Reinaldo Cunha de Oliveira Junior

Substituição total do farelo de soja por uréia ou amiréia, em dietas com alto teor de concentrado, sobre a amônia ruminal, os parâmetros sangüíneos e o metabolismo do nitrogênio em bovinos de corte

Seis novilhos da raca Nelore, nao castrados, com peso medio inicial de 420 kg, distribuidos em delineamento em quadrado latino 3x3 duplicado, foram utilizados para avaliar a substituicao total de uma fonte de proteina verdadeira (farelo de soja), em uma dieta deficiente em proteina degradavel no rumen (PDR), por ureia ou amireia (fontes de nitrogenio nao proteico), ambas em uma dieta adequada em PDR. As dietas foram isoproteicas (13,0%) utilizando-se o bagaco de cana-de-acucar in natura (BIN) como unica fonte de volumoso (20% da MS). Foram avaliados: a concentracao de amonia ruminal, nitrogenio ureico plasmatico, glicose plasmatica e o metabolismo do nitrogenio. Os tratamentos foram: 1) farelo de soja (FS); 2) ureia e 3) amireia (A-150S). A concentracao de nitrogenio amoniacal no fluido ruminal foi superior no tratamento com ureia, comparado ao tratamento com farelo de soja, sendo que o tratamento com amireia nao diferiu dos demais. O tratamento com amireia apresentou maior perda de N urinario. A retencao de N (g/d e % do consumido) e o valor biologico da proteina (N retido, % do N digerido) foram superiores para o tratamento com ureia, comparado aos demais. A concentracao de nitrogenio ureico no plasma e a concentracao de glicose plasmatica foram similares entre os tratamentos. A substituicao total do farelo de soja por ureia, ajustando a PDR na dieta de bovinos de corte, demonstrou ser viavel. A ureia na forma convencional apresentou vantagens em relacao a amireia.

Avaliação de indicadores para estimar a digestilidade dos nutrientes em novilhos Nelore alimentados com dietas contendo alto teor de concentrado e fontes nitrogenadas

Six Nellore bulls, with initial body weight of 420 kg, were used to evaluate cromium oxide determined by X-ray fluorescence as an external markers of digestibility. Cromium oxide was compared to internal indicators: indigestible NDF (NDFi) incubated in vitro for 144 hours and acid detergent lignin and total feces collection. Digestibility coefficients of DM, OM, NDF, ADF, CP and EE were estimated. Experimental diets were: 1) soybean meal, in a RDP deficient diet; 2) urea; 3) starea (non protein nitrogen source supposedly of slow release), both diets with adequate RDP. Experimental diets were composed of 80% of concentrate and 20% of forage (in natura sugarcane bagasse) on dry matter basis. Digestibility estimation by using cromium oxide showed similar results with total feces collection. Lignin determination was similar to feces collection when soybean was used; however, when urea and starea were fed, the digestibility coefficient were underestimated. NDFi underestimated digestibility for all nitrogen sources. X-ray fluorescence showed to be a promising technique for cromium determination. Internal markers, NDFi incubated in vitro for 144 hours and the acid detergent lignin did not estimated the indigestible portion of the diet.

Substituição do grão de milho pelo milheto (Pennisetum americanum) na dieta de vacas holandesas em lactação

Animal production and and ruminal parameters were analyzed to evaluate the substitution of corn by pearl millet. Four lactating cannulated Holstein cows were used in a incomplete 5X4 Latin Square design. Cows were fed a 48.6% corn silage diet (dry matter basis). Treatments consisted of substitution of corn stacrh by pearl millet in five different proportions: 100:0, 75:25, 50:50, 25:75 and 0:100. All grain substitutions were estimated in the starch content basis. There was no effect of grain source on dry matter intake, milk yield and milk fat percent. However, there was a quartic effect on milk protein content, as pearl millet grain increased. There was no treatment effect on ruminal pH, acetate, propionate, butyrate and total volatile fatty acids concentration. There was a linear effect on ruminal N-NH3 concentration, when pearl millet was increased. Pearl millet substitution for corn does not seem to affect performance of lactating Holstein cows.

Substituição do feno de "Coastcross" (Cynodon sp.) por casca de soja na alimentação de borregas confinadas

Forty-eight Santa Ines ewe lambs (23.1kg BW and 124 days old) were used to evaluate the replacement of coastcross hay by soybean hulls on feedlot performance. Animals were assigned to a complete randomized block design with four diets and six replicates. All diets were isonitrogenous and contained the same amount of NDF. Soybean hulls replaced hay at 0%, 12.5%, 25% or 37.5% on DM basis, corresponding to the experimental treatments OCS, 12.5CS, 25CS and 37.5CS, respectively. Soybean hulls NDF replaced hay NDF at 0, 25, 50 and 75%. There was a linear increased response (P<0.01) on dry matter intake (0.95, 1.02, 1.08 and 1.20kg day-1) and average daily gain (113, 137, 150 and 187g day-1) and a linear improvement (P<0.01) on feed conversion (8.55, 7.20, 7.11 and 6.25kg of DM kg of gain-1) when soybean hulls were added to the diet. When soybean hulls are added to the diet (up to 37.5%, DM basis) there is an improvement on animal performance and the ewe lambs attain breeding weight faster.