Arthy V, Venkataramanan R, Sivaselvam S N, Sreekumar C, Balasubramanyam D
Madras Veterinary College, TANUVAS, Chennai, 600007, India.
NWPSI, PGRIAS, Kattupakkam, Chennai, 603203, India.
Trop Anim Health Prod. 2018 Oct;50(7):1463-1471. doi: 10.1007/s11250-018-1581-z. Epub 2018 Apr 11.
The Network Project on Sheep Improvement (NWPSI)-Madras Red field unit is a group breeding scheme involving 198 farmers' flocks of Madras Red sheep in which selection for growth traits and rotation of rams have been practised for over two decades. Growth data collected from these flocks were used to evaluate the performance and understand the direct and expected responses to selection based on genetic parameters. The body weight at birth (BW), weaning weight (WW), 6-month weight (6W), 9-month weight (9W), 12-month weight (YW), pre-weaning average daily gain (ADG1, birth to 3 months), post-weaning ADG2 (3-6 months), ADG3 (6-9 months), ADG4 (9-12 months) and ADG5 (3-12 months) were 2.67, 10.05, 14.56, 18.36, 21.36, 80.13, 49.05, 43.00, 34.21 and 41.18 g, respectively. Univariate analyses were carried out using animal and sire models to estimate variance components. Heritability obtained from animal model for BW was 0.36 and the values for other body weight traits were almost unity. Heritability estimate for pre-weaning ADG1 was 0.31. Very high genetic variability was observed in spite of long-term selection and this sustenance of variability is one of the main advantages of a group breeding scheme, combining several flocks of smaller size. An increasing genetic and phenotypic trend was noticed for almost all the traits studied. The expected responses calculated based on genetic parameters also indicated scope for improvement.
绵羊改良网络项目（NWPSI）-马德拉斯红羊实地单元是一项群体育种计划，涉及198个农民的马德拉斯红羊群体，其中对生长性状的选择和公羊轮换已实施了二十多年。从这些群体收集的生长数据用于评估性能，并根据遗传参数了解对选择的直接和预期反应。出生体重（BW）、断奶体重（WW）、6月龄体重（6W）、9月龄体重（9W）、12月龄体重（YW）、断奶前平均日增重（ADG1，出生至3个月）、断奶后ADG2（3至6个月）、ADG3（6至9个月）、ADG4（9至12个月）和ADG5（3至12个月）分别为2.67、10.05、14.56、18.36、21.36、80.13、49.05、43.00、34.21和41.18克。使用动物模型和父系模型进行单变量分析以估计方差分量。从动物模型获得的BW遗传力为0.36，其他体重性状的值几乎为1。断奶前ADG1的遗传力估计值为0.31。尽管进行了长期选择，但仍观察到非常高的遗传变异性，这种变异性的维持是群体育种计划（结合几个较小规模群体）的主要优点之一。几乎所有研究的性状都注意到遗传和表型趋势增加。根据遗传参数计算的预期反应也表明有改进的空间。
