SCIENCE SNAPS > EXPLORE > Good-fat beef with Dr John Wallace from the Rowett Research Institute



Expert Dr John Wallace, a microbiologist from the Rowett Research Institute explores
Good-fat beef
Helping bugs make healthier meat Red meat is sometimes criticised from a health point of view because it contains relatively large amounts of saturated fat, which has long been linked to an increased risk of heart disease. But, set against this, red meat also contain amounts of the so-called healthy fats, including a special type of fat known as CLA. So what we want to do to make meat healthier is to increase the amount of the healthy fats, and reduce the amount of the saturated fat. The problem is that the type of fat that is found in meat is not directly related to the fat that is eaten by the animal. This is because grazing animals such as cows and sheep have a special type of digestive system, made-up of four stomachs, which allows them to exist on grass and other plant material. The first stomach is called the rumen and it’s like a large fermentation vat. Food eaten by cows or sheep is broken down by millions of microorganisms which live in the rumen and it’s these bugs that are responsible for changing the structure of the fats which the animal eats. Unsaturated fats are converted into saturated fats by the bugs in the rumen using a chemical process called biohydrogenation. But the healthier CLA fats are by-products of this process. So making healthier meat isn’t just a case of blocking the biohydogenation process, it’s much more complex than that and involves several different species of bugs. We have already gained some fascinating insights into why the bugs convert unsaturated fats into saturated fat. They do this to survive because some unsaturated fats (or rather their smaller component parts called fatty acids) are actually toxic to rumen bugs, so no wonder they are all busy converting the unsaturated fatty acids into saturated fats. We know that you can change the fat content of beef by feeding foods such as linseed or fish oil to cows. Up until now it has not been possible to relate these changes to specific types of bugs in the rumen. We are using state-of the-art molecular techniques which will allow us to gain a detailed knowledge of who does what, and how, in the world of the rumen microorganisms. The knowledge gained will lead to better advice to farmers on how to feed their animals for improved meat quality with health benefits for all. Listen to the SCIENCE SNAP from Monday 14th March Ask the Expert Explore this topic further on these relevant web sites: www.rowett.ac.uk/divisions/Gut/rj_wallace.html

Photo of Dr John Wallace from the Rowett Research Institute

Dr John Wallace

Rowett Research Institute

John Wallace attended school in Hamilton, Bathgate and Stirling, and in 1968 headed off to the University of Glasgow to study chemistry. In Glasgow, he was influenced strongly by J.N. Davidson, who wrote the first book 'Biochemistry of the nucleic acids', and John transferred to the biochemistry department, where in 1972 he graduated B.Sc. Hons in biochemistry. During summer vacations, he worked in the research laboratories of Distillers Company Ltd, in Menstrie, Clackmannanshire, working with the extrovert author and broadcaster (as well as research scientist), Dr Magnus Pyke. John recalls his first meeting with Dr Pyke. At interview, John was rendered speechless by the first question "Ah, Wallace ... do you play croquet?" It emerged that DCL, with Magnus Pyke in the team, were British croquet champions.

John continued in Glasgow to complete his Ph.D. in 1975, on 'Maintenance energy and molar growth yields of Escherichia coli'. A brief switch to cancer research in the Royal Infirmary, Glasgow, proved frustrating, and John returned to microbial biochemistry a year later when an opportunity arose to study ruminal bacteria at the Rowett Research Institute in Aberdeen. The expertise gained in bacterial biochemistry/physiology during his Ph.D. proved highly relevant to problems associated with low growth yields of bacteria in the rumen.

John's interest in practical solutions to nutritional problems in ruminants grew as he learned more about rumen microbiology and ruminant nutrition from eminent Rowett scientists such as Sir Kenneth Blaxter, Peter Hobson and Bob Orskov. Thus, alongside mainly academic research on protein metabolism in the rumen, he developed an interest in ways in which the rumen fermentation could be manipulated by external factors, particularly feed additives. Ionophores, probiotics, prebiotics, enzymes and plant extracts all have a role to play in ruminant nutrition.

The aims of the Rowett moved radically around 2000, to focus on nutrition and human health. John welcomed his new role, with its major input into providing foods with a healthier fatty acids profile, via manipulating ruminal microorganisms, and finding ways of replacing growth-promoting antibiotics in the food chain.

John's work has taken him around the world, with work periods in Australia, Japan and the US and collaborators in many different countries. He has published more than 130 peer-reviewed papers and currently holds grants from the EC, Scottish Enterprise and BBSRC-SEERAD. Of the three EC awards he holds, John is coordinator of one Framework V project, 'Rumen-up' and a Framework 6 project, 'REPLACE'. Both of these projects aim to use plants and plant extracts to improve farm animal nutrition and to provide a healthier environment and healthier foods for human consumption. He is also a partner in 'LIPGENE', where his role is in the Animal Nutrition work package that is providing foods of different fatty acid composition to the consortium as a whole.

John is Group Leader of the Microbial Metabolism group at the Rowett. He serves on the Editorial Board of the British Journal of Nutrition.