Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/1999
Publication Date: N/A
Technical Abstract: Anabolic steroids can be successfully utilized to enhance growth performance in growing/finishing cattle. Limited information exists on the use of anabolic steroids to enhance growth performance in swine. We hypothesized that neonatal treatment with anabolic steroids may alter or preset the somatotrophic axis which could enhance growth performance later in life. Thus, we evaluated the growth related endocrine effects of 2 ratios of trenbolone acetate (TBA) and estradiol (E2) (5:1 and 10:1, respectively) in barrows beginning at 3 d of age. At 1 d of age, 30 piglets were assigned to 1 of 3 treatment groups (n=10 piglets/group): 1) Sham-implanted controls, 2) 5:1 TBA/E2 (40 mg TBA and 8 mg E2) and 3) 10:1 TBA/E2 (40 mg TBA and 4 mg E2). Piglets were exposed to normal managerial practices (i.e., ear notching, tail docking, castration, etc.) by 3 d of age at which time they were implanted in the middle 1/3 of the dorsal region of the ear with their respective treatments. Blood samples and body weights were collected at 2-d intervals between 3 d and 6 wk to evaluate treatment effects on weight gain and plasma growth hormone (GH), IGF-1 and IGF-2. Piglets were weaned at 2 wk of age and offered a standard starting ration ad libitum in individual pens for monitoring of feed intake. At 6 wk of age, pigs were sacrificed for tissue collection. Using birth weight as a covariate, steroid treatment tended (P=0.06) to enhance body weight. Feed intake was not different among treatment groups. Serum GH (P=0.002), but not IGF-1 (P=0.155), was increased by steroid treatment. Pituitary content of mRNAs for GH-releasing hormone receptor and GH did not differ among treatment groups. Results indicated that 10:1 TBA:E2 has the most potential for effectively increasing growth performance in swine.