Rates of Production of Individual Volatile Fatty Acids in the Rumen of Lactating Cows1

Abstract

HUNGATE, R. E. (University of California, Davis), ROBERT A. MAH, AND MOGENS SIMESEN. Rates of production of individual volatile fatty acids in the rumen of lactating cows. Appl. Microbiol. 9:554-561. 1961.-The rumen fermentation rates in individual lactating cows were measured in four different experiments. The results disclosed that the amounts and proportions of volatile acids formed could vary widely. In one case, a marked difference in the proportions of the acids produced arose within the experiment and correlated with a difference in the proportion of methane formed. The average rate of production per day was 10.5 moles butyric acid, 12.8 moles propionic acid, and 40 moles acetic acid. Manometric estimations of rate gave lower results than those obtained by the zero-time method, due to delay after sampling and to failure of the acids to liberate stoichiometric quantities of carbon dioxide. For those experiments in which zero-time rates were estimated, the average specific absorption rates, i.e., the amount absorbed per hour per micromole of acid l This work was supported in part by research grant E-1266 from the National Institute of Allergy and Infectious Disease. in the rumen, were 0.37 for butyric acid, 0.38 for propionic acid, and 0.26 for acetic acid. The carbon dioxide, acids, and microbial cells produced in the rumen fermentation are estimated to account for about 90 % of the carbon found in the milk and respiratory CO2 of the cows. The carbon dioxide from the fermentation was about 27 % of the carbon dioxide exhaled. Butyrate-1-C14 infused continuously into Hay, grain, and water 12:15-12:45 the portal vein 2nd sample 16:35 AP-II 1st sample 7:40

Succinic Acid Turnover and Propionate Production in the Bovine Rumen

“…Discuss-1ON The concentrations of acetic, propionic, and butyric acids in the Jersey rumen contents averaged 80, 17, and 16 ,umoles per g, and the average increments after 1 hr of inicubation were approximately 5, 4, and 3 ,umoles, respectively. The rate of propionate production in these experiments (4 ,moles per g per hr) was low compared with the 6 to 10 ,umoles found by Hungate et al (1961). The difference can be explained by the ration; the animal in these experiments was fed alfalfa hay and no concentrates, whereas the earlier rates were for milk-producing Holstein cows on a rationincluding concentrates.…”

“…Since the quantities of rumen digesta varied, results are expressed as background corrected average counts per minute for the total amount of acid in the sample. The rate of propionate production was calculated from the amount of propionate produced by control subsamples incubated for 30 and 60 min (Hungate, Mah, and Simesen, 1961).…”

Fermentation Capacity as a Measure of Net Growth of Rumen Microorganisms

“…They pass from the rumen into the abomasum and intestine, where they are digested and the products absorbed much as in nonruminants. The quantities of the acids provided to the host have been measured (Carroll and Hungate, 1954;Hungate, Mah, and Simesen, 1961), but relatively few investigations have measured the supply of microbial cells.…”

Digestion of timothy silage and hay in reindeer

“…Ammonia and other volatile nitrogen components (NH4-N) in the reticulo-rumen digesta were liberated from an aqueous extract by addition of magnesium oxide to give pH<7.5 when boiled, the distillate was allowed to react with H2S04, and exess acid was titrated with NaOH solution (Horwitz, 1980). The zero-time in vitro technique (Carroll & Hungate, 1954;Hungate et al, 1961;Hungate, 1966;Olsen & Mathiesen, 1996) was used to calculate rumen pH, VFA (acetate, propionate and butyrate) and lactate concentration at the time of death. A sample of rumen contents (1-2 liter) was incubated in sealed thermos flasks and subsamples taken at 10-15 minutes intervals for 60 minutes after death.…”