FATTY-ACIDS IN CARCASS FAT OF STEERS TREATED WITH A BETA-ADRENERGIC AGONIST INDIVIDUALLY OR IN COMBINATION WITH TRENBOLONE ACETATE PLUS ESTRADIOL-17-BETA

Forty steers of medium maturity were allocated randomly to four treatm ent groups of 10 steers each (C = Control, beta A = beta-Agonist, TO = Trenbolone acetate + oestradiol-17 beta and beta TO = beta-Agonist in combination with trenbolone acetate + oestradiol-17 beta). After 56 d ays on treatment, the beta-Agonist treatment was stopped and the steer s slaughtered on the ninth day after withdrawal. Samples of subcutaneo us fat over the 13th rib and M. longissimus dorsi were stored in seale d polyethylene bags at -20 degrees C for fatty acid analysis. A greate r proportion of oleic acid (C18:1, P < 0.05) was deposited in the subc utaneous fat of steers treated with beta A as opposed to those treated with either TO or beta TO. Treatments altered the fatty acid composit ion of the M. longissimus dorsi, particularly through their effects on palmitic acid (C16:0, P < 0.01), palmitoleic acid (C16:1, P < 0.01) a nd oleic acid (C18:1, P < 0.01). The results suggest a shift (P < 0.01 ) towards saturated fatty acids in the M. longissimus dorsi of steers treated with either beta PA or beta TO.