Serum Levels of Insulin-Like Growth Factor-I, Thyroid Hormones and Skeletal Muscle Fiber Size in Castrated Lambs with and Without Androgen Treatment
Twelve, intact male lambs, 1-2- weeks old, were divided into 3 groups, Group W (4 lambs) were castrated at age less than 1 month, group WT (4 lambs) were castrated at the same age and treated with testosterone and group R (4 lambs) were left intact and served as control. Testosterone Propionate replacement was administered intramuscularly at a dose of 12.5 mg started at the day of castration and continued every 2 days for 21 days, then at a dose of 25 mg every 2 weeks until slaughter. Serum insulin-like growth factor-1, T3 and T4 concentrations were measured using ELISA. Lambs were slaughtered at 8 months of age and semitendinosus and splenius muscles fiber areas were measured using digital image technique. In WT and R groups, IGF-I concentrations were significantly higher (p<0.05) at 4 and 8 months compared to IGF-I levels in group W. Serum T3 concentrations were significantly lowest in group R compared to groups W and WT. Serum levels of T4 were not significantly affected by age in younger lambs, although it was significantly higher in group R at 6 and 8 months of age. In group R, splenius muscle fiber area (1458±193 um2) was significantly higher (p<0.05) than that of groups W and WT while the muscle fiber area of the semitendinosus muscle was not significantly different among all groups.
Copyright: © 2021 Bani Z. Ismail, O. M. AL-Ababneh and M. B. AL-Zghoul. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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- muscle growth
- awassi lambs
- thyroid hormones