Date of Award:

5-2015

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

Jong-Su Eun

Committee

Jong-Su Eun

Committee

Allen J. Young

Committee

Jennifer MacAdam

Committee

J. Earl Creech

Committee

Juan Villalba

Abstract

Condensed tannins (CT) are compounds that have shown potential to reduce the environmental impact of dairy farming waste products. In two live animal studies and a continuous culture study, it was hypothesized that feeding birdsfoot trefoil (Lotus corniculatus, BFT), a CT-containing legume, would improve nutrient utilization, milk, and component yield of dairy cows compared with feeding alfalfa hay or grass pasture in two studies, while feeding BFT forage would decrease methane production and improve rumen fermentation in addition to concentrate supplementation was the hypothesis of the third study. Reduction in milk urea nitrogen (MUN) and ruminal ammonia N nitrogen (NH3-N) concentrations was used to indicate reduction in N waste.

The first study resulted in increased energy-corrected milk yield and increased milk protein yield for BFT-hay fed cows compared with the alfalfa diet, and improved N utilization for milk; however MUN and ruminal NH3-N were not different between treatments.

A 2 year study showed that BFT-grazed cows increased milk yield, protein yield, and energy-corrected milk yield, but did not show a reduction in waste N compared to grassbased pastures.

A third experiment showed that feeding BFT forage pasture reduced methane production, altered rumen microbial populations and subsequent fermentation, and supplementation further improved nutrient yields and reduced methane.

Overall, diets including BFT showed improved nutritive and some reduction in N waste compared to typical alfalfa dairy diets and grass pastures. Further research is needed to understand interactive aspects of tannins and nutrient utilization with other feeds and microbial populations to reveal the full benefits of BFT.

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