Butterfat in rations for pigs fed skimmed whey: Growth rate, feed conversion, economics, carcass evaluation and fat quality

An experiment was carried out, using 81 castrated male pigs, to estimate the effect of adding butterfat (70% fat, 30% buttermilk), as an energy supplement, to the rations of pigs fed skimmed whey ad libitum. The rations were fed daily in a restricted amount and butterfat added to rations at two levels: T-2 and T-3, 140 and 280 g/day/animal, respectively. In treatment T-1, no butterfat was added. The pigs were weighed every 21 days until they reached average liveweights of 100 (group 1) or 120 kg (group 2), when they were killed for carcass studies. There were significant differences in liveweight gains and feed conversion for the pigs supplemented with butterfat. A negative result, from an economical point of view, was obtained due to the relatively high price of the butterfat. A higher yield of carcass weight on field liveweight was obtained in treatments T-2 and T-3, reflecting the higher degree of fatness. The relative carcass length, muscle depth and percentage of defatted ham were higher in T-1. Conversely, the relative depth of fat was more marked in the groups and treatments that consumed butterfat with their rations. Both groups of T-1 yielded the highest percentage of muscle and the lowest of fat in their carcasses, the differences from T-2 and T-3 being significant. T-2 and T-3 did not differ significantly from one another. There were significant differences in the fatty acid composition due to sampling location. The differences due to treatment were statistically significant in respect of the concentrations of 14:0, 16:1, 17:0, 17:1, 18:0 and 18:1 fatty acids. The unusually low concentration of 18:2 in the dissected fat tissues produces high quality porcine fats, for use in manifactured and prepared foods.