Depot fatty acids of Aberdeen Angus and Friesian cattle reared on hay and barley diets

Abstract

SummaryAberdeen Angus and Friesian cattle were reared from 4 months of age to slaughter weight at 18–24 months on either high-barley or high-hay diets. Samples of subcutaneous fat were taken by biopsy at 3 monthly intervals, and the degree of fatness of each animal was estimated ultrasonically prior to slaughter, and by visual inspection of the carcasses.The barley-fed animals gained weight more rapidly, and fattened more quickly than the hay-fed animals with the Angus being fatter than the Friesian at the same age. The percentage stearic acid (C18:0) in subcutaneous fat decreased with age and was replaced by octadecenoic acid (C18:l) and hexadecenoic acid (C16:l), these changes being more rapid in barley-fed than in hay-fed animals. At the same degree of fatness the depot fats of the Friesians were more unsaturated than those of the Angus, and in both breeds the fatter the animal the more unsaturated was its depot fat.In the hay-fed cattle the percentage C16:0 in subcutaneous fat increased during the last half of the experiment and at slaughter the percentage C16:0 was significantly higher, and C18:l significantly lower, in all depot fats compared with those of the barley-fed animals.It is concluded that the fatty acid composition of bovine depot fats is modulated by the degree of fattening, and can be affected by diet.