Nitrogen supplementation in certain ruminal indicators of sugar cane diets

Six dry Holstein rumen cannulated cows of 550 kg liveweight were used to study the effect of nitrogen supplementation on certain ruminal indicators. A Latin square design was used. Treatments were of A) 2, B) 3 and C) 4 kg of a nitrogen supplement (70% contributed by urea and 10% by sunflower meal). The base ration was sugar cane forage offered ad libitum. The ruminal content was analyzed at 0, 4, 8, 12 and 20 hr after feeding and data were evaluated according to a hierarchical fixed effect model. There were no differences between treatments in pH, NH3 or VFA. The pH ranged between 6.3 to 6.8. NH3 concentration was 4.90 mmoles/litres before adding the supplement in an interval of 12 hr and decreased (P < 0.05) until attaining the initial values at 20 hr. VFA concentration remained stable ranging between 20 and 100 mmoles/litres. The degradation constant of the cell wall increased (P < 0.05) when adding 3 and 4 kg of the nitrogen supplement. These results suggest that the supplementation used did not affect the ruminal fermentation indicators and that benefits in the cell wall degradation are not attained with 3 kg.