Sulfur Requirement of Lactating Dairy Cows. I. Sulfur Balance and Dietary Supplementation

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Abstract
Two experiments measured the effects of sulfur supplementation of rations for lactating cows. In Experiment 1, a basal diet (Ration 1) containing .10% sulfur was a semipurified concentrate mix and corn silage fed in a 1:1 ratio on a dry basis. Sodium sulfate was added to the basal diet to produce rations containing .15% (Ration 2) and .18% sulfur (Ration 3). The sulfur content of the basal ra- tion was a/so increased to .18% by supple- mentation with methionine hydroxy ana- log (Ration 4). Sulfur supplementation of the basal diet increased dry matter in- take and dry matter digestibility. Me- thionine hydroxy analog fed at 43 g/day decreased dry matter intake to the in- take of the sulfur deficient diet without affecting daily milk production. Both sod- ium sulfate and methionlne hydroxy ana- log improved the sulfur balance of lactat- ing cows with supplements of .15 and .18% sulfur in the complete diet. In Experiment 2, a basal diet contain- ing .06~ sulfur was supplemented with ei- ther sodium sulfate or a mixture of po- tassium and magnesium sulfate sulfiu" to .18 and .24% in the complete diet. The low-sulfur diet decreased dry matter in- take, dry matter digestibility, and milk production and caused the sulfur bal- ance to be negative. Regression analysis showed that dietary .12% sulfur would ap- proximate sulfur balance and .18~ sulfur would allow for a mean positive balance of 4 g of sulfur daily in cows producing between 8 and 37 kg milk.