Abstract

GONZALEZ-PENA FUNDORA, Dianelys et al. Evaluation of genetic parameters for lactation persistency in Siboney cows with random regression models. Rev. mex. de cienc. pecuarias [online]. 2011, vol.2, n.2, pp.151-160. ISSN 2448-6698.

Genetic parameters and genetic correlations, were estimated for five persistency of lactation measures, using a random regression model with Legendre polynomials. Data consisted of test-day yields (PDC) for 17,034 first lactations of 2,086 Siboney cows (5/8 Holstein 3/8 Cuban Zebu) for calvings from 1995 through 2003 in 50 dairy herds. Estimated heritability of persistency of lactation varied from 0.18±0.02 to 0.29±0.02. Genetic correlations between the five persistency measures varied from -0.71 to 0.95. Genetic correlations between the persistency measures and different PDCs and milk yield at 305 d (PL305) had values ranging from -0.06 to 0.11. Based on heritability values and the genetic correlations between persistency measures and PL305, selection can be done simultaneously for PL305 and persistency of lactation in Siboney cattle using the persistency measures of the difference between the areas below the curve in the final third of lactation (d 201 to 300) and the initial third of lactation (d 1 to 100), and the sum of each day's contribution in the period of 61 to 280 d as a deviation of yield on d 60.

Keywords : Siboney cattle; Persistency; Lactation; Genetic parameters; Legendre polynomials.