Larger Longissimus Muscle Area Research Articles

Effect of a Combination of Diethylstilbestrol and Methyltestosterone on Performance, Carcass Traits, Serum and Muscle Characteristics of Pigs

Forty barrows and 40 gilts were included in two experiments designed to study the effects of DES+MT and sex upon performance, carcass traits, muscle composition and serum components of swine. The DES+MT treatment stimulated daily gains of gilts and depressed the gains of barrows. Hormone feeding had no significant effects upon carcass traits in experiment 1, but the pigs receiving DES+MT in experiment 2 had less backfat (P<.04) and larger longissimus muscle areas (P<.06) than controls. Gilts had less fat and more muscle than barrows. The percent quadriceps femoris muscle was higher among pigs fed DES+MT than controls in experiment 1, but not in experiment 2. Neither the protein fractions of the longissimus muscle nor the area or percent of red, white or intermediate fibers were statistically influenced by DES+MT treatment. This finding is consistent with the fact that DES+MT treatment did not alter the mass of the longissimus muscle. Electrophoretic separation of serum proteins revealed that DES+MT tended to increase percent albumin and decrease the percent globulins. Free fatty acid levels were similar for DES+MT treated and control pigs and in general increased with age. The DES+MT treatment increased ovarian follicle size especially in those gilts fed DES+MT from 23 kg (experiment 2). At least one of these gilts had a cystic ovary.