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The aim of this study was to evaluate the influence of the temperature and humidity index on reticulorumen parameters such as temperature, pH, rumination index, and cow walking activity levels. Throughout the experiment, the following parameters were recorded: reticulorumen pH (pH), reticulorumen temperature (RR temp.), reticulorumen temperature without drinking cycles, ambient temperature, ambient relative humidity, cow walking activity levels, heat index, and temperature–humidity index (THI). These parameters were registered with particular smaXtec boluses. SmaXtec boluses were applied on 1 July 2022; 24 days were the adaptation period. Measurements started at 25 July 2022 and finished at 29 August 2022. The THI was divided into two classes: THI < 72 (comfort zone) and THI ≥ 72 (higher risk of thermal stress). Cows assigned to the 2nd THI class had lower average values for pH, temperature, and rumination index, but not walking activity levels. The mean differences ranged from 0.36 percent in temperature to 11.61 percent in walking activity levels (p < 0.01). An analysis of the THI revealed a significant positive linear relation with hours, where the THI had a tendency to increase on average by 0.2403. The reticuloruminal pH showed a negative linear relation with hours, where the reticuloruminal pH had a tendency to decrease on average by 0.0032, p < 0.001. Data analysis revealed a significant positive linear relationship between walking activity levels and hours, where walking activity levels had a tendency to increase on average by 0.0622 steps per hour, p < 0.001. The rumination index was not significantly related to hours (p < 0.005), although the rumination index had a tendency to increase by 0.4376 per hour, p > 0.05. The influence of HS on reticulorumen parameters increased the risk of acidosis and cows’ activity levels. HS had a negative impact on reticulorumen pH, temperature, and the rumination index. A higher THI (≥72) increased the risk of ruminal acidosis and decreased cows’ physical activity levels. From a practical point of view, we can use innovative tools for the detection of HS and its impact on reticulorumen parameters and cow walking activity levels.

The physiological function of the reticulorumen plays an essential role in ruminant nutrition, and detailed knowledge of rumen motility can further advance understanding of ruminant nutrition and physiology. Rumen motility was simulated by setting different stirrer rotation speeds in a rumen simulation technique (RUSITEC) system. The aim of this study was to investigate the effects of rotation speeds on rumen fermentation, saturation factor of dissolved gases, hydrogen (H2) and methane (CH4) emissions, microbial protein synthesis, and selected microbial population using RUSITEC. The experiment was performed according to a balanced 3 × 3 Latin square design, and each period included 7 d for adaptation and 3 d for sampling. Three motility treatments included 5, 15, and 25 rpm rotation speeds. Daily total gas and H2 and CH4 emissions had quadratic responses to the increasing rotation speed and were highest at 15 rpm. Quadratic and linear responses (highest at 5 rpm) to increasing rotation speed were observed for saturation factors of H2 and CH4, liquid-dissolved H2 and CH4 concentrations, and headspace concentration of H2 in the gas phase, whereas increasing rotation speed linearly decreased saturation factors of CO2 and liquid-dissolved CO2 concentration. Quadratic and linear responses to increasing rotation speed were observed for molar percentages of acetate, ammonia, and microbial protein concentration, whereas increasing rotation speed quadratically increased pH and decreased total volatile fatty acid concentration and acetate-to-propionate ratio. The 15-rpm rotation speed had the highest values of total volatile fatty acids, acetate molar percentage, and microbial protein concentration. Quadratic and linear responses to increasing rotation speed were observed for copy numbers of solid-associated fungi and fluid-associated bacteria, fungi, and protozoa, while increasing rotation speed linearly increased copy numbers of solid-associated protozoa. Rotation at 15 rpm increased populations of fungi and protozoa in the solid rumen contents and the population of bacteria and fungi in the liquid rumen contents. In summary, this study provides insights on the biofunction of proper rumen motility (i.e., at a rotation speed of 15 rpm), such as improving feed fermentation, increasing gas emissions with decreased dissolved gas concentrations and saturation factors, and promoting microbial colonization and microbial protein synthesis, although further increase in rotation speed (i.e., to 25 rpm) decreases feed fermentation and microbial protein synthesis.

OBJECTIVE To evaluate the reticulorumen pH of beef feedlot steers throughout the feeding period and to assess the association between the respective durations that the reticulorumen pH was ≤ 5.6 (subacute ruminal acidosis) and ≤ 5.2 (acute ruminal acidosis) and liver abscess severity. ANIMALS 59 feedlot steers (mean body weight, 349.5 kg). PROCEDURES On day 0, each steer was orally administered an electronic bolus that monitored the reticulorumen pH every 10 minutes for 150 days. Steers were transitioned from a starter to intermediate ration on day 8 (transition 1) and from the intermediate to finish ration on day 19 (transition 2). The ration carbohydrate and megacalorie contents increased with each transition. During each transition, the lower megacalorie ration was fed at the 8:00 AM feeding and the higher megacalorie ration was fed at the 2:00 PM feeding for 3 days before the higher megacalorie ration was fed extensively. Steers were sent to slaughter after 182 days; each carcass was assessed for liver abscesses. RESULTS The diurnal reticulorumen pH pattern was characterized by a peak at 7:00 AM and nadir at 8:00 PM. The mean percentages of time that the reticulorumen pH was ≤ 5.6 and ≤ 5.2 were more than 10-fold greater during transition 1, compared with during transition 2, and were significantly greater for steers with extensive liver abscesses than for steers without extensive liver abscesses. CONCLUSIONS AND CLINICAL RELEVANCE Efforts to minimize the duration that the reticulorumen pH is ≤ 5.6 might mitigate liver abscess formation in feedlot cattle.

Our objectives were to determine the effect of starter crude protein (CP) content on body composition of male Holstein calves from birth to 10 wk of age in an enhanced early nutrition program, and to compare the enhanced program to a conventional milk replacer program. Calves (n = 45) were purchased on the day of birth and assigned to a randomized block design. Eight calves were harvested at baseline and remaining calves were divided among the following 3 dietary treatments: (1) low rate of milk replacer [LMR; 20.6% CP, 21.7% fat; 1.25% of body weight (BW) as dry matter (DM)] plus conventional starter (CCS; 21.5% CP, DM basis); n = 11 calves; (2) high rate of milk replacer (HMR; 29.1% CP, 17.3% fat; 1.5% of BW as DM for wk 1, 2% of BW as DM wk 2-5, 1% of BW as DM wk 6) plus conventional starter; n = 12 calves; and (3) enhanced milk replacer (HMR) plus high-CP starter (HCS; 26% CP, DM basis); n = 14 calves. A subset of calves (n = 8) was harvested on d 2 to provide baseline data. Calves began treatments on d 2 or 3 of age. Calves were weaned at d 42. Starter was available ad libitum. Calves from each treatment were harvested at 5 (n = 18) and 10 (n = 19) wk of age and divided into 4 fractions: carcass; viscera; blood; and head, hide, feet, and tail. Fractions were analyzed for energy, CP, lipid, and ash. Average weekly starter intake did not differ between enhanced treatments. Gain of BW was greater for calves fed HMR than for LMR, but was unaffected by starter CP. Carcass weights at 5 wk were greater for HMR but did not differ between starter CP content. At 10 wk, carcass weights were heavier for HMR and had a greater percentage of empty BW for HMR + CCS than for HMR + HCS. At 10 wk, the weights of reticulorumen and liver were greater for calves fed HMR + HCS than for those fed HMR + CCS. At 5 wk, empty BW gain for HMR contained more water and less fat and ash than in calves fed LMR. At 10 wk, empty BW gain for calves fed HMR + HCS contained a greater percentage of water and less fat than for calves fed HMR + CCS. Plasma β-hydroxybutyrate was greater after weaning for calves fed HMR + HCS than for those fed HMR + CCS. After weaning, calves fed HMR had greater plasma total protein concentration than those fed LMR, and total protein was greater for calves fed HMR + HCS than those fed HMR + CCS. Plasma urea N was greater for calves fed HMR treatments, and postweaning was greater for calves fed HMR + HCS. A high-CP starter had minimal effect on empty BW gain before weaning, but after weaning it tended to increase mass of reticulorumen and liver.

The objective of this study was to determine the early responses to a moderate concentrate increase in cattle diets with regards to various behavioral and physiological responses in cattle. Eight ruminally cannulated Angus crossbred beef heifers were adapted to a 70% concentrate diet (T70) and then switched to a 90% concentrate diet (H90). Measurements of feeding behavior, ruminal pH and temperature, rumen motility, liquid passage rate, and blood acid–base status were conducted on T70 as well as first day (d1) and second day (d2) of high-grain H90feeding to monitor the beginning of the transition period. Ruminal pH was below 5.6 for longer on both days of H90 compared with T70, suggesting animals experienced subacute ruminal acidosis while switching from T70 to H90. Transitioning did not affect dry matter intake (DMI). Eating rate during meals was reduced on d1 and d2 H90 compared with T70. Ruminal contraction amplitude was reduced on both days of H90 feeding. Contraction duration was reduced on d1 H90, and returned to T70 values by d2 H90. Results indicated that a moderate transition to a finishing diet influenced feeding behavior and reduced rumen motility at the beginning time after transition, but did not influence voluntary DMI.

The objectives of the study were to use a heat stress scoring system to evaluate the severity of heat stress on dairy cows using different heat abatement techniques. The scoring system ranged from 1 to 4, where 1 = no heat stress; 2 = mild heat stress; 3 = severe heat stress; and 4 = moribund. The accuracy of the scoring system was then predicted using 3 machine learning techniques: logistic regression, Gaussian naïve Bayes, and random forest. To predict the accuracy of the scoring system, these techniques used factors including temperature-humidity index, respiration rate, lying time, lying bouts, total steps, drooling, open-mouth breathing, panting, location in shade or sprinklers, somatic cell score, reticulorumen temperature, hygiene body condition score, milk yield, and milk fat and protein percent. Three different treatments, namely, portable shade structure, portable polyvinyl chloride pipe sprinkler system, or control with no heat abatement, were considered, where each treatment was replicated 3 times with 3 second-trimester lactating cows. Results indicate that random forest outperformed the other 2 methods, with respect to both accuracy and precision, in predicting the sprinkler group's score. Both logistic regression and random forest were consistent in predicting scores for control, shade, and combined groups. The mean probability of predicting non-heat-stressed cows was highest for cows in the sprinkler group. Finally, the logistic regression method worked best for predicting heat-stressed cows in control, shade, and combined. The insights gained from these results could aid dairy producers to detect heat stress before it becomes severe, which could decrease the negative effects of heat stress, such as milk loss.

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 (NEL)] 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 NEL). At calving all cows were fed the same lactating TMR (14.9% CP, 1.68 Mcal/kg of NEL) 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 ( 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.

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.

Emerging knowledge shows the importance of preweaning nutrition on programming the gastrointestinal microbiome and development of the gut barrier function. The aim of this study was to assess the effects of supplementing cow milk with either intact dried Ulva sp., Ascophyllum nodosum, or Saccharina latissima on growth performance and several gut health parameters of preweaning dairy calves. Forty male Holstein calves were selected based on birth weight (41 ± 4 kg) and plasma Brix percentage (≥8.7%) at d 2 of life. From d 2 to d 42 of life, the control calves (n = 10) were fed with cow milk (8 L/d) without seaweed supplementation, and the experimental calves were fed with cow milk (8 L/d) supplemented with either Ulva sp. (n = 10), A. nodosum (n = 10), or S. latissima (n = 10) at a concentration of 50 g/8 L of cow milk per day (i.e., 5% on a dry matter basis). Calves were weighed every week, and body weight gain and calf starter intake were monitored weekly. At d 42 ± 3 of life, calves were slaughtered. The organ weights and digesta pH from the reticulorumen, mid- and end small intestine, and mid-colon were recorded. A tissue sample (5 cm) collected from the mid-small intestine was analyzed for histomorphology. Digesta from the mid-small intestine and mid-colon were analyzed for lactobacilli, Escherichia coli, and Enterobacteriaceae, and short-chain fatty acid profile. Weight gain of the calves was not affected by seaweed supplementation. Proportional organ weights were not affected by seaweed supplementation except for reticulorumen weight, which was higher in calves fed Ulva sp. Both the mid-small intestinal and mid-colonic digesta populations of lactobacilli, Enterobacteriaceae, and E. coli, as well as the mid-small intestinal histomorphology in seaweed-supplemented calves were not different from control calves. However, acetic acid proportion in mid-colonic digesta was increased in calves fed Ulva sp. and A. nodosum, whereas butyric acid proportion was decreased compared with the control calves. Digesta pH in mid- and end small intestine and mid-colon were not affected, whereas ruminal pH was increased in calves fed Ulva sp. compared with the control calves. In conclusion, intact dried seaweed supplementation did not improve the growth or selected gut health parameters (i.e., histomorphology, digesta pH, bacteria, and short-chain fatty acids) in preweaning Holstein calves.

Bovine respiratory disease (BRD) is the most important and costly health issue of the feedlot industry worldwide. Remote monitoring of reticulorumen temperature has been suggested as a potential tool to improve the diagnostic accuracy of BRD. The present study aimed to evaluate 1) the difference and degree of reticulorumen hyperthermia episodes between healthy and subclinical BRD feedlot steers, and 2) determine the correlation between reticulorumen hyperthermia and lung pathology, performance, and carcass traits. Mixed-breed feedlot steers (n = 148) with a mean arrival weight of 321 ± 3.34 kg were administered a reticulorumen bolus at feedlot entry and monitored for visual and audible signs of BRD until slaughter when lungs were examined and scored for lesions indicative of BRD. Post-slaughter animals with no record of BRD treatment were assigned to one of three case definitions. Healthy steers had no visual or audible signs of BRD (i.e., CIS=1), and total lung consolidation score < 5% or pleurisy score < 3 at slaughter. Subclinical BRD cases had a CIS of 1, and a lung consolidation score ≥ 5% or a pleurisy score of 3 at slaughter. Mild CIS cases had at least one CIS of 2, and a lung consolidation score < 5% and a pleurisy score < 3 at slaughter. Subclinical BRD and mild CIS cases had longer total duration of reticulorumen hyperthermia, more episodes and longer average episode duration above 40.0 °C compared to healthy steers (P < 0.05). A moderate positive correlation was found between lung consolidation and total duration (r = 0.27, P < 0.001), episode duration (r = 0.29, P < 0.001), and number of episodes (r = 0.20, P < 0.05). Pleurisy score was also found to be moderately and positively correlated with total duration (r = 0.23, P < 0.01), episode duration (r = 0.37, P < 0.001), and number of episodes (r = 0.26, P < 0.01). Moderate negative correlations were found between reticulorumen hyperthermia and carcass traits including hot standard carcass weight (HSCW) (−0.22 ≤ r ≤ −0.23, P < 0.05) and P8-fat depth (−0.18 ≤ r ≤ −0.32, P < 0.05). Subclinical BRD reduced carcass weight by 22 kg and average daily gain (ADG) by 0.44 kg/day compared to healthy steers (P < 0.05), but mild CIS cases had no effect on performance (P > 0.05). The reticulorumen bolus technology appears promising for detection of subclinical BRD cases in feedlot cattle as defined by lung pathology at slaughter.

This study evaluated the effects of corn or barley finishing diets on ruminal pH and temperature and their relationship to feed intake events using continuous reticulorumen monitoring of feedlot steers. Average daily ruminal pH and temperature were not impacted (p ≥ 0.17) by diet. However, diet did affect daily variation of ruminal pH and temperature (p &lt, 0.01). Average hourly ruminal pH displayed a diet by hour post-feeding interaction (p &lt, 0.01), where barley-fed steers had greater (p &lt, 0.01) ruminal pH than corn-fed steers at 0, 1, 18, 19, 20, 21, 22 and 23 h post feeding, but had lower (p ≤ 0.05) ruminal pH than corn-fed steers at 6, 7, and 8 h post-feeding. Variation in ruminal pH hour post-feeding also displayed a diet by hour post-feeding interaction (p &lt, 0.01), where barley-fed steers had greater (p ≤ 0.03) variation in ruminal pH at hours 1–17 post-feeding but did not differ (p ≥ 0.16) at 0, 18, 19, 20, 21, 22 and 23 h post-feeding. Additionally, average hourly ruminal temperature exhibited a diet by hour post-feeding interaction (p &lt, 0.01). In summary, basal grain interacted with time post-feeding influencing ruminal pH and temperature in feedlot steers.

Rumen content stratification and the degree of dissociation of particle and fluid retention in the reticulorumen differ between ‘moose-type’ and ‘cattle-type’ ruminant species. These differences are not strictly linked to diet, except for a seeming limitation of ‘moose-type’ ruminants to a browsing niche. Nevertheless, these differences can be plausibly linked to other observed differences in ruminants, such as the intraruminal papillation pattern, or the size of the omasum. However, many of the corresponding measures are still only available for a restricted number of species. Here, we investigated the dry matter (i.e., the inverse of the moisture) concentration in forestomach contents of 10 blackbuck (Antilope cervicapra) and 7 Arabian sand gazelle (Gazella subgutturosa marica), and quantified the rumen papillation pattern. The blackbucks had distinct rumen contents stratification, with more moisture in ventral than in dorsal contents (difference 3.6% units, P < 0.001), whereas this difference was much less pronounced in the sand gazelles (0.6% units, P = 0.227). While reticulum contents were particularly moist in both species, omasum contents were particularly dry in sand gazelles, but did not differ in moisture from rumen contents in the blackbuck. This species is an outlier among ruminants due to its extremely small omasum. The intraruminal papillation pattern did not differ between blackbucks and sand gazelles and showed a surface enlargement factor (SEF) in the dorsal rumen of 27–28% of the SEF in the Atrium ruminis. Compared to data on digesta retention in the same species, the findings are in line with the overall concept of a high fluid throughput causing a distinct stratification of rumen contents and intraruminal papillation, and necessitating a large omasum for fluid re-absorption. However, the data also show that individual species may not correspond to all the assumptions of the concept, suggesting taxon-specific differences between species. Reasons for these differences cannot be linked to a dietary grass-browse spectrum, but may lie in evolutionary contingency.

Monensin has been shown to decrease mortality and morbidity in feedlot cattle by reducing the incidence of acute and subacute rumen acidosis (SARA). Lately, the technique of real-time observance of reticuloruminal temperature and pH, which involves placement of indwelling pH probes in the reticulum or in the rumen has gained in popularity. In this study, we aimed to determine, using real-time monitoring in fresh dairy cows, how monensin controlled release capsules affect the reticulorumen temperature and pH. We used a slow-release rumen preparation, which emitted daily monensin doses of 335 mg. Following the manufacturer’s instructions, the preparation was administered through an oral balling gun. The following points indicate the method for determining the two experimental groups: (1) monensin-supplemented test group (TG) (a 32.4 g monensin controlled release capsule, MCRC, n = 20) and (2) a control group (CG) (capsule containing no monensin, n = 20). Both began a day after calving, and one month after calving the experiment was finished. A set of smaXtec boluses fabricated for animal care was used to measure the temperature and pH of the reticulorumen. After the first day of the study, a statistically significant difference between reticulorumen temperature in CG (38.67 ± 0.10 °C) and TG (39.08 ± 0.09 °C; P < 0.01) was found. The use of the monensin controlled release capsule, which emitted daily monensin doses of 335 mg, in the first 30 days after calving increased the reticulorumen pH by 1.89% (P < 0.001), and the temperature of the reticulorumen by 0.82 % (P < 0.001). We conclude that using monensin in the form of monensin controlled release capsules reduces the risk of SARA. Real time observation of temperature and pH levels in the reticulorumen in fresh dairy cows allows for evaluation of the risk of SARA and provides the opportunity to determine the prophylactic effect of those capsules.

Estrus in dairy cattle varies in duration and intensity, highlighting the need for accurate and continuous monitoring to determine optimal breeding time. The objective of this study was to evaluate precision dairy monitoring technologies (PDMT) for detecting estrus. Estrus was synchronized in lactating Holstein cows (n = 109) using a modified G7G-Ovsynch protocol (last GnRH injection withheld to permit expression of estrus) beginning at 45 to 85 d in milk. Resumption of ovarian cyclicity at enrollment was verified by transrectal ultrasonography for presence of a corpus luteum. Cows were observed visually during 30 min (4 times per day) for behavioral estrus on d -1 to 2 (d 0 = day of estrus). Periods peri-estrus were defined by the temporal blood plasma progesterone patterns on d -5, -4, -3, -2, -1, 0, 2, 4, 6, and 8. Estrous detection by PDMT, an estrous behavior scoring system, and by visual observation of standing estrus were compared with the reference (gold) standard. Only 56% of cows that ovulated were observed standing by visual observation. Sensitivity and specificity for estrous detection were not different among all PDMT. Devices in this study measuring activity in steps, neck movement, high activity of head movement, or a proprietary motion index increased on the day of estrus 69 to 170% from the baseline before estrus. The change in rumination time on the day of estrus decreased for both neck and ear-based technologies (-2 to -16%). Temperature of the reticulorumen, vagina, and ear skin were not different on the day of estrus than day peri-estrus. Daily lying times decreased on average to 24.6% on the day of estrus for IceQube (IceRobotics Ltd., Edinburgh, Scotland). In contrast, lying time increased 15.5 and 33.1% for AfiAct Pedometer Plus (Afimilk, Kibbutz Afikim, Israel) and Track a Cow (ENGS Systems Innovative Dairy Solutions, Rosh Pina, Israel), respectively. All PDMT tested were capable of detecting estrus at least as effectively as visual observation. Four of the 6 PDMT that reported estrous alerts correctly detected 15 to 35% more cows than visual observation 4 times per day. Use of temporal progesterone patterns correctly identified more cows than visual observation alone. Dairy producers considering PDMT should focus on (1) the reference (gold) standard used to test efficacy of a device's alerts and (2) the device that will have the fewest false readings in their operations.

In this study we hypothesized that the lameness of early lactation dairy cows would have an impact on inline biomarkers, such as rumination time (RT), milk fat (%), milk protein (%), milk fat/protein ratio (F/P), milk lactose (L, %), milk electrical conductivity of all udder quarters, body weight (BW), temperature of reticulorumen content (TRR), pH of reticulorumen content (pH), and walking activity (activity). All 30 lame cows (LCs) used in this experiment had a score of 3–4, identified according to the standard procedure of Sprecher et al. The 30 healthy cows (HC) showed a lameness score of one. RT, milk fat, MY, milk protein, F/P, L, milk electrical conductivity of all udder quarters, and BW were registered using Lely Astronaut® A3 milking robots each time the cow was being milked. The TRR, cow activity, and pH of the contents of each cow’s reticulorumen were registered using specific smaXtec boluses. The study lasted a total of 28 days. Days “−14” to “−1” denote the days of the experimental period before the onset of clinical signs of lameness (day “0”), and days “1” to “13” indicate the period after the start of treatment. We found that from the ninth day before the diagnosis of laminitis until the end of our study, LCs had higher milk electrical conductivity in all udder quarters, and higher milk fat to protein ratios. On the 3rd day before the onset of clinical signs of the disease until the day of diagnosis, the milk fat of the LC group was reduced. The activity of the LCs decreased sharply from the second day to the first day after treatment. RT in the HC group tended to decrease during the experiment. pH in LCs also increased on the day of the appearance of clinical signs.

The aim of the current study was to investigate the relation between reticulorumen contractions and monitored cow behaviors. A purpose-built pressure measuring device was used and shown to be capable of detecting the known contraction patterns in the reticulorumen of four rumen-fistulated cows. Reticular pressure data was used to build a random forest algorithm, a learning algorithm based on a combination of decision trees, to detect rumination and other cow behaviors. In addition, we developed a peak-detection algorithm for rumination based on visual inspection of patterns in reticular pressure. Cow behaviors, differentiated in ruminating, eating, drinking, sleeping and ‘other’, as scored from video observation, were used to develop and test the algorithms. The results demonstrated that rumination of a cow can be detected by measuring pressure differences in the reticulum using either the random forest algorithm or the peak-detection algorithm. The random forest algorithm showed very robust performances for detecting rumination with an accuracy of 0.98, a sensitivity of 0.95 and a specificity of 0.99. The peak-detection algorithm could detect rumination robustly, with an accuracy of 0.92, a sensitivity of 0.97 and a specificity of 0.90. In addition, we provide proof of principle that a random forest algorithm can also detect eating, drinking and sleeping behavior from the same data with performances above 0.90 for all measures. The measurement device used in this study needed rumen-fistulated cows, but the results indicate that behavior detection using algorithms based on only measurements in the reticulum is feasible. This is promising as it may allow future wireless sensor techniques in the reticulum to continuously monitor a range of important behaviors of cows.

In this study, cow reticulorumen content pH and temperature together with the activity were registered using smaXtec boluses, specially designed for animal care. Body weight, rumination time, milk fat/protein ratio, milk yield, milk lactose, milk electrical conductivity, milk somatic cell count and consumption of concentrated feed were registered by Lely Astronaut&reg, A3 milking robots. The cows in this study were assigned into two groups according to the milk lactose concentration: group 1&mdash, milk lactose &lt, 4.70% (n = 20), group 2&mdash, milk lactose &ge, 4.70% (n = 15). The following cows were further classified according to milk fat and protein ratio: F/P &lt, 1.2 (class 1), F/P = 1.2 (class 2) and F/P &gt, 1.2 (class 3). According to our results, we can conclude that inline registered milk lactose concentration can be used to indicate the health status and reproductive success of fresh dairy cows. Cows with an increased lactose concentration (&ge, 4.70%) showed more activity (54.47%) and had less risk of mastitis (determined by lower milk electrical conductivity (EC) and somatic cell counts (SCC)) and metabolic disorders, determined by milk F/P. A higher glucose concentration was also apparent in the cows with higher lactose concentration. Registered lower levels of milk lactose can be used for early identification of metabolic disorders and mastitis (set at milk SCC &ge, 100 thousand/mL). Lactose levels in cows&rsquo, milk were positively associated with their reproductive success.

Made available in DSpace on 2020-12-12T02:41:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-25 The objectives of this study were to compare ruminal total tract digestibility, bacterial communities, and eating and rumination activity between Holstein and Angus steers fed grain- or forage-based diets. Six Holstein steers (average body weight [BW] = 483 ± 23 kg) and six Angus steers (average BW = 507 ± 29 kg), previously fitted with rumen cannulae, were fed in a crossover design with a 2 × 2 factorial arrangement of four treatments: 1) Holsteins fed a grain-based diet, 2) Holsteins fed a forage-based diet, 3) Angus fed a grain-based diet, and 4) Angus fed a forage-based diet. Each period was 35 d with 26 d of diet adaptation and 9 d of sample collection. On days 1 and 2 of collection, feeding activity was recorded for 48 h. On day 3, rumen contents were sampled to measure ruminal pH at 0, 3, 6, 12, and 18 h after feeding. A portion of the strained ruminal fluid was subsampled at 0, 3, and 6 h for volatile fatty acids (VFA) analysis. Rumen contents were subsampled at 3 h for analysis of bacterial communities. From day 4 to 8, total fecal excretion, feed, and refusals samples were collected and analyzed for dry matter (DM), neutral detergent fiber (NDF), and starch. On days 8 and 9 (0 and 3 h post-feeding, respectively), total reticulorumen evacuation was conducted and contents were weighed. Data were analyzed using the MIXED procedures in SAS (v9.4 SAS Inst. Inc., Cary, NC). Repeated measures were used to analyze changes in ruminal pH and VFA over time. There were no interactions of diet × breed (P ≥ 0.07). While the main effects of diet were expected, unique to these data is the fact that bacterial diversity and richness were reduced (P < 0.01) in cattle fed grain-based diets. There was no main effect (P > 0.34) of breed on total tract DM, organic matter, and starch digestibility, but Angus cattle had greater (P = 0.01) NDF digestibility than Holsteins. The increased NDF digestibility may be associated with a numerical (P = 0.08) increased numbers of bacterial species in Angus steers compared with Holstein steers. Holstein steers also spent more time (P ≤ 0.05) ruminating than Angus steers. There was no effect (P > 0.80) of breed on reticulorumen content at feeding time; however, Holstein steers had greater (P = 0.04) reticulorumen content on a wet basis 3 h post-feeding. Although Holstein steers spent more time ruminating, Angus steers were better able to digest NDF when compared with Holsteins, regardless of basal diet, and this improvement may be related to changes in bacterial communities in the rumen or to rumination activity. Department of Animal Science Pennsylvania State University Department of Animal Production College of Technology and Agricultural Sciences São Paulo State University (UNESP) Department of Animal Production College of Technology and Agricultural Sciences São Paulo State University (UNESP)

Neutral detergent fiber (NDF), as the main component of structural carbohydrate in forage, is a vital factor impacting the performance of young ruminants. The objective of this study was to evaluate the effect of starter NDF level on the rumen fermentation and morphometrics of lambs fed isocaloric and isonitrogenous diets. One hundred Hu sheep lambs (18 days of age and 6.1 ± 0.1 kg body weight [BW]) were randomly assigned to one of the four starter diets differing in their NDF levels on a dry matter (DM) basis: 1) diet with 14% NDF (NDF14), 2) diet with 18% NDF (NDF18), 3) diet with 22% NDF (NDF22), and 4) diet with 26% NDF (NDF26). Lambs were fed milk replacer with designed starters from 21 to 60 d of age and then transitioned to the same starter feed until 90 d of age. Six lambs from each treatment (close to the average BW of the corresponding treatment) were selected and slaughtered at 90 d of age for measuring rumen fermentation, anatomical development, and morphometric characteristics. Lambs receiving NDF22 and NDF26 starter diets had greater (P < 0.05) intake of starter and total DM, and average daily gain during the overall period, thereby heavier (P < 0.05) final weights at 90 d of age compared with those fed NDF14 starter diet. At 90 d of age, lambs fed NDF22 and NDF26 starters had higher rumen pH, followed by lower propionate, higher acetate concentrations (P < 0.05), and a higher acetate-to-propionate ratio compared with those fed NDF14 and NDF18 starters (P < 0.05). No significant differences of the full and empty weight of reticulorumen were observed among treatments; however, the reticulorumen weight expressed as a percentage of the complex stomach weight was lower (P < 0.05) in lambs fed NDF22 and NDF26 starters compared with those fed NDF14 starter. Furthermore, NDF14 lambs had the thickest keratin layer and epithelium compared with those in the other treatments but showed the thinnest muscle layer (P < 0.05). These results suggest that increasing starter NDF levels can ameliorate the rumen fermentation environment and alleviate hyperkeratosis and plaque formation in the rumen epithelium. In summary, including 22% and 26% NDF in the pelleted starter can improve the performance of lambs.

The objective of this study was to evaluate the effect of rolled barley grain (RB) supplementation on rumen metabolism, omasal flow of nutrients, and microbial dynamics in lactating dairy cows fed fresh perennial ryegrass (Lolium perenne L.; PRG)-based diets. Ten ruminally cannulated Holstein cows averaging (mean ± standard deviation) 49 ± 23 d in milk and 513 ± 36 kg of body weight were assigned to 1 of 2 treatments in a switchback design. The treatment diets were PRG only (G) or PRG plus 3.5 kg of dry matter RB (G+RB). The study consisted of three 29-d periods where each period consisted of 21 d of diet adaptation and 8 d of data and sample collection. A double marker system was used to quantify nutrient flow entering the omasal canal along with labeled 15N-ammonium sulfate to measure bacterial, protozoal, and nonmicrobial N flow. Rumen evacuation techniques were used to determine nutrient and microbial pool size, allowing the calculation of fractional rates of digestion and microbial growth. There was no difference in daily milk yield or energy-corrected milk yield between treatments. Milk fat concentration and milk urea N decreased, whereas milk protein concentration increased in cows fed the G+RB diet. During the omasal sampling phase, dry matter intake was higher in cows fed the G+RB diet. Ruminal and total-tract neutral detergent fiber digestibility was lower in G+RB cows; however, no difference was observed in reticulorumen pH. The rumen pool size of fermentable carbohydrate was increased in cows fed the G+RB diet; however, the fractional rate of digestion was decreased. Flow of nonammonia N and bacterial N at the omasal canal increased in cows fed the G+RB diet compared with the G diet. Protozoa N flow was not different between diets; however, protozoa appeared to supply a much larger amount of microbial N and exhibited shorter generation time than previously considered. Feed N ruminal digestibility, corrected for microbial contribution, was similar for both treatments (88.4 and 89.0% for G and G+RB, respectively). In conclusion, RB supplementation did not benefit overall animal performance; however, it reduced ruminal neutral detergent fiber digestibility and increased bacterial N flow. The results demonstrate the large dependence of cows consuming PRG-based diets on microbial N as the main source of nonammonia N supply. Additional quantitative research is required to further describe the supply of nutrients and microbial dynamics in cows consuming PRG-based diets in an effort to determine most limiting nutrients.

We hypothesized possibility that inline registered reticulorumen pH can be as biomarker of cows reproduction and health status. Aim of this study was to evaluate the relationship of reticulorumen pH with biomarkers from automatic milking system (AMS) and some blood parameters and determinate reticulorumen pH as biomarker of cows reproduction and health status. According to cows reproductive status the cows were classified as belonging to the following four groups: 15-30 d. postpartum; 1-34 d. after insemination; 35 d. after insemination (non-pregnant); 35 d. after insemination (pregnant). According reticulorumen pH assay experimental animals were divided into four classes: 1) pH6.62 (10.5% of cows). Rumination time, body weight, milk yield, milk fat – protein ratio, milk lactose, milk somatic cell count (SCC), milk electrical conductivity of all quarters of udder were registered with the help of Lely Astronaut® A3 milking robots. The pH, temperature of the contents of cow reticulorumens and cow activity were measured using specific smaX-tec boluses. Blood gas parameters were analyzed using a blood gas analyzer (EPOC, Canada). We found that pregnant cows has higher reticulorumen pH during insemination time, comparing with non-pregnant. Cows with lower reticulorumen pH has lowest milk fat – protein ratio, and lactose concentration, and highest SCC. Cows with lowest reticulorumen pH has lowest blood pH. With increase reticulorumen pH, increases blood potasium and hematocrit, decreases CO2, saturation and sodium.

The aim of this study was to determine if reticulorumen ph, temperature and cow activity registered before calving can serve as indicators of diseases after calving.The cows were selected according to those fitting the profile of having had two or more lactations (on average 2.9±0.13 lactations), from 60 to 0 days before and the first 30 days after calving, and being clinically healthy. The clinical examination (identification of diseases after calving) was performed from 60 days before calving to 60 days after calving. Diseases after calving were diagnosed based on clinical symptoms specific to these diseases. The pH and temperature of the contents of the cow reticulorumens and cow activity were measured using specific smaX-tec boluses manufactured for animal care.We found that the highest pH and temperature before calving can serve as biomarkers of healthy cows after calving. The lowest reticulum temperature before calving can serve as an indicator of MF after calving. A positive correlation of reticulum pH and temperature before calving can serve as biomarkers of PR. Decreasing cow activity before calving can serve as an indicator of diseases after calving. For calving prognosis, temperature of the reticulorumen can be used; it decreased 6–7 days before calving.

Technological progress enables individual cow's temperatures to be measured in real time, using a bolus sensor inserted into the rumen (reticulorumen). However, current cooling systems often work at a constant schedule based on the ambient temperature and not on monitoring the animal itself. This study hypothesized that tailoring the cooling management to the cow's thermal reaction can mitigate heat stress. We propose a dynamic cooling system based on in vivo temperature sensors (boluses). Thus, cooling can be activated as needed and is thus most efficacious. A total of 30 lactating cows were randomly assigned to one of two groups; the groups received two different evaporative cooling regimes. A control group received cooling sessions on a preset time-based schedule, the method commonly used in farms; and an experimental group, which received the sensor-based (SB) cooling regime. Sensor-based was changed weekly according to the cow's reaction, as reflected in the changes in body temperatures from the previous week, as measured by reticulorumen boluses. The two treatment groups of cows had similar milk yields (44.7 kg/d), but those in the experimental group had higher milk fat (3.65 vs 3.43%), higher milk protein (3.23 vs 3.13%), higher energy corrected milk (ECM, 42.84 vs 41.48 kg/d), higher fat corrected milk 4%; (42.76 vs 41.34 kg/d), and shorter heat stress duration (5.03 vs 9.46 h/day) comparing to the control. Dry matter intake was higher in the experimental group. Daily visits to the feed trough were less frequent, with each visit lasting longer. The sensor-based cooling regime may be an effective tool to detect and ease heat stress in high-producing dairy cows during transitional seasons when heat load can become severe in arid and semi-arid zones.

The way that fluids and particles move through the forestomach of a ruminant is species-specific, and can be used to classify ruminants according to their digestive physiology into 'moose-types' (with little difference in fluid and small particle passage) and 'cattle-types' (where fluids move through the forestomach much faster than small particles). So far, 'moose-types' appear limited to a dietary niche of browsing, whereas 'cattle-types' are particularly prominent in the intermediate and grazing diet niches. However, some species, including members of the spiral-horned antelopes (the Tragelaphini), have a 'cattle-type' physiology but a browse-dominated diet niche. Eland (Taurotragus oryx), the largest member of the Tragelaphini, are strict browsers in the wild but have been considered intermediate feeders in the past, and can seemingly be maintained on grass diets. We quantified food intake, mean retention time (MRT) in the gastrointestinal tract and the reticulorumen (RR) of a solute, a small and a large particle marker, and diet digestibility in six eland each fed a monocot (grass hay) and a dicot (lucerne silage) forage. Food intake and digestibility was lower on the diet with higher fibre content (grass hay), with corresponding longer MRT. At the higher intakes on lucerne, the difference in MRT between small and large particles was larger, indicating a greater reliance on particle sorting and clearance under this condition of potentially limiting gut capacity. Regardless of diet or intake, the ratio of small particle and solute MRT in the RR was constant and small, at a quotient of 1.54, classifying the eland as a typical 'moose-type' ruminant. This finding is consistent with previous literature reports on low faecal metabolic nitrogen and high apparent protein digestibility in eland. Given the relative ease at which eland can be maintained under farm husbandry conditions, they appear ideal model ruminants to study the effects of differences in rumen physiology compared to cattle.

The aim of this study was to determine the effect of exogenous butyrate on the activity of carbohydrate-digesting enzymes in the reticuloruminal digesta and structure and selected functions of the small intestine in sheep. Eighteen rams (30.8 ± 2.1 kg; 12 to 15 mo of age) were fed for 14 d a diet without (CTRL) or with sodium butyrate (BUT; 36 g/kg of offered DM). Butyrate concentration in the reticuloruminal fluid and proximal small intestinal digesta was greater for BUT compared with CTRL (P ≤ 0.05). Amylolytic activity was greater, whereas cellulolytic and xylanolytic activity in the reticuloruminal digesta was less for BUT compared with CTRL (P ≤ 0.04). Relative to BW, small intestinal tissue mass and small intestine length did not differ between treatments (P ≥ 0.15); however, absolute length of the small intestine was greater for BUT compared with CTRL (P = 0.04). In the duodenum, crypt depth tended (P = 0.10) to be greater, whereas in the ileum, crypt depth and muscularis thickness tended (P = 0.10) to be less for BUT compared with CTRL. Mitosis-to-apoptosis ratio in the proximal jejunum was greater for CTRL compared with BUT (P = 0.02). Expression of G-protein-coupled receptor 43 mRNA in the duodenal epithelium was greater for BUT compared with CTRL (P < 0.01). On the other hand, peptide transporter 1 mRNA expression in the distal sections of the small intestine, as well as activity of aminopeptidase A and dipeptidylpeptidase IV, were greater for CTRL (P ≤ 0.05). In summary, exogenous butyrate supplementation in feed affects hydrolytic activity in the rumen, and increased butyrate flow out of the reticulorumen affects both proximal and distal sections of the small intestine in sheep.

Calves can be ruminally cannulated at young ages, but equipment size limitations preclude use of an infusion and sampling device in these small animals. Likewise, a procedure to easily evacuate rumen contents in young calves has not been described. Overcoming these technical complications related to assessment of ruminal passage kinetics, nutrient digestion, and volatile fatty acid absorption would aid in future studies advancing our knowledge of dairy calf nutrition. The first objective was to design and fabricate 2 devices (one device for infusion and sampling, and another for vacuum-assisted collection) suitable for use in young ruminally cannulated dairy calves. The second objective was to test the utility of these tools when performing procedures commonly used in ruminant nutrition research. A single weaned 62-d-old ruminally cannulated calf was used to evaluate the ability to infuse a solution of LiCoEDTA and sample rumen contents through the cannula cap over a period of 2 h to assess the rumen liquid passage rate (procedure 1). The device was capable of infusing the LiCoEDTA and sampling the rumen fluid, as evidenced by the presence of elevated Co concentrations in the sampled rumen fluid. Using the fluid samples obtained, liquid passage rate within the calf was estimated to be 40.2% of ruminal fluid/h. The second procedure tested the vacuum-assisted collection device and consisted of evacuating and weighing the rumen contents, which is considered a key preparatory step in washed reticulorumen technique experiments that aim to measure nutrient absorption. In agreement with existing literature, evacuated rumen contents represented approximately 4% of the calf's body weight. In conclusion, custom-built devices for infusion, sampling, and vacuum-assisted collection were efficacious when tested in a 62-d-old ruminally cannulated calf fed a diet of 100% texturized starter (18% crude protein, as-fed). Fellow scientists may employ and further modify these techniques to suit their needs when assessing passage kinetics, nutrient digestion, and volatile fatty acid absorption in calves.

International audience; Promotion of microbial butyrate production in the reticulorumen is a widely used method for enhancing forestomach development in calves. Additional acceleration of gastrointestinal tract (GIT) development, both the forestomach and lower parts of the GIT (e.g., abomasum, intestine, and also pancreas), can be obtained by dietary butyrate supplementation. For this purpose, different sources (e.g., butyrate salts or butyrins), forms (e.g., protected or unprotected), methods (e.g., in liquid feed or solid feed), and periods (e.g., before or after weaning) of butyrate administration can be used. The aim of this paper was to summarize the knowledge in the field of butyrate supplementation in feeds for newborn calves in practical situations, and to suggest directions of future studies. It has been repeatedly shown that supplementation of unprotected salts of butyrate (primarily sodium salt) in milk replacer (MR) stimulates the rumen, small intestine, and pancreas development in calves, with a supplementation level equating to 0.3% of dry matter being sufficient to exert the desired effect on both GIT development and growth performance. On the other hand, the effect of unprotected butyrins and protected forms of butyrate supplementation in MR has not been extensively investigated, and few studies have documented the effect of butyrate addition into whole milk (WM), with those available focusing mainly on the growth performance of animals. Protected butyrate supplementation at a low level (0.3% of protected product in DM) in solid feed was shown to have a potential to enhance GIT development and performance of calves fed MR during the preweaning period. Justification of this form of butyrate supplementation in solid feed when calves are fed WM or after weaning needs to be documented. After weaning, inclusion of unprotected butyrate salts in solid feed was shown to increase solid feed intake, but the effect on GIT development and function has not been determined in detail, and optimal levels of supplementation are also difficult to recommend based on available reports. Future studies should focus on comparing different sources (e.g., salts vs. esters), forms (e.g., protected vs. unprotected), and doses of supplemental butyrate in liquid feeds and solid feeds and their effect not only on the development of rumen, abomasum, and small intestine but also the omasum and large intestine. Furthermore, the most effective source, form, and dose of supplemental butyrate in solid feed depending on the liquid feed program (e.g., MR or WM), stage of rearing (e.g., pre- or postweaning), and solid composition (e.g., lack or presence of forage in the diet) need to be determined.

The temperature and pH of the contents of the reticulorumen of cattle can be monitored using sensors placed in a rumen bolus. In this research communication we test the hypothesis that these measurements can be used as a predictor of the likelihood of reproductive success. The study was performed on 20 Lithuanian Black and White dairy cows. The pH and temperature of the contents of their reticulorumens were measured using boluses manufactured for animal care (smaXtec animal care technology®). The data from reticulorumen were recording at 1 to 7 and 7 to 56 d post calving and then post insemination (on average 60 ± 12) until 170 d after calving. The pregnancies were tested with ‘Easy scan’ ultrasound 30–35 d after insemination. Those cows which were pregnant were assigned to the PD+ group (n = 12), and those which were not pregnant – assigned to the PD− group (n = 8). Rumen pH was initially lower in the PD+ group but then higher than in PD−, but temperature did not differ between the groups until after conception. We can conclude that cows with disturbed rumen metabolism (with low rumen pH) are less likely to conceive. The measurements of reticuloruminal pH may be useful as a predictor of the likelihood of reproductive success, but more research is needed before practical application.

This study was conducted to determine the effect of different starter diets and different amounts of milk on growth performance and gastrointestinal tract development in unweaned calves. 16 calves were assigned to 4 groups, 4 calves in each group. These four groups received the following treatments respectively: 1) high milk (6 L) + low starch (21%), high NDF (28%), high molasses (10%) starter (HMLS group); 2) high milk (6L) + high starch (40%), low NDF (14%), low molasses (5%) starter (HMHS group); 3) low milk (3 L) + low starch (21%), high NDF (28%), high molasses (10%) starter (LMLS group); 4) low milk (3 L) + high starch (40%), low NDF (14%), low molasses (5%) starter (LMHS group). The trial was of 2 × 2 factorial design. All calves had free access to hay and water. Results showed that the low milk allowance increased calf concentrate dry matter intake (DMI) and total DMI, reduced body height at 4 weeks of age, reduced heart girth at 6 weeks of age (P < 0.05). The low milk allowance increased complex stomach full weight, reticulorumen full weight, and the percentages of stomach full weight and reticulorumen full weight over body weight (P < 0.05). The low starch, high fiber, high molasses starters reduced the complex stomach full weight, the proportion of the complex stomach empty weight over body weight, reticulorumen empty weight, abomasum full weight, the proportion of abomasum empty weight over body weight and reticulorumen volume (P < 0.05). The low milk allowance increased calf intestine length, small intestine full weight, the proportion of small intestine full weight over body weight, but reduced the jejunum villus width (P < 0.05), increased ruminal pH (P < 0.05). The low milk allowance reduced papilla length in rumen anterior ventral blind sac, but increased papilla length in the posterior ventral sac (P < 0.05).

The digestive physiology of cattle is characterised by comparatively long digesta mean retention times (MRTs), a particle sorting mechanism (difference in MRTs of large vs. small particles) and a distinct digesta washing (difference in MRTs between particles and fluids) in the reticulorumen (RR). How these processes mature during ontogeny, and how they link to other digestion characteristics and methane production, is largely unknown. We used a set of passage markers (Co-EDTA for fluids and hay particles of 2, 5 and 8 mm length mordanted with Cr, La and Ce, respectively) to measure MRTs in 12 heifers (0.5–2.1 years; hay only) and two groups of 15 lactating cows (2.4– 10.0 years; forage-only vs. forage-concentrate diet). The MRTs differed between markers (Co < Cr < La < Ce) and were longer in heifers than cows, consistent with the lower feed intake in heifers. MRTs were mostly similar between cow groups and in- creased with age. Digesta washing was not affected by group, age, feed intake and number of chews per unit of feed. The degree of digesta washing was not related to CH4 measures. Particle sorting was more prominent in cows than heifers but did not differ between cow groups or change with age in cows. This could be the consequence of the abrupt increase in intake from heifers to cows at a time when gut capacity is not yet fully developed; particle sorting might then clear smaller particles from the RR sooner allowing a higher intake. Surprisingly, CH4 yield per ingested feed did not cor- relate with MRTs, and CH4 yield per unit of digested fibre decreased with increasing MRTs and with increasing fibre digestibility. As this pattern occurred in heifers and both cow groups, it appeared independent of age, indicating a mechanism that has not been described in the literature so far and requires further investigation.

Fifty-two 4-d-old male Holstein dairy calves (41.3 ± 0.41 kg of BW) were used in a completely randomized design to evaluate the effects of physical form of starter feed on intake, nutrient digestibility, ruminal fermentation, structural growth, and rumen development. At d 4 of age, individually housed calves were randomly allocated (n = 13 per treatment) to 1 of 4 dietary treatments: 1) ground starter feed (Ground; mean particle size of 0.72 mm diameter), 2) textured starter feed including steam flaked corn and barley grains (Textured; mean particle size of 3.61 mm diameter), 3) pelleted starter feed (Pelleted; mean particle size of 4.53 mm diameter), and 4) ground starter feed with 10% chopped alfalfa hay (Ground + AH; mean particle size of 1.02 mm diameter). Calves received 4.0 L/d of pasteurized milk from d 1 to 46 of study and 1.0 L/d from d 47 to 49. Weaning occurred at the end of d 50 and the study lasted for 70 d. During the study (d 1–70), total dry matter (DM) and starter feed intakes, and final BW were greater for calves fed Ground + AH compared with those fed Ground and Pelleted starter feeds. Compared with Pelleted group, calves fed Textured starter feed had greater total DM and starter feed intakes, and final BW with no difference between Ground and Pelleted groups. Feeding Ground + AH starter feed increased average daily gain compared with other groups through the entire of trial. Similarly, feed efficiency was increased and tended to increase in Ground + AH as compared with the Ground and Pelleted groups as well as the Textured group, respectively. Fecal score and skeletal growth measurements were not affected by the dietary treatments. Calves fed Ground + AH starter feed spent more time rumination and had greater rumen pH at d 70 compared with calves fed other starter feeds with no difference in values at d 35. Ruminal NH 3 N concentration was not different between Ground + AH and Textured groups but was greater for both groups compared with Ground and Pelleted groups. At d 70, total volatile fatty acids concentration and the molar proportion of propionate were greater for calves fed Pelleted- vs. Ground + AH starter feed with no difference across other groups. Empty viscera weights including reticulorumen, omasum, and abomasum were not different between Ground + AH and Textured groups; but Ground + AH starter feed increased viscera weights as compared with the Ground and Pelleted starter feeds which was substantiated with both greater rumen wall thickness and muscularization. Overall, Ground + AH starter feed was able to maintain rumen pH at least by induction of greater time spending rumination and promoted growth performance of calves and also influenced morphometric attributes of the rumen wall which substantiated the effect of alfalfa hay supplementation on macroscopic and microscopic appearances by decreasing plaque formation and increasing muscularization, respectively. These benefits, however, were small when Textured starter feed was provided.

The objective of this study was to evaluate the effects of lactose inclusion in calf starters on plasma glucagon-like peptide (GLP)-1 and GLP-2 concentrations and gastrointestinal tract development in calves. Holstein bull calves (n = 45) were raised on an intensified nursing program using milk replacer containing 28.0% CP and 15.0% fat, and were fed a texturized calf starter containing 0 (control), 5.0 (LAC5), or 10.0% (LAC10; n = 15 for each treatment) lactose on a DM basis. Lactose was included in the starter by partially replacing dry ground corn in pelleted portion of the starter. All calf starters were formulated with 23.1% CP. The ethanol-soluble carbohydrate concentrations of the control, LAC5, and LAC10 starters were 7.3, 12.3, and 16.8% on a DM basis, respectively. Starch concentrations of the control, LAC5, and LAC10 starters were 29.7, 27.0, and 21.4% on a DM basis, respectively. All calves were fed treatment calf starters ad libitum. Blood samples were obtained weekly from 1 to 11 wk of age, and used to measure plasma GLP-1, GLP-2, and insulin concentrations, serum β-hydroxybutyrate (BHB) concentration, and blood glucose concentration. At 80 d of age, calves were euthanized, and weights of the reticulorumen, omasum, abomasum, small intestine, and large intestine tissue were measured. Serum BHB concentration was higher for calves fed the LAC10 (171 μmol/L) starter than for those fed the control (151 μmol/L) and LAC5 (145 μmol/L) starters. Plasma GLP-1 and GLP-2 concentrations did not differ between treatments. However, relative to the baseline (1 wk of age), the plasma GLP-1 concentration was higher for the LAC10 (125.9%) than for the LAC5 (68.2%) and control (36.8%), and for the LAC5 than for the control (36.8%). Moreover, similar differences between treatments were observed for GLP-2 concentration relative to the baseline (88.2, 76.9, and 74.9% for LAC10, LAC5, and control treatments, respectively). The serum BHB concentration was positively correlated with the plasma GLP-1 concentration (r = 0.428). Furthermore, the plasma GLP-1 concentration was positively correlated with the insulin concentration (r = 0.793). The weights of the reticulorumen, omasum, abomasum, small intestine, and large intestine were not affected by the treatments. In conclusion, inclusion of lactose in calf starters resulted in higher plasma GLP-1 and GLP-2 concentrations, and BHB might be associated with higher plasma GLP-1 concentration.

The objective of this study was to compare weekly mean lying time (LT), neck activity (NA), reticulorumen temperature (RT), and rumination time (RU) among 3 breed groups, milk yield (MY), and temperature-humidity index (THI). Cows (n = 36; 12 Holstein, 12 crossbred, and 12 Jersey) were blocked by parity group (primiparous or multiparous), days in milk, and MY. Lying time, NA, RT, RU, and MY were recorded and averaged by day and then by week for each cow. For study inclusion, each cow was required to have 10 wk of LT, NA, RT, and RU data. Maximum THI were recorded and averaged daily. Mean (±SE) days in milk, LT, MY, RT, RU, NA, and maximum THI were 159.0 ± 6.0 d, 11.1 ± 0.1 h/d, 28.7 ± 0.5 kg/d, 38.8 ± 0.0°C, 6.4 ± 0.1 h/d, 323.8 ± 3.8 activity units, and 56.5 ± 0.6, respectively. The MIXED Procedure of SAS (SAS Institute Inc., Cary, NC) was used to evaluate fixed effects of breed, MY, parity, THI, and their interactions on LT, NA, RT, and RU with cow nested within breed as subject. All main effects remained in each model regardless of significance level. Stepwise backward elimination was used to remove nonsignificant interactions. The interactions of breed × parity group and maximum THI × parity group were associated with RT. Increasing THI coincided with increasing RT. Least squares means LT for multiparous cows was significantly greater than LT for primiparous cows (11.4 ± 0.3 and 10.5 ± 0.5 h/d, respectively). Least squares means NA for primiparous cows was greater than for multiparous cows of all breeds (372.1 ± 10.9 and 303.4 ± 7.8, respectively). The CORR Procedure of SAS was used to evaluate relationships among RT, RU, LT, NA, and MY. Rumination time was positively correlated with MY (r = 0.30) and negatively correlated with LT (r = −0.14). Reticulorumen temperature was negatively correlated with MY (r = −0.11). Rumination time was positively correlated with NA (r = 0.18) and negatively correlated with LT (r = −0.14). Lying time and NA were negatively correlated (r = −0.43). Neck activity was positively correlated with MY (r = 0.14). Lying time was negatively correlated with MY (r = −0.25). Milk yield was associated with RU, which may be related to cows with greater MY also having a greater feed intake. Lying time increased and NA decreased with increasing parity, which may be effects of social hierarchy, where primiparous cows are more susceptible to being pushed away from the feed bunk and freestalls. Milk yield was positively associated with RU. Greater milk production requires greater feed intake, which may result in longer RU than for low-yielding cows. Lying time decreased as milk yield increased. The behavioral and physiological differences observed in this study provide new insight into the effects that breed, parity, MY, and THI have on cows.

Made available in DSpace on 2021-06-25T15:20:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Despite the important role of digesta mean retention time (MRT) on digestive efficiency of ruminants, it is poorly investigated in total gastrointestinal tract (GIT) of growing ruminants, especially in goats. The objective of this study was to evaluate the effect of body weight (BW) and sex on GIT MRT of particles and solutes in growing Saanen goats. A dataset from two studies, comprising 103 individual records of castrated males (n = 36), females (n = 34), and intact males (n = 33) Saanen goats slaughtered at 15, 22, 30, 37, and 45 kg BW, was used. Goats were fed basically with total mixed ration composed by dehydrated corn plant (Zea mays) milled to pass a 10-mm screen, cracked corn grain, and soybean (Glycine max) meal. Variables evaluated were BW, feed intake, feed intake level, composition of ingested diet, wet weight of GIT tissues, wet digesta pool size, digesta composition (dry matter and neutral detergent fiber [NDF]), indigestible NDF:NDF ratio of ingested diet and GIT digesta, MRT of particles (MRTiNDF) and solutes (MRTCr), and reticulorumen selectivity factors (large particles/solutes). Reticulorumen, omasum, abomasum, small intestine, cecum, and colon-rectum segments were evaluated. The dataset was analyzed as mixed models considering sex, BW, and sex x BW interaction as fixed effects, and study and residual error as random effects. Sex did not affect MRTiNDF in any GIT segments. Females and intact males presented similar reticulorumen MRTCr (5.6 h; P = 0.92) and they presented lower reticulorumen MRTCr than castrated males (7.0; P = 0.11). Reticulorumen and omasum MRTCr increased as BW increased (P < 0.01), and abomasum MRTCr decreased as BW increased (P = 0.02). Feed intake, and wet tissues and wet pool size of all GIT segments increased as BW increased, except abomasum wet pool size (P

Ruminants have been classified as having a ‘moose-type’ or ‘cattle-type’ digestive physiology. ‘Cattle-type’ ruminants have a clear difference in the mean retention time (MRT) of fluid vs. small particles in the reticulorumen (RR), with a high ‘selectivity factor’ (SF=MRTparticle/ MRTfluid,>1.80), and are typically grazers and intermediate feeders. ‘Moose-type’ ruminants have lower SF (< 1.80), possibly because of defensive salivary proteins that constrain amounts of (high-viscosity) saliva, and are typically restricted to browsing. To further contribute to testing this physiology-diet correlation, we performed 55 individual passage measurements in 4/6 species that have/have not been investigated previously, respectively. Co-EDTA was used as a solute (fluid) and Cr-mordanted hay particles (< 2 mm) as particle markers. Results are related to the percentage of grass in the natural diet taken from the literature. Moose (Alces alces, n=4 on 4 to 5 diets each and n=2 on a single diet, 5% grass, SF 1.46 ± 0.22) and giraffe (Giraffa camelopardalis, n=3 on 3 to 5 diets each, 1%, 1.42 ± 0.23) as classical ‘moose-type’, and cattle (Bos taurus, n=2, 70%, 2.04) as classical ‘cattle-type’ ruminants yielded results similar to those previously published, as did waterbuck (Kobus ellipsiprymnus, n=5, 84%, 2.46 ± 0.49), corroborating that the SF represents, to a large extent, a species-specific characteristic. Results in oryx (Oryx leucoryx, n=1, 75%, 2.60) and sitatunga (Tragelaphus spekii, n=4, 68%, 1.81 ± 0.21) correspond to the concept of ‘cattletype’ ruminants being grazers or intermediate feeders. However, European bison (Bison bonasus, n=1, 10%, 2.74), nyala (T. angasii, n=6, 20%, 1.95 ± 0.25), bongo (T. eurycerus, n=3, 13%, 2.39 ± 0.54) and gerenuk (Litocranius walleri, n=1, 0%, 2.25) appear as ‘cattle-type’ ruminants, yet have a browse-dominated diet. While the results do not challenge the view that a ‘moose-type’ digestive physiology is an adaptation to browse diets, they indicate that it may not be the only adaptation that enables ruminants to use browse. Apparently, a ‘cattletype’ digestive physiology with a high SF does not necessarily preclude a browsing diet niche. High-SF browsers might have the benefit of an increased harvest of RR microbiota and grit removal prior to rumination; how they defend themselves against secondary plant compounds in browse remains to be investigated.