The effect of the anabolic agent, nandrolone laurate, on certain production and reproduction parameters in ram lambs, under intensive and extensive feeding regimes

Forty Dorper ram lambs were allocated to two trials. In the first trial (in tensively housed) and second trial (extensively maintained), one group (n = 10) in each trial was treated weekly with an intramuscular injection of an anabolic steroid (50 mg nandrolone laurate) for a 12-week period. The othe r group (n = 10) in each trial served as a control. Several body parameters were measured during this treatment period and monitored for an additional 12-week period. In the intensively and extensively housed groups, treatmen t with the anabolic steroid did not significantly increase the growth rate when compared to the controls. There was, however, a significant (p<0.01) d ifference in ADG and final body weight between intensive and extensively ho used animals. Shoulder height (66.3 vs 66.6 cm and 65.0 vs 66.5 cm); should er width (29.7 vs 28.0 cm and 19.0 vs 19.3 cm); bodylength (85.9 vs 86.0 cm and 74.5 vs 75.4cm); cannon bone diameter (2.4 vs 2.2cm and 2.1 vs 2.0 cm) ; serum testosterone concentration (1.15 +/- 0.97 vs 2.21 +/- 0.83 ng/ml an d 0.15 +/- 0.1 vs 0.89 +/- 0.58 ng/ml) and FCR (measured only in the intens ively housed animals) (7.6 vs 9.4) did not differ significantly between the treated and control animals over the entire observation period for the int ensive and extensively housed animals respectively. No significant differen ce in semen duality was recorded in the intensively housed animals from 3 m onths following treatment. Scrotal circumference was significantly (p<0.01) less in the treated groups (intensive and extensive groups) during the tre atment phase, when compared to the controls, with a decrease of 9.5% and 18 .4% respectively. Scrotal circumference recovered and increased during the recovery phase. Although use of the anabolic steroid did not result in a si gnificant increase in growth rate (intensive and extensive conditions), it would seem that nutrient availability (metabolisable energy) effected the r esponse. With higher energy diets, a better ADG and FCR could possibly have been attained. The androgenic effect of the steroid treatment retarded tes ticular development, but this phenomenon was temporary and fertility was no rmal (when compared to the controls) by 12 weeks following treatment.