Interpretive Summary: Assessment of effectiveness of deworming options in recently weaned beef cattle utilizing different anthelmintic programs in the southeast

By: Shane R Hernandez, Dylan B Davis, Brent C Credille, Jennifer J Tucker, Robert Lawton Stewart

Internal parasites are a common problem impacting grazing livestock such as beef cattle. In the United States, the most common parasites observed in beef cattle are Cooperia, Ostertagia, Haemonchus, Oesophagostomum, and Nematodirus (Stromberg et al., 2015). While species like Cooperia and Osterstagia may cause subclinical issues, other parasites like Haemonchus may cause more severe issues. When severely infected, animals may suffer from emaciation, infertility, and morbidity. Additionally, subclinical issues may also occur causing a decrease in milk yield, weight gain, carcass characteristics, and subsequently, impacting profitability (Andresen et al., 2018). To treat and mitigate internal parasite challenges, beef cattle producers rely on anthelmintic drugs. In general, anthelmintic treatments should be timed with cattle age and environment (Gasbarre et al., 2015). Unfortunately, inconsistent anthelmintic practices have led to an increase in anthelmintic-resistant parasites observed in livestock operations (Gasbarre, 2014; Lamy et al., 2012). For instance, in 1997, Gogolewski et al. (1997) reported topical application of a macrocyclic lactone reduced Cooperia, Ostertagia, and Haemonchus by 99% in cattle that were both artificially and naturally infected. However, in 2010, Edmonds et al. (2010) reported no reduction in fecal egg counts when heifers were treated with a transdermal macrocyclic lactone.

The objective of this study was to evaluate the effectiveness, economic benefit, and animal performance of oxfendazole, eprinomectin, and a combination of both anthelmintics during a 42-day preconditioning phase in naturally infected, recently weaned calves at four different research locations. We hypothesized that the concurrent application of two different classes of anthelmintics during a preconditioning phase will reduce fecal egg counts by at least 99% at all test locations. Additionally, we hypothesized that total VFA concentrations will decrease in the rumen of calves treated with the orally drenched benzimidazole.

Read the full article in Translational Animal Science.