Enhancing immune competency to improve lamb and weaner survival

Summary

​Lamb birth weight is the major determinant of lamb survival to weaning.  Lamb survival rarely exceeds 90% for singles, 75% for multiples and 60% for triplets which suggests that factors independent of birthweight must also influence lamb survival. Innate and adaptive immune deficiencies in neonatal mammals are known to predispose them to infections and increase the risk of death, however the role of immune competency in the survival of lambs is poorly understood. This project investigated the impacts of supplementation with vitamin D, vitamin E and selenium or sulphur amino acids during late pregnancy on the immune system of the ewe and lamb(s) and the subsequent impact on lamb survival.  Maternal supplementation with Vitamin E plus selenium or cholecalciferol were effective at increasing the concentration of α-tocopherol and selenium or 25(OH)D concentrations in both the ewe and the lamb at parturition, but supplementation with methionine did not elevate total glutathione in the ewe or lambs.  Whilst there was some evidence that the supplements improved lamb survival there was no evidence that this change in survival resulted from the supplements boosting the lamb's innate, passive or adaptive immune responses.