The commercial use of enzymes in ruminants is still restricted, although the increasing of feeding costs and the decline in the production costs of enzymes are providing the efforts on researches with the intent of developing and evaluate the enzymatic additives in ruminant diets. The forage and grains prices are highly increasing in the past few years, and by consequence , the producers are now searching ways to enhance the efficiency of feed conversion. The action pattern of ruminant's enzymes is until now quite unknown, due to the complexity of the ruminal environment. The necessity for more researches in this area is evident. There is a plenty of studies in witch enzymatic additives are given to ruminants, but these studies were conducted with different products and the dosages, as the experimental conditions, had a great variety. Different animal species, in different production stages, fodder variety, the methods in enzyme supply (as aerosol on the fodder or on total diet, or mixed with the concentrate) make the studies comparison hard to be done and, therefore, there is no possible conclusion on the use of enzymes with amylolitic activity in milking cattle. There is, in the literature, studies showing the efficiency of exogen amylolitic enzymes use on milking cows performance, increasing milking production by improving the nutrients total digestibility and increasing the microbial protein flow. Hence, is relevant the study of products with amylolitic activity inclusion on lactating cows' diets with corn silage as forage, which is the most used for high to medium production cows in Brazil. The scientific hypothesis to be evaluated in this project is that the usage of fungus extract with alpha-amylase (AmaizeTM, Alltech Inc., Nicholasville, KY) activity presents a positive influence on milking cows production performance , digestibility and metabolisms in the initial lactation periods. The present study will be conducted to evaluate the use of fungus extract, in increasing dosages, defined with alpha-amylase activity on lactation cows and its possible effects on: nutrients intake, apparent total digestibility of dry matter and nutrients, fermentation and microbial protein synthesis, production and milk composition, metabolic profile and nutrient balance.
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