Cattle are the original model for sustainability. They are able to take a moderate to poor forage that no other species will eat to reproduce, convert it to food for other species to consume, and provide fertilizer for the forage it took in the first place.
In 2017, it is estimated that 29% of all U.S. land is primarily used for livestock grazing. It is estimated that 20-47% of pastures are smothered by dung after 200 grazing days. In order to maintain the grazing pasture, dung beetles play a critical role in the sustainability of cattle production in the U.S.
Dung beetles, also known as scarabs, play a vital role in sustainability for cattle production in the U.S. Depending on the type of dung beetle, each has a role in releasing fertilizer and freeing pastures from the feces for new growth to form.
There are three functional types of dung beetles worldwide: dwellers, tunnelers, and rollers. Dwellers work to aerate the dung so it can be broken down by nature more efficiently by mother nature than ones that do not have dung beetles. Tunnelers burrow underneath and integrate dung into the soil to act as fertilizer. And finally, rollers spread the dung over large distances and bury it, fertilizing the soil across the pastures. All of these combined release nitrogen, ammonia, phosphate, and organic matter, and in turn reduce soil compaction as well. Which, in a study completed in Florida, has equated to $120 million saved by freeing and fertilizing grazed pastures.
Over the years, more farmers and ranchers have become more aware of the value of dung beetles, and questions are being raised about maintaining the overall population. One of the questions being asked has been whether do parasiticides we commonly use in beef cattle practice impact the effects of dung beetles in the pasture.
Several studies have shown negative effects across the globe on macrocyclic lactones (ex., Ivermectin) and the dung beetles. However, none have been done in the U.S. It is also known that macrocyclic lactones are predominately excreted through the feces, and anywhere from 62-98% of the active ingredient has been found.
Therefore, there was a need to evaluate macrocyclic lactones and the effects of fecal pat degradation and dung beetle populations in a commercial cow-calf operation in Iowa. Our original hypothesis was that macrocyclic lactone would have an effect on dung beetles compared to cattle that did not receive it.
Results from Year 1
This is preliminary data from one year of a two-year study. There was no statistical difference between treatment groups and the number of dung beetles collected between intervals. There was also no difference in dry-matter percentage between treatment groups.
Treatment did have a small statistical difference (p <0.05) in female calves only for both weaning weight and average daily gain between cows that received doramectin and cows that did not (Table 1). No treatment difference was noted in calf performance between male calves. There was no statistical difference between dung beetle populations between treated and non-treated pastures (Figure 1).
Based on this preliminary data set, there is no evidence that doramectin decreases the population of dung beetles or fecal pat degradation in a cow-calf operation in central Iowa. However, a continuation of this study needs to be completed in order to note if there is a pasture or age of cow effect from this study.
Acknowledgements: IVMA Bovine Pre-conditioning Grant for funds to complete the project, McNay Research Farm for the cattle, and Zoetis for supplying the Dectomax for this project.
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