Embryo survival, but not first-parity litter size, is increased when gilts are fed diets supplemented with omega-3 fatty acids from fish oil

摘要

The response in reproductive performance when pigs are fed diets supplemented with fats high in polyunsaturated fatty acids (PUFA) has not been widely studied. Improved fertility has been reported in sows and other species fed diets with added fish oil, a rich source of omega-3 PUFA, but results are inconsistent. The aim of the present study was to determine the effect of the duration and the level of supplementation of omega-3 PUFA from fish oil on the reproductive performance of gilts. In Experiment 1, 570 Large White and Landrace purebred gilts were fed ad libitum either an unsupplemented diet containing tallow (Control) or a diet containing 3 g fish oil/kg (Omega-3) as a partial replacement for tallow from 24 weeks (Omega-3 for 6 weeks) or 27 weeks of age (Omega-3 for 3 weeks) before mating. Liveweight and backfat gain between 24 weeks of age and mating were recorded. Gilts were then fed an unsupplemented diet during gestation and farrowing rate and first litter size were recorded. In Experiment 2, 356 Large White x Landrace F1 cross gilts were fed ad libitum diets containing either 0, 3 or 10 g fish oil/kg of diet as a partial replacement of tallow from 24 weeks of age and continued after mating at 2.2 kg/day until slaughter at 25 days of gestation. Pregnancy rate, ovulation and embryo survival were recorded. Data were analysed by general linear model ANOVA and Chi-square methods. In Experiment 1, there was no increase in farrowing rate or litter size born in gilts fed the omega-3-supplemented diet for either 3 or 6 weeks before mating compared with Control gilts. In Experiment 2, supplementation with omega-3 PUFA from 24 weeks of age through to mating and continued during early gestation did not increase ovulation rate but there was a trend (P < 0.10) for an increase in embryo survival measured at Day 25 of gestation in gilts fed diets containing fish oil. Embryo survival was higher in gilts fed diets containing 3 g fish oil/kg of diet than in those fed the Control diet (P < 0.05). Increasing the supplementation level to 10 g fish oil/kg did not increase embryo survival further. In both experiments, supplementation of omega-3 as fish oil did not affect the onset of oestrous, gilt removal and weight and backfat gain. In conclusion, supplementation of omega-3 PUFA before mating did not improve farrowing rate or litter size in gilts. It may be necessary to continue feeding diets with low concentrations of fish oil during early gestation to maximise the reproductive response to elevated omega-3 PUFA.