THE EFFECT OF DIETARY-FAT INCLUSION ON GROWTH, CARCASS CHARACTERISTICS, AND CHEMICAL-COMPOSITION OF RABBITS

Two hundred ten Californian x New Zealand White rabbits were used to s tudy the influence of diet and slaughter weight (2.0, 2.25, and 2.5 kg ) on feed intake, growth, feed efficiency, carcass characteristics, an d 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% h eated whole soybeans (WS) to increase the dietary fat by 3%. Fat addit ion did not affect ADG or dressing percentage, but it improved feed:ga in ratio (.06 for each 1% of dietary fat, P < .001). Although the main measurements of carcass were not influenced by fat addition, the rabb its fed diets containing the highest fat percentage had the highest we ights of perirenal (P < .001) and scapular (P < .01) depots and the hi ghest body fat content (P < .01). The increase in slaughter weight imp roved all the desirable carcass characteristics measured but impaired feed:gain (by 13%, P < .001). Increasing slaughter weight also increas ed the perirenal and scapular fat depots by 40 and 24%, respectively ( P < .001), and the body fat content by 28% (P < .01). There were no di fferences in the utilization of animal and vegetable fats, and only fo r some traits (ADG, feed intake, kidney weights) did the diets with so ybean oil result in better responses than those with oleins. The resul ts indicate that fat addition to fibrous diets extends the rabbit's gr owing period without impairing the feed:gain ratio. The joints of rabb its killed at heavier weights have more desirable weights for marketin g the carcass on a retail cut basis.