Effect of cereal sources and processing in diets for the growing rabbit. II. Effects on performances and mortality by enteropathy

The effects of the quality of the dietary starch on growth performance and mortality were studied on five experimental sites on 1784 growing rabbits ( 446 per diet). Four iso-fibre diets varying in starch nature (W-wheat, B-barley, M-maize, EM-Extruded maize) were compared. The diets were given ad libitum from weaning ( 30 to 35 d. of age, depending on the site) to slaughter ( 68 to 71 d). From weaning to 49 days of age, the weight gain did not differ significantly according to the starch source ( mean = 48.6 g center dot d(-1) on average). The feed intake was higher for the M diet compared to the other three diets (+ 5%, P < 0.01). During the finishing period ( 49 d to slaughter), the weight gain was significantly higher for the EM diet compared to the W or B diets (+ 2%). The feed consumption was 5% higher ( P < 0.01) for the M diet, compared to other treatments. Thus, feed conversion was the worst for the M diet, while it was the lowest for the EM diet. During the whole fattening period, the weight gain was only slightly higher with extruded maize feed, compared to the others ( meanly + 0.8 g center dot d(-1)). Correlatively, feed intake and conversion index were significantly lower for the EM diet, while they were the highest for the M diet ( - 2 to - 4% compared to B and W diets). On the five experimental sites, mortality was always caused by acute digestive disorders, without specific pathology. The mortality rate due to diarrhoea greatly varied among sites ( between 1.7 and 19.4%). The mortality rate between weaning and 49 days of age and during the finishing period was not affected by the dietary starch origin. However, the mortality in the W group was 3 points lower than in the M group ( P = 0.07).