The aim of this study was to evaluate the performance and digestive response of the growing rabbit according to a change in the nature of the lignocellulose (ADF), without a change in the ADF level. Three diets with a linearly decreasing lignin/cellulose ratio (ADL/cellulose = 0·8; 0·4; 0·2; respectively LC8, LC4, LC2) were given to a total of 162 rabbits per diet, from weaning till slaughter weight. A reduction of the ADL/cellulose ratio led to a lower food intake (LC8 v LC2: -11%), associated with a lower daily weight gain (-6% for LC2). Mortality and morbidity rate was significantly greater (+50%) for LC2 and LC4 diets compared with the LC8. Thus, the health risk index (morbidity + mortality) increased by 20 units for LC4 and LC2 compared with LC8 diet. In parallel, rate of passage was slower (mean retention time 4·5 h greater, P = 0045) with LC4 and LC2 diets. Dry-matter digestibility was slightly affected, whereas protein digestion was favoured with low ADL/cellulose ratio. It is recommended that a minimum lignin supply (about 6 g/day) is adopted as well as a minimum dietary lignocellulose to ensure growth performance and health of the growing rabbit.

Sixteen New Zealand White ✕ Californian doe rabbits (four per diet) weighing 3397 (s.e. 378) g, and surgically fitted with a glass T-cannula at the terminal ileum were used to determine the apparent ileal digestibility of non-starch polysaccharides of four fibrous foods. Four diets were formulated to contain paprika meal, olive leaves, lucerne hay or soya-bean hulls as the sole source of fibre. Fibre sources were supplemented with different proportions of soya protein isolate, wheat flour, lard, sodium chloride, calcium carbonate, calcium phosphate, DL-methionine and a mineral/vitamin mix, to obtain diets containing at least 185 g crude protein and 50 g starch per kg. All diets included 2 g/kg of the respective fibre source marked with chromium. Diets were assigned to individually caged rabbits in a completely randomized design and were offered ad libitum throughout the experiment. Dry matter intake was not affected by type of diet. Fibre source affected (P < 0·05) corrected ileal apparent digestibility of total non-strach polysaccharides (NSP), xylose, galactose, glucose and uronic acids. Uronic acids were the best digested monomer at the ileum in all the foodstuffs studied, ranging from 0·195 to 0·522 for olive leaves and paprika meal, respectively. Corrected ileal apparent digestibility of uronic acids was correlated with the uronic acids insoluble in NDF solution, expressed as proportion of total uronic acid content (r =–0·74; P = 0·001), the proportion of large particles (> 1·25 mm; r = –0·71; P < 0·01) and the proportion of fine particles (< 0·315 mm; r = 0·65; P = 0·01). Other monomers (arabinose, mannose, rhamnose and galactose) usually related to pectic substances, also showed in general a greater ileal digestibility than that of total NSP. Taking into account the uronic acids content of the diet and their digestibility, digestible uronic acids accounted for 0·572, 0·528, 0·93 and 0·353 of the total ileal digestible NSP of paprika meal, olive leaves, lucerne hay and soya-bean hulls based diets, respectively. The sum of arabinose, mannose, rhamnose and galactose accounted for 0·15 of total NSP digested at the ileum on average, over the different fibre sources studied. Glucose and xylose were the monomers least digested at the ileum. Their corrected ileal apparent digestibilities were close to zero, except for the paprika meal (0·266 and 0·216) and soya-bean hulls (0·137 and 0·057) based diets. In conclusion, the results of this study indicate that a valuable amount of total NSP is hydrolysed before the caecum in rabbits. However, this hydrolysis affects mainly pectic and readily fermentable substances.

Experiments were carried out to establish the suitability of full fat neem seed meal (FFNSM) in broiler and growing rabbit diets. In the broiler experiment, 200-day-old (Babcock) broiler chicks were used in a 10-week trial, with the FFNSM fixed at 0 (control), 25, 50, 75 and 100 g/kg diet. In the rabbit experiment 24 rabbits of three different breeds were used in an 8-week trial, with the FFNSM fixed at 0 (control), 100, 200 and 300 g/kg diet. The criteria of response were food intake, weight gain, food conversion and protein efficiency ratio and mortality. There was a significant (P < 0·05) negative correlation between the dietary inclusion of FFNSM, weight gain and food conversion efficiency of the birds in the starter phase. In the finisher phase from 5 to 10 weeks, food intake, weight gain, food conversion and protein efficiency ratio did not differ significantly (P > 0·05) between the birds on the control diet and diets containing up to 75 g FFNSM per kg. For all the measurements, rabbits on the diet with 100 g FFNSM per kg gave better results than the control. Food intake, weight gain, food conversion efficiency and protein efficiency ratio did not differ significantly (P > 0·05) between rabbits on control diet and the diet containing 200 g FFNSM per kg. Performance on the diet with 300 g FFNSM per kg was poorest.