A Study On Correlation Coefficient Between Some Traits In Arabic Ewes And Their Lambs.

Correlation coeffecent reveals the relation between two variables.This correlation coud vary from -1 to + 1. Three factors are involved in divulging different traits (both quantitative and qualitative) which make up the phenotype of an animal. These factors are:, 1) genotype, 2) environment and 3) the interaction between the two. Knowledge of phentypic correlation between different traits could assist the breeder in reaizing the value of the animal, selection and breeding for different traits at different stage of production. To study the correlation beween some productive tants of Arabic ewes and their lambs, 100 Arabic ewes Of 1.5-5 years old were choosen for Fall- mating. Dam,s body weights were recorded at different stage of porduction. Birth weights and weaning weights of all lambs were also recorded. Records were kept on milk yeild of the dam for first 3 weeks of postpartum and the body wieghts of the lambs at 3 weeks of age to be used in calculating possible correlation between traits.In this study no significant correlation was found between fertility rate and the ewes body weights at 3 stage of pre-mating, late gestation and early lactation (P0.01),even though her body weight at one year of age is correlated with fertility rate.Correlation between dam,s pre-mating body wieght with her lamb,s (male and female) birth weights (0.50 and 0.49 respectively) were significant (P0.01). Correlation of dam,s body weight at parturition and her lamb,s (male and female) birth weights (0.597 and 0.449) were significant (p0.01). There was no significant correlation between dam,s milk yeild and her lamb,s (male and female) body weight at the end of third week of postpartum (P0.01).Correlation for dam,s body weight and lamb,s (male and female) weaning weights (0.598 and 0.713) were significant (P0.01). In some cases the genotypic correlation between two traits could be negative while the phenotypic correlation between the two is possitive. In these cases the correlation between effective environmental factors on size of the traits have a possitive and powerful effects, so that while neutrilizing the negatjve effect of the genetic correlation it makes the phenotypic correlation possitive. Care is needed with phenotypic correlation between traits until the size and sign of the genetic correlation between them is known.