Effect on milk production of adding bentonite and reactive limestone to maize grain supplements for grazing cows

Abstract

Sodium bentonite and 2 types of limestone differing in rate of reactivity were each used as additives to cracked maize grain in 2 experimental periods. In the first period, maize was fed individually to 32 grazing cows at a rate of 4 kg cow-1 day-1 for 3 weeks and then 6 kg cow-1 day-1 for 4 weeks in the second. The limestones and bentonite were added at rates of 3 and 33% (w/w) of the maize in the respective periods. In the first period, the control cows produced 20.2 kg milk day-1 containing 3.34% fat and 2.97% protein; in the second period, they produced 22.5 kg milk day-1 containing 3.41% fat and 3.21% protein. None of the additives had any significant effects on milk production, milk composition or liveweight change in either of the feeding periods.