Substituição parcial de farelo de soja por ureia de liberação lenta em rebanhos leiteiros comerciais

Abstract

Dois experimentos foram conduzidos para avaliar a substituição parcial de farelo de soja por ureia encapsulada (Optigen®II, Alltech do Brasil, Curitiba, PR, Brasil). Na dieta Controle, 1kg de farelo de soja foi substituído por mistura isonitrogenada que continha 160g de Optigen®II + 2,5kg de silagem de milho no Exp.1, ou 150g de Optigen®II + 850g de milho moído fino no Exp.2. No Exp.1, 61 vacas Holandês foram blocadas e alocadas a um tratamento por 21 dias, e as medidas da mesma variável no final da padronização utilizadas como covariável. No Exp.2, 97 vacas foram alocadas a uma sequência dos dois tratamentos por 21 dias, em delineamento de reversão simples. A resposta aos tratamentos foi avaliada do dia 17 ao 21. Em ambos os experimentos, não houve diferenças entre os tratamentos na composição em nutrientes da dieta oferecida e das sobras, nas sobras como % do oferecido, no peso vivo e no escore de condição corporal dos animais. A produção diária de leite foi 38,4 kg/d no Controle e 38,9 no Optigen®II (P=0,62) no Exp.1, e 27,0kg/d e 27,2 no Exp.2 (P=0,64), respectivamente. A ureia encapsulada reduziu a porcentagem de gordura no leite no Exp.2 (P=0,04). O Optigen®II aumentou o nitrogênio ureico no leite de 16,3 para 17,3mg/dL no Exp.1 (P<0,01) e as relações entre o leite produzido e o alimento consumido (P=0,08) e entre a alantoína e a creatinina urinárias (P=0,03) no Exp.2. A substituição parcial de farelo de soja por Optigen®II não induziu queda no desempenho.

Productive evaluation of dairy cows fed with urea protected by protein nanoparticle in partial replacement of soybean meal

“…These results differ in part from Souza et al (2010) that, when adding protected urea (0.4% DM) in partial substitution of soybean meal, found a decrease only in the percentage content of milk fat and not in the yield (kg.day -1 ) of this component. Silveira et al (2012) obtained different results from those observed in this study. They found a reduction in milk fat content from 3.82 to 3.75 by adding protected urea (7.5% of the original matter) and fine ground corn in partial replacement to soybean meal in lactating cows diet.…”

“…However, there was an increase in MUN of the milk of cows in the middle third of lactation receiving conventional urea, a result that differs from the present study. Silveira et al (2012) found no difference in MUN only when protected urea was added to the diet of dairy cows with inclusion of ground corn, however, when the addition was accompanied by corn silage, MUN levels varied between groups. These results are in agreement with those obtained by Santos et al (2011), that reported higher levels of MUN when the animals were fed conventional urea with citrus pulp, compared to a control group.…”

Effect of slow release urea in sheep feed on intake, nutrient digestibility, and ruminal parameters

“…Thus, the authors recommended that common urea should be used for sheep in confinement. Silveira et al (2012) evaluated the partial substitution of soybean meal by SRU in commercial dairy herds and found that the use of Optigen ® (SRU) in the diets of lactating cows provided more ruminal nitrogen because of the continuous supply of N from the SRU, which resulted in similar milk production and an increase in protein synthesis in the microbial rumen, without inducing increased milk urea nitrogen. The authors also concluded that every 150 g of SRU in dairy cow diets replaced 1.0 kg of soybean meal in the ration, and in this way, when soybean meal is expensive, the inclusion of SRU in diets of dairy cows is economically more profitable.…”

“…In the past, it was used as much as possible, the NPN in replacing of true protein because it did not affect the production and health of the animals. In addition, the substitution of NPN for vegetable or animal protein in the diet decreases the cost of nitrogen, and as a consequence, the price of feed (MENDES et al, 2010;OLIVEIRA et al, 2001;SILVEIRA et al, 2012).…”

Effect of slow release urea in sheep feed on nitrogen balance

“…Specific characteristics of urea include mineral deficiency, lack of energy value, and being extremely soluble in water (SILVEIRA et al, 2013).…”