Researcher Commended for Industry Contributions

By Annel K. Greene, PhD, Center Director
Clemson University Animal Co-Products Research and Education Center


Dr. Tom Jenkins, Clemson University nutrition researcher and friend of the rendering industry, is retiring this fall after a long and productive career. He began his association with the rendering industry while working at the Ohio Agricultural Research and Development Center in Wooster, OH, in the early 1980s. Jenkins’ first Fats and Proteins Research Foundation (FPRF) funded research project, “Effect of Added Fat and Calcium on In Vitro Formation of Insoluble Fatty Acid Soaps and Cell Wall Digestibility” (Jenkins and Palmquist, 1982), was published in the Journal of Animal Science in 1982. Thirty years later, Jenkins has finished his final FPRF funded project.

Jenkins has been a pioneer in the understanding of lipid metabolism and has expanded the knowledge and methodology for lipid analysis. Many years ago, he noted the limitations of existing methodologies and offered alternative procedures for improving accuracy of analyses. Today, most researchers in the feed industry use Jenkins’ methodologies for lipid analyses. His work has provided a fatty acid database for feeds that is recognized as the most comprehensive database available in the world. This database has greatly improved on-farm nutrition programs for cattle. Recently, the American Oil Chemists’ Society expressed interest in using Jenkins’ work for establishing official methods of analysis for lipids for the entire animal agriculture industry.

Upon entering the rumen, dietary lipids are subjected to a two-step destruction. The ester linkages are first hydrolyzed to release the free fatty acid and the unprotected free fatty acid is then biohydrogenated. In ruminants, there is a limit to the amount of fat that can be incorporated into a diet because the building blocks of fats – free fatty acids – can kill many of the rumen microorganisms. Jenkins developed technology that protects the rumen microorganisms by preventing the free fatty acids from release until after they pass beyond the stomach.

Jenkins co-invented the patented “rumen-protected fat supplements,” which are calcium salts of fatty acids. He also invented and was awarded a patent for a different procedure in which he created fatty acyl amides to protect the fats in the rumen. Both of these procedures have a two-fold benefit: first, the procedure prevents release of free fatty acids and subsequent killing of ruminant microorganisms, and second, the procedure prevents biohydrogenation of the fatty acids so that the essential fatty acids survive to reach the small intestine where they are absorbed. In addition, the technology improved fat handling qualities for better ration mixing as opposed to a sticky, unmodified fat. Today, the use of protected fat supplements has become standard procedure in the dairy industry based on Jenkins’ and his collaborators’ work.

Jenkins also studied areas related to fatty acid biohydrogenation and its role in the beneficial formation of the anti-carcinogenic compounds known as conjugated linoleic acid and rumenic acid. These compounds have been widely investigated in dairy products for important human health benefits. He also improved the methodology and was able to determine intermediate compounds that occur during rumen biohydrogenation. This effort has revolutionized the knowledge on biochemical pathways in lipid metabolism. Jenkins’ work further allowed exploration of functions of these intermediate compounds and lead to discovery that many of the fatty acid intermediates are potent metabolism and gene expression regulators.

Jenkins proposed combining tallow fatty acids with nutraceutical compounds and protecting them through his patented technology to allow the nutrients to survive the rumen and be absorbed in the small intestine. In his last FPRF project, Jenkins investigated protection of omega fatty acids in the ruminant diet. Fish oils are excellent sources of omega fatty acids and consumption of these fatty acids has been reported to be beneficial in improving a number of health situations, including reproductive efficiencies in cattle. However, studies have indicated increased levels of fish oils in the ruminant diet can cause rapid decreases in lipolysis and biohydrogenation due to death of the ruminant microflora. Jenkins mixed the tallow with omega fatty acids and used his conversion process to create a powdered calcium salt form of the product.

Jenkins used rumen fluid collected to inoculate his “artificial rumen” vessels in the laboratory. He followed the fate of the fish oils and tallow during ruminant microbial growth. In the study, Jenkins investigated whether tallow could be a carrier for the fish oils. The results confirmed his technology of converting the tallow to calcium salts did protect the fish oils from biohydrogenation, but unexpectedly only at lower levels of fish oil supplementation. Believing the calcium salts of tallow were pH sensitive, he obtained additional funding from private companies and is completing that research now.

The significance of Jenkins’ lifetime of work has been realized in much greater use of rendered animal fats in ruminant diets. With the technologies Jenkins and his collaborators created, modified tallow can be included at higher rates in the ruminal diet, does not impede ruminant microflora, and, in a powdered form, is much more readily mixable into rations than the solid or semi-solid original form. As Jenkins pointed out, “If only 10 percent of US milking cows [approximately one million cows] consumed an additional 0.5 pound of tallow each day for 100 days of lactation, receipts from tallow would increase over $7 million annually.”

Jenkins has become the preeminent dairy cattle lipid utilization researcher in the world, and for his lifetime of work, was the recipient of the American Dairy Science Association’s (ADSA’s) 2011 Nutrition Professionals Inc. Applied Dairy Nutrition Award. Jenkins has made more than 100 invited presentations and published more than 100 refereed journal articles and six book chapters, including a chapter on rendered products in ruminant nutrition in Essential Rendering, edited by David L. Meeker. His scientific publications have been cited by other researchers more than 2,000 times, and his research has led to two patents for supplementing fat into dairy rations. During his career, Jenkins also has garnered more than $2.7 million in research funding from the United States Department of Agriculture’s National Research Initiative and Sustainable Agriculture Research and Education Program, the Department of Energy, FPRF, and the feed ingredient industry.

In 1999, Jenkins was awarded an American Feed Industry Association (AFIA) award for his work in dairy cattle nutrition and lipid utilization. At Clemson University, he was recognized with the Board of Trustees Award for Faculty Excellence in 2000 and the prestigious Godley-Snell Award for Excellence in Agricultural Research in 2005.

Jenkins has served on many private industry research boards as well as the Nutrition Committee and the Discover Conference Steering Committee for ADSA, the Journal Management Committee for ADSA, and the AFIA Nutrition Award Selection Committee. He has served on the editorial boards of both the ADSA and the American Society of Animal Science, and has been a reviewer for the Journal of Dairy Science, Journal of Animal Science, Journal of Nutrition, Trends in Food Science and Technology, Journal of Microbiology, Comparative Biochemistry and Physiology, Small Ruminant Research, and British Journal of Nutrition.

In 2008, Jenkins envisioned the 14th ADSA Discover Conference, Lipids for Dairy Cattle: Today’s Issues, Tomorrow’s Challenges. He co-chaired the event that currently holds the record for greatest number of attendees and most revenue generated for all of the ADSA Discover Conferences.

Jenkins is also a gifted educator. He has been a wise mentor to a number of graduate students and is widely sought as the leading expert on ruminant lipid digestion and metabolism. He has presented over 100 lectures and webinars to worldwide industry, scientific meetings, symposia, and conferences. Jenkins’ retirement from Clemson University closes out a distinguished and remarkable career. His lifetime of work has made a huge impact on animal agriculture and the rendering industry. We salute Dr. Tom Jenkins and wish him the absolute best in his retirement.

Congratulations and job well done, sir!


October 2012 RENDER | back