Submitted to: Animal Reproduction Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2008
Publication Date: N/A
Interpretive Summary: Optimization of semen storage methods would greatly improve the efficiency of commercial turkey production. Traditional semen storage methods do not promote the high fertility rates required by the producers during the entire period of egg production. We have previously shown that turkey sperm are damaged by lipid peroxidation during semen storage. Our objective here was to develop a method for preventing the loss of lipid from the plasma membrane during semen storage. We first demonstrated that turkey sperm are able to incorporate supplemental phosphatidylcholine from the semen extender. We then found that the fertility rates of semen stored for 24h in the presence of exogenous phosphatidylcholine are higher than control semen stored without phosphatidylcholine. We conclude that supplemental phosphatidylcholine appears to counteract the damaging effects of lipid peroxidation during in vitro storage by providing exogenous phospholipids for incorporation into the turkey sperm plasma membrane.
Technical Abstract: It has been long recognized that the ability to store turkey semen for 24h in vitro without a significant loss in fertility upon insemination would benefit the commercial turkey industry. We investigated a novel approach to circumvent the loss of phospholipids from the turkey sperm membrane in the form of exogenous phosphatidylcholine (PC). Semen was collected and diluted 1:1 with Beltsville Poultry Semen Extender containing either: 1) no phophatidylcholine (control); 2) phosphatidylcholine (0.5, 2.5 or 10.0 mg/ml PC); or 3) NBD-labeled PC (same concentrations). Extended semen was maintained aerobically for 24h at 4 °C. To determine whether turkey sperm could incorporate exogenous PC, semen aliquots were removed from NBD-treatments at 30 min intervals during the first 4h of storage and at 1h intervals from 8-24h of storage for fluorometric evaluation by flow cytometry. Turkey sperm cells incorporated NBD-labeled PC in a dose-dependent manner during the first 12h of storage (p<0.05). At 24h of storage, PC uptake increased 7.8-fold for the 0.5 mg PC treatment, 9.2-fold for the 2.5 mg PC treatment, and 6.7-fold for the 10 mg PC treatment. Fertility trials were conducted to determine if supplemental PC improved the fertilizing ability of stored semen. The mean fertility rate of eggs from hens inseminated with 24h-stored control semen was 33.5% ± 4.5. Supplementation of the extender with 0.5, 2.5 or 10.0 mg/ml PC improved (p<0.05) the fertility rates of stored semen during the first 7 wks of egg production; however, the fertility rates obtained from the 10 mg/ml PC treatment varied widely during egg production. Lower fertility rates (p<0.05) occurred in the 10 mg/ml PC treatment than the 0.5 or 2.5 mg/ml PC treatments at 1, 2 8, 10, 11, and 12 wks. We conclude that supplemental phosphatidylcholine appears to counteract the damaging effects of lipid peroxidation during in vitro storage by providing exogenous phospholipids for incorporation into the turkey sperm plasma membrane.