Improvement of intestinal microflora balance and prevention of digestive and respiratory organ diseases in calves by green tea extracts

Green tea extracts (GTE) were evaluated for their effect in inhibiting the growth of pathogenic bacteria isolated from farm animals, their effect on improving intestinal microflora balance, and their effect in preventing digestive and respiratory organ diseases in calves, GTE showed moderate and wide spectrum inhibitory effects on the growth of pathogenic bacteria, including seven strains of Staphylococcus spp., seven strains of Streptococcus spp., one strain of Corynebacterium suis, 19 strains of Escherichia coli, and 26 strains of Salmonella spp. It was suggested that the ester-linked galloyl moiety of the polyphenolic compounds contained in GTE may be one of the main active moieties in the inhibition of bacteria growth. Feed containing GTE maintained high faecal counts of Bifidobacterium spp. and Lactobacillus spp., and decreased Clostridium perfringens, which improved microflora balance and decreased the frequency of diarrhoea in transported Holstein calves. A decrease in the number of calf deaths was also observed, due to the effect of GTE in the prevention of digestive and respiratory organ diseases in calves while nursing. These results indicate that GTE could be applied as a safe and useful feed material. (C) 2001 Elsevier Science B.V. All rights reserved.