Weight gain and growth efficiency in Marwari sheep under arid condition of Rajasthan

Records of 1224 Marwari lambs of tester and elite group born during 1994 to 1998 were analysed to assess the impact of sex, genetic group and year of birth on gain in body weight and growth efficiency. The over all least-squares means of gain in body weight and growth efficiency during 0–3, 3–6, 6–9 and 9–12 months of age were 9.95±0.061, 4.28±0.054, 3.11±0.050 and 2.62±0.053 kg and 3.35±0.021, 0.33±0.004, 0.19±0.003, 0.12±0.003 kg, respectively. Sex and year of birth showed highly significant (P<0.01) influence on all body weight gains and efficiency except the influence of sex on gain in weight at 9–12 months of age, which was non-significant. The genetic group was having significant effect on gain in weight imd growth efficiency during in 0–3 and 9–12 months. Regression of dam's weight at lambing on gain during period of 0–3 months body weight was highly significant, whereas regression of birth weight was non-significant. Regression of birth weight and 3 months body weight on gain in body weight during period of 3–6 months was highly significant, whereas regression of 3 months body weight was non-significant. Regression of 3 and 6 months body weight on gain during 6–9 months and 9–12 months were significant but negative in 6 months body weight. Regression of dam's weight at lambing, birth, 3 and 6 months on efficiency of weight gain during different periods of growth was found to be significant. except growth etficiency traits during 6–9 months and 3 months body weight. The negative regression of birth weight, 3 and 6 months weight indicated that the lambs having higher body weight at birth, 3 and 6 months age might not grow taster at subsequent ages suggestive rhythmical trend in growth rate.