Acetate supply and utilization by the tissues of sheep in vivo

Abstract

1. The supply and utilisation of acetate has been estimated simultaneously in the whole animal and tissues of sheep using a combination of isotopedilution and arteriovenousdifference techniques. Animals were made alloxandiabetic and acetate metabolism was compared when stabilized to normal metabolite levels with insulin (ITA sheep) and when food and insulin had teen withdrawn for 36 h (fasted, diabetic sheep).2. Acetate was simultaneously produced and utilized by all tissues. The exogenous (or gut) supply of acetate was the most important determiniint of circulating acetate level. Endogenous acetate was produced mainly in the liver; 77 and 94% in fasted. diabe1.ic and ITA sheep respectively. The production of endogenous acetate remained fairly constant and was not related to ketogenesis, which supports the idea that circulating acetate is largely a product of fermentation. The liver, gut and muscle utilized 17,25 and 54% respectively (96% total) of the acetate entry rate in ITA sheep; a similar percentage utilization was found in fasted, diabetic sheep.3. Acetate is largely oxidized to carbon dioxide in the gut and muscles of sheep and may account for 3 0 4 0 % of their oxidative metabolism. This figure is similar to that for the whole animal. The total acetate taken up by the liver could account for 30% of the oxygen consumption; however, the liver may not directly oxidize all the utilized acetate.4. The over-all conclusion froin this study is that acetate is largely of dietary origin and the major factor determining its rate of utilization is the arterial concentration.

Pigs experimentally infected withSerpulina hyodysenteriaecan be protected from developing swine dysentery by feeding them a highly digestible diet

“…Estimation of Volatile Fatty Acid (VFA) concentrations A modification of the method of Pethick and colleagues [23] was used to estimate the VFA concentration in the intestinal contents, using gas liquid chromatography (GLC). Gut contents were diluted 1:1 w/v with 10 N phosphoric acid and centrifuged at 4°C for 10 min at 3000 rpm in a benchtop centrifuge (MSE, Sussex, UK).…”

Quantitative aspects of blood and amino acid flows in cattle

“…A set of 111 observations was collected from 23 publications concerning young ruminants (Brown et al, 1991; Crompton and Lomax, 1993;Oddy et al, 1987), sheep (Brid et ai, 1981;Early et al, 1988;Heitmann et al, 1986;Oddy et al, 1981;Pethick and Verneau, 1984;Pethick et al, 1981Pethick et al, , 1987Symonds et al, 1988;Symonds and Lomax, 1990; ) and growing cattle (Bell et al, 1975;Boisclair et al, 1993aBoisclair et al, , 1994Early et al, 1987;Eisemann et al, 1987Eisemann et al, , 1988Eisemann and Nienaber, 1990;Eisemann and Huntington, 1994;Huntington and Prior, 1985 (Bell et al, 1975), although the length of the fasting period was short in the experiment of Bell et al (1975). Furthermore, RMuBF slightly decreased with progressive underfeeding in young lambs (Crompton and Lomax, 1993) but not in fasted lambs (Oddy et al, 1987;Symonds and Lomax, 1990; (Eisemann et al, 1988;Brown et al, 1991) while bovine somatotropin had no effect (Boisclair et al, 1994).…”

Effects of Pituitary-derived Bovine Growth Hormone on Production Parameters and Biokinetics of Key Metabolites in Lactating Dairy Cows at Peak and Mid-lactation

“…Plasma non-esterified fatty acids (NEFA) were measured using the method of Dole (1956) as modified by Kelley (1965). Acetate was quantified by gas-liquid chromatography as detailed b'y Pethick et al (1981). Plasma 3-hydroxybutyrate was measured by the auto-analy'tical method of Zivan and Snarr (1973).…”