Quantitative study of genetic gain for growth, carcass, and morphological traits of Nelore cattle

Abstract

The aim of this study was to evaluate the genetic variability, genetic and phenotypic associations, and genetic gains of birth (BW), weaning (WW), and yearling (YW) weights, loin muscle area (LMA), backfat thickness (BF), rump fat thickness (RF), scores of body structure (BS), finishing precocity (FS), and muscling (MS) in Nelore cattle. Genetic parameters were obtained through Bayesian inference using BLUPF90 programs. All studied traits showed genetic variability, with heritability ranging from 0.29 to 0.47. In all studied ages, weights presented positive genetic correlations with LMA (ranging from 0.13 to 0.53), being generally stronger in comparison with the other carcass traits analyzed (BF and RF). Similarly, weights were higher genetic associated with BS (0.47–0.92) than with FS (0.18–0.62) and MS (0.22–0.65), respectively. The BF and RF showed positive and moderate genetic associations with FS and MS (0.31–0.36). Genetic trends were significant (P < 0.05) and favorable for WW, YW, and visual scores. Selection for increasing BW, WW, YW, and LMA will result in modest or no change in BF and RF (correlated response ranging from −0.04 to 0.07 mm per generation). In this population, carcass traits must be included in the selection indexes to obtain genetic gains in carcass quality, if desired.

Body size in beef cows and its influence on calf production

“…After weaning, calves born to heavy and moderate cows continue to be larger and to show greater development than calves born to smaller cows; This is probably due to their greater size and adult weight, part of which is genetically inherited from their larger mothers. This determines greater development and greater body weight at the various stages of their lives, where, during the post-weaning period, development is dependent on individual potential and on the influence exerted by the environment and management (D. D. Silveira et al, 2019a). When feeding via maternal milk is lost, calves basically need to obtain their food from the available pasture, and as such, their performance is a reflection of the quality of the food and their ability to transform it into weight gain (M. F. Silveira et al, 2019b).…”

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

“…Cienc (2024) 96(1) e20230010 13 | 18 In addition, for many combinations of traits or score pairs, genetic correlations have higher estimates than phenotypic ones, which can optimize the selection process and genetic gain, justifying the use of morphological traits as selection criteria. Genetic correlations of moderate to high magnitude between M, PS, and growth traits indicate that animals with greater accumulation of muscle mass and well-developed structure to support the body can result in the selection for greater body weight (Paterno et al 2017, Silveira et al 2019. Heavier animals are generally those with greater muscle mass.…”

Novos critérios de seleção para avaliação de bovinos de corte

“…Kamei et al (2017), avaliando bovinos Nelore apresentaram estimativa de herdabilidade direta e materna para PN de 0,17 e 0,11. Silveira et al (2019) relatou estimativas de herdabilidade direta para PN de 0,29 e para herdabilidade materna de 0,07, avaliando bovinos Nelore.…”

“…Está é uma vantagem da seleção para FP em relação a seleção para baixo PN, a qual pode proporcionar retardo no padrão de crescimento animal. Uma vez que PN é altamente e favoravelmente correlacionado com peso a desmama e peso ao sobreano (SILVEIRA et al, 2019).…”

“…No entanto, a seleção para baixo PN pode interferir no desenvolvimento dos animais, uma vez que os ganhos genéticos de peso ao nascimento até o pósdesmame podem ser obtidos pelas respostas correlacionadas dessas características (SILVEIRA et al, 2019), assim selecionar para baixo PN poderá prejudicar o ganho de peso e o peso corporal em idades superiores e, portanto, a rentabilidade. Assim, embora a seleção para baixo PN possa contribuir para a FP, a seleção direta e direcionada para reprodução visando melhora FP pode ser uma melhor escolha a longo prazo (BENNETT et al, 2021).…”