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Sodium Bentonite Effects when Fed at Various Levels with High Concentrate Diets to Lambs¹

South Dakota State University, Brookings 57006

Abstract

Two experiments were conducted to determine the effects of bentonite on the feedlot performance of lambs and on the digestion and metabolism of various nutrients.

A 20% roughage diet with 0, 2, 4, 8 or 12% powdered bentonite (99% passed through a 100 Hm sieve) was fed to 240 wether lambs for 110 days. Added bentonite at levels of 4 and 8% improved daily gain and the feed per gain ratio during the initial 28-day period, but there were no differences among the treatments in later cumulative performance.

Balance trial data showed that apparent nitrogen digestibility was lower for lambs fed 12% bentonite and a linear decline in nitrogen retention accompanied increases in dietary bentonite. Increased ether extract digestibility as a result of 8% or 12% bentonite in the diet and decreased phosphorus retention associated with the 8% bentonite treatment were observed. Lambs on the 12% bentonite diet had higher (P<.05) crude fiber digestion coefficients than the controls. There was an increase (P<.05) in magnesium and potassium retention in lambs receiving bentonite at all levels.

No effects due to treatment were observed on dressing percent, carcass quality or carcass shrinkage 24 and 48 hr after slaughter. There were no differences among treatments in lung silica content, the appearance of the rumen epithelium at the termination of the experiments or the incidence of urinary calculi.

Lambs fed bentonite had more constant feed intakes and scoured less during the initial 28 days of the trial suggesting that bentonite has the potential of being used as a dietary ingredient to aid in the adaptation of lambs to high-concentrate diets. There were no adverse effects from diets containing up to 12% bentonite, except a trend toward lowered performance over the full term of the experimental period and a linear decline in nitrogen retention with increasing levels of bentonite. The optimum level for various types of diets and the form of bentonite best suited for this purpose are aspects that require further study.

¹ Published with approval of the Director of the South Dakota Agricultural Experiment Station as Publication No. 407 of the Journal Series.

² Department of Chemistry.

³ Department of Animal Science.