Acetate Metabolism in Ovine Ketosis

Pugh, Peter; Scarisbrick, R.

doi:10.1038/170978a0

Cited by 8 publications

(4 citation statements)

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“…The rate of transport is, thus, dependent on the concentration gradient. Clearance of an acetate load will, therefore, reflect the potential maximum rate of intracellular acetate metabolism, as little acetate is voided in the urine following an acetate load (Pugh & Scarisbrick, 1952). A relatively high rate of clearance of an intravenously administered load from the circulating blood could, therefore, be indicative of an appropriate balance of acetate to propionate or amino acids, or both, among the nutrients available for tissue metabolism.…”

Section: Discussionmentioning

confidence: 99%

“…2, in which values derived from both experiments have been combined, shows that the response was consistent over a wide range. Various workers (Jarrett et al 1952;Pugh & Scarisbrick, 1952;Reid, 1958;Jarrett & Filsell, 1961 ;Egan, 1965) have suggested that the rate of clearance of an intravenous acetate load may indicate the ability of a diet to provide substrates (such as glucose) needed to enable the efficient uptake or oxidation, or both, of acetate by tissues. However, Weston (1 966) suggested that caution should be exercised when interpreting differences between diets when these provided different levels of digestible energy (DE), and suggested that acetate clearance rate was related to DE intake.…”

Section: Discussionmentioning

confidence: 99%

“…A number of workers (Jarrett e t al. 1952;Pugh & Scarisbrick, 1952;Reid, 1958;Jarrett & Filsell, 1960;Egan, 1965) have made estimates of acetate clearance rate and, in general, higher rates of acetate clearance were associated with higher-quality diets. In reviewing the literature, Egan (1965) argued that factors influencing the rate of acetate oxidation or lipogenesis from acetate would include the availability of glucose or glucogenic substrates, and the nitrogen status of the animal.…”

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confidence: 99%

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Acetate clearance rate as a potential index of the availability of glucogenic precursors in ruminants fed on roughage-based diets

1991

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Three experiments were conducted to investigate interactions between acetate and glucose metabolism in sheep fed on roughage-based diets, and to establish whether the clearance rate of an intravenous acetate load would provide a valid index of the dietary acetate:glucogenic precursors ratio. In Expt 1 lambs were fed on a basal diet of wheat straw and supplemented with propionate and protein. Both supplements increased glucose irreversible loss rate (ILR) although not to the same degree. Acetate clearance rates were increased by protein and propionate supplementation and were positively related to glucose ILR irrespective of precursor. In Expt 2 the effects of an increased dietary load of acetate given with or without propionate were investigated. Glucose ILR did not respond to acetate supplementation, but was increased when propionate was fed in addition to acetate. This was reflected in an unchanged ability to clear an intravenous acetate load from the blood when acetate alone was added, but an increased acetate clearance rate when propionate was fed in addition to acetate. In Expt 3 the effects of supplementation with various propionate: acetate ratios were investigated. Acetate clearance was consistently increased by an increased propionate :acetate ratio. These results show that the metabolism of excess acetate is responsive to the dietary supply of glucose precursors, and provide support for the concept that additional glucose precursors are necessary for the efficient utilization of acetate when roughage diets low in protein are fed.Acetate clearance rate : Gluconeogenesis : Ruminant Forage diets typically give rise to a high rumen production rate of acetate relative to that of propionate. This is usually accompanied by a reduced supply of amino acids (mainly as microbial protein), and negligible amounts of glucose and lipids; this results in a high proportion of acetate relative to glucose precursors in the absorbed nutrients. As acetate is the major energy-yielding substrate under these conditions, the efficiency with which it is used will exert a dominant influence on the overall efficiency of feed utilization. As it has been proposed that an insufficient supply of glucose relative to acetate may reduce the efficiency with which acetate is utilized (Preston & Leng, 1987), a need has arisen for some measure of the balance between the availability of acetate and precursors of glucose.A number of workers (Jarrett e t al. 1952;Pugh & Scarisbrick, 1952;Reid, 1958; Jarrett & Filsell, 1960;Egan, 1965) have made estimates of acetate clearance rate and, in general, higher rates of acetate clearance were associated with higher-quality diets. In reviewing the literature, Egan (1965) argued that factors influencing the rate of acetate oxidation or lipogenesis from acetate would include the availability of glucose or glucogenic substrates, and the nitrogen status of the animal. Weston (1966) found a linear relationship between

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Acetate clearance rate as a potential index of the availability of glucogenic precursors in ruminants fed on roughage-based diets

1991

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“…Clearance of glucose has previously been shown to become less efficient during the first few weeks of a calf's life (Bunting et al, 2000). The acetate clearance test was first used by Pugh and Scarisbrick (1952) and has been used since to characterize effects of diet on acetate supply to growing lambs (Cronjé et al, 1991;Fonseca et al, 2001;Chakeredza et al, 2002). To our knowledge, the BHB clearance test has not been attempted.…”

Section: Introductionmentioning

confidence: 97%