Growth characteristics, reproductive performance, and evaluation of their associative relationships in Brangus cattle managed in a Chihuahuan Desert production system1

Abstract

Balancing growth and reproductive performance in beef cattle managed in desert environments is challenging. Our objectives were to 1) evaluate trends in growth and reproductive traits, and 2) assess associative relationships between growth characteristics and reproductive performance in a Brangus herd managed in a Chihuahuan Desert production system from 1972 to 2006. Data were from bull (n = 597) and heifer calves (n = 585; 1988 to 2006) and cows (n = 525; repeated records of cows, n = 2,611; 1972 to 2006). Variables describing the growth curve of each cow were estimated using a nonlinear logistic function (each cow needed 6 yr of data). Mixed-effect models and logistic regression were used to analyze trends across years in growth and reproductive traits (both continuous and categorical). For continuous traits of calves, a slight cubic response (P < 0.01) described the dynamics of birth weight, 205-d BW, and 365-d BW across years. For categorical traits of females, positive linear trends (P < 0.05) across years were observed in percent pregnant as yearlings, calved at 2 yr of age, and first-calf heifer rebreeding (slopes ranged from 0.007 to 0.014%/yr). Autumn cow BW increased gradually until 1997 (509 kg +/- 8.8) and then decreased gradually by 0.6 kg/yr, whereas pregnancy percentage decreased gradually until 1995 (78.4% +/- 1.0) and then increased slightly by 0.2%/yr. A quadratic effect best described the dynamics of these 2 variables across years (P < 0.01) as well as estimates describing the growth curve of each cow. Specifically, asymptotic BW and age increased (P < 0.05) from 1972 to 1983 and 1990, respectively. Asymptotic age then decreased by 27% from 1983 to 1996 (P < 0.05). The maturing rate index was negatively correlated with age at first calving and calving interval (r = -0.42 and -0.18, P < 0.01), which suggested that early-maturing cows had enhanced fertility in this environment and production system. In summary, minimal changes were observed in measures of growth in bulls and heifers in a Brangus herd managed in the Chihuahuan Desert. Opposing relationships were observed among measures of cow size and fertility; as growth curves shifted toward earlier maturity, measures of reproductive performance suggested that fertility improved.

Multi-Tissue Omics Analyses Reveal Molecular Regulatory Networks for Puberty in Composite Beef Cattle

“…Changes in the gene expression of ADIPOQ and its receptors were associated with ovarian follicular recruitment and luteal function in Holstein cows [56]. Cumulatively, these results provide gene-specific information to support the rationale for long-term study of the relationships of adiposity with fertility in Brangus cattle [57], [48], [58].…”

“…Eight Brangus (3/8 Brahman x 5/8 Angus) heifers representing the pedigree diversity observed in GWAS of fertility traits were selected for this study from the New Mexico State University Brangus breeding program [11], [18], [19], [58]. Averages for fertility trait measures indicative of early puberty in this study were: ACL (651 days), FSC (53.3%), and HPG (78.0%)[10], [11], [19], [58].…”

Genomic analysis of stayability in Nellore cattle

“…Regions responsible for the expression of reproductive traits (quantitative trait loci, QTLs) such ovulation and twinning rate have been identified on this chromosome [30, 31, 32, 33]. Daetwyler et al [30] and Cruickshank et al [34] found that the window of 45 to 50 Mb on BTA5 is associated with AFC and twinning rate in cattle.…”

Genetic parameters of age at first calving, weight gain, and visual scores in Nelore heifers

“…The positive associations between AFC and weight gain from birth to weaning and between AFC and conformation at weaning may also be explained by the fact that weight gain is genetically determined and associated to mature size. Selection for weaning and yearling weights of replacement heifers result in cows with bigger mature sizes (Klosterman, 1972), which may negatively affect female fertility (Luna-Nevarez et al, 2010).…”