A one shot blood phenotype can identify sheep that resist Haemonchus contortus challenge.

Gastrointestinal nematodes remain a major limitation to the productivity of livestock systems. Selective breeding to produce populations that have an enhanced ability to resist infection is a viable and ongoing option to reduce this impact. The development of new phenotypes that facilitate this process is therefore of great interest. For this reason we explored relationships between haematological parameters and the ability of sheep to resist nematode infection. A multivariate analytical approach was used to define algorithms based on the blood parameters that can be used to rank the ability of sheep to resist nematode infection in a single blood sample and can be applied independent of infection status. The algorithms were shown to classify susceptible sheep with a 100% accuracy and resistant sheep with 80% accuracy. Further development of this platform approach may be an important advance for small ruminant production systems worldwide and might also be applied to other diseases of livestock or even environmental stressors such as heat. Crown