Prediction of Lambs Growth From Milk Production and Its Composition in Awassi Sheep and Description of Growth Curve of Non-Linear Function

Abstract

This study was undertaken at the Ruminant’s Research Station, Office of Agricultural Research/Ministry of Agriculture (20 km west of Baghdad). 102 ewes were used in this study from 1/1/2020- 1/10/2021 to study prediction of lambs growth from milk production and its composition in Awassi sheep and description of growth cure of non–linear function. Simple regression was used to examine relationship between growth traits such as gain, weaning weight, weight at 6 months of age and milk production and its composition. Regression of weaning weight was positive and highly significant (P≤ 0.01) with daily milk yield (DMY) and significant (P≤0.05) with dam’s milk protein percentage (MPP), Analysis of regression also showed significant positive increasing (p≤ 0.05) in lambs' weight at six months of age with increasing of DMY and MPP, where coefficient of regression (CR) amount to 5.006 kg/kg and 0.663 kg/% respectively. Results showed that CR of gain from birth to weaning was highly significant with dam’s DMY, whereas was significant with MPP. Both DMY and MPP had significant and positive relationship with gain between birth weight and weight at six months, where amount of CR was 4.859 kg/kg and 0.619 kg/% with determination coefficient (R2) amount to 0.31 and 0.19 sequentially. Also, positive and significant regression was noticed for gain from birth to 6 months with MPP and milk Solids Not-Fat(SNF) percentages. Exponential functions also were used according to analysis of non-linear regression with calculated R2 for growth in Awassi lambs. Results showed that relationship which derives from regression weight at 6 months on weight at weaning according to equation WT6^=a+b WWT2 is considered the best because increasing value of R2 which was 0.69. we conclude, possibility prediction in lamb’s growth from birth to six months depend on DMY and MPP, also dependence non-linear functions gave an important results to describe growth curves between weaning to 6 months.