Characterization of northern pintail (Anas acuta) ejaculate and the effect of sperm preservation on fertility.

Despite an abundance of waterfowl worldwide (154species are currently recognized; Ellis-Joseph et al.,1992),the survival of many individual species is threatened.According to a Conservation and Assessment ManagementPlan Workshop for waterfowl (Ellis-Joseph et al.,1992),species under threat of extinction include the Hawaiiangoose or Nene (Branta sandvicensis), Hawaiian duck (Anaswyvlliana), Laysan teal (Anas laysanensis), Tule goose(Anser albifrons gambelli) and Trumpeter swan (Olor buc-cinator). Other species, like the Northern pintail (Anasacuta) are subject to non-cyclical population decreases orlocal–regional range contractions, indicative of species orpopulations that are not yet endangered, but may becomeso in the near future (US Fish and Wildlife Service, 1999). As populations decrease in size (in nature or captivity),inbreeding can occur which, in turn, can reduce reproduc-tive fitness (Nei et al., 1975), including fecundity and sur-vivability (Ralls and Ballou, 1986). When genetic variationis maintained or increased, population vigour and the ability to adapt to environmental change are enhanced.Challenges in waterfowl management include cross-species hybridization (Ankney et al., 1986) that can resultin a loss of species uniqueness and specialized adaptiveand fitness traits, and failure to reproduce in captivityowing to behavioural problems associated with confine-ment (Hediger, 1965). One solution to these managementchallenges is the use of assisted breeding techniques in-cluding sperm preservation combined with artificial in-semination (AI). Such strategies can complement captivebreeding programs by: (1) preserving valuable genes fromindividuals for infusing into future generations; (2) reduc-ing disease transfer risk by transporting genetic material instead of birds between flocks; and (3) providing a reposi-tory of genetic material for species not yet endangered thatmay be threatened eventually by unexpected hybridization(with common species) or by natural catastrophe.Although information is available on basic sperm physiol-ogy from agriculturally valuable birds, especially chickensand turkeys (Bakst, 1990), there is a dearth of informationon non-domestic birds. If AI is to be an effective tool forthe management and conservation of rare waterfowlspecies, a high priority should be basic reproductive stud-ies that focus on consistent sperm collection and spermsensitivity to cooling and freeze–thawing.Short-term (6 h) preservation of semen has been usedextensively in the turkey industry (Sexton, 1981; Bakst,1990), but has been shown to result in reduced fertilityover time (Wishart, 1984; Sexton, 1988a; Thurston, 1995).Several studies have addressed the issue of developing cryopreservation techniques for domestic birds, includingdomestic fowls (Polge, 1951) and domestic drakes (Tai etal., 1983; Tselutin et al., 1995; Watanabe et al., 1981).