| Popis: |
Multiple births or twinning in equids are dangerous, undesirable situations that compromise the life of the dam and resulting offspring. However, embryo vitrification and freezing techniques take advantage of individuals whose multiple ovulations allow flushing more fertilised embryos from the oviduct to be collected, increasing the productivity and profitability of such techniques. Embryo preservation is especially important in highly endangered populations such as certain donkey (Equus asinus) breeds; for which conventional reproductive techniques have previously failed. For instance, becoming an effective alternative to artificial insemination with frozen semen to preserve the individuals’ genetic material. The objective of this study was to examine the historical foaling records of Andalusian donkeys to estimate genetic parameters for multiple births, assessing the historical foal number born per animal, maximum foal number per birth and multiple birth number per animal. We designed an Animal Model with single records considering the fixed effects of birthyear, birth season, sex, farm, and husbandry system, and age as a linear and quadratic covariate. Restricted maximum likelihood reported heritability estimates ranging from 0.18±0.01 to 0.24±0.01. Genetic and phenotypic correlations ranged from 0.01±0.01 to 0.83±0.01 and 0.12±0.01 and 0.53±0.01, respectively. These estimates enable the potential for selection against/for these traits, offering a new perspective for donkey breeding and conservation. |
