Genetic Analysis of Adult Body Weight and Condition Scores in Merino Sheep

Adult body weight (WT) and condition score (CS) are important traits in sheep production systems. This study aimed to estimate the correlations between these traits across time points within year and across ages. WT was highly correlated both phenotypically and genetically within and across years and with and without adjustment for previous and current physiological state. These results suggest that one assessment of adult weight is sufficient for selection purposes and this assessment can be made at any time within the year. CS, on the other hand, while highly correlated between ages was not as highly correlated between times within year of recording. Furthermore the phenotypic variation and heritability varied throughout the year with more genetic variance apparent at weaning time. WT and CS were also moderately correlated with each other suggesting that they are different traits genetically and further research is required to identify optimum measurement timing and to determine the importance of condition score in the breeding program.