Legendre polynomials were used to model milk coagulation time (R) and firmness of curd (E30) within 1-305 days in milk. Lactation curves of E30 and R were obtained for cows, each being a 3rd order polynomial with coefficients depending on the cow. Lactation curves for bulls were defined as average curves of their daughters. Bulls were compared by ANOVA procedure applied to aggregate values of E30 and R of daughters. Multiple comparison of bulls was performed with Bonferroni test. Variance components and heritability were estimated with ANOVA method, considering fixed effect of farm. Comparison of bulls indicated statistically significant difference (P<0.0001). Heritability of E30 was 0.73 and for R 0.55. Genetic variance of milk coagulation properties in Estonian Holstein population creates prerequisite for genetic improvement of milk coagulation time and curd firmness.

E. Parna, M. Vallas, T. Kaart, I. Kubarsepp, H. Kiiman, K. Parna

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume , , 01.55, 2006
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