<b>Nitrogen metabolism and microbial synthesis in sheep fed diets containing slow release urea to replace the conventional ure</b>

Abstract

This study aimed to evaluate the effects of adding slow release urea to replace conventional urea in diets for feedlot sheep on nitrogen metabolism and microbial protein synthesis. The substitution levels used as treatments were 0, 20, 40, 60 and 80%. We used 25 Santa Ines x SRD sheep distributed in the treatments in a completely randomized design. The animals were given 50% Tifton-85 hay and 50% concentrate, comprising diets with approximately 12% crude protein. The ingestion, digestion and excretion of nitrogen were not affected by the addition of slow release urea to the diet, in which the digested nitrogen accounted for 72.98% of the ingested. The concentration of plasma urea-N showed a quadratic variation, with the maximum at the level of 72.18% substitution. The microbial protein production and conversion efficiency of the protein into total digestible nutrients were not affected by the addition of slow-release urea in the diets. The replacement of conventional urea with slow release urea in the diet changes the concentrations of urea-N in plasma, however, does not affect the nitrogen balance, nor microbial synthesis and efficiency.Metabolismo do nitrogênio e síntese microbiana em ovinos alimentados com dietas contendo ureia de liberação lenta em substituição à ureia convencional RESUMO. Objetivou-se avaliar os efeitos da inclusão de ureia de liberação lenta em substituição à ureia convencional em dietas para ovinos confinados sobre o metabolismo de nitrogênio e síntese microbiana. Os níveis de substituição utilizados como tratamentos foram 0; 20; 40; 60 e 80%. Foram utilizados 25 ovinos Santa Inês x SRD, distribuídos nos tratamentos na forma de delineamento inteiramente casualizado. Os animais foram alimentados com 50% de feno de capim tifton-85 e 50% de concentrado, compondo dietas de aproximadamente 12% de proteína bruta. A ingestão, excreção e digestão de nitrogênio não foram influenciadas pela inclusão de ureia de liberação lenta na dieta, em que o nitrogênio digerido representou 72,98% do ingerido. A concentração de N-ureico no plasma variou de forma quadrática, com ponto máximo no nível de 72,18% de substituição. A produção de proteína microbiana e a eficiência de conversão da proteína em nutrientes digestíveis totais não foi afetada pela inclusão de ureia de liberação lenta nas dietas. A substituição da ureia convencional pela de ureia de liberação lenta na dieta provoca variação nas concentrações de N-ureico no plasma, entretanto, não afeta o balanço de nitrogênio nem a síntese e a eficiência de síntese microbiana.Palavras-chave: balanço de nitrogênio, eficiência microbiana, nitrogênio não proteico. 56Alves et al.

Amino Acids Metabolism in the Muscle of Sheep fed with Mitchell Grass Hay Supplemented with Gliricidia sepium

“…This is consistent with the result of N retained ( Table 1). The finding of study also consitent with the report that the amount of nitrogen retained would reflect the amount of protein synthesised in muscle [12].…”

“…It was assumed that the spesific radioactivity (SRA) of leucine in the blood would start to plateau at two hours after the infusion started. Blood flow measurement was undertaken between the 3rd and 4th hour of L- [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]leucine infusion [20] by using 3 HOH (925 kBq/mL) solution that infused for 60 minutes into the right jugular venous catheter.…”

“…It was reported that large retention of nitrogen indicated a better utilization of dietary protein for muscle deposition, which in turn increase live weight gain [12]. Leucine and isoleucine were reported as essential amino acids required for protein synthesis.…”

Effect of slow release urea in sheep feed on nitrogen balance

“…According to a study by Alves et al (2014), the substitution of conventional urea by SRU (Optigen ® ) in sheep feed altered the nitrogen intake (NI) and the plasma urea-N concentration, but no the excretion of urinary nitrogen (UN).…”

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

“…Supplementing sheep feed with DDGS also had no effect (p > 0.05) on NA [mean = 9.95 g animal -1 day -1 ; 2.92 g DM (kg 0.75 ) -1 ; 65.48% NI; Table 4], an indication that DDGS promotes rates of degradation and release in the ruminal environment similar to those induced by conventional CP (i.e., soybean meal). This may favor maintenance of the ruminal environment, as well as rumen efficiency and bacterial activity, in relation to the synchronization of the sources of N as the energy within the rumen (ALVES et al, 2014).…”