Early workers in the field of ruminant physiology were aware of the presence of formic, acetic, propionic and butyric acids (Tappeiner, 1884), and of smaller amounts of higher members of the saturated fatty acid series (Mangold, 1934), in the rumen fluid. Accurate data were not reported, however, until recently, when partition chromatography became available as an analytical procedure for the a...

Four Friesian steers (mean BW = 282 kg) were given mixtures of VFA and casein by intragastric infusion to give a total energy input of 675 kJ/kg BW.75. Casein supplied 16.3% of the energy and 777 mg N/kg BW.75. The molar proportion of butyric acid was held constant at 8 mol/100 mol, and the acetic and propionic acids varied inversely. Acetic acid was varied in 12 increments from 11 to 91 mol/10...

this experiment was conducted to investigate the effects of using protexin, propionic acid growth promoters, and a blend of them on broilers performance. in a completely randomized design, three hundreds and twenty unsexed 1-d-old chicks were divided into four groups. dietary treatments were consisted of 1) control diet without any supplement, 2) the control diet + 0.01 % protexin, 3) the contr...

I. Studies were made of the fermentation of D-glucose, D-fructose, D-galactose, D-xylose, L-arabinose and sucrose by rumen contents from two cows fed I kg hay and 4 or 5 kg flaked maize once daily. The proportions of volatile fatty acids (VFA) in the rumen before addition of carbohydrates varied widely but on average acetic acid constituted about 52%, propionic acid about 29 % and n-butyric aci...

Volatile fatty acids are the most important intermediates in anaerobic digestion, and their degradations are extremely complicated thermodynamically. In this research, syntrophic anaerobic digestion of volatile fatty acids using enriched acetogenic and methanogenic cultures in a batch reactor at mesophilic conditions was investigated. Interactive effects of key microbiological and operating var...

Infrared-ultraviolet double resonance spectroscopy has been applied to study the infrared spectra of the supersonically cooled gas phase complexes of formic acid, acetic acid, propionic acid, formamide, and water with 9-hydroxy-9-fluorenecarboxylic acid (9HFCA), an analog of glycolic acid. In these complexes each binding partner to 9HFCA can function as both proton donor and acceptor. Relative ...

I . The effect of reducing the hay and of increasing the proportions of concentrate and flaked maize in the diet of cows on the secretion of milk fat and its component fatty acids and on the proportions of volatile fatty acids in the rumen liquor has been studied. 2. The low-hay diet caused a fall in the milk fat content to about half of the values in the initial control period and the secretio...

Ruminal pH in dairy cows follows a diurnal fluctuation; low values are indicative of subacute ruminal acidosis and associated with alterations rumen fatty acids concentrations. The objective the present study was to prospectively associations between fluid concentrations short, medium, long chain acids, under field conditions during first half lactation 53 Holstein farm. obtained by rumenocente...

Bacterial metabolism of Tyr and Phe has been associated with the formation of aromatic compounds that impart barny-utensil and floral off-flavors in cheese. In an effort to identify possible mechanisms for the origin of these compounds in Cheddar cheese, we investigated Tyr and Phe catabolism by Lactobacillus casei and Lactobacillus helveticus cheese flavor adjuncts under simulated Cheddar chee...