Submitted to: Journal of Dairy Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/23/2001
Publication Date: 4/1/2003
Citation: MUSCATO, T.V., RUSSELL, J.B. THE EFFECT OF RUMINAL FLUID PREPARATIONS ON THE GROWTH AND HEALTH OF SUCKLING DAIRY CALVES. JOURNAL OF DAIRY SCIENCE. 2003. Interpretive Summary: The National Animal Health Monitoring System (1993, 1996) indicates that dairy calf mortalities range from 8 to 11% each year. Calves are often given low levels of antibiotics as growth promotants or larger doses as veterinary therapy, but widespread use of antibiotics in the animal industry has been criticized. We examined the effect of ruminal fluid preparations on the growth and health of new-born suckling dairy calves. Results indicated that ruminal fluid preparations improved the average daily gain by as much as 100%, and the number of days that the calves had diarrhea was 5-fold lower. Because autoclaved preparations had as much activity as those containing live bacteria, disease transmission would not be a problem. This research has elucidated a new mechanism for fighting disease and provides an alternative to antibiotics.
Technical Abstract: Suckling heifer dairy calves (n=12) that were fed colostrum and then whole milk (4.5 kg/day) supplemented with fresh ruminal fluid (8 ml per day for 6 week) gained more weight (P < 0.001) and had fewer scours (P < 0.01) than calves fed only milk (n=12). Calves fed colostrum and then milk replacer (7.5 kg/day) containing ruminal fluid (8 ml per day for 6 week) that had been centrifuged to remove the bacteria (n = 12) or bacterial pellets that had been resuspended in a similar volume of 0.9% NaCl (n=12) gained more weight (P < 0.01) and had fewer scours (P < 0.0001) than calves that were fed only milk replacer (n=12). Calves fed colostrum and then whole milk (6.0 kg/day) containing autoclaved ruminal fluid (8 ml per day for 6 weeks, n=12) gained more weight (P < 0.01) and had fewer scours (P < 0.01) than calves that were fed only milk (n=12). We had originally thought that fresh ruminal bacteria might act as a probiotic, but this hypothesis was contradicted by the observation that even autoclaved preparations gave a positive response. The raw and autoclaved preparations provided a small amount of microbial protein (< 8 mg/day) and vitamins, but even centrifuged preparations that lacked bacteria had activity. Ruminal fluid has volatile fatty acids, but even cell suspensions lacking volatile fatty acids improved performance and health. Based on these results, the benefit of ruminal fluid preparations as a milk supplement cannot be explained by nutritional effects. Further work is needed to define more precisely the mechanism of action, but is conceivable that the lipopolysaccharides of ruminal bacteria are acting as antigens to modulate the calf's immune system.