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Dr. Marshall D. Stern: Improving protein and amino utilisation by dairy cattle

Dr. Marshall D. Stern’s primary research objective has been to improve efficiency of protein and amino acid utilisation by dairy cattle.

He has been a pioneer in developing methodology to measure protein degradation and microbial protein synthesis in the rumen, and protein absorption from the small intestine.
Stern’s research was the first in the U.S. to use intestinally cannulated lactating dairy cows to measure protein absorption from the small intestine. Dr. Stern’s laboratory developed a non-invasive three-step in situ/in vitro procedure as an alternative to using duodenal and ileal cannulated animals for estimating intestinal digestion of dietary protein. The use of this procedure has generated estimates of intestinal protein digestion for a wide variety of feedstuffs including protein supplements, grains and forages that have been used to formulate diary diets. In addition, this technique provided invaluable data to the National Research Council (NRC, 2001) Nutrient Requirements of Dairy Cattle that were previously lacking.

Dr. Stern uses innovative methodologies such as transmission and scanning electron microscopy to elucidate the ultrastructure of ciliated protozoa found in the rumen. He also modified the original dual flow continuous culture fermenter system to provide a non-invasive model for studying “the rumen”.

This system has been used to study various factors affecting rumen microbial fermentation and ecology. Compared to using animal models, the continuous culture system is less harmful, less expensive, less time-consuming and more controlled. This continuous culture system has enabled Dr. Stern’s research group to study potentially negative effects of certain compounds such as patulin (a secondary metabolite of toxigenic strains of certain bacteria) and the sulphur binder compound bismuth subsalicylate on microbial growth and fermentation. Dr. Stern’s most current research focuses on reducing gas emissions from the rumen and using metagenomics to evaluate how diet and various feed additives can alter the rumen microbial population.

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RESEARCH INTERESTS

● Analysis of animal byproducts and protected plant proteins (mainly protected soybean products) as sources of supplemental protein for lactating dairy cattle
● Influence of direct-fed microbial additives on rumen microbial fermentation and populations
● Interaction of carbohydrate and protein source on intestinal protein supply in dairy cattle
● Effects of methionine supplementation on amino acid metabolism in lactating cows
● Dynamics of soluble crude protein digestion of various protein sources by ruminal microbes
● Effects of dietary roughage and sulfur in diets containing corn dried distillers grains with solubles on hydrogen sulfide production and rumen fermentation
● Evaluation of bismuth subsalicylate to reduce hydrogen sulfide emissions from the rumen
● Effects of enzyme additives on rumen microbial fermentation
● Metagenomic evaluation of the ruminal microbial population of dairy cows compared with rumen microbes supplied the same diet in dual flow continuous culture fermenters

RECENT PUBLICATIONS

Profile in SciTech Europa Quarterly issue 31

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