The Relationship of Stage of Lactation, Pasturage and Environmental Temperature to the Degree of Unsaturation of Cow Milk Fat

Bartley, E.E.; Zaletel, Jelka; Bird, E.W.; Cannon, C.Y.; Wise, George; Kempthorne, O.

doi:10.3168/jds.s0022-0302(51)91742-0

Cited by 8 publications

(8 citation statements)

References 13 publications

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“…Samples analysed in this present survey decreased in content of C18 unsaturated acids from 29-5 moles % at the commencement of lactation in July, to 23-4 moles % in November, and only after that date did the content of these acids increase as the season advanced, reaching a peak (29-8 moles %) at the end of lactation. Whereas Bartley et al (1951) found that the iodine value of the butterfat was 5 units lower at the end of the lactation period than at the beginning, our results show that the New Zealand butterfats produced at the beginning and at the end of the lactation period have approximately the same iodine values. Tables 1 and 2 are consistent with the changes in fatty acid composition resulting from the varying planes of nutrition throughout the season.…”

Section: Relation8hip Between Chemical and Phy8ical Constant8contrasting

confidence: 83%

“…The former observed that the volatile acids showed a uniform decline from the beginning to the end of the lactation period, andthat the iodine value underwent a gradual increase, the highest point being reached at the end of the season. Similar trends in iodine values which appeared, regardless of seasonal changes in temperature, and in which the variations in iodine value were associated largely with changes in the estimated oleic acid content of the fat, have been reported by Bartley et al (1951). Hilditch & Sleightholme (1930, when commenting on the milk-fat analyses published by Holland & Buckley (1918), also considered that the amount of unsaturated acids in butter increased with the time the cows had been in lactation.…”

Section: Relation8hip Between Chemical and Phy8ical Constant8supporting

confidence: 83%

“…Tables 1 and 2 are consistent with the changes in fatty acid composition resulting from the varying planes of nutrition throughout the season. Furthermore, they conform to those seasonal trends in content of C18 unsaturated acids observed by Bartley et al (1951) to accompany the advance of lactation.…”

Section: Relation8hip Between Chemical and Phy8ical Constant8supporting

confidence: 83%

“…In this present study of New Zealand butterfats, the contents of C18 unsaturated acids (which have been shown to be closely correlated with iodine values) do not gradually increase throughout the season as anticipated from the investigations of Eckles & Shaw (1913), but rather do they follow the trends of Bartley et al (1951), who observed that milk fats possessed a high iodine value during the early stages of lactation followed by a decline (about 8 units of iodine value) to the fourth or fifth month of lactation, and then a slight increase (about 3 units of iodine value) to the end of lactation. Samples analysed in this present survey decreased in content of C18 unsaturated acids from 29-5 moles % at the commencement of lactation in July, to 23-4 moles % in November, and only after that date did the content of these acids increase as the season advanced, reaching a peak (29-8 moles %) at the end of lactation.…”

Section: Relation8hip Between Chemical and Phy8ical Constant8supporting

confidence: 78%

“…Although the iodine values are not directly proportional to the C18 unsaturated acid contents, the figures suggest that the iodine values are an indication of the amount of these acids present (cf. Bartley et al 1951).…”

Section: Relation8hip Between Chemical and Phy8ical Constant8mentioning

confidence: 99%

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Seasonal variations in fatty acid composition of New Zealand butterfat

Hansen¹,

Shorland²

1952

Biochemical Journal

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14-METHYLHEXADECANOIC ACID IN MUTTON FAT 207 37.5°. In the sample of extemal tissue fat analysed, (+)-14-methylhexadecanoic acid constitutes not less than 0-2 % of the total fatty acids. Examination ofother fractions from mutton fat is in progress, and the evidence already accumulated suggests that appreciable quantities of branched-chain acids are present. The work now reported establishes that certain branched-chain acids isolated from wool grease (Weitkamp, 1945) and presumably secreted by the sebaceous glands of the sheep are also present in the extemal tissue fat, and possibly in the other fatty tissues of this animal. SUMMARY (+)-14-Methylhexadecanoic acid has been shown to occur as a minor constituent of mutton fat. We wish to acknowledge the assistance given in this work by Mr M. Fieldes, Soil Bureau, Department of Scientific and Industrial Research, Wellington, who kindly carried out all X-ray measurements. To Mr M. S. Carrie, Chemist to The Hawkes Bay Farmers Freezing Company Ltd., and to the management of that Company, we are indebted for arranging supplies of suitable material for this investigation.

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Section: Relation8hip Between Chemical and Phy8ical Constant8contrasting

confidence: 83%

Section: Relation8hip Between Chemical and Phy8ical Constant8supporting

confidence: 83%

Section: Relation8hip Between Chemical and Phy8ical Constant8supporting

confidence: 83%

Section: Relation8hip Between Chemical and Phy8ical Constant8supporting

confidence: 78%

Section: Relation8hip Between Chemical and Phy8ical Constant8mentioning

confidence: 99%

See 3 more Smart Citations

Seasonal variations in fatty acid composition of New Zealand butterfat

Hansen¹,

Shorland²

1952

Biochemical Journal

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Animal fats: Recent researches in the fats research laboratory, D.S.I.R., New Zealand

Shorland¹

1953

J Sci Food Agric

102

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The views recorded in the first section of this survey dealing with the relationship between the dietary and depot fats are in some cases based on the results of other investigators. In the second section the work of this Laboratory on the fatty-acid composition of butter fat has been examined in the light of the recent British discoveries on the synthetic activity of the mammary gland. Finally, the work of the Fats Research Laboratory on the isolation from animal fats of trace constituents, particularly the branched-chain fatty acids, is reviewed. I . The efect of dietary fat on the depot fats of animals The fats from animals are from two sources : (a) endogenous or ' synthetic ', made in the animal from dietary carbohydrate,' or from protein,z presumably via ' acetate ' units which are condensed to yield the long-chain fatty acids3 characteristic of natural fats ; (b) exogenous from the dietary fat.The respective contributions of the dietary fat and the ' synthetic ' fat to the depot fat are difficult to assess precisely, but useful information about the exogenous fat may be obtained by feeding diets containing fatty acids not normally found in the ' synthetic ' fat, e.g. deuterofatty acids,4 fatty acids with uneven numbers of carbon atoms,5 conjugated linoleic,s elaidic' or linolenic acid.8The composition of the ' synthetic ' fat may be deduced approximately (a) from feeding animals on ' fat-free ' diets,z (b) from comparisons between the weights of fatty acids in the diet and in the depot lo or ( c ) from the composition of ruminant depot-fat, which appears to consist almost entirely of ' synthetic ' fat.ll The fatty-acid composition of ' synthetic ' fat may be given as : oleic, 17-53 ; palmitic, 27-38 ; stearic, 4-29 ; hexadecenoic (with tetradecenoic), 2-16 ; and myristic (with lauric), 3-5 moles per cent. The traces of C,, diene and of C,,-,, unsaturated acids invariably present probably originate from the dietary fat, though the possibility of some synthesis cannot be excluded.l2 I t would seem that dietary fat has some influence on the nature of the ' synthetic ' fat. For example, rats fed on diets rich in palmitic acid will deposit less than the normal proportions of this acid.13 But the ' synthetic ' fats of pasture-fed rabbits and horses (see Table I) contain a higher-than-normal content of palmitic acid (45.8 and 36.3% respectively, calculated from linolenic acid content). Rats fed on diets with 3 3 % of fat normally deposit fat with 5-8% of hexadecenoic acid,I4 but the proportions of this acid may be increased two or three times by withdrawing fat from the dietZ or possibly by means of a hypothalamic lesion to induce obesity.15The first clear recognition of the role of dietary and of synthetic ' fat in the formation of animal depot-fat appears to be due to Callow.lB In 1935 he expressed the view that the softness and iodine value of fats in different parts of the body of the same animal, or between the same parts of different animals fed on the same diets, were determined by the rate of growth. This...

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Neuseeländische Fettforschung unter besonderer Berücksichtigung der Arbeiten des Instituts für Fettforschung

Shorland¹

1952

Fette Seifen

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The Relationship of Stage of Lactation, Pasturage and Environmental Temperature to the Degree of Unsaturation of Cow Milk Fat

Cited by 8 publications

References 13 publications

Seasonal variations in fatty acid composition of New Zealand butterfat

Seasonal variations in fatty acid composition of New Zealand butterfat

Animal fats: Recent researches in the fats research laboratory, D.S.I.R., New Zealand

Neuseeländische Fettforschung unter besonderer Berücksichtigung der Arbeiten des Instituts für Fettforschung

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