The overall frequency of mastitis was 6.8 percent. The incidence of mastitis increased with number of lambs born. Ewes that were kept on mountain pastures had a lower incidence than ewes kept on cultivated pastures.
Ewes that had bad udder scores had much higher incidences of mastitis. The heritability of resistance to mastitis was determined to be 0.13. The average reduction in weaning weight due to mastitis was 8.8 pounds.
Source: Abstract. Small Ruminant Research. December 1993.