Bonamy Martin, Kluska Sabrina, Peripolli Elisa, de Lemos Marcos Vinícius Antunes, Amorim Sabrina Thaise, Vaca Roberto Jose, Lôbo Raysildo Barbosa, de Castro Letícia Mendes, de Faria Carina Ubirajara, Borba Ferrari Fabio, Baldi Fernando
Departamento de Producción Animal, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata, Argentina.
Facultad de Ciencias Veterinarias, Instituto de Genética Veterinaria "Ing. Fernando N. Dolout" (IGEVET), Universidad Nacional de La Plata- CONICET, La Plata, Argentina.
J Anim Breed Genet. 2019 Jan;136(1):15-22. doi: 10.1111/jbg.12366. Epub 2018 Nov 21.
The aim of this study was to estimate genetic parameters for different precocious calving criteria and their relationship with reproductive, growth, carcass and feed efficiency in Nellore cattle using the single-step genomic BLUP. The reproductive traits used were probability of precocious calving (PPC) at 24 (PPC24), 26 (PPC26), 28 (PPC28) and 30 (PPC30) months of age, stayability (STAY) and scrotal circumference at 455 days of age (SC455). Growth traits such as weights at 240 (W240) and 455 (W455) days of age and adult weight (AW) were used. Rib eye area (REA), subcutaneous fat thickness (SFT), rump fat thickness (RFT) and residual feed intake (RFI) were included in the analyses. The estimation of genetic parameters was performed using a bi-trait threshold model including genomic information in a single-step approach. Heritability for PPC traits was moderate to high (0.29-0.56) with highest estimates for PPC24 (0.56) and PPC26 (0.50). Genetic correlation estimates between PPC and STAY weakened as a function of calving age. Correlation with SC455, growth and carcass traits were low (0.25-0.31; -0.22 to 0.04; -0.09 to 0.18, respectively), the same occurs with RFI (-0.09 to 0.08), this suggests independence between female sexual precocity and feed efficiency traits. The results of this study encourage the use of PPC traits in Nellore cattle because the selection for such trait would not have a negative impact on reproductive, growth, carcass and feed efficiency indicator traits. Stayability for sexual precocious heifers (PPC24 and PPC26) must be redefined to avoid incorrectly phenotype assignment.
本研究的目的是使用单步基因组最佳线性无偏预测法（single-step genomic BLUP）估计内洛尔牛不同早熟产犊标准的遗传参数，以及它们与繁殖、生长、胴体和饲料效率的关系。所使用的繁殖性状包括24（PPC24）、26（PPC26）、28（PPC28）和30（PPC30）月龄时的早熟产犊概率（PPC）、持续力（STAY）以及455日龄时的阴囊周长（SC455）。使用了生长性状，如240（W240）和455（W455）日龄时的体重以及成年体重（AW）。分析中纳入了眼肌面积（REA）、皮下脂肪厚度（SFT）、臀部脂肪厚度（RFT）和剩余采食量（RFI）。遗传参数的估计采用双性状阈值模型，在单步方法中纳入基因组信息。PPC性状的遗传力为中度至高（0.29 - 0.56），其中PPC24（0.56）和PPC26（0.50）的估计值最高。PPC与STAY之间的遗传相关估计值随着产犊年龄的增加而减弱。与SC455、生长和胴体性状的相关性较低（分别为0.25 - 0.31； - 0.22至0.04； - 0.09至0.18），RFI也是如此（ - 0.09至0.08），这表明雌性性早熟与饲料效率性状之间相互独立。本研究结果鼓励在内洛尔牛中使用PPC性状，因为选择该性状不会对繁殖、生长、胴体和饲料效率指标性状产生负面影响。必须重新定义早熟小母牛（PPC24和PPC26）的持续力，以避免表型分配错误。
