The inheritance of somatic cell counts (index of mastitis) in Chios sheep

摘要

Data on 1,457 Chios ewes, collected from two experimental flocks (Athalassa and Orites), were used to estimate genetic parameters for milk production and somatic cell counts in milk. The data refer to individual test-day records for milk and milk samples collected 7+-3 days following weaning (35+-3 days post-partum). Somatic cell counts (SCC) were determined using the Fossomatic counter from chilled milk samples. Small but significant differences in milk production and SCC were found between flocks. Test-day individual milk yield was highest when SCC was low and lowest when SCC was above 10X10~6 cells/ml. Estimated heritabilities for test-day individual milk yield (0.26+-0.07) and SCC (0.18+-0.06), although moderately low, are sufficient to permitgenetic progress from selection. The repeatability estimates for the traits studied were higher. Genetic and phenotypic correlations were low and insignificant. Somatic cell counts as an index of mastitis are relatively easy to measure and heritable. Itmay be suggested that they could be used towards the improvement of the health status of sheep.