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Development of Rumen Fermentation in Calves in the Period of Milk Nutrition

BOMBA A, ZITNAN R
Veterinarni Medicina 37, 1992, 75-82

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 concentration of total VFA (P < 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 < 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. These changes influenced the acetate to propionate ratio, which dropped from 4.67 to 3.79 (Fig. 4), and simultaneously the energetic efficiency of VFA production (Fig. 4), which increased from the value of 71.65 % at the age of three weeks to 73.58 % at the age of eleven weeks. The acetate: propionate ratio was directly, but negatively dependent on the energetic efficiency, the correlation coefficient being r = -0.970. The molar proportion of butyrate (Fig. 3) ranges on an average from 5.79 to 9.13 mol %. The propionate proportion did not reach the lower boundary of the reference value range of adult animals in 80 %, 100 %, 80 %, 90 % and 60 % of calves at the age of three, five, seven, nine and eleven weeks, respectively (Fig. 2). A significant increase (P < 0.05 and P < 0.01) was observed in isobutyrate and isovalerate levels (Fig. 5) at the age of 3-5 weeks while the highest values of their proportion were recorded at five weeks of age over the whole experimental period (the value of isobutyrate reached 1.08 mol % and of isovalerate 1.38 mol %). The molar proportion olf valerate (Fig. 6) ranged on an average from 1.31 to 1.50 mol % and the capronate proportion was decreasing insignificantly with the age of the animals (Fig. 6). The age period of 7-9 weeks in calves can be recommended as convenient for the gradual transition to vegetable nutrition


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