A total of 296,627 lactation records which include milk, fat, protein yields (leche120, KgG120, KgP120)
and fat and protein content (%G120, %P120) belonging to 102 herds of Manchega sheep breed were
used to estimate genetic parameters for milk traits. Because the higher number of data available, random
samplings from the initial population were carried out. A multivariate animal model with repeated
measures was used to estimate variance conponents. Model included comparison group herd-yearseason
of lambing, lambing number-age at lambing, number of lambs born and the period of time
between lambing and the first test-day, as fixed effects and the additive genetic and the permanent
environmental as random effects. Estimated heritabilities were 0.16, 0.13, 0.14, 0.09 and 0.28 and
repeatabilities were 0.37, 0.31, 0.35, 0.15 y 0.41 for leche120, KgG120, KgP120, %G120 y %P120
respectively, which were lower than those found in other dairy sheep breeds and in previous studies in
Manchega breed. Results from samples were quite similar among them and with the results obtained from univariate animal models for each single trait using all data available and no lost in precision using random samplings with a multivariate model were reported. Genetic correlations were high
and positive between yields and moderately positive between %G120 and %P120, and negative or
null between yields and composition. Because the economic importance of %G120 and %P120, it
would be interesting to include both traits in the breeding objective.
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