Genetic parameters of growth traits in Nellore cattle

Abstract

This study evaluated non-genetic factors and calculated heritability estimates of direct and maternal effects for growth traits in Nellore cattle raised in southern Brazil. Performance records of 4170, 1538, 3139, 1830, and 1151 calves born from 2005 to 2011 were analyzed for birth weight (BW), adjusted120-day weight (W120), adjusted 205-day weight (W205), adjusted365-day weight (W365), and adjusted 550-day weight (W550), respectively. The components of (co)variance used to calculate heritability estimates were determined by Derivative-Free Restricted Maximum Likelihood using the MTDFREML software. Contemporary groups were included in the model as fixed effects, and direct and maternal effects, permanent environmental effects, and residual errors were included as random effects. Phenotypic correlations were estimated using the PROC CORR procedure from SAS. Overall means for BW, W120, W205, W365, and W550 were 38, 138, 201, 270, and 376 kg, respectively. Heritability estimates for direct and maternal effects were 0.17 ± 0.04 and 0.11 ± 0.03 (BW), 0.14 ± 0.03 and 0.03 ± 0.04 (W120), and 0.17 ± 0.04 and 0.09 ± 0.03 (W205). Genetic, phenotypic, and environmental correlations were 0.79, 0.44, and 0.32 for BW and W120, 0.79, 0.39, and 0.26 for BW and W205, and 0.96, 0.74, and 0.75 for W120 and W205. The results indicate that selection for pre-weaning weight would be more efficient using W205, and genetic correlation coefficients indicate that selection at any age should produce a positively correlated response at older ages. Genetic, phenotypic, and environmental correlation coefficients between W365 and W550 were 0.99, 0.75, and 0.76, respectively. Selection for adjusted 550-day weight should produce the greatest genetic gains. Genetic correlation coefficients between weight traits indicate that selection for weight at older ages, which could help reduce the number of weighings and increase accuracy of selection at younger ages, produces gains at older ages. Key words: Beef cattle. Body weight. Correlation. Direct heritability. Maternal heritability. ResumoCom o objetivo de estudar os fatores ambientais e estimar os parâmetros genéticos, para os efeitos diretos e maternos, para as características de crescimento, foram utilizadas 4170, 1538, 3139, 1830 e 1151 observações de peso ao nascer (PN), peso ajustado aos 120 dias de idade (P120), peso ajustado aos 205 dias de idade (P205), peso ajustado aos 365 dias de idade (P365) e peso ajustado aos 550 dias (P550), de bovinos da raça Nelore nascidos no município de Amaporã-PR. As médias estimadas para PN, P120, P205, P365 e P550, foram 38 kg, 138 kg, 201 kg, 270 kg e 376 kg, respectivamente. Os componentes de (co) variância utilizados para estimar as herdabilidades foram obtidos por meio do programa MTDFREML, o modelo utilizado considerou o efeito fixo do grupo de contemporâneos, o efeito da idade da vaca ao parto como covariável, além dos efeitos aleatórios genéticos aditivo direto e materno e o efeito de ambiente permanente. As correlações fenotípicas foram estim...

Genetic selection indices for growth traits in Blanco-Orejinegro cattle

“…I1 could be used in herds where the main objective is the rearing of calves or the production of dams with good maternal aptitude. In accordance with what was proposed by Emanoela et al (2015) , the early relationships between the dam and calf have an important effect on the survival of the calf, in addition to being a good indicator of the production ability of the cow due to the high effect that this has on the weight of the calf at this stage ( Kamei et al, 2017 ). I2, I3, and I4 prioritized increases in W480 and W720 and a reduction in CFA, aspects related to sexual precocity and entry to reproductive life ( De León et al, 2019 ), although the IBC was increased.…”

Effect of age at first conception as selection criteria on growth and carcass traits in Nellore cattle

“…Genetic and phenotypic correlation estimates with their respective standard errors (se) between age at rst conception (AFCo) and at rst calving (AFCa) and carcass traits in Nellore cattleDiscussionFor BW, a direct heritability estimate of 0.39 (Table2) was observed, being similar to that reported by Araujo et al (2014) and higher than reported byKamei et al (2017) in Nellore cattle. Moderate direct heritability estimates were also obtained for the weights at 120, 210, 365, and 450 days of age and were higher than values reported for Nellore cattle byKamei et al (2017), but similar to the one presented by Araujo et al (2014), Bonamy et al (2019), and Kluskaa et al (2018).…”

Associações genéticas entre os critérios seletivos de bovinos de corte - Revisão de literatura

“…O peso ao nascimento é resultante do desenvolvimento fetal oferecido pela matriz. Em animais da raça Nelores esse peso está na faixa de 25 a 35 Kg (Kamei, et al, 2017;Junior, et al, 2019) com herdabilidades próximas de 0,17 a 0,27 (Kamei, et al, 2017;Correia, et al, 2020). O problema do peso relativo ao nascimento quando exagerado é no momento do parto a vaca ter alguma complicação e necessitar de alguma interferência, conhecido como parto distócico (Atashi e Asaadi, 2019) e para o peso muito abaixo da média da raça é que reflete a um baixo desempenho comparado com o resto de seu grupo contemporâneo, no qual pode estender por toda a sua vida.…”

“…meses) e tradicional (7-8 meses). Para estes pesos corporal é encontrado herdabilidade direta os quais variaram de 0,25 a 0,41 para a desmama precoce e de 0,14 a 0,48 para a tradicional (Ambrosini et al, 2016;Pires et al, 2016;Kamei et al, 2017;Lopes et al, 2017;Pereira et al, 2017;Silva Neto et al,2020). Denotando uma alta variância nas médias contudo as magnitudes para estes critérios de seleção foram desejáveis.…”

“…Na literatura suas estimativas de herdabilidades do peso ao ano foram de 0,24 a 0,38 (Pires et al, 2016;Kamei et al, 2017;Lopes et al, 2017;Pereira et al, 2017;Barros et al, 2018) Em estudo oriundo de meta analise com bovinos Nelore, Felipe et al ( 2021) obtiveram valores médio de estimativas de herdabilidades iguais a 0,35, 0,24, 0,31 e 0,39, respectivamente, para peso ao nascimento a desmama, peso adulto e peso ao sobreano.…”