Fitting of growth models and evaluation of Marwari sheep under field conditions

A survey on farmers’ sheep flock was conducted to study the geographical distribution, flock management practices, morphometric characteristics, reproduction and production characteristics and socio-economic utility of the Marwari sheep breed. Comparison of four nonlinear models, viz. Gompertz, Von Bertalanffy, Logistic and Brody, revealed that Gompertz model was the best fit to describe growth of Marwari ewe-lambs from birth to 12 months of age. The predicted body weights by the best fitted model showed that there was consistent increasing trend in the body weights of ewe lambs and that nearly 90% of the sexual maturity weight (two-tooth stage) was attained at 12 months of age. Average adult body weights of 24 rams and 246 ewes were 40.7±1.13 and 30.1±0.28 kg respectively. Chest girth (cm) was 81.71±0.81 in rams and 74.25±0.27 in ewes. It was found that the breed was very large in number and widespread but has been diluted substantially due to out-breeding with the local rams and reduction in distribution area of the breed.