NUTRITIVE VALUE OF SUN-DRIED SULLA (HEDYSARUM FLEXUOSUM) AND ITS EFFECT ON PERFORMANCE AND CARCASS CHARACTERISTICS OF GROWING RABBITS

Abstract

The nutritive value and potential use of sundried sulla hay ( Hedysarum flexuosum, g/kg as feed: 885 dry matter, 438 neutral detergent fibre (NDF), 337 acid detergent fibre (ADF), 80 acid detergent lignin and 147 crude protein (CP) for growing rabbits was studied by comparing three diets (regression method) containing an increasing inclusion rate of sulla hay (S): 0% (control, S0), 15 % (S15) and 30% (S30) in substitution for control diet (294 g NDF and 179 g CP/ kg). Three groups of 30 rabbits (individually caged) were fed ad libitum the three diets from weaning (35 d, mean weight: 572 ± 93g) to 84 d of age. Faecal digestibility of the diets was measured between 42 and 46 days of age on 10 rabbits per group. The digestible energy (DE) concentration of sulla hay estimated by regression was 8.96±0.57 MJ/kg DM, thus 7% higher than standard alfalfa meal, which would account for its high NDF digestibility (54.9%). Digestibility of crude sulla protein was estimated at 42.8%, corresponding to a digestible crude protein concentration of 71.1±8.9 g/kg DM. Even at a high incorporation rate in the feed (30%), sulla hay did not cause adverse effects on the animal growth (mean 36.0 g/d), feed intake (mean 119 g/d) or health. Feed conversion was better for a moderate rate of sulla inclusion in the diet (about 15%) than for a higher inclusion rate (3.14 vs. 3.36, P < 0.001). Health status and slaughter traits were not affected by the sulla incorporation rate. Sun-dried sulla hay ( Hedysarum flexuosum ) could thus be considered a good fibre source for the rabbit as a substitute for alfalfa meal.