Abstract

Genetic parameters of clinical mastitis were estimated in first-lactation Finnish Ayrshire using two random regression threshold models. The models were random regressions on third-order Legendre polynomials (RRLP), and random regressions on linear splines (RRLS) with four-knots. Posterior means of heritability of liability to clinical mastitis were between 4% to 10% and 4% to 5% before calving to one month after calving from RRLP and RRLS models, respectively. Heritability was lowest in mid to late lactation until it began to rise slightly at day 275. Estimates of heritability from RRLS showed slight peaks at the knots but there was no sharp rise at the end of the trajectory. Most Genetic correlations between clinical mastitis in different time intervals ranged between 0.30 and 0.85.

E. Negussie, I. Stranden, Esa A Mäntysaari, Shogo Tsuruta

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume , , 24.11, 2006
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