Seasonal influence on fecundity and litter performance characteristics in Iberian pigs

Abstract

The Iberian breed was developed in an extremely adverse environment. Data recorded in an experimental herd in Oropesa (Spain) are used to study the seasonal influence on productive performance. Results of 2621 planned matings, classified according to year, mating season, strain and fecundity, have been analysed through a log-linear model. Significant effects of year and strain on fecundity have not been detected, while mating season shows a marked effect. Percentages of non-pregnant sows are 23.5, 22.9, 35.5 and 28.7 in winter, spring, summer and autumn. Least-Squares Anovas carried out on litter recordings, show that farrowing season has clear effects on litter size at birth and piglets' survival and development. Constant estimates and their standard errors coresponding to winter, spring, summer and autumn are 0.29 ± 0.11, −0.19±0.10, −0.01±0.11 and −0.09±0.10 piglets in litter size at birth, −0.50 ±0.19, 0.00±0.18, 0.49±0.19 and 0.01±0.18 piglets in litter size at 3 weeks and −1.53 ±0.31, 0.96±0.30, 1.36±0.29 and −0.79±0.32 kg in litter weight at 3 weeks.