Early growth, backfat thickness and body condition has major effect on early heifer pregnancy in Nellore cattle

Abstract

The aim was to evaluate the association between growth, carcass and visual scores traits with precocious calving in Nellore cattle. Birth weight (BW), weight at 120, 210, 365 and 450 days of age, pre and post-weaning average daily gain, rib eye area, backfat thickness (BF), rump fat thickness and visual scores obtained at 18 months were used for the analysis. Records from 700 females born between 2009 and 2015, exposed to mating starting at 11 months of age were analyzed. Discriminant analyzes were performed with the software Statistica. BW and BF showed the highest (P>0.01) discrimination value for early heifer pregnancy (EP). Extreme intrauterine growth retardation can result in slower growth, which refl ects in the worst reproductive performance, confi rmed by the variation in BW between precocious and conventional heifers. The results also demonstrate that the level of body fat affects begin of puberty. Bone structure, musculature, depth, tail insertion and rump scores presented the highest discrimination value for EP. These traits can be used as selection tools to improve sexual precocity in female Nellore cattle. The results obtained in this study would support farmers to guide the heifer management and decisions in order to enhance the EP.

Genetic parameters for visual scores, growth and carcass traits in Nellore Cattle

“…The high heritability estimates for REA (0.42), BFT (0.46), and RFT (0.46) suggest that genes with additive effects have a considerable influence on carcass yield and finish. These results demonstrate that these traits can respond similarly to selection, due to the proportion of phenotypic variance attributed to genetics (Brunes et al 2022). The results of this study demonstrate the existing genetic variability for these traits, which can be included as selection criteria to obtain genetic progress in the herd.…”

“…That is, post-weaning traits are less influenced by the environment than pre-weaning traits. Considering that the animals are subjected to the same management conditions, there should be little variation in the environment (Brunes et al 2022). Intensifying selection for yearling weight can influence the adult weight and maintenance requirement of animals (Miranda et al 2006, Silva 2016.…”

“…Intensifying selection for yearling weight can influence the adult weight and maintenance requirement of animals (Miranda et al 2006, Silva 2016. To address this problem, selection indexes composed of traits associated with weight and body composition such as carcass and visual scores, leading to precocious animals, are recommended (Brunes et al 2022).…”

Efeito da idade a primeira concepção como critério de seleção em características de crescimento e carcaça em bovinos Nelore

“…A relação entre essas características pode ser atribuída à influência que o desenvolvimento fetal, refletido no peso ao nascer, tem no desempenho reprodutivo e na idade ao primeiro parto (44) . Uma extensa discussão sobre isso pode ser encontrada em Brunes et al (45) .…”

Novos critérios de seleção para avaliação de bovinos de corte

“…However, Brunes et al (2022) pointed out that rump fat thickness obtained by ultrasound can be used as an indicator trait to improve the female sexual precocity in Nellore cattle, since the level of body fat showed the highest discrimination power (discrimination analyses) between early and late-pregnancy heifers.…”