To Study Factors Affecting Appetite

Press, Volume CIX, Issue 32233, 27 February 1970, Page 7

To Study Factors Affecting Appetite

An American authority on ruminant nutrition, Professor D. R. Jacobson, of tb* University of Kentucky, hi come to New Zealand on Fulbright fellowship 1 spend eight months at tt Applied Biochemistry Div sion of the Department < Scientific and Industrial R search in Palmerston Nortl While here, he will stud

s a factors which regulate appeo tile in ruminant animals. e Research in this field has been carried on in Palmer- ' ston North for some years, f and Professor Jacobson will •- work in close association , with D.S.I.R. scientists whose projects are related y to his own. The work could have practical implications. An important, though not generally recognised problem in animal production is that ' sheep and cattle often eat ' less than they need for best performance, regardless of the amount of feed available. Getting them to eat the optimum amounts of feed 1 will requite much better knowledge of the factors which control their appetite. Among these factors is the acetic pcid normally released by fermentation in the rumen. When acetic acid is experimentally added to the rumen via a fistula, or directly to the bloodstream by intravenous injection, the animal’s food intake is reduced. Other volatile acids, propionic and butyric, are also released by rumen microorganisms, and these too have been shown experimentally to reduce appetite. One of Professor Jacobson’s interests is in finding out whether acetic acid is the dominant factor causing i the animal to stop eating. 1 Another factor may be that feedstuffs with a high content of fibrous material move more slowly through ■’ the gastro-intestinal tract. Here the question is 1 whether food intake is re-

duced by simple clogging of the tract or by some effect on the chemistry of the ab-, sorbed materials. 1 Yet another, and superfict-1 ally the most obvious propo-! sition, is that the animal eats until it is “full.” But! Professor Jacobson thinks, that, so far as appetite is concerned, “fullness” is a resultant phenomenon rather than a causative one In some cases, he says, the animal may feel sated when its rumen is only half full. In others, the rumen will enlarge to accommodate the animal’s desire to consume more food. In studying the action and Interaction of these various factors, the ultimate aim is to be able to influence animals’ appetite. “For better rates of' weight gain or milk production we want to be able to, encourage them to eat more,' even of lower quality .and more economical feedstuffs,” . says Professor Jacobson.' “For other purposes, such as the maintenance of mature animals, we might want to regulate appetite at a lower level of intake, or get the animals to eat more low-cost materials.”