Replacement of digestible fibre by starchin the diet of the growing rabbit. II. Effects on performances and mortality by diarrhoea

Abstract

The effects of the level of dietary starch on growth performance and mortality were studied in six experimental sites on 2 328 growing rabbits (582 per diet). Four iso-lignocellulosic (ADF) diets (A12, A16, A20, A24) with increasing starch content (12, 16, 20, 24%) instead of digestible fibre (hemicelluloses and pectins) were compared. Diets were given ad libitum from weaning (28 and 35 d old, depending on the site) to slaughter (between 68 and 71 d old). The increase (12 points) of dietary starch level led to a double-rise of mortality rate by digestive disturbances: 4.6% and 10.1% respectively for A12 and A24 for the whole period. In parallel, the feed conversion ratio decreased slightly but significantly by 0.15 point between A12 and A24. The feed intake and the digestible energy intake was respectively reduced by only 4.5% and by 1.5% (P < 0.01), between the A12 and A24 diets. During the whole period the growth rate remained similar for the four diets (mean = 42.5 g . d -1 ). To ensure digestive security of the growing rabbit, it is recommended to maintain a dietary starch level below 14% during the post-weaning period, while for the end-fattening period dietary starch could reach 18%. rabbit / feeding / starch / fibre / growth / diarrhoea / mortality