Turkish Journal of Veterinary & Animal Sciences




Twenty-eight growing Granadina goat bucks, divided into 4 groups of 7, in a 2 × 2 factorial arranged design, were used to study the effect of post-weaning levels of dietary energy and administration of recombinant bovine somatotropin (rbST) on growth and semen characteristics. Every 14 days, bucks were offered sustenance at rates of either 1.0 (standard diet, 2.36 Mcal EM kg^{-1}; 15% CP) or 1.25 (increased diet, 2.95 Mcal EM kg^{-1}; 18% CP) times the requirements for growth energy and protein, for a total of 99 days and in combination with or without subcutaneous administration of 125 mg rbST. The average daily gains (ADG) were greater (P < 0.01) in bucks fed the high energy diet (133 ± 25 vs. 111 ± 23 g day^{-1}) and the ADG were greater (P < 0.05) in the bucks treated with rbST than in the untreated bucks (130 ± 28 vs. 114 ± 23 g day^{-1}). The percentage of live sperm cells was not different between bucks fed increased diet of NRC recommendations and bucks fed standard diet. Similarly, the sperm output of bucks on the increased diet did not differ from that of bucks on the standard diet (2282 ± 1137 vs. 1946 ± 529 × 10^6/mL). Semen volume (0.51 ± 0.29 vs. 0.55 ± 0.28 mL), sperm concentration (2210 ± 1139 vs. 2055 ± 656 × 10^6/mL), total sperm cells (1233 ± 962 vs. 1014 ± 572 ×x 10^6), and motile sperm cells (67.1 ± 14.5 vs. 60.9 ± 19.3) were not affected by rbST. No significant differences due to dietary and hormonal treatments were observed in scrotal circumference. Dietary and hormonal treatments had no effect on either serum concentration of particular metabolites, except cholesterol. Results from this study indicate that both high energy diets and chronic application of rbST enhanced the growth performance of young Granadina goat bucks; nevertheless, none of these effects altered the final scrotal circumference, particular blood metabolites, and sperm output.


Growth, scrotal circumference, blood metabolites, sperm

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