Results And Discussion

Male breeding history and assessment of morphometric and testicular traits

Of the 17 evaluated males, 10 were captive-born within China and seven were wild-born. Twelve of the 17 (70.6%) had never mated naturally, despite most having the opportunity with an oestrual female. Of these, four (33.3%) were wild-born and the remaining eight (66.7%) were captive-born. Of the five males that had naturally mated, three were wild-born and two captive-born.

The mean (and range) measures for body weight, chest girth, neck girth and body length for 16 of the 17 sampled males are provided in Table 7.1. These same body metrics for SB 356 (weight 67 kg, chest girth 84 cm, neck girth 52 cm and body length 150 cm) were excluded from these average values because of his Stunted Development Syndrome (see Chapter 4). Similarly, no attempt was made to collect semen from this male due to his extraordinarily small inguinal testes (total testicular volume, 4.2 cm3). Of the other 16 giant panda males, 15 had large testes with a total testicular volume averaging 300 cm3 (range 100-455 cm3) (see Table 7.1). On average, each testis was more than 8 cm long and 5 cm wide with no size difference (p > 0.05) between the right and left gonads.

The remaining male (SB 400) was 5.5 years old with bilaterally small testes held closely adjacent to the body and a total testicular volume of only 99.8 cm3 (Table 7.2). This was probably due to his youth or a delayed pubertal onset, because his other age-matched counterparts (three 5.5-year-old males) all had larger testes and total testicular volumes (see Table 7.2). Interestingly, SB 400 also had the lowest body weight (87 kg), chest girth (97 cm) and neck girth (61 cm) despite having an overall good conformation and above-average body length (184 cm) (see Table 7.2).

Seminal quality, sperm morphology and acrosomal integrity

Most reports on male reproduction in giant pandas have focused on semen collection and processing techniques for AI with fresh spermatozoa

Table 7.1. Morphometric, testicular and ejaculate traits of giant pandas evaluated during the 1998 to 2000 Giant Panda Biomedical Survey (16 males, 5.5 to 16.5 years of age)

Traits

Mean (± SEM)

Range

Morphometry

0 0

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