Inbreeding Depression on Female Fertility and Calving Ease in Spanish Dairy Cattle

Abstract

Inbreeding depression on female fertility and calving ease in Spanish dairy cattle was studied by the traditional inbreeding coefficient (F) and an alternative measurement indicating the inbreeding rate (DeltaF) for each animal. Data included records from 49,497 and 62,134 cows for fertility and calving ease, respectively. Both inbreeding measurements were included separately in the routine genetic evaluation models for number of insemination to conception (sequential threshold animal model) and calving ease (sire-maternal grandsire threshold model). The F was included in the model as a categorical effect, whereas DeltaF was included as a linear covariate. Inbred cows showed impaired fertility and tended to have more difficult calvings than low or noninbred cows. Pregnancy rate decreased by 1.68% on average for cows with F from 6.25 to 12.5%. This amount of inbreeding, however, did not seem to increase dystocia incidence. Inbreeding depression was larger for F greater than 12.5%. Cows with F greater than 25% had lower pregnancy rate and higher dystocia rate (-6.37 and 1.67%, respectively) than low or noninbred cows. The DeltaF had a significant effect on female fertility. A DeltaF = 0.01, corresponding to an inbreeding coefficient of 5.62% for the average equivalent generations in the data used (5.68), lowered pregnancy rate by 1.5%. However, the posterior estimate for the effect of DeltaF on calving ease was not significantly different from zero. Although similar patterns were found with both F and DeltaF, the latter detected a lowered pregnancy rate at an equivalent F, probably because it may consider the known depth of the pedigree. The inbreeding rate might be an alternative choice to measure inbreeding depression.

Effects of inbreeding and other genetic components on equine fertility

“…In dairy cattle, there is evidence that effects of inbreeding on fertility are more pronounced on higher levels of inbreeding (Wall et al, 2005;Gonzá les-Recio et al, 2007). Correspondingly, our results showed that the effect on fertility became more distinct after reaching a certain level of inbreeding.…”

Individual increase in inbreeding allows estimating effective sizes from pedigrees

“…Notice that, on average, for a given reference subpopulation, t is equivalent to the 'discrete generation equivalents' proposed by Woolliams and Mäntysaari [24], thus characterizing the amount of pedigree information in datasets with overlapping generations. Parameter t has been widely used to characterize pedigree depths both in real [1,9,21] and simulated datasets [2]. The set of DF i values computed for a number of individuals belonging to the reference subpopulation can be used to estimate the N e regardless of the presence of individuals which would be assigned to different discrete generations according to their pedigree depth.…”

Pedigree analysis and inbreeding depression on growth traits in Brazilian Marchigiana and Bonsmara breeds1

“…This reduction in genetic diversity and its effects have been extensively studied in different species, particularly in beef cattle (Swiger et al, 1961;Burrow, 1998;Santana et al, 2010). One of the most relevant effects resulting from reduced genetic diversity is inbreeding depression, which compromises the performance of domestic animals (Croquet et al, 2007;González-Recio et al, 2007;Panetto et al, 2010).…”