Digestion, growth performance and caecal fermentation in growing rabbits fed diets containing foliage of browse trees

This study aimed to evaluate the effect of feeding dried foliage (leaves and petioles) of Acacia saligna, Leucaena leucocephala or Moringa oleifera on the performance, digestibility, N utilisation, caecal fermentation and microbial profiles in New Zealand White (NZW) rabbits. One hundred weaned male NZW rabbits weighing 819.2±16.6 g and aged 35±1 d were randomly allocated into 4 groups of 25 rabbits each. Rabbits were fed on pelleted diets containing 70% concentrate mixture and 30% Egyptian berseem (Trifolium alexandrinum) hay (Control diet) or one of the other 3 experimental diets, where 50% of berseem hay was replaced with A. saligna (AS), L. leucocephala (LL) or M. oleifera (MO). Compared to Control diet, decreases in dry matter (DM; P=0.004), organic matter (P=0.028), crude protein (CP; P=0.001), neutral detergent fibre (P=0.033) and acid detergent fibre (P=0.011) digestibility were observed with the AS diet. However, DM and CP digestibility were increased by 3% with the MO diet, and N utilisation was decreased (P<0.05) with AS. Rabbits fed AS and LL diets showed decreased (P=0.001) average daily gain by 39 and 7%, respectively vs. Control. Feed conversion was similar in Control and MO rabbits, whereas rabbits fed AS diet ate up to 45% more feed (P=0.002) than Control rabbits to gain one kg of body weight. Caecal ammonia-N was increased (P=0.002) with LL, while acetic acid was decreased (P=0.001) with AS diet vs. other treatments. Caecal E. coli and Lactobacillus spp. bacteria counts were decreased with MO by about 44 and 51%, respectively, vs. Control. In conclusion, under the study conditions, tree foliage from M. oleifera and L. leucocephala are suitable fibrous ingredients to be included up to 150 g/kg in the diets of growing rabbits, and can safely replace 50% of berseem hay in diets of NZW rabbits without any adverse effect on their growth performance. Foliage from M. oleifera had a better potential as a feed for rabbits than that from L. leucocephala. Although foliage from A. saliga may be also used at 150 g/kg in the diets of growing rabbits, this level of inclusion may result in reduced feed digestibility and growth performance.