Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India.
Department of Livestock Farm Complex, LUVAS, Hisar, India.
Reprod Domest Anim. 2020 Dec;55(12):1698-1705. doi: 10.1111/rda.13826. Epub 2020 Oct 14.
The present study was conducted on Hardhenu cattle to screen genomic region of leptin gene with an objective to find the association of genotypes with fertility and production traits. The association analysis with traits under study was analysed by least squares analysis of variance by taking SNPs genotype as fixed effects in the statistical model. The genotypic frequencies with respect to targeted loci g.92450765 G > A indicated that AG (0.54) genotype was highest in Hardhenu cattle. Chi-squared tests showed that g.92450765G > A SNP meet with the Hardy-Weinberg equilibrium (p > .05).The association analysis revealed significant association of genotypes with total milk yield (TMY) and 305 days milk yield (MY) (p < .05). Service period (SP) and calving interval (CI) were also found significantly associated with genotypes (p < .05). Whereas, lactation length (LL), dry days (DD) and age at first calving (AFC) did not divulge any significant association with genotype. The AG and GG genotypes were associated with higher milk yields as compared to AA genotype, indicating that allele G was associated with superior milk performance. However, AA genotyped cattle found to be favourable with SP, CI and artificial insemination (AI) per conception compared to AG and GG genotyped cows. Chi-square analysis revealed that genetic variants of g.92450765 G > A SNP of leptin gene differ significantly with regard to reproductive disorders incidence (p < .05). The frequency of GG genotype (88.89%) in the affected animal group was very high followed by AG. The animals with GG genotype were found to be more susceptible to reproductive disorders as suggested by the higher odd ratio value (16.00) in logistic model. These observations and their differential association with the fertility and production traits can be utilized as an aid to selection for genetic improvement of antagonistic traits in dairy cows.
本研究以 Hardhenu 牛为研究对象，旨在筛选瘦素基因的基因组区域，以寻找基因型与繁殖和生产性状的关联。通过将 SNP 基因型作为统计模型中的固定效应，采用最小二乘方差分析对研究性状进行关联分析。针对目标基因座 g.92450765G > A 的基因型频率表明，Hardhenu 牛中 AG（0.54）基因型最高。卡方检验表明，g.92450765G > A SNP 符合 Hardy-Weinberg 平衡（p >.05）。关联分析表明，基因型与总奶产量（TMY）和 305 天奶产量（MY）显著相关（p <.05）。发情周期（SP）和产犊间隔（CI）也与基因型显著相关（p <.05）。然而，泌乳天数（LL）、干奶天数（DD）和首次产犊年龄（AFC）与基因型没有明显关联。AG 和 GG 基因型与较高的产奶量相关，表明等位基因 G 与优越的产奶性能相关。然而，与 AG 和 GG 基因型的奶牛相比，AA 基因型的奶牛在 SP、CI 和人工授精（AI）每配种次数方面具有优势。卡方分析表明，leptin 基因 g.92450765 G > A SNP 的遗传变异在生殖障碍发生率方面存在显著差异（p <.05）。受影响动物组中 GG 基因型（88.89%）的频率非常高，其次是 AG。逻辑模型中的更高优势比（16.00）表明，GG 基因型的动物更容易受到生殖障碍的影响。这些观察结果及其与繁殖和生产性状的差异关联可以作为选择的辅助手段，用于奶牛的遗传改良。
