Cattle acclimate more substantially to repeated handling when confined individually in a pen than when assessed as a group.

Chute (CS) and exit (ES) scores are common subjective methods used to evaluate temperament in cattle production systems. A pen test, which allows behavior to be observed in a non-restrained setting, may also be an effective method to evaluate temperament by allowing more variation among animals to be expressed. The merit of pen scores in assisting producers in evaluating temperament is equivocal. The objectives of this study were to validate the usefulness of a pen score in delineating temperamental cattle and to determine whether these behavioral scores change under repeated and routine management. Over 3 consecutive years, a factorial design of two measurement protocols (frequent [F], infrequent [IN]) and three recording periods was used. The F measurements were collected over 3 consecutive days and IN measurements only on day 1 within a recording period. Each year, 20 mostly Angus commercial Bos taurus heifers were randomly assigned to each protocol. Behavior was measured using a CS, ES, and exit velocity. Body temperature and heart rate also were recorded. A fecal and blood sample were collected and analyzed for levels of various metabolites including glucose concentration and serum cortisol. Following routine handling, each heifers' response to 30 s of exposure to a human stressor was recorded both individually and in groups of four. An individual (IPS) and group (GPS) pen scores were assigned from 1 (docile) to 6 (aggressive). For all heifers, protocol, event, and their interaction, were compared on the first day of an event. For F heifers, event and day within event were instead used. Body weight was included as a covariate, with sire and year fitted as random effects. Reliability of IPS and GPS were determined using a kappa (K) coefficient. Both IPS and GPS were reliably assigned (K = 0.64 and 0.44 for IPS and GPS, respectively) and positively correlated with body temperature, heart rate, glucose, and serum cortisol (r = 0.28 to 0.37). Furthermore, F heifers acclimated to repeated handling in an individual pen setting (P < 0.05) while acclimation to handling within groups was not evident (P > 0.14). IPS provides a reliable evaluation of temperament in a non-restrained setting that is indicative of an animal's response to stress and may be useful when attempting to make phenotypic selection decisions. However, temperamental heifers became calmer with repeated gentle handling.

Chute and exit scores are common subjective methods used to evaluate temperament in cattle production systems. A pen test, which allows behavior to be observed in a non-restrained setting, may also be an effective method to evaluate temperament by allowing more variation among animals to be expressed. However, the merit of pen scores in assisting producers in evaluating temperament has yet to be discerned. Therefore, the objectives of this study were to validate the usefulness of pen scores in delineating temperamental cattle and to determine whether these behavioral scores change under repeated and routine management. Pen scores collected on heifers either individually or as a group could be assigned reliably and were indicative of an animal's response to stress during normal handling practices. Temperamental heifers, when handled more frequently, acclimated to repeated handling in an individual pen setting but not in a group. Therefore, regardless of method, when cattle are excitable during their first handling experience, more than one observation of temperament may be beneficial before assessing temperament.

A Causality Perspective of Genomic Breed Composition for Composite Animals.

Genomic breed composition (GBC) of an individual animal refers to the partition of its genome according to the inheritance from its ancestors or ancestral breeds. For crossbred or composite animals, knowing their GBC is useful to estimate heterosis, to characterize their actual inheritance from foundation breeds, and to make management decisions for crossbreeding programs. Various statistical approaches have been proposed to estimate GBC in animals, but the interpretations of estimates have varied with these methods. In the present study, we proposed a causality interpretation of GBC based on path analysis. We applied this method to estimating GBC in two composite breeds of beef cattle, namely Brangus and Beefmaster. Three SNP panels were used to estimate GBC: a 10K SNP panel consisting of 10,226 common SNPs across three GeneSeek Genomic Profiler (GGP) bovine SNP arrays (GGP 30K, GGP 40K, and GGP 50K), and two subsets (1K and 5K) of uniformly distributed SNPs. The path analysis decomposed the relationships between the ancestors and the composite animals into direct and indirect path effects, and GBC was measured by the relative ratio of the coefficients of direct (D-GBC) and combined (C-GBC) effects from each ancestral breed to the progeny, respectively. Estimated GBC varied only slightly between different genotyping platforms and between the three SNP panels. In the Brangus cattle, because the two ancestral breeds had a very distant relationship, the estimated D-GBC and C-GBC were comparable to each other in the path analysis, and they corresponded roughly to the estimated GBC from the linear regression and the admixture model. In the Beefmaster, however, the strong relationship in allelic frequencies between Hereford and Shorthorn imposed a challenge for the linear regression and the admixture model to estimated GBC reliably. Instead, D-GBC by the path analysis included only direct ancestral effects, and it was robust to bias due to high genomic correlations between reference (ancestral) breeds.