The effect of feeding different sources of crude fibre during pregnancy on the reproductive performance of sows

Abstract

A long-term experiment was designed to study the effect of feeding different sources of crude fibre during pregnancy on the reproductive performance of sows. The four treatments imposed during pregnancy were: C, a control compound diet; CS, the same control diet with additional chopped straw (0·2 kg/day); CM, the same control diet in which 0·25 kg was replaced daily by 1·5 kg maize silage; and CFR, a compound diet with a higher crude fibre content. In total 567 sows were used. On the treatments C, CM, CS and CFR the number of sows was 147, 142, 147 and 133 respectively. The sows remained on the experiment for five successive parities on a treatment or until the moment of culling. Feeding levels were about 32 MJ digestible energy (DE) per day during the first months of pregnancy and about 40 MJ DE per day in the last month of pregnancy. During lactation the feeding level ranged between 75 and 90 MJ DE per day.In sows giving birth to five litters, the effect of parity was calculated irrespective of the treatments. The optimum litter size was observed in the fourth litter and the percentage of successful services within 10 days post weaning stabilized after the third parity. The live weight of the sows increased gradually up to the fifth parity.Compared with the sows on the control treatment the proportional changes in consumption of the sows on the other treatments were: 0·45 more crude fibre, up to 0·02 more digestible energy and up to 0·06 less digestible protein.There were only slight differences in reproductive performance. The mean number of weaned piglets per sow per year were 19·7, 19·3, 20·1 and 20·2, respectively for the treatments C, CM, CS and CFR. Higher piglet birth weights were observed for sows on the CM treatment and a higher proportion of the culled sows had leg disorders. On the CS treatment a higher number of weaned piglets per litter was observed and this was due to the higher number of piglets born and lower piglet mortality during lactation. The sows on this treatment tended to have more difficulty in becoming pregnant after the third and fourth parities. The sows on the CFR treatment had the highest body weights and had a higher number of litters per year mainly due to lower numbers returning to service and less nonproductive days. The results from this experiment gave no clear evidence that either the inclusion of roughage or a higher crude fibre content in the diet improved reproductive performance.