A national survey of the gastrointestinal nematode control practices used by goat producers in the United States

Gastrointestinal nematode (GIN) parasites are a major constraint to goat production. GIN parasite control has relied primarily on the use of anthelmintic drugs. A major issue in goat operations globally, including in the United States (U.S.), is that GIN populations have developed widespread resistance to current anthelmintic drugs. Widespread anthelmintic resistance is a major concern to U.S. goat producers, but there currently remains limited information on what goat production practices are used nationally to combat GIN infections and prevent anthelmintic resistance. The current practices used by goat producers to control GIN parasites and reduce anthelmintic resistance on their operations were evaluated as part of the 2019 National Animal Health Monitoring System (NAHMS) study, which was conducted by the U.S. Department of Agriculture (USDA). The study aims were to determine GIN parasite burden at both the individual animal- and operation-level, investigate geographic patterns of GIN parasitism, and identify risk factors associated with infection prevalence and intensity. The study covered 24 U.S. states, representing 80.4 % of U.S. goats on operations with ≥ 5 goats and 75.8 % of operations with ≥ 5 goats. Data from fecal samples submitted for fecal egg count (FEC) analysis and individual goat- and operation-level questionnaires were collected from 9879 goats across 623 operations. The estimated, weighted mean operation- and animal-level FEC for goats was 658 and 651 eggs per gram, respectively. Across all goats tested, parasite burden was found to be over-dispersed, with the top 24.1 % of animals contributing to 80 % of the total FEC. Geographically, lungworm prevalence was significantly lower in the Southwest region compared with the Northeast, Northwest, and Southeast regions. For GIN FEC values, the highest operation-level counts were found in the Northeast and Southeast region, and the highest animal-level counts were found in the Southeast region by univariate analysis and the Northeast and Southeast regions by multiple regression analysis. Univariate analysis revealed that primary operation production type, primary land/facility management type, primary grazing/browsing management, FAMACHA© card usage, body condition categorization, and month of sample collection were significant factors impacting mean FEC at both the operation- and animal-level. U.S. regionality, goat type, breed, FAMACHA© score, and browsing schedule were found to be significant at the animal-level. Multiple regression analysis at the operation-level revealed that deworming frequency in the previous 12 months, pasture housing practices, and the interaction between region and sample collection date were significant factors that impacted the mean FEC. Multiple regression analysis at the animal-level revealed that goat type, FAMACHA© score, body condition categorization, primary grazing/browsing management, primary operation production type, the interaction between region and multiple species grazing, and the interaction between region and sample collection date, were significant factors that impacted mean FEC. This study provides valuable information to help guide future GIN research and regionally specific control practices.