Research Summary: Effects of Cattle Manure on Fate and Transport of Hormones in the Feedlot and the Field

Last Updated: February 14, 2011

Purpose

The objective of this research focuses on the occurrence, fate and transport of exogenous and endogenous hormones from manure that is produced from concentrated animal feeding operations during the management of cattle. The central hypothesis is that hormones in cattle manure may persist and accumulate in soil, but the fate and transport of hormones will be affected by the waste management and handling strategies utilized.

Current Activities

This is a multi-disciplinary project involving scientists from various academic backgrounds. The study involves a cattle feeding component to produce the animal waste (manure) plus measuring hormone levels in collected waste throughout composting and crop land application processes. Reasons for conducting the study vary but the main interest is to characterize the availability, degradation and migration of naturally produced and synthetic hormones in and around the soil, which has had animal waste applied to it as fertilizer.

Generally speaking hormones, estrogens in particular, are produced by molds, plants, animals and humans. Their fate and rates of degradation are not entirely known. However, the use of synthetic hormones in animals and humans add to the overall hormone levels introduced into the ecosystem. The main questions are: Can hormones or their metabolites be found in the cattle feeding facilities, do they survive long enough to be found in the solid or liquid waste fractions, and if they are collected will they remain intact through either composting or stockpiling? If they do remain intact, will they degrade and/or move once land applied and are they naturally occurring or synthetic in nature?

Research tasks will address the objectives of this study. These tasks are:

1. to sample and survey existing feedlots in Nebraska to determine the occurrence of hormones in the manure handling pathway over a climatic gradient;
2. to quantify fate of hormones as influenced by manure handling practices such as stockpiling, composting, and runoff retention basins;
3. to determine the effect of manure application strategies on hormone losses in runoff and erosion through the use of rainfall simulators;
4. to quantify hormones in select grass species in buffer strips fertilized by manure; and
5. to determine hormone fate and transport within irrigated soil systems.

What We Have Learned

To date one cattle feeding study has been completed with stockpiled and composted manure prepared for field application this spring. Hormone assays are on-going but not yet summarized. Results of the cattle feeding study, found that the use of hormonal supplements improved cattle gain 21.7% and efficiency of feed utilization by 11.0%, while decreasing cost of gain by 11% when compared to cattle which did not receive any growth promotants.

Why is This Important?

The results of the project will serve as a research base to enable the scientific and regulatory communities to better understand the role of growth promotants in the cattle industry and show how waste management practices influence the fate of hormones introduced into the environment from animal manures. The data from this project will provide valuable information to both regulators and farm operators to promote and balance agricultural production and environmental protection.

For More Information

Contact Terry Mader < tmader1@unl.edu> or Dan Snow < dsnow1@unl.edu>

Terry Mader, Department of Animal Science, and Dan Snow, School of Natural Resources University of Nebraska-Lincoln

This report was prepared for the 2008 annual meeting of the regional research committee, S-1032 "Animal Manure and Waste Utilization, Treatment and Nuisance Avoidance for a Sustainable Agriculture". This report is not peer-reviewed and the author has sole responsibility for the content.

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