Effect of Level of Soluble Fiber and N-6/n-3 Fatty Acid Ratio on Performance of Rabbit Does and Their Litters

The aim of this work was to study whether the dietary supplementation with soluble fiber (SF) and the reduction of the n-6/n-3 fatty acid ratio or the combination of both influences the survival, body and milk composition, and reproductive performance of rabbit does during the first four parturitions. Four diets in a 2 × 2 factorial arrangement were used with two levels of SF (7.8 vs. 13.0, on dry matter [DM] basis; high soluble fiber [HSF] and low soluble fiber [LSF]) and two different n-6/n-3 fatty acid ratios (13.4/1 vs. 3.5/1). Nulliparous does (24/diet) were inseminated 11 d after parturition. Body chemical composition and energy content of rabbit does and their performance, litter growth, and milk production were measured between birth and weaning (25 d) along four parturitions, and milk composition and fecal digestibility were also recorded. The proportion of total removed does decreased in HSF respect to LSF groups (22.9 vs. 50.0%; P = 0.005), and it tended to decrease in LSF groups when the n-6/n-3 ratio increased and in HSF groups when the n-6/n-3 ratio decreased (P = 0.059). The increase of the level of SF reduced the digestible crude protein (CP)/digestible energy ratio (by 4%; P < 0.001) and improved the digestibility of all fibrous fractions (P < 0.001). The reduction of the n-6/n-3 ratio reduced the total dietary fiber digestibility in rabbit does fed LSF diets, but it had no effect in those fed HSF diets (P = 0.043). Treatments had no effect on average daily feed intake among parturitions (P = 0.16), but the digestible CP intake among parturitions was lower in HSF than in LSF groups (P = 0.003). Treatments had no effect on the total number of kits born, litter or average kit weight at birth, or litter size at weaning, fertility, feed efficiency, total milk production, and body chemical composition and energy content of rabbit does (P ≥ 0.29). The average weight of kits at weaning of LSF_Hn-6/n-3 and HSF_Ln-6/n-3 groups decreased by 6% compared with those from the other two groups (P = 0.030). The reduction of the dietary n-6/n-3 ratio increased the milk fat content by 12% with no effect on protein and DM content (P = 0.031). The proportion of milk odd fatty acids and saturated fatty acid increased in rabbit does fed the HSF diets compared with those fed LSF diets (P ≤ 0.037) with no effect of the n-6/n-3 fatty acid ratio. In conclusion, SF reduced the replacement rate of rabbit does with no effect of the n-6/n-3 ratio, while both dietary factors modified milk composition and fatty acid profile with minor influence on litter productivity.