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

Abstract

<p>This study aimed to evaluate the effect of feeding dried foliage (leaves and petioles) of <em>Acacia saligna</em>, <em>Leucaena leucocephala</em> or <em>Moringa oleifera</em> 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 (<em>Trifolium alexandrinum</em>) hay (Control diet) or one of the other 3 experimental diets, where 50% of berseem hay was replaced with <em>A. saligna</em> (AS), <em>L. leucocephala</em> (LL) or <em>M. oleifera</em> (MO). Compared to Control diet, decreases in dry matter (DM; <em>P</em>=0.004), organic matter (<em>P</em>=0.028), crude protein (CP; <em>P</em>=0.001), neutral detergent fibre (<em>P</em>=0.033) and acid detergent fibre (<em>P</em>=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 (<em>P</em>&lt;0.05) with AS. Rabbits fed AS and LL diets showed decreased (<em>P</em>=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 (<em>P</em>=0.002) than Control rabbits to gain one kg of body weight. Caecal ammonia-N was increased (<em>P</em>=0.002) with LL, while acetic acid was decreased (<em>P</em>=0.001) with AS diet vs. other treatments. Caecal <em>E. coli</em> and <em>Lactobacillus</em> spp. bacteria counts were decreased with MO by about 44 and 51%, respectively, vs. Control. In conclusion, under the study conditions, tree foliage from <em>M. oleifera</em> and <em>L. leucocephala</em> 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 <em>M. oleifera </em>had a better potential as a feed for rabbits than that from <em>L. leucocephala</em>. Although foliage from <em>A. saliga </em>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.</p>