The inter-relationships of individual proteins and carbohydrates during fermentation in the rumen of the sheep. I. The fermentation of casein in the presence of starch or other carbohydrate materials

Abstract

1. The metabolic interactions of casein and starch or other carbohydrates are measured by estimating the concentrations of volatile fatty acids, ammonia, lactic acid and amino acids in the rumen after administering the protein and carbohydrate supplements alone or together. 2. The ammonia concentration is reduced (i.e. its utilization is probably increased), by the carbohydrate materials; levan and starch achieve this slightly more effectively than glucose or xylan and the effect of cellulose is very slight. 3. Under conditions when the normal ration fed is not of high quality a small supplement of casein stimulates the rate of fermentation of starch and other carbohydrates. 4. The findings indicate that the best utilization of protein supplements is probably obtained when a carbohydrate is also present that can be fermented at a comparable rate, conditions which stimulate microbial synthesis in the rumen.