Mashitah Shikh Maidin

Thesis

Nutritional control of goat reproduction

Summary

This project focuses on the effects of nutrition during a specific period of the reproductive process in female goats, namely the period around ovulation, fertilisation and early embryo development. Specifically, I will be testing whether the feeding of a supplement that is high in energy and protein will increase ovulation rate but reduce embryo survival. Although these issues have been addressed for sheep, they have never been considered for goats. We expect the two species to differ because of subtle but important differences in the reproductive biology: i) goats are generally more fecund than sheep (ie, have more multiple ovulations) so the processes in the ovary that control ovulation are different and may respond differently to a nutritional supplement; ii) goats generally have higher concentrations of progesterone than sheep, so the ability of a supplement to reduce progesterone concentrations, and thus induce embryo mortality, may not be an issue in goats.

The outcomes of these studies will benefit the goat industry by contributing to both basic and applied research effort and allowing producers to meet better the feeding requirements of their animals.

Why my research is important

The biological and economic efficiency of small ruminant production systems is strongly influenced by production losses related to the production of offspring. This is particularly important in countries such as Malaysia where sheep and goats contribute heavily to the household economy. In these countries, the relationship between nutrition and reproduction is an important topic that is widely discussed among producers, veterinarians, feed dealers and extension workers.

A recent review has shown that the general area of nutrition and reproduction in goats requires more attention, particularly nutritional adaptation to harsh environments, underfeeding, factors influencing energy consumption, quality of goat products and reproductive performance, along with the connections between nutrition and pathology. Good nutrition of female sheep and goats is generally considered to improve the success of reproductive events such as ovulation and embryonic and fetal development. However, there are specific dietary requirements for specific stages of the reproductive process, such as the time in the cycle when ovulation rate is determined. Deficiencies in nutrition prior to mating that reduce body weight and body condition will severely disturb reproductive performance. Most of this work is done with sheep but, at a superficial level, we would expect the same to apply to goats because their reproductive processes are very similar. However, at a detailed level, there are differences that may alter the outcomes of nutritional manipulation.

My investigations of these aspects of the reproductive process will provide some contribution and, at the same time, help us to formulate better nutritional management strategies for goat farmers.

Funding

• Rural Industry Research & Development Cooperation (RIRDC)