7Savolainen P, Zhang YP, Luo J, et al. Genetic evidence for an East Asian origin of domestic dogs [ J ]. Science, 2002, 298 ( 5598 ) : 1610 -1613.
8Barkawi A H,Elsayed E H,Ashour G,at al.Seasonal changes in semen characteristics,hormonal profiles and testicular activity in Zaraibi goats[J].Small Ruminant Research,2006,66 (3):209-213.
9Azeredo G A,Esper C R,Resende K T,at al.Evaluation of plasma membrane integrity of frozen-thawed goat spermatozoa with or without seminal plasma[J].SmallRuminant Research,2001,41 (3):257-263.
10Ahmad N,Noakes D E.Seasonal variations in testis size,libido and plasma testosterone concentrations in British goats[J].Animal Science,1995,61 (3):553-559.