respectively. In this study, Staphylococcus aureus was the most prevalent pathogen isolated from the population. Recategorizing the threshold for LowSCC cows as ≤150,000 cells/mL or ≤100,000 cells/mL in the previous lactation had no effect on the results. The results indicate that herds with good mastitis control programs may use ITS alone at dry-off in cows with SCC <200,000 cells/mL across lactation with only a small effect on herd SCC. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the potential of oral acidogenic mineral boluses (196 g) containing anionic salts to facilitate the transition from lactation to the dry stage by inducing a mild and temporary metabolic acidosis at dry-off. In experiment 1, 84 lactating cows were randomly allocated to 1 of 3 treatment groups consisting of an oral administration of 0, 1, or 2 boluses 5 d before dry-off to evaluate the effects on milk production. In experiment 2, 16 lactating cows were involved in a crossover study to evaluate the effects of the administration of 2 boluses on milk production, feed intake, and urine pH. In experiment 3, 152 lactating cows were allocated to 1 of 2 treatments (control: no treatment; bolus: 2 oral boluses the day before last milking) to evaluate udder pressure, incidence of milk leakage, and lying behavior during the first days following dry-off. Also, milk yield in the subsequent lactation for all enrolled cows was recorded during the first 60 DIM. In experiment 1, cows receiving 2 boluses had the greatest reduction in milk production (-2.56 kg/d of milk) compared with those receiving 1 bolus or no treatment (-1.15 and -0.23 kg/d, respectively) the second day after bolus application. In experiment 2, the application of oral boluses decreased feed intake of cows during the first 3 d following treatment, and milk production was reduced on d 2 and 3 after bolus application. Reduced urine pH at 8 and 24 h after treatment was observed in bolus cows compared with control cows. In experiment 3, bolus cows had lower udder pressure after drying off, but incidence of milk leakage did not differ between treatments. Bolus cows had an additional 85 min of lying time in the 24 h following dry-off. Serum P and β-OH-butyrate concentrations were lower in bolus cows than in control cows after dry-off, but no other differences in blood parameters between treatments were observed. Also, no differences in milk yield in the subsequent lactation were observed between treatments. It is concluded that oral bolus application diminishes feed intake and milk production, and, if applied at dry-off, it decreases udder pressure and increases lying time during the first 24 h after dry-off. [ABSTRACT FROM AUTHOR]

Selective serotonin reuptake inhibitors have been considered for use in the dairy industry to aid in dry-off procedures because of their ability to delay the onset of lactation. Fluoxetine (a selective serotonin reuptake inhibitor; FLX) is an agent that has been shown to delay the onset of lactogenesis stage II when taken during pregnancy and lactation in women. Two experiments were conducted to determine whether ewes would be an appropriate model to evaluate the effects of FLX on milk production at weaning. In the first experiment, 12 Suffolk cross ewes (body weight = 83.4 ± 12.2 kg; body condition score = 2.1 ± 0.4) in late lactation were assigned to treatments of 0 (control), 40, or 80 mg of FLX. They were given a single subcutaneous injection with the appropriate level of FLX mixed with propylene glycol at 0700 h on approximately d 78 of lactation (the day lambs were removed). In the second experiment, 18 Suffolk cross ewes (body condition score = 1.8 ± 0.3) from a previous lactation study were selected in late lactation. On approximately d 66 following parturition, weaning was initiated and ewes received a single oral bolus treatment (0, 80, or 160 mg of FLX). Treatment was administered using gelatin capsules containing the appropriate dose of FLX. For both experiments, milk production was estimated: in experiment 1 on d 0 (before treatment), 1, 2, and 3 (after treatment) at 0800 and 1100 h, and in experiment 2 on d 0, 1, and 2 following treatment at 0800 or 1100 h. Milk production was measured over a 3-h period. We observed no treatment differences or day effects on milk production in either experiment. In experiments 1 and 2, as the dose of FLX increased, milk production decreased linearly. Serum lactose concentrations were depressed in ewes treated with FLX in experiment 1 but similar across treatments in experiment 2. Overall, FLX depressed milk production in ewes; therefore, there is potential to use FLX as a dry-off agent in the dairy industry. [ABSTRACT FROM AUTHOR]

• In this study, based on the proliferative responses of peripheral immune cells challenged in vitro with common mitogens, we concluded that: • Cows in the final week of gestation and the first 2 wks of lactation had lower cell-mediated immune responses compared with 21 d of lactation. • Cows transitioning from late lactation to dry period maintained unchanged cell-mediated immune function. Parturition and dry-off are challenging events for dairy cows partially due to changes in endocrine responses. The aim of this experiment was to evaluate blood concentrations of cortisol and prolactin and their effects on proliferation of peripheral blood mononuclear cells (PBMC) with or without stimulation by common immune cell mitogens (lipopolysaccharide [LPS], and concanavalin A [ConA]) of multiparous dairy cows from late lactation to the dry period and from the dry period to early lactation. Two groups of cows were enrolled: cows from late lactation to the dry period enrolled at 8 d before dry-off (LTD, n = 6, days in milk at dry-off = 332 ± 41 d) and cows from the dry period to early lactation enrolled at 7 d before expected calving date (DTL, n = 7). Blood was collected on d -8, 3, 7, and 15 relatives to dry-off for LTD cows, and on d -7, 3, 7, and 21 relatives to calving for DTL cows to analyze circulating stress hormones and to isolate PBMC. The PBMC were stimulated in vitro with prolactin (PRL), hydrocortisone (HDC), LPS, ConA, PRL + LPS, PRL + ConA, HDC+LPS, and HDC + ConA to assess proliferative responses. Plasma cortisol and PRL concentrations of LTD and DTL cows were not affected by time. Regardless of time, addition of HDC reduced PBMC proliferation stimulated by LPS, but PRL had no effect. No time effect was observed for proliferation of PBMC collected from LTD cows, but PBMC collected at 21 d after calving had higher proliferative responses to LPS and ConA than those from late dry period or early lactation. In conclusion, results from this experiment confirmed the lower PBMC proliferation during the transition period from the final week of gestation to early lactation and suggested that cows transitioning from late lactation to dry period maintained unchanged cell-mediated immune function. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of milking cessation method (abrupt or gradual) and daily milk yield before dry-off on milk leakage following dry-off and intramammary infections (IMI) at calving. Data from 1,086 quarters of 285 cows from 5 Ohio dairy herds were analyzed. All cows that were due to be dried off within a week were assigned to the same study group to facilitate management. Abrupt-cessation cows kept the farm's regular milking schedule through dryoff, and gradual-cessation cows were milked once daily for the final week of lactation. Aseptic technique was used to collect quarter foremilk samples at the time of enrollment (7 to 14 d before expected dry-off), the final milking before dry-off (D-O), and within 7 d of calving. Cows in the gradual-cessation group were observed for milk leakage during the period of once-daily milking. In the only herd that did not use internal teat sealants at dry-off, milk leakage after dry-off was recorded in both abrupt and gradual groups. Gradual cessation decreased milk production by 33.4% during the final week of lactation, causing milk yield at D-O to be lower for these cows compared with abrupt-cessation cows (13.2 vs. 19.8 kg/d, respectively). Logistic regression models were used to model the probability of a quarter being infected at calving with any pathogen, accounting for clustering of quarters within cows and cows within herds. The final model investigating the probability of IMI at calving was stratified by parity of cows at the time of dry-off (primiparous and multiparous). Among quarters of cows that ended their first lactation, abrupt cessation of milking before dry-off and milk leakage after dry-off were associated with an increased risk of IMI at calving. Among quarters of multiparous cows, on the other hand, gradual cessation of milking before dryoff, presence of IMI at D-O, and thrice-daily milking during lactation increased the odds of IMI at calving. These results indicate that implementation of differing management practices near dry-off for different parity groups may improve mammary health within a herd. [ABSTRACT FROM AUTHOR]

The forced cessation of milk production, or dry-off, is a routine management practice in dairy cattle, sheep, and goats. This practice initiates a dry period, during which the animal is not milked. Milking begins again after parturition. Most of the literature on the dry period has focused on how various drying-off strategies affect milk production and disease; little work to date has addressed how dry-off affects the overall welfare of the dairy animal. The first aim of this review was to present an overview of the importance of dry-off and how it is commonly achieved. Our review shows that much scientific progress has been made in improving health status between lactations. The second aim was to identify important gaps in the literature, of which 2 key research disparities have been identified. We find that much of the work to date has focused on cattle and very little research has examined dry-off in dairy sheep and goats. We also find a lack of research addressing how common dry-off methodologies affect animal welfare on more than just a biological level, regardless of species. [ABSTRACT FROM AUTHOR]

Concentrate withdrawal and feed restriction reduce milk production to facilitate dry-off. We investigated the impact of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dryoff (56 d before scheduled calving). Cows were fed experimental concentrates rich in either crude protein (nitrogenic, n=14), glucogenic precursors (glucogenic, n=14), or lipids (lipogenic, n=15). On d 3 before dryoff, total feed allowance was restricted to 50 % in onehalf of the animals of each dietary group whereas feed allowance remained unchanged in the other animals. Statistical analysis (SAS, version 9.4) was carried out using a mixed model with dietary group, time, and diet×time interaction as fixed effects (Significance assumed at P< 0.05). Feed restriction immediately resulted in a negative energy balance (NEB) and decreased milk production (P< 0.05). Concomitantly, concentrations of non-esterified fatty acids (NEFA) increased, whereas insulin, insulin-like growth factor-1 (IGF-1), and glucagon decreased (P< 0.05). After dry-off, energy balance turned positive and plasma NEFA decreased again. Plasma glucose, insulin, and IGF-1 concentrations increased in all groups after dryoff. Glucose, insulin, and glucagon concentrations in plasma were greater in non-restricted compared with restricted animals after dry-off (P< 0.05). Milk and plasma urea concentrations were increased in cows fed the nitrogenic concentrate (P< 0.05). Overall, metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood. [ABSTRACT FROM AUTHOR]

Mastitis is a prevalent and expensive disease in dairy herds worldwide. Blanket dry cow therapy (BDCT), in which all quarters of all cows are infused with antimicrobials at the dry-off, is a cornerstone for mastitis control in many countries. An alternative approach is the use of selective dry cow therapy (SDCT), in which only cows with high risk for intramammary infection (IMI) at dry-off receive antimicrobials. Our objectives in this cross-sectional study were to estimate the potential reduction in the use of antimicrobials if SDCT was adopted in the US by using cow-level dairy herd data and to describe the factors associated with cows being classified as high-risk for an IMI at dry-off. Besides, we aimed to describe the seasonality in IMI at dry-off. We used cow-level somatic cell score (SCS) test-day data from herds in the western US (DHIA, Dairy Herd Improvement Association, AgriTech, Visalia, CA) to create five scenarios to classify cows as high risk for IMI at dry-off. Associations between cow-level data and state were also used in logistic regression models. We also calculated the average animal-defined daily dosage of antimicrobials per cow per year around the dry period if a BDCT or SDCT approach is used, adjusting for the risk of cases of clinical mastitis in the next lactation for the SDCT approach. The point prevalence of IMI at the last test-day before dry-off varied between 15.0 % and 54 % for primiparous and 34.0 % and 85 % for multiparous cows, depending on the scenario. By extrapolating our results obtained from using data from dairies enrolled in the DHIA testing program for the western US, we demonstrated that regardless of the criteria used to classify cows as high risk of IMI at dry-off (scenarios 1–5), if selective dry cow therapy is adopted in the US, the dairy industry could reduce the use of antimicrobials around the dry-off between 31 % and 66 %. Multiparous cows had greater odds of being classified as high-risk than primiparous cows. Cows dried off in the spring, summer, and fall had lower odds of being classified as high-risk compared to cows dried off in the winter. Advanced days in milk at dry-off was associated with greater risk of IMI at dry-off. Greater milk yield and higher protein percentage at the last test-day before dry-off were associated with decreased odds of a cow being classified as high-risk at dry-off, cows in small herds had greater odds of being classified as high-risk at dry-off, and a variation among states was observed. • Dairy herds in the US may adopt selective dry cow therapy to reduce the use of antimicrobials. • Potential reduction in antimicrobial use around the dry period was found to be between 31 % and 66 %. • Primiparous cows hold the greatest opportunity to reduce the use of antimicrobials at dry-off. [ABSTRACT FROM AUTHOR]

Sudden dry-off is an established management practice in the dairy industry. But milk yield has been increasing continuously during the last decades. There is no information whether the dry-off procedure, which often results in swollen and firm udders, causes stress, particularly in high-producing dairy cows. Therefore, we evaluated the effect of a sudden dry-off on extramammary udder pressure and the concentration of fecal glucocorticoid metabolites (i.e., 11,17-dioxoandrostane, 11,17-DOA) as an indirect stress parameter. Measurements were carried out within the last week before dryoff and until 9 d after dry-off considering 3 groups of milk yield (i.e., low: <15 kg/d, medium: 15-20 kg/d, and high: >20 kg/d). Udder pressure increased in all yield groups after dry-off, peaked at d 2 after dry-off and decreased afterwards. Pressures were highest in high-yielding cows and lowest in low-yielding cows. But only in high-yielding cows was udder pressure after dry-off higher than before dry-off. Baseline 11,17-DOA concentrations depended on milk yield. They were highest in low-yielding (121.7 ± 33.3 ng/g) and lowest in high-yielding cows (71.1 ± 30.0 ng/g). After dry-off, 11,17-DOA increased in all yield groups and peaked at d 3. Whereas in medium- and high-yielding cows 11,17- DOA levels differed significantly from their respective baseline during the whole 9-d measuring period, lowyielding cows showed elevated 11,17-DOA levels only on d 3 after dry-off. However, especially the increase in 11,17-DOA after dry-off between the 3 yield groups was considerably different. Mean 11,17-DOA increase from baseline to d 3 was highest in high-yielding cows (129.1%) and considerably lower in low-yielding cows (40.1%). The highest fecal 11,17-DOA concentrations were measured on d 3 after dry-off, indicating that the stress was most intense on d 2, which is due to an 18-h time lag; at about the same time, udder pressure peaked. Our results showed a negligible effect of a sudden dry-off on low-yielding cows. High-yielding cows, however, faced high extramammary pressures and increased glucocorticoid production. Considering animal welfare aspects, a review of the current dry-off strategies might be warranted. [ABSTRACT FROM AUTHOR]

The dry period plays an important role in maintenance of udder health. Cows are most susceptible to intramammary infections (IMI) after dry-off and near parturition and drying-off procedures may affect the likelihood of IMI at calving. The objective of this study was to evaluate the association of milk yield and infection status at dry-off with the likelihood of IMI at calving by examining different drying-off methods. Cows (n=112) at the Ohio State University Waterman Dairy Teaching and Research Herd were randomly assigned to either an intermittent or a standard, twice-daily milking group 1 week prior to dry-off. All quarters of all cows in the herd were treated with an antibiotic dry-cow product after the last milking. Milk samples were collected 1 week prior to dry-off (pre-dry), on the day of dry-off, and within 3 d of parturition to determine infection status of the quarters. Association between IMI at calving and cumulative milk yield for the final week of lactation and drying-off method was examined using generalized estimation equations with logic link, accounting for potential confounders, such as pre-dry and dry-off infection status, and for the correlated data structure due to quarters clustered within cows. Intermittent milking significantly reduced milk yield at the end of lactation. Increasing cumulative milk yield during the last week of lactation was significantly associated with a greater probability of IMI at calving for quarters that were uninfected prior to dry-off : uninfected quarters of cows producing more than 115 kg during the last week of lactation were 7.1-times more likely to be infected at calving (P=0.0081) than uninfected quarters of cows producing less than 75 kg. Even though the overall cure rate over the dry period was relatively high at 84%, the odds of a quarter being infected at calving was 7.6- and 3.3-times higher if it was infected at dry-off with major pathogens (P<0.0001) or minor pathogens (P=0.028), respectively, compared with an uninfected quarter at dry-off. The results suggest that decreasing milk yield prior to dry-off may serve as an effective means to maintain good udder health in a herd. [ABSTRACT FROM AUTHOR]

Concentration of natural protective factors (NPFs) which have the ability to inhibit growth of mastitis-causing pathogens increase rapidly following the cessation of milking of dairy cows. One such NPF is lactoferrin, an iron-binding protein present in high concentrations in dry-cow secretions. Earlier studies have demonstrated that intermittent milking at the end of lactation increases levels of NPFs in milk and may decrease prevalence of intramammary infections at calving; however, most of these studies date back several decades and may not apply to current high-producing cows. The objective of this study was to assess whether an intermittent milking schedule prior to dry-off increases the concentration of lactoferrin in mammary secretions at the end of lactation and what other factors influence lactoferrin concentration at dry-off. One week prior to dry-off (pre-dry), cows were randomly assigned to an intermittent milking schedule or they continued to be milked twice daily. Duplicate quarter milk samples for microbiological culture were taken at pre-dry and at dry-off to determine infection status of quarters. Quarter somatic cell counts (SCC) were measured on the day of dry-off. Lactoferrin concentrations were quantified by ELISA. Intermittent milking, mean SCC for the last three months prior to dry-off, SCC at dry-off, lactoferrin concentration at pre-dry, quarter infection status at pre-dry and dry-off, days in milk at dry-off, breed, parity, cumulative milk yield for the final week of lactation and season were considered as potential explanatory variables. Their effect on lactoferrin concentration at dry-off was assessed using a mixed-effects linear regression model. Lactoferrin concentration increased significantly during the final week of lactation for cows on an intermittent milking schedule and was significantly associated with initial lactoferrin concentration and infection status at dry-off. [ABSTRACT FROM AUTHOR]

Serotonin (5-HT), a neurotransmitter synthesized from tryptophan, has been proposed as a feedback inhibitor of lactation. We determined that the gene coding for tryptophan hydroxylase 1, the rate-limiting enzyme for 5-HT synthesis, is expressed in bovine mammary epithelial cells in vitro and is upregulated by prolactin. In addition, 5-HT reduced the expression of α-lactalbumin and casein genes in vitro. Furthermore, inhibiting 5-HT synthesis with p-chlorophenylalanine or blocking the 5-HT receptor with methysergide (METH) increased milk protein gene expression. We then evaluated effects of intramammary 5-HT or METH infusion on production and milk composition in 6 multiparous Holstein cows. Cows were assigned to a repeated measures design of contralateral intramammary infusions of METH (20 mg/quarter per d) or saline for 3 d followed by a 7-d washout period before administering 5-HT (50 mg/quarter/d) or SAL for 3 d. For each udder half, milk yield was recorded twice and composition was determined once per day. Blood samples were harvested each day for plasma to determine glucose and nonesterified fatty acid concentrations. Evaporative heat loss, respiration rate, left and right udder temperatures, and rectal temperatures were obtained after each milking to evaluate possible systemic effects of infusions. During METH and saline infusions milk yield increased 10.9%. During 5-HT and saline infusion milk yield decreased 11.1%. Milk yield and physiological responses suggested intramammary 5-HT and METH doses were high enough to cause systemic effects. Infusing saline, METH, and 5-HT increased milk SCC. Infusing 5-HT tended to reduce mean lactose concentration (4.3 vs. 4.6%) relative to saline. Milk protein content was decreased by METH and SAL (2.0%) and was increased (5.8%) by 5-HT followed by a 33% decrease postinfusion. Infusion of METH increased evaporative heat loss 11%, which decreased 11% postinfusion. Infusions of 5-HT or METH did not affect plasma nonesterified fatty acid or glucose concentrations, respiration rate, or milk fat content. We conclude 5-HT infusion reduced milk synthesis, whereas blocking the 5-HT receptor with METH increased milk synthesis. Doses of 5-HT and METH used in this study likely resulted in systemic effects. These data support the concept that 5-HT is a feedback inhibitor of lactation in the bovine. [ABSTRACT FROM AUTHOR]