Genetic parameter estimations of fertility traits in Nero di Parma breed

Nero di Parma is an endangered Italian pig breed officially recognised in 2016 with nowadays roughly 1,600 alive animals. Since reproductive traits are key in terms of breed sustainability, the purpose of the study was to estimate genetic parameters of several fertility traits in Nero di Parma swine breed. First, a pedigree analysis was performed in Endog 4.8 to investigate the current breed’s genetic variability. The dataset consisted of 2484 litters from 1035 different sows. The litter size, mortality rate, number of piglets weaned, and survival rate were evaluated in function of i) inbreeding divided in quartile classes, ii) season, iii) year, iv) herd and v) parity order. Univariate and bivariate animal models were performed using ASReml software (version 4.1) to estimate heritability and genetic correlations among traits. Litter size was found to be the most heritable trait (h² =0.075) which was also strongly correlated with weaned piglets and survival rate while a negative correlation was found with mortality. Since inbreeding seemed not to significantly affect fertility, we suspect that in Nero di Parma the increase of inbreeding is still well tolerated probably due to its rusticity. However, breeding strategies must be applied to ensure long-term survival of this breed.