Factors affecting lamb survival in crossbred sheep

Area of Science:

• Animal Science
• Sheep Breeding
• Genetics

Background:

• Native carpet wool breeds (Chokla, Malpura, Jaisalmeri) are crucial for local economies.
• Introduction of exotic breeds like Rambouillet aims to enhance wool quality.
• Understanding crossbreeding impacts on lamb survival is vital for successful integration.

Purpose of the Study:

• To evaluate the survival rates of native carpet wool sheep crossed with Rambouillet.
• To determine the influence of genetic group, birth year, season, sex, and dam's weight on lamb survival.
• To assess the viability of introducing up to 50% exotic fine-wool inheritance.

Main Methods:

• Least-squares analysis was used to analyze survival data (1 for survival, 0 for mortality).
• Survival was assessed across different age periods: birth to 1 month, 1 month to weaning, weaning to 1 year, and birth to 1 year.
• Factors including genetic group, birth year, season, sex, and ewe's weight were considered.

Main Results:

• Birth year and season significantly affected survival, except from birth to 1 month and 1 month to weaning.
• Ewe's weight influenced survival from 1 month to weaning.
• No significant differences in survival were observed among genetic groups, with Rambouillet X Malpura F1s showing higher survival.
• Increasing Rambouillet inheritance up to 50% did not significantly decrease survival.

Conclusions:

• Introduction of up to 50% Rambouillet inheritance into native carpet wool breeds is feasible without compromising lamb survival.
• Interbreeding of halfbreds (F1) and three-quarterbreds is also viable, indicating no significant decline in survival.
• Crossbreeding strategies can be employed to improve wool quality while maintaining robust lamb survival rates.