Hormones are crucial in livestock and animal fertility management. Hormones are classified as protein-based or chemical-based, with each having its own set of activities and applications. Animals' hypothalamus, pituitary, and placenta naturally manufacture protein-based hormones, which are totally digested in the body and therefore safe to use. Chemical hormones are steroidal and produced artificially.
1. Protein-based Reproductive Hormones
Protein-based hormones are classified into two types: peptide hormones and gonadotropins, which are commonly employed in veterinary reproductive.
1.1 Peptide hormones
- GnRH (Gonadotropin-Releasing Hormone): Causes the pituitary gland to produce FSH and LH, which promotes ovulation and improves reproductive success in sows.
Oxytocin: Causes uterine contractions during labour and aids in milk ejection; widely used in artificial insemination and labour induction.
1.2 Protein-Based Gonadotropins.
- FSH (Follicle-Stimulating Hormone): A hormone that promotes ovarian growth and follicular development. It is employed in superovulation programs.
- LH (Luteinizing Hormone): Combines with FSH to stimulate ovulation.
- PMSG (Pregnant Mare Serum Gonadotropin) combines FSH and LH activity and is used to induce estrus in cattle.
- hCG (Human Chorionic Gonadotropin): Promotes ovulation and increases conception rates; also used in aquaculture for fish reproduction.
Protein-based hormones are completely digested in animals, resulting in no medication residues and promoting food safety.
2. Chemically Based Reproductive Hormones
Chemical-based hormones are steroidal substances produced in laboratories. They have important roles in controlling estrus, ovulation, and parturition.
- Androgens (such as testosterone) promote spermatogenesis and the development of male secondary sexual characteristics.
- Estrogens (e.g., estradiol) induce estrus, govern reproductive tract alterations, and cause ovulation through an LH surge.
- Progestogens (e.g., Progesterone): Inhibit estrus through negative feedback, commonly used to synchronize reproductive cycles.
- Prostaglandins (e.g., Cloprostenol): Induce luteolysis and facilitate parturition, widely used to synchronize or induce delivery in sows.
Conclusion
Understanding the many types and activities of reproductive hormones is essential for better fertility management in cattle and animal husbandry. Protein-based hormones are natural and harmless, but chemical-based hormones enable flexible, targeted control over reproductive processes, increasing breeding efficiency and productivity.
