Resumen

SARMENTO, José Lindenberg Rocha et al. Litter size of crossbreed dairy goats in the northeastern semi-arid. R. Bras. Zootec. [online]. 2010, vol.39, n.7, pp. 1471-1476. ISSN 1806-9290.  http://dx.doi.org/10.1590/S1516-35982010000700011.

The aim of this study was to evaluate the influence of some environmental effects on the litter size, using 526 records of kidding of dairy crossbreed goats. The statistical analyses were carried out through generalized linear models, using a binomial distribution function and the logistic link function. The probabilities of occurrence of multiple kidding were calculated by a model that included the effects of year and month of mating, order of kidding, age at first kidding, weight at mating, milk yield, lactation length, and kidding interval. The average litter size of the herd was 1.49 kids. The effects of month of mating, order of kidding, weight at mating, age at first kidding, and kidding interval were significant. Chances of multiple kiddings tended to increase with the age of dam (order) and weight at mating. Females mated during food availability period presented larger probabilities of multiple births. The age at first kidding was another important variable because females with higher age presented higher probability of multiple kiddings. Females with larger kidding intervals tended to present higher probabilities of kidding more than one kid. The litter size of crossbreed goats is highly affected by environmental changes, physiologic maturity (age), body condition and age at beginning of the reproductive life.

Palabras clave : environment effects; generalized linear models; mating weight; order of kidding; reproductive efficiency.