Dietary fatty acid profile: effects on caecal fermentation and performance of young and fattening rabbits

Abstract

[EN] The present work was performed to study the effect of dietary inclusion of different fatty acid combinations (saturated, n-3 and n-6 polyunsaturated fatty acids; PUFA) on caecal fermentation activity, feed intake, growth rate and feed efficiency of young rabbits around weaning (17 to 44 d) and fattening rabbits (28 to 63 d of age). Five diets were formulated using the same raw materials and including 3% of lard (A diet, rich in saturated fat), sunflower oil (S diet, rich in n-6 PUFA), linseed oil (L diet, rich in n-3 PUFA), sunflower oil and lard at 1:1 rate (SA diet), or linseed oil and lard at 1:1 rate (LA diet). In the first trial, the effect of the 5 diets on rabbit performance was evaluated in a fattening period from 28 to 63 d of age, with 490 rabbits allocated in individual cages; mortality rates were measured with 1670 rabbits (750 allocated in individual cages and 920 in collective cages, 8 rabbits/cage). In the second trial, 120 young rabbits were used from 17 to 44 d of age, weaned at 28 d, allocated in collective cages and randomly fed with A, S or L diets, evaluating performance and gut weight and caecum fermentation activity. The use of animal fat or vegetable oil and the richness in n-3 or n-6 PUFA of vegetable oils had no significant effect on the feed intake (130 g dry matter/d) and growth rate of fattening rabbits (45.5 g/d), but the inclusion of sunflower oil in diet improved feed conversion rate (2.79 for S diet vs. 2.87 for the rest of diets; P<0.01). Mortality rate was lower when vegetable oils were included in diet (34 and 37% for S and L diets respectively vs. 45% for A diet; P<0.05). Feed intake and growth rate increased quickly from 17 to 44 d, but only small occasional differences were recorded in growth rate of young rabbits, in favour of rabbits receiving animal fat from 17 to 21 d (P<0.05) or sunflower oil from 28 to 30 d (P<0.05). Caecal traits of rabbits at 30 and 44 d of age were similar for the different dietary groups, although butyric acid concentration in caecum content at 44 d was the lowest (P<0.05) with L diet.