Comparative peri-parturient rise in faecal egg counts in divergent lines of sheep at an organized farm in semi-arid Rajasthan

A study was conducted to evaluate the comparative effect of peri-parturient relaxation in immunity on strongyle faecal egg counts in two divergent lines (resistant - R and susceptible - S) of Malpura and Avikalin ewes. The study was conducted from February, 2006 to August, 2021 during two different lambing seasons viz., spring and autumn in semi-arid Rajasthan. A total of 6452 faecal samples from 523 ewes that lambed in spring (857 lambings) and autumn (797 lambings) seasons were evaluated. The study indicated the absence of relaxation in immunity around lambing in R-line ewes in both the lambing seasons, while S-line ewes that lambed in autumn season showed marked relaxation in immunity around lambing. In spite of relaxation in immunity around lambing, the degree of natural resistance to strongyle infection in R-line ewes showed a substantial impact on the build-up of larval infestation on pasture. The study suggests that breeding of sheep genetically resilient to nematodesinfection contributes inreducingthe pasturelarval burden.