Comparison of a simple cereal based diet with two complex isoenergetic diets, through the association of fibre and fat

Three isoenergetic diets differing by their crude fibre content (36, 47 and 58 g/kg) and their fat content (27, 51 and 75 g/kg) were fed to 330 sows which weaned 1105 litters. The diets were composed of cereals (type "Starch" in the control diet) partly replaced by two different amounts of sunflower meal, wheat bran, maize gluten feed and animal fat (complex diets).The number and the total weight of piglets weaned per sow and per year were similar in the three groups: 24.1 ± 0.4 piglets and 187 ± 2 kg.The variation of backfat thickness was greater with the 2 complex diets. It was then more often necessary to adjust the pregnancy feeding level to maintain the amount of body fat in these sows. The sows fed the diet with the intermediate level of fibre and fat had a lower number of piglets weaned during the second reproductive cycle. This disadvantaged their overall numerical performance, but piglet growth rate was higher in this group. With the higher level of fibre and fat, lactation problems were more frequently encountered, piglet mortality was higher, and sow food intake was lower during lactation. This cancelled the higher numerical productivity observed in this group.The Starch diet led to slightly increased constipation. Number of piglets weaned per year and per sow was increased by 0.7. Backfat thickness variations were reduced, fat deposition increased during the reproductive life, and sows were in a better physical condition than in the other groups. Despite a higher elimination of sows in the second cycle due to a lower fecundation rate in that group, the non productive period was shorter. Moreover, the lower nitrogen level in that diet contributed to a lower nitrogen excretion.