When we are discussing about additives and specifically Yeast’s in dairy cows exist a large number of brands, types and qualities. I remember when start to came up into the market some of these products, I made some trails with yeast in suckling calves, and then I see improving the growing and the calf performance also reducing the incidence of diarrhea and mortality. I believe that the Yeast in hot environment’s when the cows reduce the intake for the stress factor, is an interesting tool specifically the type of yeast that helps in the degradation of the fiver and this process improving the intake of the feeds and conversion. I advice to my costumers to used according to the type and brand, because not all the additives and Yeast’s fulfill the same target then if we relate to the economic factor then is advice to made specific trails and comparisons to test the quality and results. In the end, the economic result is the most important.