Dr. Peter J Van Soest 1929-2021 Legendary Ruminant Nutritionist

 This blog could also be entitled "I know you don't care but..." I do care so I will write it for me.

Dr. PJ Van Soest

When I was a kid, skipping school to go to Agricultural Short Courses organized by Alan Rugg, the local Ag Rep, beef cattle were the simplest farm animals to feed. What ever you fed them was torn apart in the rumen by the bacteria and protozoa, recombined by them to suit their needs and the cow digested their by products and the bugs themselves. Nutrition was pretty crude, all done by wet analysis ; crude protein (N x 6.25), crude fat (ether extract), nitrogen free extract (not crude protein, fibre, fat or ash) and crude fibre, all added together (fat x 2.5) produced TDN (Total Digestible Nutrients) which was a crude estimate of useful feed value in use since 1860s . 

We knew the basic requirements for different classes of animals and fed to those. Dairy cattle were a bit different as there was as much art as science because things worked but at the time people didn't know why. Reading Hoard's Dairyman from the last 135 years is an education in its own right. But beef cattle were my main interest, so that is how I ended up in the University of Saskatchewan, College of Agriculture studying Animal Science.

Dr. Dave Christensen graduated from UofS in 1958 and started as Associate Professor at Animal Science the same year I started as a student. He was a Ruminant Nutritionist, specializing in dairy nutrition but taught the general ruminant nutrition courses. We learned that TDN tended to over estimate the feed value of forage because it underestimated the cell walls. The contents of a cell are highly digestible and the cell walls are quite variable. 

We also learned that Dr PJ Van Soest, a brilliant scientist from the USDA Research Centre at Beltsville Maryland, had come up with a superior method of estimating feed value, including TDN. Instead of Crude Fibre he developed two analyses ADF (Acid Detergent Fibre) and NDF (Neutral Detergent Fibre). ADF is used to estimate energy eg TDN, and NDF is used to estimate animal intake (rumen fill).  Van Soest’s detergent analysis gave researchers a way to precisely separate the chemical components of feeds into three categories: parts that were digestible to all animals; indigestible without fermentation; and completely indigestible. Those two analyses today form the basis of estimating feed quality ruminant nutrition and permanently changed animal science.

In Fourth Year, we had to write a thesis which was basically a heavy duty term paper. Dr. Christensen was my supervisor and my topic was Estimating forage Quality as I recall. It was anticipated that I would focus on Van Soest's work. However in May 1968, Lofgreen and Garrett had just published their seminal work A System for Expressing Net Energy Requirements and Feed Values for Growing and Finishing Beef Cattle.

Well! This was mind blowing and right up my ally. I paid lip service to the original intent and then poured the coals to net energy. Besides the Lofgreen and Garrett's formulae were based to a great degree on Van Soest's Analyses. Dr. Christensen was not overly pleased and gave me a B. He said it deserved an A but he had to nag me constantly to get it finished (by end April 1969 after all the other students had gone home).

In 1968, Dr Van Soest moved from Beltsville to Cornell University in Ithica NY, where he spent the rest of his career. At Cornell he was as a co-inventor of the Cornell Net Carbohydrate and Protein System, a cattle nutrition model currently used to formulate diets for over 70% of dairy cattle in North America and used in over forty other countries. 

Net energy estimates and net carbohydrate and protein system revolutionized ruminant nutrition all based on detergent fibre analysis. Dr Van Soest once said, “I participated in something that was very remote, a backwater in science, and then it became very important.”

Dr Van Soest died in March 2021. I ran across his obituary while searching for information for a Saskatchewan rancher. He should have lived forever. After retirement he continued teaching and research, publishing hundreds of papers over his life time, the last at age 90 in 2020. He was the kind of researcher that should have been sent funding, no questions asked.