The effect of feeding soyabeans with different particle size on the content of conjugated linoleic acid and other fatty acids of longissimus dorsi muscle, backfat and liver of beef cattle

Fourteen 24-month-old castrated crossbred bulls (Luxi × Limousin) weighing 504.7±15.6 kg were used to study the effect of feeding soyabeans with different particle size on fatty acid composition of longissimus dorsi muscle, backfat and liver. The cattle were divided into three groups with 5, 5 and 4 bulls in groups 1, 2 and 3, respectively. The cattle were fed diets containing 69.4 kg dry matter finely ground roasted soyabeans, coarsely ground roasted soyabeans, or roasted whole soyabeans as Treatments 1, 2 and 3, respectively. The cattle were slaughtered at the end of the 28-day experiment and longissimus dorsi muscle, backfat and liver were sampled for fatty acid analysis. It was found that the total conjugated linoleic acid (CLA) content of liver in Treatment 3 was significantly higher than in Treatments 1 and 2 (P<0.05). The total CLA content of backfat of Treatment 3 tended to be higher than that of Treatments 1 and 2, and the total CLA content of Treatment 2 tended to be higher than that in Treatments 1 and 3, but the differences did not reach statistical significance (P>0.05). It is concluded that the supplementation of roasted whole soyabeans to fattening beef cattle was feasible for increasing the total CLA content of backfat and liver in beef cattle. Higher supplementation levels of soyabeans in the diet of beef cattle and longer feeding experiments to validate the effect are needed.