Sheep Parasite Resistance Breeding: FAMACHA and Selection

Breeding sheep with natural resistance to internal parasites reduces anthelmintic use and improves individual sheep welfare through reduced parasite burden.

Key Facts

Haemonchus contortus (barber's pole worm) is the most welfare-relevant internal parasite in warm-climate sheep
FAMACHA scoring assesses anaemia from barber's pole worm through conjunctival colour
Heritability of internal parasite resistance is moderate - genetic progress is achievable in 3-5 years
Targeted selective treatment using FAMACHA reduces anthelmintic use while protecting individual welfare
New Zealand and Australia lead in parasite-resistant sheep breeding programme development

Welfare Considerations

Breeding for parasite resistance is one of the most elegant welfare solutions in sheep production. Rather than repeatedly treating all sheep to control parasites - which drives anthelmintic resistance - selecting breeding rams with proven resistance passes genetic advantage to offspring. Over several generations, flock-level parasite burden reduces, individual welfare improves through lower worm burden, and anthelmintic use declines. This welfare-genetics-resistance triple benefit makes parasite resistance breeding one of the highest-return welfare investments in sheep production.

What You Can Do

Support sheep producers selecting breeding stock for parasite resistance
Advocate for parasite resistance genetic indices to be promoted in sheep breeding schemes
Learn about FAMACHA scoring and targeted selective treatment as welfare tools
Choose lamb from producers with documented low parasite burden management