The effect of parenteral use of estradiol, progesterone, testosterone and trenbolone on growth and carcass composition in pigs.

One hundred sixty-two Belgian Landrace pigs were fed ad libitum from 20 to 100 kg in individual pens (Exp. 1 and 2) or in group pens (Exp. 3). Boars were implanted in the range of 54 to 61 kg live weight with either estradiol-17 beta + progesterone (Exp. 1) or estradiol-17 beta + trenbolone (Exp. 2 and 3); barrows were treated in the same weight interval with either estradiol-17 beta + trenbolone (Exp. 1) or estradiol-17 beta + testosterone (Exp. 2); gilts received either estradiol-17 beta + testosterone at 60 kg (Exp. 1) or estradiol-17 beta + trenbolone at 57 kg (Exp. 2) and at 51 kg (Exp. 3). Growth performances and carcass characteristics were recorded. Carcass composition was evaluated by chemical analysis of the carcass (Exp. 1) or of the loin (Exp. 2). Regardless of sex of the pig, all hormone treatments adversely affected growth rate of the pigs, except that of gilts of Exp. 1 which had an improved rate of growth (P less than .05). There was a concomitant reduction of the voluntary feed intake in the cases of growth depression. The feed:gain ratio in this period was only improved (P less than .01) in the barrows of Exp. 1. The most striking feature concerned the carcass composition, which became leaner in all treated animals except for the boars in Exp. 1, where the carcass composition was unaffected by treatment.