use of clay in poultry feed

“ Clays and Clay Minerals,
1968, Vol. 16, pp. 267-270. Pergamon Press. Printed in Great Britain

THE USE OF CLAY IN POULTRY FEED* - A White Paper from 1967


Department of Poultry Science, Texas A&M University, College Station, Texas 77843

(Received 30August 1967)

Abstract-Dietary clay supplements (bentonite and kaolinite) have been used as binding and lubricating

agents in the production of pelleted feeds for chickens. The high-swelling and water absorbing

capacity of some bentonites make them attractive dietrary additives for control of wet droppings in

caged layers. In addition, experiments show that layers fed on these diets exhibit significant increases

in body weight, egg size, and life expectancy even though their total caloric intake is less than that of

the control group. Dietary kaolin improves caloric efficiency even more than bentonite but without apparent effect upon growth or carcass quality. Kaolins of smaller particle size are superior to those of

larger size in improving caloric efficiency. The effective kaolins are estimated to be worth approximately

two calories of metabolizable energy per gram. The major beneficial effect appears to be due to

a slowing down of the rate of feed passage through the intestinal tract. Possible uptake of trace elements required for optimum nutrition has not yet been evaluated.



THE USE of clay supplements in animal and poultry feed manufacturing is not new. Certain bentonites have long been used as a binding and lubricating agent in production of pelleted feeds. A number of early publications on the performance of animals receiving pelleted as compared with unpelleted feeds reported improved performance from animals receiving the pellets. Because the degree of improvement was related to the fiber level, increasing the density was thought to be the reason for improved performance. No doubt, this was partly true. However, experiments in which improved performance was obtained after re-grinding the pellets into mash suggested that other factors might be, in part, responsible. Hydrolysis of the starch in the grain portion of the feed was suspected of accounting for the additional improvement. Recent studies involving the use of clays as dietary supplements have given results which suggest that some clay products may have direct beneficial effects upon animal performance. Few such studies have provided evidence that the clay products were themselves making nutritive contributions but most have demonstrated an improved caloric efficiency resulting from their use. If control diets were deficient in any one or more of the trace elements required for optimum nutrition of the particular type of animal under test, many clay supplements containing the suboptimum element might be expected to make a direct nutritive contribution. Clay supplements have generally been used in animal diets for reasons other than the nutrients they supply. Recent reports have shown that lowlevel additions of selected bentonites (1-5 per cent) to poultry diets improved caloric efficiency and slowed down feed passage (Kurnick and Reid, 1960; Quisenberry and Bradley, 1964; Eshleman, 1966; Quisenberry, 1966; Almquist, 1967;   and Ousterhout, 1967). Erwin et al. (1957) used 3 per cent sodium bentonite in cattle rations  and reported no significant influence on rate of gain, feed efficiency, digestibility of dry matter or crude fiber, or hepatic vitamin A and carotene retention when the steers were fed a diet containing 25 per cent of dehydrated alfalfa.

These workers concluded that sodium bentonite would probably have no deleterious effect on carotene use if the clay were incorporated into rations rich in this pigment. Rotermel et al. (1964) reported an increase in chest width and carcass fat of two groups of swine fed diets containing 1 per cent bentonite, suggesting an increase in calorie retention. Jordon (1953, 1954) reported an increase in rate of gain and feed efficiency for lambs fed diets containing supplementary bentonite. In the latter paper, he reported that pregnant ewes fed as much as ı8l9b of Bentonite per day exhibited no toxic effects. The remainder of this paper will be devoted to a summary of the experimental work, completed or in progress, with chickens. *Invited paper presented at the 16th Clay Conference,

Denver. 267-268 J. H. QUISENBERRY 

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