Addition of probiotic to feeds with different energy and ADF content in rabbits. 1. Effect on the digestive organs

Abstract

Effects of feed composition, addition of the probiotic Acid-Pak 4-Way (AP4W), sex, age at slaughtering (53 or 67 d.) and interactions between feed and AP4W, age and feed, age and AP4W and age and sex on gastrointestinal (GI) tract weight and dressing percentage of 84 weaned New Zealand White rabbits were studied. Three complete feed mixtures with different levels of digestible energy (DE, MJ/kg of feed) and ADF content (g/kg of dry matter-DM) were tested (feed I had recommended DE and high ADF content: 9.22 MJ DE and 299 g ADF; feed II had 11.60 MJ DE and 254 g ADF; feed III had high energy and recommended ADF content: 13.14 MJ DE and 187 g ADF), each with and without the addition of 0.5 % AP4W. High-energy/recommended-ADF diet (feed III) increased  carcass weight (1 : 970ª ; II : ª976ª ; III :  1005^bg; P≤05), improved dressing percentage (1 : 50.2^a , II : 50.6^a , III : 52.0^b %, P≤0.05), decreased GI weight (1 : 411.1^ab, II : 420.2ª , III : 391.3^b g, P≤0.05) and decreased caecum weight (I 151.3^a , II 148.8^a , III 133.7^o g, P≤0.05). The proportions of small intestine and caecum (of total GI weight) differed between feed I and III (% of small int.: 20.2 vs. 22.3; % of caecum: 36.9 vs. 34.0, P≤0.05). The effect of AP4W was observed only in the decreased proportion of stomach and increased proportion of caecum (% of stomach: 28.0 vs. 29.9, % of caecum: 36.2 vs. 34.8 %, (P≤ 0.05). Sex significantly (P≤0.05) influenced caecum weight (females: 151.1, males 138.2 g), % of caecum (f. 36.6, m. 34.4 %) and % of small intestine (f. 20.7, m. 21.7 %). Older rabbits had (P≤0.05) better dressing percentage (52.0 vs. 49.9 %), higher carcass weight (1007 vs. 961 g), lower GI tract (392.7 vs. 422.4 g) and small intestine weight (80.0 vs. 92.1 g), higher weight and % of large intestine (63.0 vs. 54.8 g, 14.9 vs. 13.8 %).