Room 952 Animal Science Building
1675 Observatory Drive
Madison, WI 53706
Biochemical & Molecular Nutrition
Principal Research Interest:
Ruminant nutritional physiology, especially in the role of the liver to integrate nutrient transfer among tissues in support of lactation and growth.
Dairy cattle are vital to the economy of Wisconsin and feed costs are a major cost of milk production. While legitimate concerns about the negative environmental impacts of animal production exist, ruminant animals are capable of using by-products of human food production that would otherwise be waste products. Feeding these by-products to cattle requires careful consideration of the feeds major energy and protein components and how they interact to affect animal productivity. High levels of productivity are consistent with good environmental outcomes as well as economic viability.
Our recent studies began by focusing on the feed by-products obtained from corn based ethanol production. As these products concentrate corn oil into the by-product feed, we became interested in the effects of various fatty acids on animal productivity. Unsaturated fatty acids fed to ruminant animals result in the production of various trans-fatty acids in trace amounts in the rumen. Once absorbed, these very bioactive fatty acids can reduce milk fat synthesis. This decrease can be estimated in whole animal trials by measuring short chain fatty acid yields in milk. Absorbed feed fatty acids also provide increased fatty acids for long chain milk fat secretion. Therefore, dietary unsaturated fatty acids have opposing effects on milk fat yield: decreasing short chain yield through bioactive fatty acid generation, while increasing long chain yeild. Our research has begun to define these relative effects for the major fatty acids fed to cattle. The long-term goal of this research is to define the best fatty acid profiles for dairy cattle feeds. Available plant breeding techniques or supplemental fat sources can then be chosen that maximize milk fat yield.
Students in my laboratory work directly with dairy cattle and whole animal experiments are critical to most of our work. Feed and milk fatty acid analysis is also critical. Experiments are designed based on thorough understanding of metabolism and in turn use that knowledge to advance the practice of feeding dairy cattle. Students acquire a strong understanding of whole animal physiology. Strengthening quantitative aspects of data analysis and metabolic processes is a major component of the training. Due to the expense and duration of dairy cattle feeding experiments, and the high cost and limited availability of experimental units; much emphasis is placed on optimizing experimental design.
Leonardi C, Armentano LE. Short communication: Feed selection by dairy cows fed individually in a tie-stall or as a group in a free-stall barn. J Dairy Sci. 2007 May;90(5):2386-9.
Gressley TF, Armentano LE. Effects of low rumen-degradable protein or abomasal fructan infusion on diet digestibility and urinary nitrogen excretion in lactating dairy cows. J Dairy Sci. 2007 Mar;90(3):1340-53.
Gressley TF, Reynal SM, Colmenero JJ, Broderick GA, Armentano LE. Technical note: development of a tool to insert abomasal infusion lines into dairy cows. J Dairy Sci. 2006 Oct;89(10):3965-7.
Gressley TF, Armentano LE. Effect of abomasal pectin infusion on digestion and nitrogen balance in lactating dairy cows. J Dairy Sci. 2005 Nov;88(11):4028-44