Breeding Technology
(i) Reproductive Characteristics: One important group of vertebrates represents an intermediate stage in the transition from aquatic to terrestrial life. These animals are characterized by their reproductive process, where adult males and females release their gametes into the water, and external fertilization occurs outside the body. The fertilized eggs develop and hatch in the water, and during early development, they breathe through gill-like structures similar to those found in earthworms. After approximately 60 days, a remarkable transformation takes place—these creatures undergo metamorphosis, their tails disappear, and they develop a beak-like mouth, marking the beginning of their life on land. At this stage, they start breathing with lungs. Their skin secretes mucus, which helps in respiration, and their internal organs gradually mature. By around 16 months of age, they reach sexual maturity. Most individuals mate in spring, with males typically embracing females. When females release their eggs, males complete the fertilization process externally, ensuring the next generation begins its life cycle.
(B) Artificial Breeding and Sexual Dimorphism: In species like the pheasant, males and females exhibit distinct physical characteristics. Males usually have black-green or dark brown feathers on their backs, with striped patterns along their sides, while females display lighter colors, often with white underbellies and markings in milky yellow, brown, or black. Each year, from March to April, healthy, disease-free adult males and females are selected for artificial breeding. They are placed in spawning ponds filled with water at a depth of 20–50 cm, maintained at a consistent temperature of 25°C. Approximately 3–5 pairs are kept per square meter. To stimulate reproduction, males receive daily injections of 300 units of chorionic gonadotropin for two consecutive days, while females receive 600 units of human chorionic gonadotropin. Once sexually mature, mating typically occurs at night, and spawning takes place in the morning. A single female can lay around 5,000 eggs. These eggs are then collected and transferred to a hatching area. Under controlled conditions, fertilized eggs usually hatch within 25 hours when kept at 25°C. This process ensures a high success rate in artificial breeding programs.
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