Estimation of the Genetic Parameters for Test-Day Milk, in Teleorman Black Head Sheep

Abstract

The objective of this study was to determine the genetic parameters represented by heritability for test-day milk yield and the genetic correlation between test-days milk yield and the breeding value for Teleorman Black Head sheep. The genetic parameters of daily milk yield during the first three lactations of Teleorman Black Head ewes were estimated with the random regression test-day animal model. Data consisted of 631 test-day records of 81 ewes at first lactation, 351 test-day records of 58 ewes at second lactation and 229 test-day records of 33 ewes at third lactation from experimental farm of INCDBNA Balotesti. Lactations were analysed separately. The heritability estimates for test-day milk yield of ewes at first lactation ranged from 0.015 at 200 day in milk to 0.19 at 10 day in milk. For the ewes at second lactation the heritability estimates ranged from 0.016 at 180th in milk to 0.246 at 10 day in milk. For the ewes at third lactation the heritability estimates for test day milk yield ranged from 0.018 at 180th in milk to 0.249 at 10th day in milk. Genetic correlations between individual test days milk yield were high and positive.

Keywords

• breeding value
• random regression model
• test day milk yield
• ewes
• genetic parameters