EFFECT OF CONCENTRATION AND BLEND OF ADDED FAT IN THE DIET ON THE PERFORMANCE OF GROWING PIGS

Diets with added fat at 25, 50 and 100 g/kg were formulated with four blends of beef tallow:soya oil, namely 100:0, 75:25, 50:50 and 0:100. An additional diet had no added fat (control diet) to give an experimental design of (3 x 4) + 1. A total of 96 individually penned pigs was used (mean initial and final live weights of 22.4 and 87.5 kg, respectively). The experiment was carried out during the period July 1985 to February 1986 at the Agricultural Research Institute, Hillsborough. Equal numbers of boar and gilt blocks were used and the pigs were fed individually to a scale to give equal amounts of digestible energy: live weight0.75. Neither concentration of fat nor blend of fat had any significant effect on the rates of live weight or carcass weight gain. Increasing concentration of fat significantly improved the carcass feed conversion ratio (P < 0.001), but the blend of fat had no significant effect. Neither killing-out yield nor the intake of digestible energy per unit of carcass gain was significantly affected by the concentration of added dietary fat nor the blend of fat. Fat treatments did not significantly affect the lean plus bone content of the ham joint, drip loss from or the depth of colour of the longissimus dorsi or the weight of flare fat. No evidence was found of synergistic effects between the fat and nonfat components of the diet nor between fats within the blends of fat on growth, digestible energy consumed per unit of carcass gain and carcass attributes. Boars had a more efficient conversion of feed to carcass gain than gilts (P < 0.01).