Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/19/2004
Publication Date: 4/19/2004
Citation: Long, J.A., Kulkanri, G. 2004. An effective method for improving the fertility of glycerol-exposed poultry semen. Poultry Science. 83:1594-1601. Interpretive Summary: A growing percentage (>37%) of important poultry research stocks have disappeared in recent years. For example, in 1995 a large and unique collection of 17 turkey research lines at Oregon State University was eliminated due to funding difficulties. Storing germplasm from these lines in the form of frozen semen would provide a way to preserve the genetics without having to maintain live production. Of the cryoprotectants studied to date, glycerol appears to be the most effective for protecting poultry sperm during freezing; however, the concentration of glycerol needed to provide adequate protection (~1M) are contraceptive in the hen and must be lowered to <0.1M prior to insemination of thawed semen. We examined the feasibility of using density gradient centrifugation as a new method of glycerol reduction, and found that our method provides acceptable fertility rates for poultry semen. This innovation will permit semen banking from critical poultry stocks until new cryopreservation protocols are developed.
Technical Abstract: Semen cryopreservation is necessary for banking germplasm from critical poultry stocks. To date, glycerol is the most effective cryoprotectant for poultry sperm; however, the contraceptive effects of glycerol require a significant reduction of the cryoprotectant from thawed semen prior to artificial insemination. The effectiveness of glycerol reduction by dialysis and two density gradient procedures (Accudenz vs. Percoll) was evaluated by fertility trials with highly inbred chicken research lines and commercial turkey lines. Semen was extended 1:1 and then diluted with glycerolized extender to yield a final 11% glycerol concentration. Glycerolized rooster semen was aliquoted for control, Accudenz density gradient and dialysis treatments. A total of 90 pure line and 85 F1 hybrid hens were each inseminated with 100x106 sperm at 7-day intervals for periods of 4-6 wks. All eggs from the glycerolized control semen were infertile, and fertility rates from dialyzed semen decreased steadily from 26.4 to 0% within the first 4 weeks. In contrast, fertility rates for Accudenz-processed semen increased from 17.9 to 37.17% during the first 4 weeks. Similar fertility rates occurred with the F1 hybrid cross lines. For turkey fertility trials, glycerolized semen was processed with either Accudenz or Percoll density gradients to reduce glycerol. A total of 36 hens were inseminated with 150x106 sperm at 7-day intervals for a period of 6 wks. Similar to the chicken trials, fertility rates of Accudenz-processed semen steadily increased to 49.4% by the 6th week of insemination. The average fertility of Percoll-processed semen was only 19.1%. These data demonstrate that the Accudenz density gradient is an acceptable glycerol reduction method for poultry semen.