Impacto de la prolificidad en la politica de reemplazamiento de cerdas reproductoras

The curve of averaged prolificity was estimated in five populations from a sample of 53 commercial farms (24 Spanish, 19 Danish and 10 Cuban). The aim of the paper is to compare the curves of prolificity and analyze the impact on the optimal replacement policy of sows. The parameters of prolificity curves showed propusiedifferences among the five populations (P<0.05). As a result, an association between litter size in the first parity and maximum litter size with higher prolificity was observed. However, the slope described by the steady decline of prolificity with age did not show differences among populations. Later on, we analyzed the impact of prolificity on optimal replacement policies. For this purpose, production dynamics of five farms were simulated using identical parameters except on their prolificity. The prolificity in each simulated farm corresponded to the five estimates from previous populations. For each case, the optimal policy was calculated and corresponding herd structure, technical and economic indexes were analyzed. Indexes associated to each optimal policy revealed differences among farms (P<0.05). Hence, while the reproductive rhythm was similar, the longevity and herd structure were different. Longevity was shorter with higher prolificity and vice-versa. In fact, farms with higher prolificity concentrate more sows between 2 and 7 parities and without increasing culling rates. It was also demonstrated that net incomes in analyzed farms depended strongly on the number of piglets weaned per sow per year and that lower prolificity lead to later replacements in direct relationship with the amortization of sows