Department of Animal Science, Federal University of Pelotas, Pelotas, RS, 96160-000, Brazil.
Animal Improvement Group of Mato Grosso (GMAT), Federal University of Rondonópolis, Avenida Dos Estudantes, 5055, Cidade Universitária, Rondonópolis, MT, CEP 78736-900, Brazil.
Trop Anim Health Prod. 2024 Apr 25;56(4):143. doi: 10.1007/s11250-024-03977-1.
The growth of Nelore cattle was analysed considering the following performance parameters; the effect of the calving order of cows on the phenotypic expression of birth weight (BW), average daily gain from birth to weaning (BWG), and weaning weight (WW), the estimated genetic parameters for the traits, including the covariance components between direct and maternal genetic effects. Genetic trends and correlated responses were also obtained for the studied traits. The calving order of cows, as well as other fixed effects used to obtain the adjusted phenotypic means, were statistically significant (p < 0.001) for studied traits. Direct heritability was estimated at 0.24 ± 0.01 (BW), 0.15 ± 0.01 (BWG), and 0.18 ± 0.01 (WW), while maternal heritability was 0.06 ± 0.01 (BW), 0.12 ± 0.01 (BWG), and 0.11 ± 0.01 (WW). The correlations between direct and maternal effects within the same trait were negligible. Moderate to higher direct genetic correlations (ranging from 0.54 ± 0.04 to 0.98 ± 0.01) and maternal genetic correlations (ranging from 0.34 ± 0.09 to 0.99 ± 0.002) were estimated between the studied traits. Unlike direct genetic effects, there was no significant change in maternal genetic effects over time (p > 0.05). These results indicated the need for revising selection indexes for enhancing maternal ability. Correlated responses were generally lower compared to direct responses, except for BWG. The selection for BWG, considering the maternal genetic effect, would be more efficient to improve maternal ability of the cows for pre-weaning growth in relation to selection for WW. Our results found that direct genetic merit improves pre-weaning weight and this trait can be incorporated into the breeding goal as reflected in the WW.
对尼洛拉牛的生长进行了分析，考虑了以下性能参数; 母牛产仔顺序对初生重 (BW)、出生至断奶日增重 (BWG) 和断奶重 (WW) 的表型表达的影响，性状的估计遗传参数，包括直接和母体遗传效应之间的协方差分量。还获得了研究性状的遗传趋势和相关反应。牛的产仔顺序以及用于获得调整后的表型均值的其他固定效应对研究性状具有统计学意义 (p < 0.001)。直接遗传力估计值为 0.24 ± 0.01 (BW)、0.15 ± 0.01 (BWG) 和 0.18 ± 0.01 (WW)，而母体遗传力为 0.06 ± 0.01 (BW)、0.12 ± 0.01 (BWG) 和 0.11 ± 0.01 (WW)。同一性状内直接效应和母体效应之间的相关性可以忽略不计。直接遗传相关 (范围从 0.54 ± 0.04 到 0.98 ± 0.01) 和母体遗传相关 (范围从 0.34 ± 0.09 到 0.99 ± 0.002) 估计在研究性状之间中等至较高。与直接遗传效应不同，母体遗传效应在时间上没有显著变化 (p > 0.05)。这些结果表明需要修订选择指数以增强母体能力。除了 BWG 外，相关反应通常低于直接反应。考虑母体遗传效应，选择 BWG 将比选择 WW 更有效地提高母牛的哺乳期生长能力。我们的研究结果发现，直接遗传优势可以提高哺乳期前的体重，并且该性状可以包含在 WW 中反映的选育目标中。
