Metabolismo de nitrogênio em novilhas alimentadas com dietas contendo cana-de-açúcar tratada com óxido de cálcio

Abstract

RESUMO -Esta pesquisa foi realizada para avaliar o balanço de nitrogênio, as concentrações de ureia na urina e no plasma e a síntese de proteína microbiana em novilhas alimentadas com dietas contendo cana-de-açúcar tratada com óxido de cálcio.Utilizaram-se 20 novilhas mestiças Holandês-Zebu com peso corporal médio inicial de 200 kg distribuídas em delineamento inteiramente ao acaso, com quatro tratamentos e cinco repetições. Os animais foram alojados em baias individuais cobertas, com piso de concreto, providas de cocho individual de concreto para alimentação e bebedouro automático comum a duas baias. O período experimental foi de 21 dias, e a coleta de dados foi realizada nos sete dias finais. As dietas foram formuladas para ser isoproteicas, com 14% de proteína bruta, e continham 71% de cana-de-açúcar (com 0; 0,75; 1,5 ou 2,25% de óxido de cálcio na matéria natural) corrigida com 1% de mistura ureia e sulfato de amônio (9:1) e 29% de concentrado. A canade-açúcar foi fornecida aos animais após 24 horas de tratamento com óxido de cálcio. O tratamento da cana-de-açúcar com óxido de cálcio influenciou o balanço de nitrogênio, pois ocasionou redução tanto no consumo como na quantidade de nitrogênio digerido e retido. O nitrogênio retido (em % do N ingerido e do N digerido) também reduziu linearmente conforme aumentaram os níveis de óxido de cálcio na cana-de-açucar. O uso de óxido de cálcio em níveis de até 2,25% no tratamento da cana-de-açúcar não afeta as concentrações de ureia na urina e no plasma nem a excreção de ureia na urina e a síntese de proteína microbiana em novilhas.Palavras-chave: cal, plasma, purinas microbianas, retenção de nitrogênio Nitrogen metabolism in heifers fed with diets containing sugar cane treated with calcium oxideABSTRACT -This study was carried out to evaluate the nitrogen balance, the urea concentrations in urine and plasma and the microbial protein synthesis in heifers fed diets containing sugar cane treated with calcium oxide. Twenty Holsteinzebu crossbred heifers, with average initial body weight of 200 kg were used, distributed in a completely randomized design, with four treatments and five repetitions. The animals were housed in covered individual stalls, with concrete floor, provided with individual concrete trough for feeding and automatic drinkers common for every two stalls. The experimental period was of 21 days, and data collection was performed on the last seven days. The diets were formulated to be isoprotein, with14%crude protein and they contained 71% sugar cane (with 0; 0.75; 1.5 or 2.25% CaO, in natural matter) corrected with 1% of urea and ammonium sulfate (9:1) and 29% of concentrate. Sugar cane was offered to the animals after 24 hours of treatment with chromium oxide. Treatment of sugar cane with calcium oxide affected nitrogen balance by reducing intake and quantity of retained and digested nitrogen. The retained nitrogen (in % of ingested N and digested N) was also linerarly reduced according to increases in levels of calcium oxide in the sugar cane. Use of ca...

Digestibility and nitrogen balance of lambs fed sugarcane hydrolyzed under different conditions as roughage in the diet

“…This difference is due to the higher N intake and a lower N excreted in feces and urine obtained in our study. The sugarcane hydrolysis using CaO (alkaline additive) could have changed the fermentative ruminal environment and reduced the nitrogen balance (CARVALHO et al, 2011); our results, however, show that the 0.6% CaO content used in the sugarcane hydrolysis did not have a negative effect in the ruminal degradation. Conversely, the readily available carbohydrates in the rumen coming from the sugarcane resulted in a higher N retained (NB).…”

“…MORENO et al (2010) did not find effect on the N intake (27.26g day -1 ), N excreted in the feces (12.57g day -1 ) and in the urine (6.37g day -1 ) in lambs fed corn or sugarcane silage in different proportions. CARVALHO et al (2010) and CARVALHO et al (2011) however, assessing the NB of goats and heifers fed diets containing IN sugarcane or hydrolyzed using CaO in different levels (zero, 0.75%, 1.50% and 2.25%), found a negative effect for N intake for heifers, whereas it was a crescent linear effect for goats fed hydrolyzed sugarcane. They have justified the effects by a possible relation in the changes of the fermentative patterns by the use of alkaline additive CaO.…”

“…To overcome this issue, hydrolysis using alkalizing treatments, e.g. calcium oxide (CaO), has been promoted on sugarcane, which can also improve the nutritive value of sugarcane by increasing the digestibility of fibers (CARVALHO et al, 2011). The alkalizing agents act in the hydrolysis solubilizing part of the hemicellulose and promoting the expansion of the cellulose molecules.…”

“…Hydrolyzed sugarcane showed an improvement of 6.61% in the in vitro dry matter digestibility, 12.95% for the neutral detergent fiber and 9.28% for the acid detergent fiber (OLIVEIRA, 2010). CaO improves the sugarcane nutritive value and because it is an alkaline additive, it can alter the ruminal environment and change the fermentation pattern, which reduces the metabolism and the nitrogen balance (CARVALHO et al, 2011).…”

Quantitative measures of lambs fed hydrolyzed sugarcane under aerobic and anaerobic conditions

“…It has, however, some disadvantages: low crude protein content that requires protein supplementation, and a need for daily cut due to the high concentration of soluble carbohydrates which makes the environment propitious for the development of microorganisms that deteriorate the chopped sugarcane. To overcome the latter disadvantage, alkaline treatment of sugarcane has been promoted using calcium oxide (CaO), which can also improve the nutritive value of sugarcane by increasing the digestibility of fibers (ZEOULA et al, 2006;MORENO et al, 2010;OLIVEIRA, 2010;BERCHIELLI;OLIVEIRA, 2011;CARVALHO et al, 2011).…”