The composition of the faecal microbial flora of milking cows on feeds containing urea as the sole or partial source of nitrogen

Authors

• T. Ettala Biochemical Research Institute, Kalevankatu 56 B, SF-00180 Helsinki 18, Finland
• A. Seuranen Biochemical Research Institute, Kalevankatu 56 B, SF-00180 Helsinki 18, Finland
• M. Kreula Biochemical Research Institute, Kalevankatu 56 B, SF-00180 Helsinki 18, Finland

DOI: https://doi.org/10.23986/afsci.72031

Abstract

Using a variety of culture media, counts of live bacteria in the faeces of milking cows on purified, protein-free feed in which urea was the only source of nitrogen (0-cows) and on urea-rich, low-protein feed (ULP-cows) were made. Samples were taken from 3 0-cows and 3 ULP-cows weekly. Counts of lactobacilli, micrococci, propionic acid bacteria and lactate-utilising butyric acid bacteria were made during a period of 41 weeks, and counts of anaerobic and aerobic bacteria, enterococci and coliform bacteria for 26 weeks. Counts are given as log10 number/g fresh faeces. In the 0 cows anaerobic bacteria counts were 5—9, ULP cows 6—9; aerobic bacteria were 5—7 and 5—8 respectively. »Propionic acid bacteria» counts were 4—7 with both 0- and ULP-cows, lactobacilli 3—8 in 0 cows and 4—8 in ULP cows, and micrococci 2—7 in both groups. Enterococci were 2—6 in 0 cows and 37 in ULP cows, and coliforms 3—6 and 2—6respectively. Lactate utilising butyric acid bacteria were 0—4600/g fresh faeces, being fewer in 0-cows than in ULP cows. There was large variation in the counts of all bacteria from one week to the next. In a single cow almost all the bacterial counts could be low at the same time and the following week they could all be high. In different animals the timing of these variations was not the same. The counts of bacteria growing under anaerobic conditions were the main exception to the above variations. The ratio between gram-negative and gram-positive bacteria in faeces was measured and it was found that with both types of test feed the gram-negative were more numerous. In addition the occurrence of bacterial spores was studied; their counts, as a proportion of the total number of bacteria reacting to stain, averaged 6.5 and 26.7 % respectively in 0- and ULP-cows.