Genetic parameters for bodyweight, wool, and disease resistance and reproduction traits in Merino sheep. 3. Genetic relationships between ultrasound scan traits and other traits

The Australian Merino is the predominant genetic resource for both the lamb and sheep meat industries of Australia. There are very few studies that provide information on the relationships between wool and non-wool traits. This paper describes the genetic relationships between ultrasound scan traits and wool, disease resistance and reproduction traits in Merino sheep. Fleece weight and fibre diameter coefficient of variation were negatively correlated with ultrasound scanned fat and eye muscle depth (–0.10). Staple length, fibre curvature, and scrotal circumference were not correlated with scanned fat or eye muscle depth. Staple strength, number of lambs born and number of lambs weaned had a positive genetic correlation with fat and eye muscle depth (0.20–0.30). Faecal egg count had a negative genetic correlation with scanned fat (–0.10) and scanned eye muscle depth (–0.20). Results indicate that the combined improvement of carcass and wool characteristics in Merino sheep is possible.