White Lupin (cv. Amiga) Seeds as a Protein Source in Diet for Growing Rabbits: Effect on Growth Performance, Digestibility of Nutrients and Carcass Traits

This study aimed to evaluate whole white lupin (cv. Amiga) seeds as an alternative dietary crude protein source to soybean and sunflower meal. Diets contained soybean meal (10%, SBM diet), sunflower meal (17%, SFM diet) or white lupin seeds (15%, WL diet) as the main protein source. The experimental diets were similar in the level of crude protein (16.2%), starch (15.0%), fat (4.6%) and in the limiting amino acids. In comparison with the SBM diet, the diet based on sunflower meal contained slightly more cellulose and lignin, and less hemicelluloses and digestible energy. Diet based on white lupin seeds contained a higher level of raffinose-series oligosaccharides than other diets. Ninety Hyplus rabbits (30 rabbits per group; 1058±72 g), weaned at 37 d of age, were used for growth performance evaluation (from 37 to 79 days of age). At the end of the growth trial, 18 rabbits of average body weight were slaughtered without fasting in each group, and used for the evaluation of carcass traits. Other 39 Hyplus rabbits (13 rabbits per group; 950±92 g), weaned at 33 d of age, was used in a digestibility trial to determine digestibility coefficient of diets. No significant effects was detected on the weight gain (38.4, 40.1, and 40.0 g/d in rabbits fed the SBM, SFM and WL diet, respectively; P>0.05). The feed intake was higher in rabbits fed the sunflower meal-based diet than in other rabbits (135.0, 122.9 and 128.7 g/d in rabbits fed the SFM, SBM and WL diet, respectively; P=0.02). Similarly, feed conversion tended to be higher in rabbits fed the diet based on sunflower meal (3.40, 3.22 and 3.24 kg/kg in rabbits fed the SFM, SBM and WL diet, respectively; P=0.12). Dressing out percentage was significantly higher in rabbits fed the lupin-diet (58.7, 57.4 and 57.3% in rabbits fed the WL, SFM and SBM diet, respectively; P=0.01). There were no significant differences in digestibility of organic matter, crude protein, starch or fat. Digestibility of energy tended to be lower in rabbits fed the diet based on sunflower meal (66.5, 69.5 and 68.2% in rabbits fed the SFM, SBM and WL diet, respectively; P=0.06). Digestibility of NDF (35.7, 41.1 and 40.9% in rabbits fed the SFM, SBM and WL diet, respectively; P=0.03) and ADF was lower in rabbits fed the sunflower mealbased diet (26.8, 31.9 and 31.9%; P=0.09). In conclusion, white lupin seeds (cv. Amiga) are suitable dietary protein source for growing rabbits which can fully replace the traditionally used sources of protein, without adverse effect on the parameters evaluated in this study.