Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/1999
Publication Date: N/A
Technical Abstract: Anabolic implants are an integral part of beef production. This study tested the use of similar implants in growing pigs. Fifty-four crossbred barrows were blocked by weight at 53 d and randomly assigned within block to treatment. Treatments consisted of implanting one of three compounds in the middle 1/3 of the ear at 56 d. Implants were either a sham implant (control); 120 mg trenbolone acetate (TBA)/24 mg estradiol (E2) (TBA/E2, 5:1); or 120 mg TBA/12 mg E2 (TBA/E2, 10:1). At 56 d all pigs were penned in groups of three by weight within treatment. Feed disappearance and ADG were measured weekly. Feed efficiency was calculated as the ratio of pen weight gain to pen feed disappearance (G:F). Ultrasound evaluations of backfat thickness (BF) and loin muscle area (LMA) were determined every other week after the heaviest pig reached 65 kg. There were no significant differences among treatments for ADG or LMA. After a significant starting weight x treatment interaction was found for BF, pairwise comparisons were made by quartile; controls were fatter than TBA/E1,10:1 for the first quartile (P=0.027). Least-squares means and standard errors for G:F from 56 d to slaughter at 118 kg were 0.33+/.010, 0.361+/.010 and 0.357+/.010 for controls, TBA/E2,10:1 and TBA/E2,5:1, respectively. Covariance analysis of this trait revealed no significant treatment effect (P=0.1239). Similarly, pairwise comparisons showed tendencies for treatment differences which were not significant (P=0.059 and P=0.113 for control vs TBA/E2,10:1 and control vs TBA/E1,5:1, respectively). When control was compared to the mean of the other two treatments combined, a difference was detected in G:F (P=0.048; approximately 8% improvement). Use of TBA/E2 may prove to be a valuable tool to enhance efficiency of swine production.