Valor nutricional do resíduo seco de cervejaria e sua utilização na alimentação de ruminantes

Abstract

In ruminant feeding soybean meal is often used as a protein food, but its high cost burdens feeding cattle. The use of brewers grains replacing soybean meal is an alternative that reduces costs, but its high moisture content makes it difficult to conservate this material. This study aimed to evaluate the efficiency of dehydration of sun-dried wet brewers grains (WBG), as well as the effect of dried brewers grains (DBG) storage period on the nutritional quality. The WBG sun-dried dehydration curve was determined, and the nutritional value of DBG stored for 10, 20, 30, 60, 90, 120, 150 and 180 days. Dehydration of sun-dried WBG was effective in ensuring the conservation of the material. The DBG storage up to 180 days did not affect the waste composition, but reduced the ruminal degradability of protein (P<0.01), without compromising the total protein digestibility. In this context the dehydration of the sun-dried WBG is an efficient conservation practice for this ingredient and allows a high storage time. In order to determine the best level of DBG in the diet of lactating dairy cows a study was conducted using five lactating cows fed diets containing levels (0%, 25%, 50%, 75% and 100%) of DBG replacement in relation to soybean meal. The cows were distributed in a 5x5 Latin Square Design, evaluating the nutrientes intake and digestibility, microbial synthesis, production and milk composition and the economic viability of diets. A reduction in dry matter intake, crude protein and total digestible nutrients (P<0.05) was obtained and increases in ether extract intake and neutral detergent fiber (P<0.05). The dry matter digestibility, crude protein, ether extract and neutral detergent fiber increased (P<0.05) with DBG levels. There was no influence on milk production (P>0.05), but the levels of fat, protein and total milk solids reduced (P<0.05). In this context the use of DBG in the supply of dairy cows is cost effective and can be performed up to 75% replacement of soybean meal. Another objective was to evaluate the effect of soybean meal replacement by DBG on ruminal fermentation parameters. Four rumen cannulated steers were used fed diets containing levels (0%, 33%, 66% and 100%) of DBG replacing soybean meal, distributed in a 4x4 Latin Square evaluating the nutrients intake and digestibility, pH and nitrogen in rumen fluid. The intake of ether extract, neutral detergent fiber and acid detergent fiber increased with DBG (P<0.05). The dry matter digestibility decreased (P<0.05) with increasing substitution of soybean meal. The ruminal pH was not affected by treatments (P>0.05), however the ammonia concentration decreased (P<0.05) as soybean meal was replaced by DBG. Thereby providing the DBG does not interfere in ruminal pH but reduces the intake of total digestible nutrients, dry matter digestibility and ammonia from the rumen