ABSTRACT The objective of this study was to evaluate the effect of substituting soybean meal for urea in diets based on deferred buffelgrass on the performance of feedlot sheep. Thirty mixed-breed sheep with an average initial body weight of 17±1.5 kg were distributed in a completely randomized design in which the experimental treatments consisted of five diets with six replicates. Diets were composed of deferred buffelgrass plus concentrates and calculated to be isoproteic. Treatments were represented by the substitution of soybean meal for the urea levels (0, 25, 50, 75, and 100%). Nutrient intake did not differ among animals fed diets with urea levels. Hot and cold carcass weights, hot and cold carcass dressing percentages, initial and final pH, and weight of commercial cuts did not differ among animal fed diets with urea levels. There was no difference for non-carcass components among animals, except for the empty carcass, gall bladder, and perirenal fat weights, which were influenced by dietary urea levels. Substituting the crude protein from soybean meal for the protein from urea provides a similar performance in sheep consuming deferred buffelgrass.

Objetivou-se quantificar a população de mofos e leveduras, avaliar as perdas de matéria seca e a composição bromatológica de fenos de capim-buffel amonizados com ureia. Utilizou-se um delineamento inteiramente casualizado, com cinco tratamentos e cinco repetições. Os tratamentos compreenderam aos níveis de ureia (0; 0,5; 1,0; 2,0; 4,0%), que foram adicionados aos fardos de feno com base na matéria seca. A inclusão de 1,0% de ureia elevou a recuperação de matéria seca (93,21%) em relação ao feno não amonizado. Observou-se efeito quadrático para o pH, com o maior valor observado no nível de 0,5% de ureia (8,88), reduzindo nos demais níveis de ureia. A adição de níveis de ureia foi eficiente em reduzir a população de mofos e leveduras, reduzindo de 6,50 log UFC/g no feno sem tratamento com ureia para 3,65 log UFC/g quando adicionados 4% de ureia no feno. A adição de ureia proporcionou aumento nos teores de matéria orgânica e proteína bruta dos fenos de capim-buffel, atingindo os maiores valores com a utilização de 4,0% de ureia, com 90,96% e 14,03% para matéria orgânica e proteína bruta, respectivamente. A aplicação de ureia não proporciona diminuição em relação às perdas de matéria seca, exceto na dose de 1,0%, no entanto, é eficiente em reduzir a população de mofos e leveduras e elevar os teores de proteína bruta de fenos de capim-buffel.

The objective of this study was to quantify the population of molds and yeasts, evaluate losses dry matter and chemical composition of buffelgrass hay ammoniated with urea. We used a completely randomized design with five treatments and five replicates. The treatments consisted the urea levels (0, 0.5, 1.0, 2.0, and 4.0%) that were added to the hay bales based on dry matter. The inclusion of 1.0% of urea increased dry matter recovery (93.21%) compared to non-ammoniated hay. There was quadratic effect for the pH with highest value observed at the level of 0.5% of urea (8.88), reducing the other levels of urea. The addition of urea levels was efficient to reduce the population of molds and yeasts, reducing from 6.50 log CFU/g in untreated hay with urea to 3.65 log CFU/g when added 4% of urea in the hay. The addition of urea resulted in increased contents of organic matter and crude protein hay buffelgrass, reaching the highest values with the use de 4.0% of urea, with 90.96% and 14.03%, respectively. The application of urea does not provide decreased in respect losses of dry matter, except at a level of 1.0%, however it is efficient in to reduce the population of molds and yeasts and elevate the crude protein of buffel grass hay.