Balanço de nitrogênio, concentrações de ureia e síntese de proteína microbiana em caprinos alimentados com dietas contendo cana-de-açúcar tratada com óxido de cálcio

Abstract

RESUMO -Objetivou-se avaliar o efeito da hidrólise da cana-de-açúcar com óxido de cálcio (CaO) sobre o balanço de nitrogênio, as concentrações de ureia na urina e no plasma e a síntese na proteína microbiana em caprinos. Foram utilizados oito caprinos da raça Saanen, machos castrados, com peso corporal médio de 22,6 kg e 4 meses de idade, distribuídos em dois quadrados latinos 4 × 4, em quatro períodos experimentais de 14 dias. As rações, formuladas para ser isoproteicas, com 14% de proteína bruta (PB), foram compostas de 70% de cana-de-açúcar (tratada com 0; 0,75; 1,5 ou 2,25% de óxido de cálcio na matéria natural e corrigida com 1% de ureia) e 30% de concentrado e fornecidas à vontade.A cana-de-açúcar com óxido de cálcio foi picada em desintegrador estacionário, pesada, acondicionada em baldes plásticos de 50 litros e tratada com o óxido de cálcio para ser fornecida aos animais após 24 horas de armazenamento. O balanço de nitrogênio, as concentrações de ureia na urina e no plasma e as excreções de ureia na urina não foram influenciadas pelo tratamento da cana-de-açúcar com óxido de cálcio. A concentração de alantoína (% das purinas totais) foi maior e a de ácido úrico menor nas dietas com cana-de-açúcar hidrolisada com óxido de cálcio em relação à cana in natura. A produção e a eficiência microbiana não foram afetadas pela adição de óxido de cálcio à cana-de-açúcar em dietas para caprinos em crescimento.Palavras-chave: cal, derivados de purinas, eficiência microbiana Nitrogen balance, urea concentrations and microbial protein synthesis in goats fed diets containing sugar cane treated with calcium oxide ABSTRACT -The objective of this work was to evaluate the effect of sugar cane hydrolysis with calcium oxide (CaO) on nitrogen balance, concetrations of urea in the urine and in the plasma and synthesis in microbial protein in goats. Eight castrated male Saanen breed goats, with 22.6 kg average body weight and at four months of age were used distributed in two 4 × 4 Latin squares, during four 14-day experimental periods. The rations which were formulated to be isoprotein, with 14% crude protein (CP) were composed of 70% sugar cane (treated with 0; 0.75; 1.5 or 2.25% of calcium oxide in natural matter basis and corrected with 1% urea) and 30% of concentrate given ad libitum to animals. Sugar cane with calcium oxide was chopped in a stationary chopper, weighted and stored in 50-L plastic buckets and treated with calcium oxide to be given to the animals after 24 hours of storage. Nitrogen balance, urine and plasma urea concentrations and urine urea excretion were not affected by sugar cane +calcium oxide treatment. Concetration of allantoin (% total purine) was higher and the uric acid concentration was lower in diets with sugar cane hidrolised with calcium oxide in relation to in natura sugar cane. The microbial production and efficiency are not affected by addition of calcium oxide to sugar cane in diets for growing goats.

Effect of slow release urea in sheep feed on nitrogen balance

“…During ruminal fermentation, when the pool of ammonia exceeds the level of utilization by ruminal microorganisms, it is absorbed, reaching the liver through the enterohepatic circulation, where it is transformed into urea, which, together with the urea produced in the liver from amino acid metabolism, constitutes the majority of the plasma urea (ALVES et al, 2012). If urea is in excess in the blood circulation only part of it is recycled, via the saliva and the rumen wall, and goes back to the rumen, whereas the rest is excreted in the urine, causing endogenous losses of nitrogen (KOZLOSKI, 2002;CARVALHO et al, 2010). This was shown by Geron et al (2016) who, when evaluating the inclusion of SRU in sheep feed, observed a quadratic behavior with a point of maximum digestibility of 69.92% for DM and 63.55% for CP estimated for the levels of inclusion of 0.50% and 0.70% SRU.…”

“…circulation, where it is transformed into urea, which, together with the urea produced in the liver from amino acid metabolism, constitutes the majority of the plasma urea (ALVES et al, 2012). If urea is in excess in the blood circulation only part of it is recycled, via the saliva and the rumen wall, and goes back to the rumen, whereas the rest is excreted in the urine, causing endogenous losses of nitrogen (KOZLOSKI, 2002;CARVALHO et al, 2010). This was shown by Geron et al (2016) Nevertheless, the amount of UN is related to the content of CP in the diet, with increased excretion of urea via the urine when NI increases, as this results in higher production of urea in the liver, whereas a low NI leads to a decrease in the excretion of urea via the urine to maintain the plasma urea pool, under Nevertheless, the amount of UN is related to the content of CP in the diet, with increased excretion of urea via the urine when NI increases, as this results in higher production of urea in the liver, whereas a low NI leads to a decrease in the excretion of urea via the urine to maintain the plasma urea pool, under homeostatic physiological control (ZEOULA et al, 2006).…”

Distiller’s dried grains with solubles (Zea mays L.) in feeding sheep on nitrogen balance

“…Thus, excess N in the rumen is absorbed by the ruminal wall and enters the bloodstream, where it remains until eventually reaching the liver, where it is transformed into urea. This circulating urea can be partially recycled via saliva or returned to the rumen by transport facilitated by the ruminal wall, but when urea is in excess in the bloodstream, a part of it is excreted in the urine, resulting in endogenous N losses (KOZLOSKE, 2002;CARVALHO at al., 2010;GERON et al, 2015b). This process was not evident in the present study, most likely because most of the protein in DDGS is in the form of the B2 fraction (true protein of ruminal intermediary degradation) (GERON et al, 2017), which may have caused a small change in the rate of ruminal N release compared to diets containing a higher proportion of soybean meal, which corroborates with the results obtained for the UN of sheep fed DDGS.…”

Qualidade seminal e perfil metabólico de caprinos alimentados com semente de linhaça na dieta

“…Neste estudo, houve uma diminuição na concentração de glicose no plasma sanguíneo dos animais alimentados com semente de linhaça. Por esse motivo, provavelmente, as concentrações plasmáticas de ureia estão acima dos valores relatados na literatura (Carvalho et al, 2010) para a espécie caprina.…”