Fiber in Animal Nutrition

Fiber in Rabbit Nutrition 56 for important morbidity characterized by growth depression and poor feed efficiency. Till the eighties, only the crude fiber criterion was used to define the fiber requirements for the growing rabbit, and the value ranges from 6 to 18% according to the authors. Consequently, the precise assessment of the fiber requirements with more “adequate” criteria is essential to reduce the risk of digest ive troubles without a too large impairment of the growth and feed efficiency. The respective effects of fibers and starch on the incidence of diarrhoea in the growing rabbit have been subject to many studies comparing the fiber: starch ratio, since in complete feed formulations one nutrient is substituted by another one. Since ileal flow of starch is very low (<2 g/d) in the rabbit, compared to that of f iber (>40g TDF/d) an overload of starch appears very unlikely linked to digestive pathology. This was demonstrated by large-scale studies showing that only the fiber level plays a role in digestive trouble occurrence, and not the starch level (Gidenne, 2015). Thus in France, large-scale studies were performed to validate the relationships among dietary fiber fractions and digestive health, and to analyse the relevance of the Van-Soest criteria for elaborating new requirements for the growing rabbit. 4.4.4 Quantity and quality of lignocellulose (ADFom). A too low intake of ADF produced by fiber deficient diets (<12%ADF) is associated to a low intake and lower growth performances. In addition, the beneficial effect of a high dietary ADF level on digestive disorders and mortality in fattening rabbits was demonstrated independently by several studies. However, when correlating ADF dietary level to the health risk index (HRi= mortality+morbidity) only 41 % of the variations of HRi are explained by those of ADF (figure 12). Thus a single criterion, Figure 12: The risk of digestive trouble for the growing rabbit is reduced according to the dietary lignocellulose “ADF” level Health risk index= mortality+morbidity, from weaning to slaughter y = 0.2274x 2 – 9.1568x + 121.04 R 2 = 0.41 Health Risk index, a er weaning % Gidenne et al., 2004a Debray et al., 2002 Bennegadi et al., 2001 Gidenne et al., 2000 Tazzoli, 2012 (exp 1) Gidenne et al., 2004b Gidenne et al., 2004b Dietary ADF concentration, % as fed basis 70 60 50 40 30 20 10 0 8 13 18 23 28 © ERLING Verlag