Authors
A M Sparks2; R Zamoyska2; T N McNeilly1; D H Nussey2; 1 Moredun Research institute; 2 University of Edinburgh Discussion
Maternally derived antibodies (MatAbs) are crucial in protecting offspring against pathogens and parasites during early life, however the benefits of MatAbs have rarely been examined in wild populations. Soay sheep on St Kilda have been studied individually for 30 years and are heavily infected with strongyle gut nematodes. This system offers an excellent opportunity to investigate the role of MatAbs in the wild. A total of 585 lambs born between 1997-2007 were assayed for levels of IgA and IgE antibodies against the prevalent nematode Teladorsagia circumcincta (Tc) in plasma samples collected just after birth in April (neonate) and again in August (around 4 months old). Mixed effects models were used to investigate predictors of variation in MatAbs and consequences of MatAbs on early growth, survival and immunity measures. Neonate anti-Tc antibodies declined with lamb age, increased with lamb birth weight but also peaked with middle-aged mums. Maternal identity accounted for around a third of the variation in neonatal antibody levels. Neonate anti-Tc antibodies positively predicted survival to four months of age and lamb August weight, but not strongyle FEC or antibody levels in August. Our data suggest that circulating neonatal anti-Tc antibody levels are transient and are under strong maternal control. They also provide rare evidence that high levels of MatAbs are associated with improved offspring fitness in a wild mammal population. 
