Factors affecting lamb survival in crossbred sheep

Survival from birth to 1 month, 1 month to weaning, weaning to 1 year and birth to 1 year was studied in crosses of native carpet wool breeds (Chokla, Malpura and Jaisalmeri) with Rambouillet. Least-squares analysis of data considering survival as 1 and mortality as 0, showed that the year and season of birth affected survival significantly during all age periods except from birth to 1 month and from 1 month to weaning where season had no significant effect. Sex (studied only for pre-weaning survival), ewe's weight at lambing and birth weight of lamb did not influence survival except that the ewe's weight a significant influence on survival from 1 month to weaning. Genetic groups did not differ significantly. Rambouillet X Malpura F1s had a higher survival rate than the other 2 F1s. There was a non-significant decline in survival with an increase in Rambouillet inheritance, except that 5/8 Rambouillet -3/8 Chola crossbreds had a slightly higher survival rate than Rambouillet X Chokla F1s. Interbreeding F1 and 3/4 crossbreds did not result in any significant decline in survival. The results show that the introduction of exotic fine-wool inheritance up to 50% and interbreeding of halfbreds will not result in any decline in survival.