Two experiments were conducted to evaluate if supplementing rumen-protected choline (RPC; Reashure, Balchem Encapsulates, Slate Hill, NY) could prevent or alleviate fatty liver in dairy cattle. The first experiment evaluated the effect of supplementing RPC on hepatic triacylglycerol (TAG) accumulation during fatty liver induction. Twenty-four dry cows between 45 to 60 d prepartum were paired by body weight (BW) and body condition score (BCS) and randomly assigned to control or supplementation with 15 g of choline as RPC/d. From d 0 to 6, before treatment application, all cows were fed 1.4 kg/d of concentrate and forage ad libitum. Samples of blood and liver, obtained during the pretreatment period, were used for covariate adjustment of blood metabolites and liver composition data. During fatty liver induction (d 7 to 17), cows were fed 1.4 kg/d of concentrate with or without supplementation with RPC, and forage intake was restricted, so cows consumed 30% of the total energy requirements for pregnancy and maintenance. Supplementation with RPC during fatty liver induction did not affect plasma glucose and plasma beta-hydroxybutyrate (BHBA) concentration but did decrease plasma nonesterified fatty acid (NEFA; 703 vs. 562 microEq/L, SE = 40) and liver TAG accumulation (16.7 vs. 9.3 microg/microg of DNA, SE = 2.0). In the second experiment, we evaluated the effect of supplementing RPC on the clearance of liver TAG when cows were fed ad libitum after the induction of fatty liver by feed restriction. Twenty-eight cows between 45 and 60 d prepartum were paired according to BCS and BW and assigned to treatments. Fatty liver was induced by feeding 1.4 kg/d of concentrate (without RPC) and restricting forage intake, so cows consumed 30% of maintenance and pregnancy energy requirements for 10 d. From d 11 to 16, after feed restriction, cows were fed forage ad libitum and 1.4 kg/d of concentrate with or without RPC. Treatments were not applied during fatty liver induction; however, following feed restriction, liver for cows assigned to control and RPC treatments contained 6.8 and 12.7 microg of TAG/microg of DNA, respectively. Measurements obtained before treatment served as covariates for statistical analysis. During the depletion phase, plasma glucose, BHBA, and NEFA were not affected by treatment. Liver TAG, expressed as covariate adjusted means, was 6.0 and 4.9 microg/microg of DNA (SE = 0.4) on d 13, and 5.0 and 1.5 microg/microg of DNA (SE = 0.9) on d 16 for control and RPC, respectively. Rumen-protected choline can prevent and possibly alleviate fatty liver induced by feed restriction.

Beef production needs to increase from 60 million to 130 million tons by 2050 to feed a growing world population, and 70% of this production increase is expected from beef industries located in subtropical and tropical regions of the world. Bos indicus-influenced cattle predominate in these regions but are often managed using practices developed for Bos taurus breeds reared in temperate climates. Hence, a fundamental step to meet the increasing global demand for beef is to develop specific management for B. indicus-influenced cattle in tropical or subtropical environments. Bos taurus and B. indicus are different subspecies, and diverge in social and biological functions due to selection pressure caused by complex evolutionary and domestication processes. Bos indicus cattle display different social responses compared with B. taurus counterparts, which must be taken into account by management planning as these traits directly impact cattle performance and welfare. In tropical and subtropical regions, warm-season perennial C4 grasses are the dominant forages, and their availability has a significant influence on the productivity of beef cattle systems. The resilience of C4 grasses under adverse conditions is one of their most important characteristics, even though these forages have reduced nutritive value compared with forages from temperate climates. Accordingly, nutritional planning in tropical and subtropical conditions must include management to optimize the quantity and quality of C4 forages. Nutritional requirements of cattle raised within these conditions also require special attention, including inherent metabolic compromises to cope with environmental constraints and altered energy requirements due to body composition and heat tolerance. Nutritional interventions to enhance beef production need to be specifically tailored and validated in B. indicus-influenced cattle. As an example, supplementation programs during gestation or early life to elicit fetal programming or metabolic imprinting effects, respectively, yield discrepant outcomes between subspecies. Bos indicus-influenced cattle produce carcasses with less marbling than B. taurus cattle, despite recent genetic and management advances. This outcome is mostly related to reduced intramuscular adipocyte volume in B. indicus breeds, suggesting a lesser need for energy stored intramuscularly as a mechanism to improve thermotolerance in tropical and subtropical climates.

The objective of this study was to compare the effects of 24-h road transport or 24-h feed and water deprivation on acute-phase and performance responses of feeder cattle. Angus × Hereford steers (n = 30) and heifers (n = 15) were ranked by gender and BW (217 ± 3 kg initial BW; 185 ± 2 d initial age) and randomly assigned to 15 pens on d –12 of the experiment (3 animals/pen; 2 steers and 1 heifer). Cattle were fed alfalfa–grass hay ad libitum and 2.3 kg/animal daily (DM basis) of a corn-based concentrate throughout the experiment (d –12 to 28). On d 0, pens were randomly assigned to 1 of 3 treatments: 1) transport for 24 h in a livestock trailer for 1,200 km (TRANS), 2) no transport but feed and water deprivation for 24 h (REST), or 3) no transport and full access to feed and water (CON). Treatments were concurrently applied from d 0 to d 1. Total DMI was evaluated daily from d –12 to d 28. Full BW was recorded before treatment application (d –1 and 0) and at the end of experiment (d 28 and 29). Blood samples were collected on d 0, 1, 4, 7, 10, 14, 21, and 28. Mean ADG was greater (P < 0.01) in CON vs. TRANS and REST cattle but similar (P = 0.46) between TRANS and REST cattle (1.27, 0.91, and 0.97 kg/d, respectively; SEM = 0.05). No treatment effects were detected for DMI (P ≥ 0.25), but CON had greater G:F vs. TRANS (P < 0.01) and REST cattle (P = 0.08) whereas G:F was similar (P = 0.21) between TRANS and REST cattle. Plasma cortisol concentrations were greater (P ≤ 0.05) in REST vs. CON and TRANS cattle on d 1, 7, 14, and 28 and also greater (P = 0.02) in TRANS vs. CON cattle on d 1. Serum NEFA concentrations were greater (P < 0.01) in REST and TRANS vs. CON cattle on d 1 and greater (P < 0.01) in REST vs. TRANS cattle on d 1. Plasma ceruloplasmin concentrations were greater (P = 0.04) in TRANS vs. CON cattle on d 1, greater (P = 0.05) in REST vs. CON on d 4, and greater (P ≤ 0.05) in REST vs. TRANS and CON on d 14. Plasma haptoglobin concentrations were greater (P < 0.01) in TRANS vs. CON and REST cattle on d 1 and greater (P ≤ 0.05) for REST vs. TRANS and CON cattle on d 7. In conclusion, 24-h transport and 24-h nutrient deprivation elicited acute-phase protein reactions and similarly reduced feedlot receiving performance of feeder cattle. These results suggest that feed and water deprivation are major contributors to the acute-phase response and reduced feedlot receiving performance detected in feeder cattle transported for long distances. Copyright © 2013. American Society of Animal Science .

The objective of this study was to evaluate, over 2 consecutive years, the effects of acclimation to human interaction on performance, temperament, plasma concentrations of hormones and metabolites, and pregnancy rates of Brahman-crossbred cows. A total of 160 Braford and 235 Brahman × British cows were assigned to the 2-yr study. Approximately 45 d after weaning (August 2006) in yr 1, cows were evaluated for BW, BCS, and temperament (chute score, pen score, and exit velocity), stratified by these measurements in addition to breed and age, and randomly allocated to 14 groups (Braford = 8; Brahman × British = 6). Groups were randomly assigned to the control or acclimation treatment. In yr 2, cows were reevaluated within 45 d after weaning (August 2007) for BW, BCS, and temperament, stratified, and divided into 14 groups similarly as in yr 1, but in such a way that cows received the same treatment assigned in yr 1. Cows were acclimated to human interaction from August to January, and the acclimation process consisted of the same person visiting groups twice weekly and offering approximately 0.05 kg of range cubes per cow (as-fed basis). In January of both years, cow temperament, BW, and BCS were reassessed and cows were exposed to a 90-d breeding season. Blood samples were collected at the beginning of the acclimation period (August) and breeding season (January) for determination of plasma cortisol, IGF-I, and acute phase proteins. A treatment × breed interaction was detected during yr 1 (P < 0.01) for pregnancy analysis because acclimated Braford cows conceived earlier and at a greater percentage (P < 0.01) compared with control cows. According to values obtained at the beginning of breeding and pooled across treatments and breeds, IGF-I concentrations and BCS affected quadratically (P < 0.05), and concentrations of ceruloplasmin and haptoglobin decreased linearly (P < 0.05), the probability of pregnancy during both years. Temperament and cortisol concentrations decreased the probability of pregnancy linearly (P < 0.05) during yr 1 (only Braford cows for cortisol analysis) and affected the probability of pregnancy quadratically (P < 0.05) during yr 2. Results from this study indicate that acclimation did not affect cow temperament and physiological responses but did increase pregnancy rates of Braford cows during yr 1. Further, measurements and physiological responses associated with temperament influenced the probability of cows becoming pregnant during the breeding season. Copyright © 2009. American Society of Animal Science .