干旱区生态环境知识资源中心

Four multi-stage selection indices were constructed for genetic improvement using information on body weight at 3 (W3), 6 (W6), 9 (W9) and 12 (W12) months; greasy fleece weight at first (GFW1) and second (GFW2) clips; medullation percentage (Med%) and fibre diameter (FD) of 482 Marwari sheep maintained at the arid region campus of CSWRI, Bikaner.

Single-stage indices were more accurate and expected to produce higher genetic gain than their corresponding multistage indices.. However, considering the cost of rearing animals for a long period, it has been proposed that 3 stage selection strategy with 50% selection at 6 months,next 50% selection at 9 months and further 80% selection at 12 months would be more practical and economic with an acceptable rate of genetic improvement.

The recommended selection indices at 3 stages were: First stage index (S1): 0.956 W3 - 0.121 W6 + 6.342 GFW1; second stage index (S2): 1.030 (SI) + 0.327 W9 - 0.070 FD - 0.09 Med%, and third stage index (S3): 0.072 (S2) + 0.063 W12 + 1.993 GFW2.