Date of Award:

5-2015

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Committee Chair(s)

Jennifer MacAdam

Committee

Jennifer MacAdam

Committee

Jerrad Legako

Committee

Juan Villalba

Abstract

Conventional production of meat products from ruminant animals in the United States requires inputs including the cultivation and nitrogen fertilization of annual grains such as corn and barley, and transportation of cattle and grain to feedlots. Consumers have concerns about the impact of feedlot conditions on animal health, and about the implications of pharmaceutical inputs such as growth hormones and antibiotics on the environment and human health. These concerns have led to a growing interest in pasture-finished meat production by consumers. Such smaller-scale livestock production systems can be healthier and lower-stress for animals, are integrated into local food systems and are more transparent to consumers, and have higher potential profitability for producers than traditional ruminant production methods.

There is a strong market for pasture-finished beef products, and prices for naturally or organically raised beef have remained well above feedlot-produced product prices. There is also concern about the impact of ruminant production on the environment, including air and water pollution from feedlot production and greenhouse gasses that are emitted from ruminant animals during feed digestion. This thesis project explored the potential of a beef production system based on perennial legumes, including the non-bloating legume birdsfoot trefoil (BFT; Lotus corniculatus L.) for producing meat products from cattle while reducing concentrate feeding and methane production. The condensed tannins that are produced by BFT bind proteins in the rumen but allow them to be digested in the abomasum and intestines, which in turn leads to better utilization of forage nutrients during the finishing period and higher gains or milk production. The higher digestibility of legumes compared with grasses reduces methane emissions in cattle both through higher digestibility of the forage and through direct impacts on methanogens operating in the rumen.

As reported in this thesis, steers finished on BFT gained significantly more weight per day than steers fed another perennial forage legume, cicer milkvetch, but did not gain as rapidly as feedlot-fed steers. At the end of summer grazing, the blood plasma of pasture-fed steers was lower in saturated and omega-6 fatty acids and higher in trans-vaccenic and omega-3 fatty acids than the blood plasma of feedlot-fed steers. When beef cows grazed grass and legume pastures, enteric methane emissions were lower on the legume pastures than the grass pasture. These results demonstrate that, compared with other feed sources, perennial legume pastures used for cattle production can improve cattle gains and reduce environmental impacts.

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