Reproductive characteristics of native bucks at different ages

ABSTRACT

This study was devoted to evaluate reproductive parameters in native Egyptian bucks. Attention was also directed to evaluate variation of plasma testosterone levels and semen quality as well as correlate between the influence of age and physical body status [body weight, height, crown rump "CR" length and girth] as well as testis length and width in addition to scrotum circumference "SC" of bucks and their reproductive performance. Semen was collected twice a week for 12 successive weeks during the spring season 2006. Semen volume, sperm concentration, mass and progressive forward motility, percentage of live sperm in addition to percent of abnormal sperm as well as total number of live-normal sperm were also evaluated. The obtained data showed that semen volume, sperm motility, percent of live sperm and abnormal sperm, testicular size, scrotum circumferences, libido and testosterone hormone differed significantly [P <0.002] in bucks according to changes in physical conditions. Therefore, it was concluded from the present study that the optimal native bucks expected to be used for either natural service or artificial insemination should be of age >/= 2 years, body weight >/= 35.83 kg, CR >/= 63.16 cm, testis length >/= 12.40 cm, testis width >/= 5.30 cm, SC >/= 22.50 cm, body height > /=70.83 cm, girth >/= 75.33 cm, libido index [MPD] >/= 2.66 concomitant with serum testosterone level >/= 2.30 ng/ml