Mamede M M S, Rosa G J M, Eifert E C, Lopes F B, Baldi F, Costa M F, Sainz R D, Carmo A S, Mascioli A S, Magnabosco C U
School of Veterinary and Animal Science, Federal University of Goiás, Goiânia, GO, Brazil.
Department of Animal Science, University of Wisconsin, Madison, WI, USA.
Trop Anim Health Prod. 2023 Mar 17;55(2):119. doi: 10.1007/s11250-023-03541-3.
Considering the economic and commercial efficiency of the beef production chain, the yield and quality of the meat produced must also be included in breeding programs. For the Nellore breed, including the polled herd, these aspects have not been much studied. The aim of this study was to estimate genetic parameters for scrotal circumference adjusted to 365 (SC365) and 450 (SC450) days of age, age at first calving (AFC), accumulated productivity (AP), stayability (STAY), longissimus muscle area (LMA), thickness of subcutaneous fat over the 12th-13th ribs (BF), thickness of subcutaneous fat over the rump (RF), and shear force measured by Warner-Bratzler shear force (WBSF) of polled Nellore cattle. Bayesian analyses were performed by adopting a linear animal model, whereas STAY analyses used the linear threshold model. Heritability estimates were 0.31 (SC365), 0.37 (SC450), 0.16 (AFC), 0.25 (AP), 0.16 (STAY), 0.30 (LMA), 0.13 (BF), 0.24 (RF), and 0.15 (WBSF), indicating moderate response to selection. Genetic and residual correlations between SC365 and SC450 were high (0.91 and 0.74, respectively), as well as the genetic correlations of AP with SC365, SC450, AFC, and STAY (0.61, 0.62, - 0.69, and 0.83, respectively). Genetic and residual correlations of WBSF with reproductive and carcass characteristics exhibited high standard deviations, however favorable. Based on the results, it is expected that in the medium term, animals with greater sexual precocity will also have greater accumulated productivity and longer permanence of females in the herd, along with superior carcass traits. However, due to the low heritabilities and small genetic associations with reproductive traits, fat thickness characteristics (BF and RF) will still require direct selection.
考虑到牛肉生产链的经济和商业效率，育种计划中还必须纳入所产肉类的产量和质量。对于内洛尔牛品种，包括无角牛群，这些方面的研究还不多。本研究的目的是估计无角内洛尔牛365日龄（SC365）和450日龄（SC450）时的阴囊周长、初产年龄（AFC）、累计生产力（AP）、留种率（STAY）、背最长肌面积（LMA）、第12 - 13肋骨处皮下脂肪厚度（BF）、臀部皮下脂肪厚度（RF）以及通过沃纳-布拉茨勒剪切力（WBSF）测量的剪切力的遗传参数。采用线性动物模型进行贝叶斯分析，而留种率分析使用线性阈值模型。遗传力估计值分别为0.31（SC365）、0.37（SC450）、0.16（AFC）、0.25（AP）、0.16（STAY）、0.30（LMA）、0.13（BF）、0.24（RF）和0.15（WBSF），表明对选择有中等反应。SC365和SC450之间的遗传和残差相关性较高（分别为0.91和0.74），AP与SC365、SC450、AFC和STAY的遗传相关性也较高（分别为0.61、0.62、 - 0.69和0.83）。WBSF与繁殖和胴体特征的遗传和残差相关性表现出较高的标准差，但呈有利趋势。基于这些结果，预计从中期来看，性早熟程度较高的动物也将具有更高的累计生产力和更长的母牛在牛群中的留存时间，以及更优的胴体性状。然而，由于遗传力较低且与繁殖性状的遗传关联较小，脂肪厚度特征（BF和RF）仍需要直接选择。
