Effect of cereal sources and processing in diets for the growing rabbit. I. Effects on digestion and fermentative activity in the caecum

摘要

Four high-starch diets (20%) varying only by the source of starch (wheat = diet W: barley = diet B; maize = diet M; extruded maize = diet EM) were given ad libitum before weaning (at 29 d old) from 18 days of age, to 8 litters (2 litters per diet) of8 rabbits caged separately from their mother. Starch concentration in the ileal digesta and caecal fermentative characteristics were assessed at weaning and at 50 d oi' age. while faecal digestibility was measured between 46 and 50 d of age. The energy digestibility coefficient was the highest for the barley based diet while the lowest were observed for wheat and maize based diets (P < 0.05). At weaning, the level of starch in the ilcum was high and similar for W, B and M diets (meanly: 8.8% DM), but was 5 points lower for the EM diet. At 7 weeks of age, it remained high (>10% DM) with the maize based diet, while it decreased for the other groups (less than 6% DM). The faecal digestibility of the glucidic fraction (NNCC) was almost complete (> 92%) andsignificantly higher with the EM diet followed by the B diei. NNCC digestibility was negatively correlated with ilcal starch concentration (r = -0.63, P < 0.001). The fibre and protein digestibility remained unaffected by the dietary treatment, and no significant correlation was detected between the ileal starch level and fibre digestibility (NDF or ADF). Caecal VFA concentration increased by 1 1 mmol (+20%) from weaning to 7 weeks of age, while ammonia level decreased by 15%. Compared to weaning, at 7weeks of age, the butyrate proportions were 5 units higher. The starch source did not significantly affect the caecal traits or fermentations, except for a slight increase in the empty caecal weight for EM and B compared io the W and M diets (P < 0.05).The ileal starch concentration was not correlated with caecal fermentative activity.