Farm Animal Welfare

Sheep Internal Parasite Resistance Genetics

Genetic selection for resistance to internal parasites offers a sustainable long-term solution to the parasite control challenge in sheep.

Key Facts

Sheep vary considerably in their genetic resistance to gastrointestinal nematodes
Fecal egg count data from individual animals allows breeding value estimation for parasite resistance
Suffolk, Texel, and some other breeds show heritable resistance differences within breeds
Breeding resistant sheep reduces treatment frequency and slows resistance development in parasites
Selection indices now include parasite resistance in several national breeding programs

Welfare Considerations

Genetic resistance to parasites is one of the most sustainable long-term solutions to the gastrointestinal parasite welfare challenge. Selecting resistant genetics reduces reliance on anthelmintics while inherently improving animal welfare by reducing parasite burden.

What You Can Do

Support sheep breeding programs incorporating parasite resistance selection
Choose rams from flocks with documented parasite resistance EBVs for breeding
Advocate for parasite resistance recording in national breed programs