Volatile fatty acid metabolism of ruminants, with particular reference to the lactating bovine mammary gland and the composition of milk fat

1951 ◽  
Vol 2 (2) ◽  
pp. 158 ◽  
Author(s):  
GL McClymont
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Milk Fat ◽  
Volatile Fatty Acid ◽  
Close Association ◽  
Blood Levels ◽  
Acid Uptake ◽  
Bovine Mammary Gland

Studies are reported on the volatile fatty acid (V.F.A.) metabolism of sheep and bovines with particular reference to the association between (i) ingestion of food and ruminal levels of V.F.A.s and arterial levels of acetic acid and (ii) the utilization of arterial acetic acid by the bovine mammary gland and the association between this utilization and the proportion of lower fatty acids (Reichert-Meissl value) in the milk fat. Ruminal levels of V.F.A. and arterial levels of acetic acid were found to be similar in cattle and sheep, and similar to those reported by earlier workers for sheep. There was a close association between changes in ruminal V.F.A. and arterial acetic acid levels. Arterial acetic acid levels were found on the feeds studied to reach a maximum value of 8-14 mg. per cent. by 2-5 hours after feeding, declining to 5-8 mg. per cent. by 8 hours after feeding and to 2-6 mg. per cent. by 16 hours after feeding. On starvation for approximately 72 hours, values fell as low as 1.5 mg. per cent. Acetic acid was found to be a major metabolite of the bovine mammary gland, arterio-venous (A-V.) differences being directly dependent on the arterial level and of the order of 2-6 mg. per cent. or 40-80 per cent. of the arterial level in the fed animal. Arterial levels and mammary A-V. differences of acetic acid were unaffected by cod-liver oil feeding or low roughage-high concentrate diets, both of which depressed the fat percentage and the Reichert- Meissl (R-M.) value of the milk fat. Hyperinsulinism and recent or delayed milking also had no effect on the A-V. differences. The depression in R-M. value during fasting was not reversed by intraruminal or intravenous acetic acid infusions despite the maintenance of high blood levels of acetic acid. There was no detectable correlation between carbon dioxide output by the mammary gland and the acetic acid uptake of the gland, indicating that the acid served some 'useful' purpose in the gland. It is concluded, taking into account other evidence, that acetic acid is utilized in the gland for fat synthesis and oxidation, depending on the requirements of the gland, but that the proportion of lower fatty acids in milk fat is not dependent on the uptake of acetic acid.

scholarly journals Effect of Feefing Protected Lipid on the Uptake of Precursors of Milk Fat by the Bovine Mammary Gland

1973 ◽  
Vol 26 (5) ◽  
pp. 1201 ◽  
Author(s):  
JM Gooden ◽  
AK Lascelles
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Dairy Cows ◽  
Milk Fat ◽  
Bovine Mammary Gland ◽  
Lactating Dairy Cows

The feeding of protected lipid to lactating dairy cows resulted in a substantial increase in the proportion of fatty acid 18:2 and a decrease in fatty acids 4:0 to 16:0 in milk fat.

Effect of feeding protected lipid to dairy cows in early lactation on the composition of blood lipoproteins and secretion of fatty acids in milk

1980 ◽  
Vol 94 (3) ◽  
pp. 503-516 ◽  
Author(s):  
J. E. Storry ◽  
P. E. Brumby ◽  
B. Tuckley ◽  
V. A. Welch ◽  
D. Stead ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Milk Fat ◽  
Low Density Lipoproteins ◽  
Total Serum ◽  
Low Density ◽  
Dietary Intakes ◽  
Vldl Triglyceride

SummaryEffects of 0, 1·7, 3·3 or 5·0 kg/day of a protected soya bean – tallow supplement, incorporated into a hay:concentrate diet (25:75) and fed ad libitumto Friesian cows, on intake and digestion of fatty acids, on output of milk fatty acids and on blood lipoprotein composition were measured.Most of the increased intake of fatty acids, approximately 1 kg/day, was accounted for by increased intakes of C16:0, C18:0 and C18:1. At low intakes, amounts of all fatty acids apparently digested were linearly related to their respective intakes. At high intakes of C16 and C18 acids, curvilinear relationships were established.Yield of total milk fat was related positively to dietary intakes of total fatty acid and carbohydrate and negatively to live-weight change. Yields of short and intermediate chain acids in milk, synthesized within the mammary gland, were negatively correlated and yields of C18 fatty acids positively correlated with respective dietary intakes of these acids. Decreased proportions of C4–16 and increased proportions of C18:0 and C18:1 fatty acids in milk were associated with increased protected tallow in the diet. Yields of C16:1 and C18:1 were positively related to corresponding outputs of saturated acids and negatively to weeks of lactation. The proportion of C18:1 in milk was positively related to the corresponding proportion of C18:0.The increased intake of fatty acids resulted in increased concentrations of very low density lipoproteins (VLDL, d < 1·019 g/ml), low density lipoproteins (LDL1 + LDL2, 1·019 < d < 1·06 g/ml), high density lipoproteins (d > 1·060 g/ml) and serum free fatty acids. Most of the increase in low density lipoproteins was accounted for by a very large increase in LDL1, whose proportion increased from 17 to 75% (2 to 22% of total serum lipid). The proportion of triglyceride in the combined low density lipoprotein fraction decreased from 11 to 2% whilst phospholipids increased from 29 to 36%. These changes were attributed to the increased proportion of LDL1 present.The proportions of VLDL and LDL triglyceride taken up by the mammary gland averaged 0·79 and 0·34 respectively. The proportion of VLDL+LDL triglyceride taken up by the gland decreased with increased amounts of fatty acid digested. Yields of C18 fatty acids in milk tended to be positively related to apparent uptakes of VLDL triglyceride and to VLDL C18 fatty acids, but negatively related to apparent uptakes of LDL triglycerides and LDL C18 fatty acids. It is suggested that the increased LDL1 resulted from the utilization of VLDL triglyceride for milk fat formation.Protected lipid feeding increased the proportion of C14:0, C16:0 C16:1 and C18:1 and decreased the proportions of C14:1 and C18:0 fatty acids in jugular serum triglycerides. Similar changes were observed in jugular VLDL triglycerides. Differences in the compositions of VLDL and LDL triglycerides across the mammary gland were observed and attributed either to selective uptake or to interchange of fatty acids between triglycerides and free fatty acids.

scholarly journals A Review of the Metabolic Origins of Milk Fatty Acids

2013 ◽  
Vol 5 (3) ◽  
pp. 270-274 ◽  
Author(s):  
Anamaria COZMA ◽  
Doina MIERE ◽  
Lorena FILIP ◽  
Sanda ANDREI ◽  
Roxana BANC ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Milk Fat ◽  
De Novo ◽  
Long Chain Fatty Acids ◽  
De Novo Synthesis ◽  
Ruminal Biohydrogenation ◽  
Long Chain ◽  
Chain Fatty Acids

Milk fat and its fatty acid profile are important determinants of the technological, sensorial, and nutritional properties of milk and dairy products. The two major processes contributing to the presence of fatty acids in ruminant milk are the mammary lipogenesis and the lipid metabolism in the rumen. Among fatty acids, 4:0 to 12:0, almost all 14:0 and about a half of 16:0 in milk fat derive from de novo synthesis within the mammary gland. De novo synthesis utilizes as precursors acetate and butyrate produced through carbohydrates ruminal fermentation and involves acetyl-CoA carboxylase and fatty acid synthetase as key enzymes. The rest of 16:0 and all of the long-chain fatty acids derive from mammary uptake of circulating lipoproteins and nonesterified fatty acids that originate from digestive absorption of lipids and body fat mobilization. Further, long-chain fatty acids as well as medium-chain fatty acids entering the mammary gland can be desaturated via Δ-9 desaturase, an enzyme that acts by adding a cis-9-double bond on the fatty acid chain. Moreover, ruminal biohydrogenation of dietary unsaturated fatty acids results in the formation of numerous fatty acids available for incorporation into milk fat. Ruminal biohydrogenation is performed by rumen microbial population as a means of protection against the toxic effects of polyunsaturated fatty acids. Within the rumen microorganisms, bacteria are principally responsible for ruminal biohydrogenation when compared to protozoa and anaerobic fungi.

Responses in rumen fermentation and milk-fat secretion in cows receiving low-roughage diets supplemented with protected tallow

1974 ◽  
Vol 41 (2) ◽  
pp. 165-173 ◽  
Author(s):  
J. E. Storry ◽  
P. E. Brumby ◽  
A. J. Hall ◽  
V. W. Johnson
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Dietary Supplement ◽  
Fatty Acid Synthesis ◽  
Milk Fat ◽  
Acid Synthesis ◽  
Rumen Fermentation ◽  
Total Fatty Acids ◽  
Friesian Cows

SummaryThe effects on rumen fermentation and milk-fat secretion of a dietary supplement of protected tallow given to 4 Friesian cows established on a low-roughage ration and with depressed milk fat is reported. The ratios of acetate to propionate in the rumen were unaffected by the supplement and remained typical of those associated with low-roughage diets in that the proportion of propionate was increased. The supplement produced almost complete recoveries in yield and content of milk fat without any increase in intramammary fatty-acid synthesis. The recoveries were due to transfer of about 20% of the total fatty acids of the tallow supplement. These results are discussed in relation to the effects of low-roughage diets on milk-fat secretion and it is concluded that in the ‘low-fat syndrome’ the capacity of the mammary gland to absorb preformed fatty acids is not impaired.

Effect of inclusion of different forms of dietary fatty acid on the yield and composition of cow's milk

1984 ◽  
Vol 51 (3) ◽  
pp. 387-395 ◽  
Author(s):  
William Banks ◽  
John L. Clapperton ◽  
Anne K. Girdler ◽  
William Steele
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Free Fatty Acids ◽  
Milk Fat ◽  
Control Diet ◽  
Protein Matrix ◽  
Lactating Cows ◽  
Fatty Acid Mixtures ◽  
Long Chain

SummaryIn addition to a control diet, lactating cows were offered saturated fatty acid mixtures in three forms, free acids, free triglycerides and protected triglycerides, i.e. triglyceride encapsulated within a protein matrix which was cross linked by exposure to formaldehyde. Relative to the control diet, all three supplements increased milk yield. However, only the free fatty acids gave rise to increased yields of the three major milk components. The free fat and the protected fat caused significant increases only in the lactose yield. The different effects of the supplements on the yield of milk fat are suggested to be due to the types of long chain acid reaching the mammary gland rather than to any change in rumen activity. Changes in the concentrations of the soluble multivalent ionic constituents of the milks were consistent with this conclusion.

scholarly journals The Effect of Starvation on the Uptake of the Precursors of Milk Fat by the Bovine Mammary Gland

1965 ◽  
Vol 18 (5) ◽  
pp. 1025 ◽  
Author(s):  
PE Hartmann ◽  
AK Lascelles
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Free Fatty Acids ◽  
Milk Fat ◽  
Bovine Mammary Gland ◽  
Lactating Cows ◽  
Arteriovenous Difference

The relative changes imposed by a 4.day starvation on the arteriovenous difference across the mammary gland, for triglyceride, free fatty acids, glucose, B-hydroxybutyrate, and acetate have been studied in three lactating cows.

scholarly journals The effects of hormones on milk-fat synthesis in mammary explants from pseudopregnant rabbits

1972 ◽  
Vol 128 (3) ◽  
pp. 509-519 ◽  
Author(s):  
Christopher R. Strong ◽  
Isabel Forsyth ◽  
Raymond Dils
Keyword(s):  
Fatty Acids ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Milk Fat ◽  
Time Course ◽  
Acid Synthesis ◽  
Milk Fatty Acids ◽  
Time Required ◽  
Rabbit Milk

1. When freshly prepared explants from pseudopregnant-rabbit mammary gland were incubated with sodium [1-14C]acetate plus glucose, they synthesized triglyceride and phospholipid containing long-chain fatty acids. Explants cultured with insulin and corticosterone also synthesized these products. The addition of prolactin to this culture medium increased the rate of fatty acid synthesis up to 40-fold and the explants synthesized predominantly triglyceride enriched with C8:0 and C10:0 fatty acids characteristic of rabbit milk. 2. The maximum rates of fatty acid synthesis obtained by explants from pseudopregnant-rabbit mammary gland after culture with insulin, corticosterone and prolactin were similar to those observed with freshly prepared explants from lactating-rabbit mammary gland. The time in culture required to attain these maximum rates varied between animals, and did not appear to be connected with the time required (6–7 days) to synthesize the maximum proportions of C8:0 and C10:0 acids. 3. As the pattern of short- and medium-chain milk fatty acids is characteristic for many species, the techniques described to determine the time-course for the development of this pattern can be used to investigate hormonal response.

scholarly journals Lipoprotein lipase and the disposition of dietary fatty acids

1998 ◽  
Vol 80 (6) ◽  
pp. 495-502 ◽  
Author(s):  
Barbara A. Fielding ◽  
Keith N. Frayn
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Mammary Gland ◽  
Fatty Acid ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Dietary Fatty Acids ◽  
The Body ◽  
Acid Uptake ◽  
Peripheral Tissues

Lipoprotein lipase (EC 3.1.1.34; LPL) is a key enzyme regulating the disposal of lipid fuels in the body. It is expressed in a number of peripheral tissues including adipose tissue, skeletal and cardiac muscle and mammary gland. Its role is to hydrolyse triacylglycerol (TG) circulating in the TG-rich lipoprotein particles in order to deliver fatty acids to the tissue. It appears to act preferentially on chylomicron-TG, and therefore may play a particularly important role in regulating the disposition of dietary fatty acids. LPL activity is regulated according to nutritional state in a tissue-specific manner according to the needs of the tissue for fatty acids. For instance, it is highly active in lactating mammary gland; in white adipose tissue it is activated in the fed state and suppressed during fasting, whereas the reverse is true in muscle. Such observations have led to the view of LPL as a metabolic gatekeeper, especially for dietary fatty acids. However, closer inspection of its action in white adipose tissue reveals that this picture is only partially true. Normal fat deposition in adipose tissue can occur in the complete absence of LPL, and conversely, if LPL activity is increased by pharmacological means, increased fat storage does not necessarily follow. LPL appears to act as one member of a series of metabolic steps which are regulated in a highly coordinated manner. In white adipose tissue, it is clear that there is a major locus of control of fatty acid disposition downstream from LPL. This involves regulation of the pathway of fatty acid uptake and esterification, and appears to be regulated by a number of factors including insulin, acylation-stimulating protein and possibly leptin.

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