Effect of dietary energy source on the performance and perirenal fat thickness evolution of primiparous rabbit does

Abstract

AbstractSeventy-four New Zealand ✕ Californian females were used to determine the influence of dietary energy source on the performance and perirenal fat thickness (PFT) change measured by ultrasound of primiparous rabbit does. Three highly concentrated diets were designed with different dietary energy sources: animal fat (diet F), vegetable oil (diet O) and cereal starch (diet S), and does were fertilized by artificial insemination after parturition (AP group) or around weaning (AW group), litters being weaned at 28 days of age. There were no significant differences in live weight and food intake of females throughout gestation, but does given diet S showed a higher increase in their PFT until 28th day than those given diets F and O (P < 0·01), although all females had a similar PFT at parturition. Rabbit does given diets S and O showed a significantly higher dietary energy intake than those given diet F (P < 0·01) during the first weeks of lactation, and similar thereafter until the second parturition. Milk yield and litter weight gain were significantly higher with fat-enriched diets (P < 0·05), and milk composition of rabbit does given diet F showed a higher total solids content (P = 0·01), fat (P < 0·001) and energy (P < 0·01) than milk of does receiving diets O or S. Although pups on fat diets showed a higher weaning weight (P < 0·05), dietary treatment during lactation did not have any effect on the performance of pups during the subsequent growing period. PFT always decreased during lactation for does given fat-enriched diets, while it increased for does given diet S and fertilized after parturition. Live weight of AP does was significantly higher at 21st day of lactation (P < 0·01) and at weaning (P < 0·001), and they showed a significantly lower food intake during the final week of lactation. The period from weaning to parturition was too short for AP does, which showed a decrease of their PFT, while AW does showed an increase of their PFT and a greater number of pups alive at birth (P < 0·05). Due to the lower milk yield of rabbit does fertilized AP, their pups showed a significantly higher solid food intake (P < 0·001), resulting in a similar value for the live weight of pups in both groups at weaning. The earlier promotion of solid food intake significantly affected the food intake of litters during the subsequent growing period, presenting higher values for pups coming from AP does. In conclusion, the addition of dietary fat, especially from animal origin, seems to improve the utilization of energy for milk production, while the use of a high level of starch could decrease the negative balance of primiparous rabbit does during lactation.