The effect of dietary fat inclusion on growth, carcass characteristics, and chemical composition of rabbits.

Abstract

Two hundred ten Californian x New Zealand White rabbits were used to study the influence of diet and slaughter weight (2.0, 2.25, and 2.5 kg) on feed intake, growth, feed efficiency, carcass characteristics, and body chemical composition. Seven diets were formulated to contain 24% ADF: Diet C (control) had no added fat; Diets T, O, and S contained 3% of added beef tallow, oleins, and soybean oil, respectively; Diets TWS, OWS, and SWS contained the same level and types of fat plus 18% heated whole soybeans (WS) to increase the dietary fat by 3%. Fat addition did not affect ADG or dressing percentage, but it improved feed:gain ratio (.06 for each 1% of dietary fat, P < .001). Although the main measurements of carcass were not influenced by fat addition, the rabbits fed diets containing the highest fat percentage had the highest weights of perirenal (P < .001) and scapular (P < .01) depots and the highest body fat content (P < .01). The increase in slaughter weight improved all the desirable carcass characteristics measured but imparied feed:gain (by 13%, P < .001). Increasing slaughter weight also increased the perirenal and scapular fat depots by 40 an 24%, respectively (P < .001)< and the body fat content by 28% (P < .01). There were no differences in the utilization of animal and vegetable fats, and only for some traits ADG, feed intake, kidney weights) did the diets with soybean oil result in better responses than those with oleins. The results indicate that fat addition to fibrous diets extends the rabbit's growing period without impairing the feed:gain ratio. The joints of rabbits killed at heavier weights have more desirable weights for marketing the carcass on a retail cut basis.