Development of rumen fermentation in calves during milk feeding]

The concentration of total volatile fatty acids (VFA) in the rumen fluid were increasing with the age of the animals (Fig. 1). A significant increase in the concentrations of total VFA (P less than 0.01) from 70.93 to 90.71 mmol/l was observed in the age period of 5-7 weeks and a highly significant increase (P less than 0.001) in the age period of 9-11 age. At the average age of seven weeks the lower boundary of the reference value range (80-120 mmol) of the total VFA concentrations in the rumen fluid as mentioned for adult animals was exceeded in the experimental calves. As to this parameter in individual calves, the level of the total VFA concentrations in the rumen fluid of adult animals was not reached in 50% of calves at the age of three weeks, in 80% of calves at the age of five weeks, in 20% of calves at the age of seven weeks and in 10% calves at the age of nine weeks. At the age of 11 weeks the concentrations of total VFA reached the level of adult animals in all experimental animals (Fig. 2). The molar proportion of acetate (Fig 3) decreased from 74.04 mol% at the age of three weeks to 67.54 mol% at the age of 11 weeks, and the propionate proportion increased from 16.73 to 19.53 mol% within the same interval.(ABSTRACT TRUNCATED AT 250 WORDS)