The Development of Rumen Function in the Dairy Calf I. Some Characteristics of the Rumen Contents of Cattle of Various Ages

Abstract

Rumen function was studied by age groups in 33 cows on a normal diet. These included 5 under 1 month of age, 5 from 1 to 2 months, 5 from 2 to 3 months, 5 from 5 to 6 months, 6 from 10 to 12 months, and 7 adults. Samples of the rumen contents were taken by stomach tube. Rumen function was measured by cellulolytic activity of the rumen liquor as indicated by digestion of cotton string and by volume of gas production. Direct microscopic counts of total bacteria, of aerobes, and of protozoa were compared. It was also evaluated on the presence of certain types of microorganisms characteristic of adult rumen and by the amounts of acetic, propionic, butyric, succinic-lactic, and formic acids in the rumen samples. The youngest group differed from the adult in all respects studied except total and aerobic bacteria counts. In most respects, there was progressive development of adult-like rumen characteristics, with few differences from adult remaining in the 6-month and older groups.