Genetic analysis of growth and feed conversion efficiency of Muzaffarnagari lambs under intensive feeding system

Abstract

Data on 534 Muzaffarnagari lambs, maintained under intensive feeding management system at the Central Institute for Research on Goats, Makhdoom, Mathura, Uttar Pradesh, India were recorded between 1989 to 2002, so as to study the growth performance and feed conversion efficiency of lambs and their genetic control. The overall least-squares means for 3-month weight, 6-month weight and average daily weight gain during 3 to 6 months of age of lambs were 16.11 ± 0.34 kg, 26.84 ± 0.51 kg and 119.23 ± 4.35 g, respectively. The average Feed Conversion Efficiency (FCE) of lambs during this stage of development was 16.24 ± 0.47%. Significant (P<0.01) differences among sires existed for all the growth traits and feed conversion efficiency of lambs. There were marked period-wise differences of all the traits under study but no definite pattern was observed among different birth periods. The parity of dam had only significant (P<0.01) influence on 3 and 6-month body weights of lambs. Season of birth significantly (P<0.01) affected the 3 month weight and average daily weight gain during 3 to 6 months of age of lambs in this study. Male lambs excelled (P<0.01) over their female counterpart in respect of 3 and 6 months weights, average daily weight gain and feed conversion efficiency of lambs during this stage of growth. Single kids had a distinct advantage over those born in multiple births for weights at 3 and 6 months of age. The regression of weight of dam at lambing showed significant (P<0.01) effect on all the traits under study. The heritabilities of 3 and 6 month weight, average daily weight gain and feed conversion efficiency during 3 to 6 months of age were moderate in magnitude ranging from 0.17 to 0.32. Genetic correlations among 3 and 6 month weight, average daily weight gain and feed conversion efficiency of lambs obtained in this study were medium (0.51 ± 0.32) to high (0.97 ± 0.24) except the correlation between average daily weight gain and feed conversion efficiency (0.10) of lambs.