Male reproductive biology in giant pandas in breeding programmes in China

jogayle howard, zhihe zhang, desheng li, yan huang, rong hou, guanghan li, meijia zhang, zhiyong ye, jinguo zhang, shiqiang huang, rebecca e. spindler, hemin zhang, david e. wildt introduction

The goal of the giant panda ex situ breeding programme is to produce healthy, genetically diverse and reproductively sound offspring. However, reproduction in this species has been poor, in part, due to lack of male libido or aggressive behaviours towards conspecific females. Although giant panda breeding facilities have made progress in producing more surviving young, only about 29% of captive male giant pandas have ever sired offspring (Lindburg et al., 1998), and most of these males were wild born. Of the 104 giant pandas in the ex situ population in China in 1996 (at the time of the first masterplanning meeting in China; Zheng et al, 1997; see also Chapter 2), there were 33 adult males of reproductive age (6-26 years old). Only five (15.2%) had ever mated naturally and sired young. This was the main reason for 'male reproduction' being a primary target of the Biomedical Survey conducted under the umbrella of the Conservation Breeding Specialist Group (CBSG) (see Chapter 2).

We had three goals, the first being to measure the presence or absence of any obvious physiological or anatomical abnormalities. The second was to learn more about species reproductive biology, specifically comparing males of different ages, successful versus unsuccessful

Giant Pandas: Biology, Veterinary Medicine and Management, ed. David E. Wildt, Anju Zhang, Hemin Zhang, Donald L. Janssen and Susie Ellis. Published by Cambridge University Press. # Cambridge University Press 2006.

breeders and wild-born versus captive born. Our approach also allowed a third opportunity: studies that would enhance our understanding on how better to use male gametes (sperm) to advance genetic management (see Chapter 21). In this case, our focus was on:

1. sperm morphology and acrosomal integrity;

2. testes development during the breeding season;

3. sperm processing that would allow consistently successful artificial insemination (AI) with fresh or thawed spermatozoa.

The latter objective involved a comparative examination of media, cryodiluents, freezing methods, freezing rates and sperm function (via assessments of biological phenomena known as capacitation, the acro-some reaction, decondensation and zona pellucida penetration).

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