A study of the effects of diet composition, within the bounds of normal diversity, on the characteristics of backfat lipid in pigs

Abstract

SUMMARYThe experiment described was carried out to compare the effects of some combinations of dietary ingredients which were within the bounds of current commercial use but which differed in their lipid characteristics.The four dietary treatments used were either low or high in lipid content with a high or low proportion of unsaturated fatty acids in that lipid. Fourteen pigs (seven gilts and seven barrows) were assigned at random to each dietary treatment. The major dietary constituents were barley × wheat × dried skim milk (treatment 1), barley × wheat × soyabean meal (treatment 2), barley + wheat + dried skim milk × tallow (treatment 3) and barley × wheat × maize × fish meal (treatment 4).Production performances were satisfactory on treatments 1, 3 and 4. The pigs on treatment 2 ate less food, grew more slowly, had poorer feed conversion ratios and fatter carcasses than the animals on the other treatments; the reason for the poor performance on this diet is not clear.Comparison of the fatty acid compositions of the backfat triglycerides and the dietary lipid shows that the dietary lipid had little effect on the backfat lipid characteristics; only in the case of linoleic acid was there a dietary-induced effect on the amount of this fatty acid in the backfat triglycerides of pigs on treatment 4.Treatment 4 which produced the backfat with the greatest linoleic acid content also produced the softest backfat. The subjective fat scores of the carcasses of pigs fed the other diets were not related to the fatty acid compositions of the backfat triglycerides or the monoene/saturated fatty acid ratio.These results are discussed in relation to the effects of diet and triglyceride structure on pig backfat lipid characteristics.