220. Equine growth hormone enhances motility and extends longevity of ram spermatozoa in vitro
B. J. King A , V. V. Da Silva A , J. D. Harper A , C. J. Scott B and M. N. Sillence AA School of Agriculture and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
B School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
Reproduction, Fertility and Development 17(9) 85-85 https://doi.org/10.1071/SRB05Abs220
Submitted: 26 July 2005 Accepted: 26 July 2005 Published: 5 September 2005
Abstract
Sperm survival in vitro decreases with time at room temperature, but may be improved by treatment with recombinant bovine growth hormone in rats1, bulls2 and horses3. Two experiments investigated the effect of equine growth hormone (eGH) on the longevity of ram spermatozoa in vitro. The aim of experiment 1 was to determine if the addition eGH would improve the motility of ram spermatozoa after 24 h and identify any interaction with semen dilution rates used for ram semen preservation. Semen was collected from five mature Merino rams. Ejaculates were assessed for good quality and were diluted 1 + 50, 1 + 4, 1 + 3, 1 + 2 (semen + diluent) with a Tris-based cryoprotectant. Aliquots from each ram were mixed with eGH to achieve a final concentration of 100 ng/mL eGH and stored at 20°C for 24 h. Motility of spermatozoa was then assessed manually. eGH improved the motility of spermatozoa at all dilution rates compared to controls (P < 0.0001) but most markedly in the 1 + 3 and 1 + 2 samples (42.6 ± 0.8% eGH v. 22.7 ± 2.6% control; 40.5 ± 1.4% eGH v. 22.7 ± 2.2% control, respectively, P < 0.01). The aim of experiment 2 was to determine the optimum eGH concentration for improving sperm motility. eGH was added to aliquots of diluted semen (1+3 dilution rate) to produce samples with final concentrations of 1000, 100, 10 and 1 ng eGH/mL. The samples were placed in a water bath at 20°C for 24 h at which time the motility of sperm was assessed as before. Sperm motility was higher in the 100 ng/mL eGH sample (P < 0.05; 39.6 ± 0.7%) compared to other concentrations (1000 ng/mL 11.8 ± 0.7%, 10 ng/mL 21.5 ± 0.7% and 1 ng/mL 11.3 ± 0.7%). We conclude that growth hormone is effective in promoting the longevity in vitro of ram spermatozoa stored at room temperature, and that this effect is concentration dependent.
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