Developments in Reproduction in Dromedary Camels

Introduction

Reproductive efficiency of camels under natural pastoral conditions is low for reasons such as a short breeding season, long gestation period of 13 months and an 8 – 10 month period of lactation-related anoestrus. Therefore, a better understanding of reproductive physiology in the camel and the introduction of assisted reproductive techniques are important to try and increase the productivity of this species. This review looks at some of the developments in camel reproduction.

Reproductive physiology

All camelids are induced ovulators, usually ovulating only after mating, and if the camel does not conceive the corpus luteum has a very short lifespan of only 8 – 10 days. In the pregnant animal the embryo arrives in the uterus between days 5 and 6 and has to move rapidly around the uterus liberating its maternal recognition of pregnancy (MRP) signal before day 8 if it is to prevent luteolysis occurring. In ruminants, that have a cotyledonary placenta, this MRP signal is thought to be interferon tau (IFN-τ), whereas in the pig and horse, non-ruminants with a diffuse epithelialchorial placenta, fetal oestrogens secreted from the early conceptus are thought to be involved. The camel ruminates but has a diffuse epithelialchorial placenta, and studies involving culture of early embryonic tissue has shown that IFN-τ is not secreted, but large amounts of oestradiol-17β and oestrone are produced by the early embryo from day 10 after ovulation. This onset of oestrogen synthesizing ability coincides well with the observed time of luteolysis following a sterile mating, thereby suggesting that fetal oestrogens maybe an important part of the MRP signal (Skidmore et al, 2005). This hypothesis is further supported by the production of large multinucleate trophoblast cells that develop at frequent and irregular intervals along the trophoblast layer that, immunocytochemical staining studies have demonstrated, possess the enzymes necessary for the conversion of cholesterol to oestrogens. […]