Prevalence of Gastrointestinal Parasitisms Among Milking Cows in Wisconsin, Pennsylvania, and North Carolina

Abstract

SUMMARY A survey of gastrointestinal parasitisms among milking cows in Wisconsin, Pennsylvania, and North Carolina dairy herds was conducted by examination of feces for oocysts of coccidia and eggs of helminths. Fecal samples were collected during the summer, fall, spring, and winter seasons of 1975–1976. Milking cows were found parasitized by nematodes, tapeworm, and coccidia during all seasons. The greatest prevalence of gastrointestinal nematodes was seen among the pastured cows in Pennsylvania and North Carolina; the Wisconsin herds were closely confined. Prevalences were lower during winter and increased during spring, summer, and fall. For all seasons, the overall prevalence of gastrointestinal nematodes, tapeworms, and coccidia were, respectively, 80.1, 5.1, and 37.3% in Pennsylvania; 60.0, 5.1, and 40.0% in North Carolina; and 47.8, 4.0, and 23% in Wisconsin. Based on nematode egg identification, Haemonchus and Osteriagia were the most common genera, followed by Trichostrongylus, Oesophagostomum , and Cooperia . Other genera in much lower prevalences were Bunostomum, Strongyloides, Trichuris, Capillaria, Nematodirus , and Neoascaris . Numbers of eggs/5 g were typical of “subclinical” parasitism now being described in terms of economics. Nine species of coccidia oocysts were identified among milking cows, Eimeria bovis being the most common of the species observed. A search for infective larvae of gastrointestinal nematodes in scrapings and suspension samples collected during summer and fall in Wisconsin established the presence of infective larvae of Haemonchus, Ostertagia , and Trichostrongylus inside the barns, in easy access to milking cows. The positive samples (7.5-cm square surfaces) collected in the fall and summer averaged 63.1 and 11.0 infective larvae, respectively.