Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 25, 2012
Publication Date: August 12, 2012
Citation: Long, J.A., Conn, T.L. 2012. Use of phosphadtidylcholine to improve the function of turkey semen stored at 4 °C for 24 hours. Poultry Science. 91(8):1990-1996. Interpretive Summary: All commercial turkeys in the United States are produced by artificial insemination. Current insemination technology relies on semen extenders developed over 30 years ago, and turkey semen retains high fertility rates for only the first 6 hours after dilution with these extenders. It is known that the phospholipids in the sperm membrane are affected by the length of time that semen is stored after collection, resulting in a 30% loss over time. We used a novel approach to prevent this problem by supplementing the extender with phosphatidylcholine. Use of this phospholipid improved the fertilizing ability of semen stored for 24h prior to insemination. Although more development is required, this will be a valuable tool for the turkey industry to enable better management of birds for insemination.
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 the use of exogenous phosphatidylcholine (PC) to (1) prevent the loss of phospholipids from the turkey sperm membrane that occurs during semen storage and (2) evaluate the effects of PC on sperm viability, mobility, hydrolyzing ability and fertility of stored turkey semen. For Experiment 1, pooled turkey semen was aliquoted and diluted 1:1 with Beltsville Poultry Semen Extender (BPSE) containing 0, 0.5, 2.5 or 10.0 mg PC/mL labeled with the fluorochrome 7-nitro-2, 1, 3-benzoxadiazyl-4-yl (NBD); diluted semen was maintained under aerobic conditions for 24h at 4 °C. Semen aliquots were removed at 30 min intervals during the first 4h of storage and at 1h intervals from 8 to 24h of storage for fluorometric evaluation by flow cytometry. Turkey sperm 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 treatment, 9.2-fold for the 2.5 mg treatment, and 6.7-fold for the 10 mg NBD-labeled PC treatment. For Experiment 2, pooled turkey semen was aliquoted and diluted with BPSE containing 0, 0.5, 2.5 or 10.0 mg PC/mL and maintained under aerobic conditions for 24h at 4 °C. After 24h, the viability, mobility, hydrolyzing ability and fertility of turkey sperm was assessed for control and PC treatments. Supplemental PC did not improve (P>0.05) the viability or mobility of stored semen. Supplemental PC at 2.5 mg/mL improved the hydrolyzing ability of stored semen compared to control or other PC treatments (P<0.05). 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 PC/mL improved (P<0.05) the fertility rates of stored semen during the first 11 wks of egg production; higher fertility rates occurred with 2.5 mg PC/mL compared to other PC treatments for 5 of those 11 wks (P<0.05). We conclude that supplemental PC appears to counteract the damaging effects of lipid peroxidation and/or enzymatic degradation during in vitro storage by providing exogenous phospholipids for incorporation into the turkey sperm plasma membrane.