Metabolism of cod-liver oil in relation to milk fat secretion
- 1 February 1972
- journal article
- research article
- Published by Cambridge University Press (CUP) in Journal of Dairy Research
- Vol. 39 (1), 167-182
- https://doi.org/10.1017/s0022029900013960
Abstract
The effects of daily supplements of 300 g native and 2 hydrogenated cod-liver oils (CLO) to the diets of lactating cows have been examined. Native CLO supplements increased the proportion of propionate and decreased the proportion of acetate in the rumen and also decreased the yields in milk of fatty acids synthesized within the mammary gland and those derived from plasma triglycerides. These effects were reduced or eliminated when the hydrogenated oils were given instead of the native CLO. With all 3 supplements about 15% of the dietary C20and C22 acids was secreted in milk.Both native and hydrogenated CLO supplements increased the concentrations of the cholesteryl ester and phospholipid components of the α-lipoproteins in the blood plasma. These components contained most of the C20 and C22 acids of the CLO supplements that were incorporated into the blood plasma lipids. With the native CLO supplement about half of the C20 and C22 acids present in the blood plasma were polyunsaturated.There were no differences in the effectiveness of high-density plasma lipoproteins as activators of triglyceride emulsions for lipoprotein lipase hydrolysis whether the lipoproteins were from cows receiving the native or the hydrogenated CLO supplements or the control diets. Significant rates of hydrolysis by lipoprotein lipase could not be demonstrated using as substrates low- or high-density plasma lipoproteins or activated emulsions of their extracted lipids.Additional in vitro experiments using activated triglyceride emulsions as substrates for mammary lipoprotein lipase showed that replacement of a soybean oil emulsion by an emulsion of native CLO reduced the rate of hydrolysis considerably, whereas an emulsion of hydrogenated CLO was without effect unless it was present at levels in excess of 50%.It is concluded that the change in rumen fermentation induced by the polyunsaturated fatty acids of CLO is implicated in the decreased intramammary synthesis of fatty acids, but that additional information is required before the reason for the reduced mammary uptake of plasma fatty acids can be established.Keywords
This publication has 41 references indexed in Scilit:
- A specific apoprotein activator for lipoprotein lipaseBiochemical and Biophysical Research Communications, 1970
- Section A. Physiology. Ruminant metabolism in relation to the synthesis and secretion of milk fatJournal of Dairy Research, 1970
- Fractionation of bovine serum lipoproteins and their characterization by gradient gel electrophoresisJournal of Dairy Research, 1970
- The effects of intravenous infusions of cod-liver and soya-bean oils on the secretion of milk fat in the cowBritish Journal of Nutrition, 1969
- The effects of intravenous infusions of triglycerides on the secretion of milk fat in the cowBritish Journal of Nutrition, 1969
- The effect of increasing amounts of dietary red palm oil on milk fat secretion in the cowBritish Journal of Nutrition, 1968
- The magnitude and mechanisms of the uptake of milk precursors by the mammary glandProceedings Of The Nutrition Society, 1968
- Vascular permeability to particulate fat: morphological observations on vessels of lactating mammary gland and of lungProceedings of the Royal Society of London. B. Biological Sciences, 1968
- The effect of the amount and type of dietary fat on milk fat secretion in the cowBritish Journal of Nutrition, 1967
- THE ADDITION OF BUFFERS TO RUMINANT RATIONS: IV. THE EFFECT OF ADDITIONS OF SODIUM BICARBONATE, SODIUM PROPIONATE, LIMESTONE AND COD LIVER OIL ON INTRA-RUMEN ENVIRONMENTCanadian Journal of Animal Science, 1963