Oestrous Cycle Pharmacological Manipulation - Anatomy & Physiology
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Introduction
The manipulation of normal cyclic activity ensures optimum production or is convenient for the herdsmen or owner. In the case of seasonal breeders, it allows them to breed out of season, or to advance the onset of cyclic activity. There are also advantages in ensuring all animals in a group come into oestrus at the same time for ease of management. There are two methods of oestrus synchronisation. One is physiological manipulation of the oestrous cycle, and the other pharmacological manipulation of the cycle. Various factors must be considered before deciding which method to use. These factors will be specific to the type of production unit and species, also the stage of the natural oestrous cycle in the animal/herd involved.
Factors Influencing Reproduction
Hormones
- Pulsatile GnRH secretion.
- Gonadotrophins LH and FSH
- Gonadal steroids e.g. Oestrogen and Progesterone
- Inhibin, inhibiting FSH
- Prostaglandin F2α, causes luteolysis in the non-pregnant cycle
Environment
- Day length (short and long day breeders)
- Housing conditions (group v.s individual)
Nutrition
- For example, feeding a higher plane of nutrition (flushing) to increase fertility before oestrus.