Abstract Avikalin sheep has been developed for higher growth rate and wool yield, however, wool has lost its market value over time. The aim of the study was to know the genetic potential of Avikalin for growth and also to suggest a selection criterion for higher growth with feed conversion efficiency. A total of 6296 animals descended from 2048 dams and 390 sires spread over a period of 41 years (1976–2016) at ICAR-Central Sheep and Wool Research Institute (CSWRI), Avikanagar were used for the analysis. Genetic trends were obtained for average daily gain (ADG) from birth to weaning (ADG1), weaning to 6-month (ADG2), 6-month to 12-month (ADG3) and Kleiber ratios of corresponding age (KR1, KR2 and KR3) in crossbred Avikalin sheep. Co(variance) components and genetic parameters were estimated by univariate and bivariate animal models using the average information restricted maximum likelihood (AIREML) by excluding or including maternal genetic or maternal permanent environmental effects. Significant and high additive genetic variances were observed for all the traits. Decreasing trends were observed for maternal effects as age advances. The genetic trends for ADG and KR up to 6 month age were positive and had substantial increment over the years indicating the impact of selection that favored higher gain in body weight at early ages. However positive and desired genetic trend at early ages (≤6 months), had an inverse relationship with genetic gain or trend at a later age (>6 month). Moderate estimates of the total heritability ( h T 2 ) 0.14, 0.18, 0.11, 0.19, 0.13 and 0.14 were obtained for ADG1, ADG2, ADG3, KR1, KR2 and KR3, respectively. This indicates the scope of direct selection for these traits for further improvement. The positive and desired genetic and phenotypic correlations between ADG and their corresponding KR suggested the scope of indirect selection for growth rate if lambs are selected for higher feed efficiency based on KR.

中文翻译：

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阿维卡林羊生长率和克莱伯比的遗传趋势

摘要 阿维卡林羊已被开发用于更高的生长速度和羊毛产量，但随着时间的推移，羊毛已经失去了其市场价值。该研究的目的是了解 Avikalin 生长的遗传潜力，并提出一个选择标准，以提高饲料转化效率。在 41 年（1976-2016 年）的 41 年期间（1976-2016 年），共有 6296 只动物来自 2048 只水坝和 390 只公牛，用于分析。获得了从出生到断奶 (ADG1)、断奶到 6 个月 (ADG2)、6 个月到 12 个月 (ADG3) 的平均日增重 (ADG) 和相应年龄的 Kleiber 比率（KR1、KR2 和 KR3）的遗传趋势) 在杂交阿维卡林羊中。Co(variance) 分量和遗传参数通过单变量和双变量动物模型使用平均信息限制最大似然 (AIREML) 通过排除或包括母体遗传或母体永久环境影响来估计。观察到所有性状的显着和高加性遗传变异。随着年龄的增长，观察到母体效应的下降趋势。ADG 和 KR 的遗传趋势直到 6 个月大都是正的，并且随着时间的推移显着增加，表明选择的影响有利于早期体重增加更多。然而，早期（≤ 6 个月）的积极和理想的遗传趋势与后期（> 6 个月）的遗传增益或趋势呈负相关。总遗传力 (h T 2 ) 的中等估计值为 0.14、0.18、0.11、0.19、0.13 和 0。ADG1、ADG2、ADG3、KR1、KR2和KR3分别获得14个。这表明直接选择这些性状以进一步改进的范围。ADG 与其相应的 KR 之间的正和理想的遗传和表型相关性表明，如果根据 KR 选择羔羊以获得更高的饲料效率，则间接选择生长率的范围。