Angus Calves Research Articles

Development of the calf grimace scale for pain and stress assessment in castrated Angus beef calves

Grimace scales have been used to assess pain in various animal species. This study aimed to develop the calf grimace scale (CGS), evaluate its responsiveness and the effect of external factors (change of environment and dam separation, and restraint) on CGS. Sixty-nine Angus calves, 6–8 weeks old, were randomly allocated into castrated (n = 34) and sham castrated (n = 35) groups. Images were extracted from videos pre- (M1-M4), during- (M5), and post-castration/sham castration (M6, M7). Six facial action units (FAUs) were identified: ear position, orbital tightening, tension above the eye, nostril dilation, straining of chewing muscle, and mouth opening. Final CGS median scores increased after castration (P < 0.001) for both non-restrained (M7 versus M2) and restrained (M6 versus M3) calves, indicating scale responsiveness. Final CGS median scores increased (P < 0.001) when calves were subjected to external factors before castration (M1 [baseline] versus M2 and M3). However, there was no difference (P > 0.05) in CGS median scores before and after sham castration, regardless of restraint (M3 versus M6, and M2 versus M7), indicating that the external factors may have reached a maximum effect. The CGS is composed of six FAUs, responsive to acute pain and can identify stress unrelated to pain.

509 Growth and health of Holstein and Holstein x Angus calves from birth to the end of the grower phase

Abstract Feedlot growth performance and carcass traits often differ between Holstein and dairy-beef crossbred calves. However, little is known about their performance and health during the growing phase when reared under similar conditions. This study aimed to compare purebred Holstein (n = 20) and Holstein x Angus crossbred (n = 20) steers from birth until the end of the grower phase. Male calves sourced from one commercial farm arrived at a calf rearing facility at 4.7 ± 1.94 d of age. Calves were fed milk replacer (24 % CP, 20% fat) twice daily at 12 % of birth body weight (BW) for the first 2 wk after arrival and 15 % BW thereafter until wk 6. Calves were gradually weaned from wk 7 to 9. Calves were offered starter (21 % CP, 28% starch) ad libitum until wk 12, and were fed a grower diet (15 % CP, 56 % starch) until wk 32. Milk intake was recorded daily and starter intake on a weekly basis. Once on the growing diet, feed intake was recorded daily using automated feed bins (Roughage Intake Control system, Hokofarm Group). Until wk 12, fecal and respiratory scores were recorded twice daily to estimate the incidence of disease, BW was measured weekly and frame measurements (hip and wither heights, and heart and chest girth) were recorded on wk 4, 7 and 12. From wk 12 to 32, BW and frame measurements were recorded monthly. Data were analyzed using PROC GLIMMIX (SAS 9.4), with breed as fixed, and calf and time as random effects. There were no differences between breeds in initial BW (P = 0.69), proportion of days with diarrhea (P = 0.21) or respiratory disease (P = 0.11), intake of milk (P = 0.45), starter (P = 0.83) or grower diet (P = 0.28). Crossbred calves tended to have greater average daily gain during the rearing phase (P = 0.07) and were growing 250 g/d faster than Holstein calves throughout the growing phase (P &amp;lt; 0.01). Thus, at the end of the growing phase, crossbred calves were 33.5 kg heavier than Holstein calves and had a better feed conversion rate (P &amp;lt; 0.01). During the growing phase, crossbred calves had larger heart and chest girths (P &amp;lt; 0.01) than Holstein calves, whereas hip and wither heights were higher (P &amp;lt; 0.01) for Holstein calves throughout the study. Overall, crossbred calves had greater average daily gain and improved feed conversion rate than Holstein calves during the growing phase, but it remains unknown if these differences will affect their feedlot performance.

Evaluation of the effect of dietary supplementation with Allium mongolicum regel bulb powder on the volatile compound and lipid profiles of the longissimus thoracis in Angus calves based on GC–IMS and lipidomic analysis

The effect of A. mongolicum Regel bulb powder (AMRP) supplementation on the flavour of beef from Angus calves has not been investigated thus far. We used GC–IMS and untargeted lipidomics techniques to examine the volatile compound and lipid metabolic profiles and reveal the effects of dietary AMRP supplementation on the flavour of beef. A total of 6 characteristic volatile compounds and 30 key lipid compounds were identified in the AMRP treatment group. AMRP promoted the release of triglycerides and phosphatidylinositols from beef and accelerated the production of volatile compounds such as ethyl acetate, 1-penten-3-one, and tetrahydrofurane, and the production of these three characteristic volatile compounds was significantly correlated with the UFAs in triglycerides according to correlation analysis. In summary, dietary AMRP supplementation had a positive effect on the flavour of beef, and these findings provide a theoretical basis for the development and utilisation of AMRP as a feed additive.

Choosing the optimal combination of lungs lobe evaluation during focused pulmonary ultrasonography in calves

Bovine respiratory disease (BRD) poses significant challenges on beef and dairy farms, impacting mortality rates, animal welfare, and production efficiency. Although pulmonary ultrasonography is highly sensitive and specific for monitoring lung lesions and diagnosing BRD, its practical application could be optimized by focusing on the most commonly affected lung lobes. This study first evaluated the efficacy of focused lung ultrasonography for diagnosing BRD in calves, examining individual lung lobes and their associations versus the extensive lung scanning under various disease prevalence scenarios. Then, the relationship between individual and combined clinical respiratory signs vs lung consolidation was analyzed. In a combined analysis, 193 Holstein calves from a longitudinal study and 112 Angus calves from a cross-sectional study underwent a total of 1265 complete bilateral thoracic ultrasonographic evaluations from 1 to 6 mo of age. Then, it was assessed the agreement and sensitivity of specific lung lobe combinations compared with the findings from total lung ultrasonography. The Classification and Regression Tree (CART) algorithm was used to suggest an optimal examination sequence, and logistic regression was applied to associate specific clinical signs with the presence of lung consolidation adjusting for breed and calf age. Findings reveal that the most sensitive areas are cranial (K: 0.867; Se: 84.7%) and the caudal (K: 0.433; Se: 40.3%) portions of the right cranial lobe, the caudal portion (K: 0.235; Se: 20.6%) of the left cranial lobe, and the middle lobe (K: 0.25; Se: 22%). The optimal lobe combinations for focused lung ultrasonography were identified as the right cranial lobe paired with either the left cranial lobe or the middle lobe. Focused techniques achieved sensitivity over 94% and maintained good agreement. Using these focused techniques were relatively robust to various true lung consolidation scenarios. CART analysis recommended initiating examinations with the right cranial lobe, proceeding to the left cranial lobe, and concluding with the middle lobe. While spontaneous cough was linked to pneumonia presence, reliance on a single clinical sign is not advised due to low sensitivity (26.8%) and high specificity (85.4%); it should merely prompt further ultrasound assessment. In conclusion, focused lung ultrasonography, especially utilizing the right cranial lobe in conjunction with the left cranial lobe or the middle lobe, emerged as effective strategies for focused pulmonary ultrasonography, preserving the accuracy of the results.

Profitability, greenhouse gas emissions and feed-food competition of strategies to exploit compensatory growth in Uruguayan weanling-to-beef systems

This study evaluates nutritional and management strategies aimed at exploiting compensatory growth (CG) in weanling-to-beef systems in Uruguay. The evaluation encompassed productivity, economic viability, and environmental impact. The Grange Beef System Model, augmented with Uruguayan national technical coefficients, was used. Four weanling-to-beef systems were modeled: 1) forage only with no CG (FNC), 2) forage only with management improvements to exploit CG (forage with CG; FWC), 3) forage with concentrate supplementation during two winter feeding periods (forage with supplementation; FWS), and 4) forage with supplementation during the first winter followed by feedlot finishing (forage with feedlot; FWF). The systems purchased spring-born Angus calves at 8 months of age and 180 kg live weight (LW) and finished with a slaughter weight of 550 kg. FWS system was used as reference with the performance parameters obtained during 5 years of systems experimentation. FNC used the performance parameters of FWS but during winter periods, LW gain was lower due to the absence of concentrate supplementation. FWC used the previous FNC performance parameters, but increased LW gain after the first and second winter restriction period due to improved grazing management practices thereby exploiting CG. FWF is based on the FWS system but instead of moderate supplementation during the second winter (concentrate: 3.0 kg/d/head), steers are feedlot finished (concentrate: 9.5 kg/d/head) exploiting CG due to previous summer-autumn restriction period. FNC and FWC increased age at slaughter, reducing net beef production by 21 and 11 % relative to FWS, respectively. In contrast, FWF reduced age at slaughter, increasing beef production by 93 % compared to FWS. FWS and FNC had similar profitability expressed in net margin; however, FWC and FWF increased net margin by 33 and 107 % compared to the FWS, respectively. FNC and FWC increased greenhouse gas (GHG) emissions intensity per beef produced by 17 and 3 % relative to FWS, respectively; meanwhile, FWF reduced GHG intensity by 10 % relative to FWS. Due to the inclusion of concentrates in the diet for FWS and FWF systems, the only net producers of human edible energy and protein were the forage-only systems (FNC and FWC). In summary, strategically harnessing CG in both pasture and feedlot finishing stages within a weanling-to-beef system in Uruguay successfully increased profitability. Feedlot finishing reduced GHG emissions per beef produced. However, the forage-only farm systems emerged as the only net producers of human-edible energy and protein.

Effects of dietary Allium mongolicum Regel powder supplementation on the growth performance, meat quality, antioxidant capacity and muscle fibre characteristics of fattening Angus calves under heat stress conditions

The aim of this study was to investigate the effects of dietary Allium mongolicum Regel powder (AMRP) supplementation on the growth performance, meat quality, antioxidant capacity and muscle fibre characteristics of fattening Angus calves. Growth performance data and longissimus thoracis (LT) samples were collected from four groups of fattening Angus, which were fed either a basal diet (CON) or a basal diet supplemented with an AMRP dose of 10 (LAMR), 15 (MAMR), or 20 g/animal/day AMRP (HAMR) for 120 days before slaughter. AMRP addition to the feed improved growth performance and meat quality and altered muscle fibre type. Some responses to AMRP supplementation were dose dependent, whereas others were not. Together, the results of this study demonstrated that dietary supplementation with 10 g/animal/day AMRP was the optimal dose in terms of fattening calf growth performance, while 20 g/animal/day AMRP supplementation was the optimal dose in terms of meat quality.

Bovine medicine: Whats´s your diagnosis?

Two Angus calves housed in the Swiss Alps for two months were presented with brisket edema, jugular distension, and diarrhea. Hematological and biochemical examination included elevated concentration of erythrocytes and increased activity of liver enzymes. Ultrasonography revealed small amount of pleural effusion hepatomegaly and congested caudal vena cava. The diagnosis of congestive heart failure secondary to high-altitude disease was confirmed in pathology.

PSII-8 Analysis of maternal influence on phenotypic ultrasound measurements of weaned Angus calves

Abstract Ultrasound carcass data can be used to accurately estimate the body composition of beef cattle in comparison with a body composition score. Literature regarding the analysis of phenotypic carcass data has focused predominately on yearling or mature cattle with limited measurements on weaned calves. Therefore, the influence of the milking ability of the dam on body composition traits measured via carcass ultrasound is unknown. The objective of this study was to estimate correlations between the maternal influence of the dam on the phenotypic ultrasound measurements of the calf. To quantify maternal influence, the expected progeny difference (EPD) for milk (MILK) of the dam was correlated to three ultrasound measurements of the calf: backfat thickness (BFAT), ribeye area (REA), and intramuscular fat (IMF). Ultrasound measurements were collected 1 wk after weaning on 104 purebred Angus heifer calves from the Iowa State University McNay Memorial Research and Demonstration Farm located outside Chariton, Iowa. The average age and body weight for heifers were 187 d and 195 kg, respectively. The milk EPD of the dam was correlated to the ultrasound measurements taken on the calves. For each trait, Pearson’s correlations were calculated between the ultrasound traits of the calf to the dam’s milk EPD using R Statistical Software version 4.3.1. A small positive correlation was identified between MILK and REA (r = 0.28, P = 0.004). This suggests a weak phenotypic relationship between MILK and REA for weaned heifers. The correlation between MILK to BFAT and IMF was 0.10 (P = 0.318) and -0.05 (P = 0.619), respectively. These correlations were not significantly different from zero. This suggests the potential for milk production of the dam has little association with BFAT and IMF for weaned heifers. Although further research is needed, the results from this study indicate little to no relationship between milk EPD of the dam on ultrasound measures of the calf for BFAT, REA, and IMF.

Production and economic justification of different methods of feeding roughage to calves

The purpose of the research is to study the timing of technological operations and the effect of different methods of feeding roughage to Aberdeen Angus calves on age-related changes in the body weight and the effectiveness of cultivation during the dairy period. 3 groups of newborn Aberdeen Angus calves of 10 heads each were formed: 1st (control) – calves fed roughage together with adult livestock, 2nd (control) – calves fed in a separate pen (canteen) from their mothers, 3rd (control) – calves fed in an experimental feeder with limited access for adult livestock located in a separate pen. For the entire period of research, 201 seconds or 3.35 minutes were spent on performing basic technological operations in the 3rd experimental group, which is 3847 seconds or 64.12 minutes, less than in the 1st group and 609 seconds or 10.15 minutes, less than in the 2nd group. The actual palatability from the experimental feeder (calves of the 3rd group) was higher by 132 kg (p &gt; 0.999) than in the 1st group and by 66 kg (p &gt; 0.99) than in the 2nd group. The smallest amount of uneaten hay residues was in the experimental feeder and amounted to 99 kg which is 54 kg less (p &gt; 0.999), than in the 1st group and 18 kg less than in the 2nd group (p &gt; 0.99). The minimum hay losses were 36 kg in the 3rd group, while in the 1st group this figure was 114 kg, and in the 2nd group 84 kg, which is more by 78 (p &gt; 0.999) and 48 kg (p &gt; 0.999), respectively. At the age of six months, the calves of the 3rd group surpassed the live weight of the herdmates of other groups by 4.2–6.1 kg (p &gt; 0.95–0.99). Their superiority in average daily growth over the entire study period was 21–33 g (p &gt; 0.95–0.99). It turned out to be more cost-effective (by 2.8–4.7 abs. %) to raise the calves which were fed hay from a developed feeder.

A small proportion of Zebu genetic background in crossbred calves may not be enough to improve resistance against natural bovine Babesia spp. infections

The main objective of cattle breeders in tropical and subtropical regions is to acquire animals with taurine-productive traits adapted to the broad weather range of these regions. However, one of the main challenges on using taurine genetics in these areas is the high susceptibility of these animals to tick-borne diseases. Consequently, the present study evaluated from 10 November 2021–19 April 2022, the over 13 assessments, the Babesia bovis and Babesia bigemina DNA loads and the IgG anti-B. bovis and anti-B. bigemina levels in Angus (n = 17, 100% Taurine) and Ultrablack (n = 14, ∼82% taurine and 18% Zebu) calves. Data were analyzed using a multivariate mixed model with repeated measures of the same animal including the fixed effects of evaluation, genetic group, sex, Babesia spp., and their interactions. The repeatability values were estimated from the (co)variances matrix and expressed for each species. The correlations between the DNA loads (CNlog) and IgG titers (S/P) values for the two species were also estimated using the same model. Regarding the specific IgG antibody titers for both Babesia spp., no significant differences were observed between the two genetic groups. However, for B. bovis and B. bigemina DNA loads, Ultrablack calves presented significantly higher values than Angus calves. Under the conditions evaluated in this study, our findings suggest that the low percentage of Zebu genetic in the Ultrablack breed was insufficient to improve resistance against babesiosis. Further studies must demonstrate if the low percentages of Zebu genetics in Taurine breeds can modify the susceptibility to babesiosis infections.

A de novo mutation in CACNA1A is associated with autosomal dominant bovine familial convulsions and ataxia in Angus cattle.

Bovine familial convulsions and ataxia (BFCA) is considered an autosomal dominant syndrome with incomplete penetrance. Nine Angus calves from the same herd were diagnosed with BFCA within days of birth. Necropsy revealed cerebellar and spinal cord lesions associated with the condition. Parentage testing confirmed that all affected calves had a common sire. The sire was then bred to 36 cows across two herds using artificial insemination, producing an additional 14 affected calves. The objective of this investigation was to identify hypothesized dominant genetic variation underlying the condition. Whole-genome sequencing was performed on the sire, six affected and seven unaffected paternal half-sibling calves and combined with data from 135 unrelated controls. The sire and five of the six affected calves were heterozygous for a nonsense variant (Chr7 g.12367906C>T, c.5073C>T, p.Arg1681*) in CACNA1A. The other affected calves (N = 8) were heterozygous for the variant but it was absent in the other unaffected calves (N = 7) and parents of the sire. This variant was also absent in sequence data from over 6500 other cattle obtained via public repositories and collaborator projects. The variant in CACNA1A is expressed in the cerebellum of the ataxic calves as detected in the transcriptome and was not differentially expressed compared with controls. The CACNA1A protein is part of a highly expressed cerebellar calcium voltage gated channel. The nonsense variant is proposed to cause haploinsufficiency, preventing proper transmission of neuronal signals through the channel and resulting in BFCA.

Selenium status of beef cattle in the Czech Republic

The aim of the study was to determine the prevalence of selenium (Se) deficiency in Angus Aberdeen (AA) cows and calves during the grazing season on several farms in different geographical locations of the Czech Republic. Selenium deficiency was diagnosed by measuring Se concentrations in whole blood. A total of 78 cows and 78 calves aged 3 to 6 months were examined in eight herds. The reference range of blood Se in cows and calves is 80 to 120 ug/l. Lower values are indicative of deficiency. Overall, Se deficiency was observed in 39.75% cows and 80.76% calves. Suboptimal Se status was mainly a consequence of low Se concentration in pasture vegetation. The Se concentration in plants ranged from 0.032 to 0.086 mg/kg on dry matter basis. Selenium deficiency adversely affected fertility and natality in cattle. In the herd with the highest prevalence of Se deficiency (Herd 2), the number of calves reared till 6 months of age per 100 cows (natality) was as low as 80. The findings show that the grazing cattle suffered from major Se deficiency. The results of the study highlight the importance of implementing early diagnosis, effective prevention, and use of appropriate mineral supplements.

Effect of different levels of serum lead concentrations on weight growth and hematological parameters of aberdeen angus bull calves

The studies were performed on physiologically healthy Aberdeen Angus bulls. Animals based on data on the content of lead in blood serum, by percentile method, were divided into three groups: group I – up to the 25th percentile; group II – within the limits of 25-75 percentiles; group III – above the 75th percentile. The estimated parameters are: the elemental composition of blood, morphological and biochemical compositions of blood, the antioxidant status of blood serum. It was found that in terms of the average daily gains over the two-month period preceding sampling, bulls of groups II and III were inferior to individuals from group I by 3.8 and 11.3% (P≤0.05), respectively. The blood serum of group I bulls contained more Ca, Zn, Se, while minimal Cd concentrations were noted. In bulls with a minimum concentration of lead, an increased content of total protein, uric acid, monocytes, erythrocytes, and hemoglobin in the blood was noted. As the concentration of lead increased from minimum to maximum, the activity of the enzymes of primary antioxidant protection – superoxide dismutase and catalase - decreased, against the background of an increase in the level of malonyldialdehyde.

PSIII-3 Effects of Milk Replacer Composition on Beef X Dairy Calf Growth and Muscle Fiber Cross-Sectional Area

Abstract Increased availability of female-sexed semen for the generation of replacement heifers within the dairy industry has expanded the opportunity for production of crossbred beef x dairy (BxD) calves. However, data evaluating feeding strategies for BxD calves are limited. The objective of this study was to determine the effects of two different milk replacers on muscle growth of BxD calves compared with dam-reared Angus calves. We hypothesized that both male and female BxD calves fed added fat and protein through milk replacer would have muscle fiber cross-sectional area (CSA) similar to that of purebred Angus calves. SimAngus x Holstein calves (n = 40) were assigned to one of two treatments: a) additional 32.0% crude protein (CP), 30% crude fat (CF) milk replacer (ADD, n = 10 males, 10 females), or b) control 22% CP, 20% CF milk replacer (CON, n = 10 males, 10 females). BxD calves were fed milk replacer 3 times daily from 0 to week 8 of age. BxD calves received starter grain and hay ad libitum at ±3 days of age. Twenty Angus calves (n=10 males, 10 females) were group housed in cow-calf pairs with ad libitum access to maternal milk. Calves were weighed within 24 h of birth. Longissimus muscle biopsies were performed on week 2 and 8. Samples were cryosectioned, stained with wheat germ agglutinin, and analyzed for muscle fiber CSA. Body weight and CSA were analyzed with PROC MIXED of SAS with animal as the subject and fixed effects of treatment, breed, age, sex, and their interactions. Repeated measures analysis was used for CSA. At birth, Angus calves were 24% lighter than BxD (P &amp;lt; 0.0001). Females were 8% lighter than males for both breeds (P ≤ 0.02). At week 2 of age, CSA of ADD BxD calves was 16% smaller than Angus or CON BxD calves (P ≤ 0.07). At week 8 of age, relative to CON, Angus calves had 22% larger CSA (P = 0.02) and ADD BxD calves had 17 % larger CSA (P = 0.07). There was no difference detected in CSA between Angus and ADD calves (P = 0.54). In conclusion, feeding milk replacer with additional CF and CP may increase muscle growth in BxD calves.

PSXIV-12 Evaluation of an Ensiled, Self-Fed Diet for Backgrounding Beef Cattle

Abstract Self-feeding of ensiled forages consists in allowing the animals to feed from the silo face through a physical barrier. Energy, protein, and mineral supplements are offered separately in free-choice portable feeders. Compared with offering a total mixed ration, the self-feeding system could result in differences in ensiled forage and supplement intake and may increase animal performance variability. Ensiling a complete diet may contribute to overcome these drawbacks. This study compared the performance of calves that consumed an ensiled backgrounding diet from a silo-bag face (self-feeding, SF) with that of calves fed a diet mixed and delivered daily in a feed bunk (TMR). A single forage sweet sorghum crop was harvested and bagged to be used in the TMR treatment, or harvested and added a dry supplement (45% finely-ground corn grain, 50% extruded soybean meal, and 5% vitamin-mineral premix without ionophore) during bagging, using an adjustable-discharge hopper mounted above the bagger’s packing rotor, to be used in the SF treatment. Regardless of treatment, the diet consisted of 61% forage sorghum and 39% dry supplement (DM basis; 9.9 and 11.6% CP, 42.3 and 43.8% NDF, and 9.8 and 9.5% starch for TMR and SF diets, respectively). Bagged feeds were allowed to ensile for 50 d before experiment began. Two hundred fifty-two, non-implanted Angus calves (224 ± 4.6 kg) were blocked by body weight (BW) and coat color resulting in 6 blocks and 1 pen/block per treatment with 12 or 30 animals per TMR or SF pen, respectively; more animals were required in the SF pens to maintain feed fresh and reduce spoilage, though BW was measured on 12 calves. Pens assigned to SF treatment were each equipped with a silo bag blocked off with an iron fence. The TMR animals were fed ad libitum once a day. In SF pens, feed was carved from the silo-bag face manually twice daily using a pitchfork onto a pile on the fence’s bag side. Cattle were fed for 70 d and held off feed and water for 16 h to record initial (day 1) and final BW (day 70). Data were analyzed as a randomized complete block design. Rate of BW gain, DMI, and DMI relative to BW were greater (P &amp;lt; 0.01; Table 1) for SF calves compared with TMR, resulting in greater (P = 0.03) final BW but similar (P = 0.36) ADG:DMI. Coefficient of variation (CV) of final BW and ADG and the increase in CV of BW did not differ (P ≥ 0.93) between treatments. Similar feed efficiency and animal performance variability were achieved by feeding an ensiled ration offered in a self-feeding system or a traditional TMR. The former might represent a simple and feasible feeding alternative for small-size beef cattle operations.

370 Evaluation of Nutrient Digestibility By Calves Born from Early and Late Shedding Angus Dams

Abstract Researchers have investigated several factors that could alter fetal growth, including nutrient restriction (Valiente et al., 2021), hair shedding (Gray et al., 2011), and extreme hot and cold temperatures (Davidson et al., 2022). Hot temperatures and increased humidity percentages in the southeast United States caused researchers to investigate the hair coats of Angus cattle in the commercial production setting. An improvement in fiber digestibility and calf birth and weaning weights has been observed in Angus dams that shed 50% of the winter hair coat by May (Gray et al., 2011; Burnett et al., 2021). Our objective of this experiment was to investigate the nutrient digestibility of Angus calves born to cows that on average, shed early compared with calves from cows that shed later. Newly weaned, purebred Angus bull calves (early; n = 6, late; n = 6) were housed in metabolism crates for 10 d. Before the trial, calves had a 14-d adaption period to a 14% CP textured feed (CPC 14% Developer, CPC Commodities, Fountain Run, KY) and offered ad libitum Cynodon dactlyon hay and water. After 3 d crate acclimation period, urine, feces, orts, and hay samples were collected for 7 d. Concentrate was offered at 0.25% of average BW. Approximately 5% samples were taken of feces, and urine samples had 1 to 1.5% of 25% metaphosphoric acid added to prevent ammonia volatilization, and both collections were composited by animal. Orts were collected at 0600 h daily, dried, and composited by animal. Laboratory analysis included dry matter (DM), organic matter (OM), ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), Kjeldahl N (CP), and fat. Data were analyzed using the GLM procedure of SAS 9.4 in a completely randomized design with calf as the experimental unit. Significant (P ≤ 0.05) means were separated using Fischer’s protected LSD. The model for intake included average daily DM and OM (kg) and adjusted by body weight (BW%). For digestibility analysis, the model included: DM, OM, ash, NDF, ADF, hemi-cellulose (HC), CP, and fat. The N retention model included: N retained (g/d), N retained/consumed (%), and N retained/DM intake (%). There were no differences between early or late calves for DM intake (5.502 ± 0.2774 kg/d; 2.251 ± 0.1247 %BW), or OM intake (5.199 ± 0.2591 kg/d; 2.128 ± 0.1166 %BW). There were no differences in digestibility for either group for DM, OM, Ash, NDF, ADF, HC, CP, or fat (Table 1.). There were also no differences in N retention in either group of calves (3.686 ± 2.0242 g/d; 4.366 ± 2.3964 %; 0.064 ± 0.0355 %). Further research is needed in this area to adequately understand factors influencing nutrient digestibility in calves born from early and late shedding dams.

Increasing the prepartum dose of rumen-protected choline: Effects of maternal choline supplementation on growth, feed efficiency, and metabolism in Holstein and Holstein × Angus calves

Feeding pregnant cows rumen-protected choline (RPC) may have the potential to affect the growth and health of offspring, but little is known about the optimal dose, or the potential mechanisms of action. The objectives of this experiment were to 1) determine if increasing RPC supplementation during late gestation in multiparous Holstein cows would improve calf growth and 2) determine if maternal choline supplementation alters global DNA methylation patterns. Pregnant multiparous Holstein cows (n = 116) were randomly assigned to diets targeting 0g choline ion (0.0 ± 0.000 choline ion, %DM, control; CTL), 15g of choline ion (recommended dose; RD) from an established RPC product (0.10 ± 0.004 choline ion, %DM, RPC1RD; ReaShure, Balchem Corp.; positive control), or 15g (0.09 ± 0.004 choline ion, %DM, RPC2RD) or 22g (0.13 ± 0.005 choline ion, %DM, high dose; RPC2HD) of choline ion from a concentrated RPC prototype (RPC2; Balchem Corp.). Treatments were mixed into a total mixed ration and cows had ad libitum access via a roughage intake control system (Hokofarm Group, Marknesse, Netherlands). All female Holstein (n = 49) and Holstein × Angus calves (male, n = 18; female, n = 30) were enrolled and fed colostrum from a cow within the same treatment. Holstein calves and Holstein × Angus calves were fed an accelerated and traditional milk replacer program, respectively, and offered ad libitum access to calf starter. Jugular vein blood samples were collected, and body weight was measured at 7, 14, 28, 42, and 56 d of age. Categorical treatment and continuous effects of actual prepartum maternal choline ion intake were analyzed using mixed effect models. An interaction of treatment with sex, nested within breed, resulted in any choline treatment increasing the proportion of methylated whole blood DNA in male, but not female calves. Although 37% of Holstein calves across all treatments experienced abomasal bloat, no evidence for differences in health measurements (signs of respiratory disease and fecal consistency) were observed across treatments. During the first 2 wk of life in Holstein calves, RPC2HD tended to increase average daily gain (ADG) and feed efficiency (FE) compared with CTL and increasing maternal choline ion intake linearly increased ADG and FE. Maternal choline supplementation increased plasma glucose compared with CTL, while increasing serum insulin-like growth factor-1 and decreasing serum lipopolysaccharide binding protein at 7 d of age in Holstein calves. In Holstein × Angus calves, the effect of treatment on ADG tended to interact with sex: in males, RPC2HD increased ADG after 2 wk of life compared with CTL, without evidence of a treatment effect in female calves. Increasing maternal choline ion intake linearly increased ADG after 2 wk of age in male Holstein × Angus calves, while quadratically increasing FE in both sexes. Altered global DNA methylation patterns in male Holstein × Angus calves, and changes in blood metabolites in Holstein calves, provide 2 potential mechanisms for observed improvements in calf growth. Continuous treatment models demonstrated that the effects of maternal choline supplementation are sensitive to the amount of maternal choline ion intake, with greater benefit to calves observed at higher maternal intakes.

Plasma metabolomics reveals major changes in carbohydrate, lipid, and protein metabolism of abruptly weaned beef calves

1H NMR-based metabolomics was used to study the effect of abrupt weaning on the blood metabolome of beef calves. Twenty Angus calves (258 ± 5 kg BW; 5 to 6 months old) were randomly assigned to a non-weaned (NW) group that remained grazing with their dam or a weaned (W) group that underwent abrupt separation from their dam to a separate paddock on d 0 of the study. Body weight, behaviour, and blood samples for cortisol and metabolomics were measured at d 0, 1, 2, 7, and 14 of the study. On d 1 and 2, W calves spent less time grazing and ruminating, and more time vocalising and walking, had a greater concentration of cortisol, NEFA, 3-hydroxybutyrate, betaine, creatine, and phenylalanine, and lesser abundance of tyrosine (P < 0.05) compared to NW calves. Compared to NW calves at d 14, W calves had greater (P < 0.01) relative abundance of acetate, glucose, allantoin, creatinine, creatine, creatine phosphate, glutamate, 3-hydroxybutyrate, 3-hydroxyisobutyrate, and seven AA (alanine, glutamate, leucine, lysine, phenylalanine, threonine and valine) but lesser (P < 0.05) relative abundance of low density and very low-density lipids, and unsaturated lipids. Both PCA and OPLS-DA showed no clustering or discrimination between groups at d 0 and increasing divergence to d 14. Blood metabolomics is a useful tool to quantify the acute effects of stress in calves during the first 2 days after abrupt weaning, and longer-term changes in carbohydrate, lipid and protein metabolism due to nutritional changes from cessation of milk intake and greater reliance on forage intake.

The Effect of Dietary Supplementation with Zinc Amino Acids on Immunity, Antioxidant Capacity, and Gut Microbiota Composition in Calves.

The aim of this study was to investigate the effect of dietary supplementation with zinc (Zn) amino acids at different concentrations on immunity, antioxidant capacity, and gut microbiota composition in calves. Twenty-four one-month-old healthy Angus calves of comparable body weight were randomly divided into three groups (four males and four females in each group) based on the amount of Zn supplementation added to the feed the animals received: group A, 40 mg/kg DM; group B, 80 mg/kg DM; and group C, 120 mg/kg DM. The experiment ended when calves reached three months of age (weaning period). The increase in dietary Zn amino acid content promoted the growth of calves, and the average daily weight gain increased by 36.58% (p < 0.05) in group C compared with group A. With the increase in the content of dietary Zn amino acids, the indexes of serum immune functions initially increased and then decreased; in particular, the content of immunoglobulin M in group A and group B was higher than that in group C (p < 0.05), whereas the content of interleukin-2 in group B was higher than that in the other two groups (p < 0.05). In addition, the content of superoxide dismutase and total antioxidant capacity in the serum of calves in group B was higher than that in group C (p < 0.05), and the MDA level was lower than in group C (p < 0.05). Moreover, alpha diversity in the gut microbiota of calves in group B was higher than that in group A and group C (p < 0.05); the dominant phyla were Firmicutes and Bacteroidota, whereas the dominant genera were Unclassified-Lachnospiraceae and Ruminococcus. Linear discriminant analysis showed that the relative abundance of Bacteroides in the gut microbiota of calves in group B was higher than that in group A, and the relative abundance of Prevotellaceae-UCG-003 was higher compared to that in experimental group C. Thus, dietary supplementation of 80 mg/kg of Zn amino acids to calves could improve the immune function and antioxidant capacity, as well as enrich and regulate the equilibrium of gut microbiota, thus promoting the healthy growth of calves.

White coat color of a Black Angus calf attributed to an occurrence of the delR217 variant of MITF.

A white calf, with minimal pigmented markings, was born to two registered Black Angus parents. Given the possibility of an unknown recessive or de novo dominant mutation, whole-genome sequencing was conducted on the trio of individuals. A 3-bp in-frame deletion in MITF was identified; this mutation was unique to the calf but identical to the delR217 variant reported in both humans and murine models of Waardenburg syndrome type 2A and Tietz syndrome. Given the coat color phenotype and identity of the mutation, our data support that this calf represents the first instance of this recurring MITF mutation in cattle.