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Age of Dam and Direct and Maternal Effects on Calf Livability¹

Department of Animal Science, Iowa State University, Ames 50011

ABSTRACT

The genetic relationships between calf livability (alive or dead) were investigated for first and subsequent parturitions of dams, and genetic correlations between direct and maternal effects were estimated. Data were 95,106 Holstein calvings. Heritabilities of direct effects were .4% for heifers and .6% for cows. The genetic correlation between calf livability for heifers and cows was .32. Regardless of age of dam, calf mortality was more frequent for male than female calves when calf livability was estimated as either a direct or maternal trait.

Effects of gestation length on calf livability were quadratic and differed for heifers and cows. Largest rates of survival were with gestation lengths of 276 and 283 days for heifers and cows.

Maternal heritabilities (estimated as four times the maternal component of variance divided by the maternal plus residual components) of .5% and .6% and dam heritabilities (estimated as four times the maternal grandsire component of variance divided by the maternal grandsire plus residual component) of .4 and .5% were small for both heifers and cows, respectively.

¹ Journal Paper No. J-10684 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Project No. 1053.

² Brazilian Agricultural Research Cooperation (EMBRAPA). CNP-Gado de Leite. 36155-Coronel Pacheco. MG. Brazil.