The Effect of Mineral Buffers on Milk Yield, Milk Components and Heat Tolerance In Lactating Dairy Cows

Abstract

Twelve Holstein and eight Jersey cows in mid-lactation were blocked in groups of four based on breed and parity, and assigned randomly to four treatments in a ten week continuous feeding trial. Treatments were four concentrate formulations to provide: a) .5% NaCl; b) .72% NaHCO₃; c) .5% NaCl + .72% NaHCO₃; d) 1.44% NaHCO₃ in the total diet dry matter. Rye grass hay was fed ad libitum once daily on a group basis. Milk yield was recorded at the a.m. and p.m. milking three times per week and samples were taken for analysis of milk fat, protein and total solids. The objectives of this study were to measure the responses of milk yield and composition to different dietary levels of sodium, chloride and bicarbonate during hot weather. The four sodium supplements imposed as treatments had no detectable effects/on milk yield and composition in Holsteins and Jerseys in mid-lactation.