THE MICROFLORA OF THE RUMEN OF THE YOUNG CALF: II. SOURCE, NATURE AND DEVELOPMENT

Abstract

SUMMARY Twelve calves of different sex and breed divided into four groups were used in the experiments. Each group received different rearing and diet treatment. Three hundred and nine samples of rumen contents were obtained by means of a stomach tube during the period from birth to three months of age. Streptococci, lactobacilli and coli‐aerogenes organisms were isolated and studied, and isolates were also made from various elements of the calves’ environment. Rapid development of the rumen flora occurred immediately after birth of the animals. During the first week of life, streptococci and coli‐aerogenes organisms predominated, whereas no lactobacilli were isolated from calves on any of the treatments. The coliaerogenes count (10 7 ‐10 8 /g wet weight) was higher than in the adult rumen, but dropped to its normal level during the succeeding two weeks. The streptococcus and lactobacillus counts varied according to treatment. Streptococcus bovis was the predominating streptococcal species, except during the first week of life, when Strep. faecium predominated and Strep. bovis amounted to only 28·6% of the total streptococcal isolates. The variation in physiological characteristics within the Strep. bovis strains was greater than normally found within strains from adult cattle. Lactobacillus acidophilus, L. plantarum and a group of strains which resembled L. brevis predominated among the lactobacilli. Most of the coli‐aerogenes organisms were Escherichia coli , faecal type I. The diet was found to influence the proportion of streptococci and lactobacilli in the rumen, whereas the incidence of various species of the two groups of bacteria, particularly the streptococci, was associated with the age of the animals. The microflora of the environment influenced the rumen flora only during its early development, soon after birth of the calves.