SÍNTESE DE PROTEÍNA MICROBIANA E BALANÇO DE NITROGÊNIO EM NOVILHAS MESTIÇAS HOLANDEZ /ZEBU ALIMENTADAS COM DUAS FONTES DE TANINOS

Tannins have been used to trigger positive effects on ruminal metabolism. So, increasing levels of tannic acid in a sorghum-based diet for five Holstein/Zebu crossbred lactating heifers were subject 5 × Latin square experimental design, x tannins periods. The excretion total purine derivatives, through the collection spot urine samples, and N concentration values milk used. All received 9.87 kg/DM corn silage as roughage 6.38 kg concentrate (not fed ad libitum). Diet 1 (control) contained low-tannin sorghum (0.027kg tannin), other diets high-tannin sorghum. added established based quantity condensed tannin Thus, 2, 3, 4, supplemented with 1.5g (13.%DM), 79.5g (2.6%DM), 157.5g (3.9%DM), 235.5g (5.2%DM) totalling 0.078, 0.156, 0.234, 0.321 kg/day respectively. urinary excretions urea (2.0055), allantoin (185.12 mmol/day-1) , derivatives (222.32 mmol/day-1); absorbed purines 179.3 microbian synthesis (130.358 (g)N/day-1); concentrations (36.40 not affected by diets. Diets using two sources supplementation did affect animal’s health, that is, it change blood metabolic rates above normality indices animal category, neither improved efficiency microbial nor balance production