Semen characteristics and plasma testosterone of New Zealand male rabbits as affected by environmental temperatures

Abstract

Sixteen adult New-Zealand White rabbit males at the age of 6 months and weight of 2.5 ± 0.14 kg were used to study semen characteristics and some biochemical and enzymatic properties of seminal plasma, and blood plasma testosterone during spring and summer seasons. The averages of maximum and minimum ambient temperature in both seasons were 27.1 ºC and 18.9 ºC in spring, versus 32.2 ºC and 26.5 ºC in summer, while the averages of relative humidity were 86.1 % in spring, and 89.5 % in summer. Results showed that sperm concentration, percentages of dead sperm, and sperm with intact acrosome were decreased (P<0.01) during summer, while percentages of live sperms and acrosome-reacted sperm were increased (P<0.01). Ejaculate volume and percentages of motile and abnormal spermatozoa were slightly affected by the season. Biochemical analysis of seminal plasma showed increase in total protein (TP), globulin (P<0.01) and albumin (P<0.05) during summer. Seminal plasma total lipids (TL) were decreased (P<0.01) while cholesterol was increased (P<0.05) during summer. Alkaline phosphatase (ALP) decreased (P<0.01) and lactate dehydrogenase (LDH) increased (P<0.05) during summer. Initial fructose and blood plasma testosterone were increased (P<0.01) during the summer season. Thus, changes in environmental conditions from spring to summer season were accompanied with marked alterations in some seminal plasma parameters and related reproductive functions of rabbits.