Heritability estimation and genetic correlations for mature weight, visual scores, and growth traits in Nellore cattle

Abstract

This study was intended to estimate the genetic associations between growth traits and visual scores with possible changes in mature weight (MW) in 397,900 Nellore animals. A bi-character analysis was performed to estimate the (co)variances and genetic parameters for MW, which comprises the following traits: conformation, finishing precocity, musculature at weaning (WC, WP, and WM) and yearling (YC, YP, and YM), birth weight (BW), weight from birth to weaning (WG), weight from weaning to yearling (YG), and final index (FIND). The observed mean MW was 417.6±56.2 kg, and the direct genetic effect mean estimated heritability (h² a1 ) of MW was 0.45. Overall, the BW was 31.0±3.7 kg, and the estimated h² was 0.34. The heritability estimate of the maternal additive genetic component (h² m2 ) of BW was 0.07. We calculated the mean WG to be 144.1±26.3 and estimated the h² a2 as 0.18 and h² m2 as 0.07. The value for h² a YG (0.17) and YW (0.26) were also estimated. The heritability of the weaning WC (0.17), WP (0.19), and WM (0.17) and yearling YC (0.25), YP (0.27), and YM (0.25) were estimated using visual scores. The h² m values for weaning WC, WP, and WM (0.06) with visual scores were estimated. The genetic correlations between body weight (BoW) at YC and WC (0.62) were considered moderately high and positive. In addition, YP (0.18), YM (0.15), WP (0.13), and WM (0.14) were considered moderately low compared with MW. The genetic correlation between BW and FIND (0.38) was considered positive and moderate. The heritability estimation indicates that growth traits, visual scores, and weight of adult cows could be changed by selection. Cows that presented the highest h² a values for live weight responded rapidly to selection based on growth characteristics, visual scores, and FIND and might result in increased final MW.

Genetic-Quantitative Uni- and Bi-Trait Analysis for Growth Traits in the Colombian Creole Breed Blanco Orejinegro (BON)

“…For YW, similar results were found in Brahman (0.22 ± 0.02) (Manuel et al, 2019) and in Nelore breed, these the estimates varied between 0.17 and 0.44 (Moreira et al, 2015;Teixeira et al, 2018;Koetz Junior et al, 2019).…”

“…𝐀 is the numerator of the additive kinship matrix, and 𝐈 is an identity matrix. The bivariate animal model used was the one employed by Koetz Junior et al, (2019).…”

Analysis of the influence of the birth period on the body weight of Nelore cattle

“…Estudos demonstraram (BOLIGON et al, 2009;KOETZ JUNIOR et al, 2019) que existe correlação genética de magnitude moderada a alta entre o peso ao nascimento e peso a desmama, e com isso, animais com menores pesos ao nascer, teriam menores pesos à desmama. Entretanto, pode-se ressaltar que, a semelhança de pesos à desmama entre machos e fêmeas do presente trabalho pode estar associado ao manejo do rebanho, nutrição adequada, e seleção genética.…”

Associação de escores visuais com características reprodutivas em bovinos Nelore utilizando Inferência Bayesiana

“…Nesse contexto, a seleção baseada em caraterísticas morfológicas como os escores visuais podem auxiliar em mudanças genéticas efetivas no rebanho de bovinos de corte, visto que as estimativas de herdabilidade obtidas para as características avaliadas variam de baixa a alta magnitude (2),( 3),( 4),( 5),( 6), (7), (8) . Além disso, a utilização de escores visuais permite que um amplo número de animais seja avaliado, sendo menos invasiva em comparação a mensurações objetivas, permitindo a seleção de animais mais equilibrados com o ambiente em que estão sendo criados.…”