A Survey of Strongyle Nematodes in New England Dairy Goats

The paucity of information concerning the occurrence of strongyle nematodes in New England dairy goats prompted a survey of 241 dairy goats from throughout New England. Of the 241 goats examined using the McMaster technique, 104 (42.7%) were infected with strongyles with a mean intensity (+ SE) of 369.7 + 45.8 eggs per gram. Subsequent molecular examination of 50 random samples from these goats revealed a prevalence of 88% infection specifically with Haemonchus contortus. Haemonchus contortus is the most important internal parasite of sheep and goats, exerting a crushing economic burden on the livestock industry worldwide due to lowered milk production, poor weight gain, substandard wool quality, and sudden death of animals in all production stages. Nigerian Dwarf (ND) goats have become exceedingly popular in New England and constituted nearly half of the goats surveyed. Comparison of strongyle infections between ND goats and all other goats combined, revealed a 60.7% prevalence of strongyle infection in breeds other than ND goats, while the ND goat infection rate was 25.2%. Likewise, the intensity of infection in ND goats was roughly half that of other breeds combined. The generally accepted threshold of intensity for clinical/economic importance for H. contortus is 1,000 eggs per gram feces. ND goats exhibited a significantly lower prevalence of clinical/economically important infection (2 of 119; 1.7%) than goats of other breeds (9 of 122; 7.4%). This higher prevalence, lower mean intensity, and level of heavy infection exhibited by ND goats suggests the possibility that ND goats in this New England population may possess some level of innate resistance to infection with strongyle nematodes. Further studies are warranted to investigate possible resistance and its biological significance.