In the present study, we examined the suitability of seven asymptotic nonlinear models to describe body weight growth of Hemsin male and female sheep from birth to 36 months of age and, using the selected functions, to provide a biological interpretation for this growth. The weight-age data for this study were obtained from records of 108 Hemsin female and male sheep held in variety breeder flocks of Artvin province in Turkey. The sheep records were collected between 2008 and 2010 with measurements taken at birth, 2nd, 3rd, 6th, 12th, 18th, 24th, and 36th months of age. Body weight-age data from Hemsin sheep were used to obtain a growth pattern for sheep, with the use of Negative exponential, Brody, Gompertz, Logistic, Bertalanffy, Richards, and Janoschek nonlinear functions. Comparisons between these functions were based on coefficients of determination and residual squared error. The R 2 values of the models ranged from 0.971 to 0.989 for males and from 0.951 to 0.991 for males. In both sexes, the Brody, Richards, and Janoschek models, with equal R 2 as 0.99, were superior to the others. However, the Brody was precise on its parameters and easy to interpret than Richards and Janoschek functions.

Abstract. Many researchers who have studied the relationships between milk protein polymorphisms and some yield traits in dairy cattle have reported incompatible results. In this study, in order to examine the overall relationships between milk protein genes known as major genes (CSN1S1, CSN2, CSN3, and BLG) and some yield traits (daily milk yield, lactation milk yield, fat yield, fat content, protein yield, and protein content), a meta-analysis was performed using some genetic models reported in the results of previous studies on cattle. The results suggest that the relationships of major milk protein genes with other factors should be studied using the codominant genetic model in general. Relationships among some CSN3 genotypes and fat yield, fat content, and protein content, and relationships between some BLG genotypes and daily milk yield, fat content, protein yield, and protein content were significant (P<0.05). No significant (P>0.05) relationships were found between these genotypes and other milk production traits. In addition, no significant (P>0.05) relationships between the CSN1S1 and CSN2 genotypes with the milk production traits examined were observed.

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