Effect of bentonite on the productivity of dairy cows fed a pasture diet.

Abstract

EFFECT OF BENTONITE ON THE PRODUCTIVITY OF DAIRY COWS FED PASTURE DIET P.J. MOATE* , G.L. ROGERS and T. CLARKE Sodim bentonite ** (NaB) is cmcmly used as a feed additive with grain diets to improve rumen fermentation and nitrogen retention (Coiling and Britton 1975) and has been observed to decrease bloat in pasture fed cows (Carruthers 1985). This experiment examined whether NaB affected the milk production of cows fed solely on pasture. Twelve sets of identical twin cows in the fourth moanth of lactation were individually fed in stalls on pasture to appetite (DM % 18.7; DMD % 69; N % 1.7; Soluble Carbohydrate % 13.1; Ca % 0.49; Mg % 0.17). One twin of each set received 600 g of NaB per day mixed with its feed. The results are presented in the table. The effect of sodium bentanite on pasture intake, rumen fluid and plasma parameters, and yields of milk andmilk ccnstituents. In this experiment, NaB had no beneficial.effects on the production of dairy cows fed a pasture diet. NaB significantly decreased pasture intake and as a consequence, milk protein % and protein yield were depressed. NaB had no effect on plasma calcium and magnesium concentrations. No bloat occurred in this experiment. Rumen pH and rumen fluid concentrations of ammonia and volatile fatty acids were not affected by bentanite. CARRUTHERS, COLLIE, D.P. * V.R. (1985). N.Z. J. Ag. Res. 28 : 221. and BRITTON, R.A. (1975). J. Anim. Sci. S : 395 - 396. 41 Dairy Research Institute, Ellinbank, R.M.B. 2460, Warragul, Victoria, 3820 ** Sodim Bentonite (Cudgen R.Z. Pty. Ltd., Brisbane)