Evaluating acid and base catalysts in the methylation of milk and rumen fatty acids with special emphasis on conjugated dienes and total trans fatty acids

Milk analysis is receiving increased attention. Milk contains conjugated octadecadienoic acids (18∶2) purported to be anticarcinogenic, low levels of essential fatty acids, and trans fatty acids that increase when essential fatty acids are increased in dairy rations. Milk and rumen fatty acid methyl esters (FAME) were prepared using several acid-(HCl, BF₃, acetyl chloride, H₂SO₄) or base-catalysts (NaOCH₃, tetramethylguanidine, diazomethane), or combinations thereof. All acid-catalyzed procedures resulted in decreased cis/trans (Δ9c, 11t-18∶2) and increased trans/trans (Δ9t, 11t-18∶2) conjugated dienes and the production of allylic methoxy artifacts. The methoxy artifacts were identified by gas-liquid chromatography (GLC)-mass spectroscopy. The base-catalyzed procedures gave no isomerization of conjugated dienes and no methoxy artifacts, but they did not transesterify N-acyl lipids such as sphingomyelin, and NaOCH₃ did not methylate free fatty acids. In addition, reaction with tetramethylguanidine coextracted material with hexane that interfered with the determination of the short-chain FAME by GLC. Acid-catalyzed methylation resulted in the loss of about 12% total conjugated dienes, 42% recovery of the Δ9c,11t-18∶2 isomer, a fourfold increase in Δ9t,11t-18∶2, and the formation of methoxy artifacts, compared with the base-catalyzed reactions. Total milk FAME showed significant infrared (IR) absorption due to conjugated dienes at 985 and 948 cm⁻¹. The IR determination of total trans content of milk FAME was not fully satisfactory because the 966 cm⁻¹ trans band overlapped with the conjugated diene bands. IR accuracy was limited by the fact that the absorptivity of methyl elaidate, used as calibration standard, was different from those of the other minor trans fatty acids (e.g., dienes) found in milk. In addition, acid-catalyzed reactions produced interfering material that absorbed extensively in the trans IR region. No single method or combination of methods could adequately prepare FAME from all lipid classes in milk or rumen lipids, and not affect the conjugated dienes. The best compromise for milk fatty acids was obtained with NaOCH₃ followed by HCl or BF₃, or diazomethane followed by NaOCH₃, being aware that sphingomyelins are ignored. For rumen samples, the best method was diazomethane followed by NaOCH₃.     

Comparison of silver-ion high-performance liquid chromatographic quantification of free and methylated conjugated linoleic acids

Silver-ion high-performance liquid chromatography was used to fractionate a mixture of conjugated linoleic acid (CLA) isomers (as the free fatty acids, CLAFFA) in commercial CLA mixtures and biological samples. Due to the unchanged retention mechanism, it was assumed that the elution order of the isomers remained the same as that of methyl esters separated on the same column. The most abundant isomers, cis/trans 10,12-18:2 and cis/trans 9,11-18:2, were separated better as free acids on a single column than in the methyl ester form. Quantification of the CLA standard was used as the reference profile to evaluate different methylation methods commonly used to prepare CLA methyl esters for quantitation. Acid- and vuigi base-catalyzed derivatization methods resulted in CLA intraisomerization and losses in total conjugated dienes content. Acid (HCl and BF₃) methylations significantly elevated the level of trans,trans isomers and significantly reduced the cis/trans isomers. Base methylation, tetramethylguanidine/methanol, resulted in loss of trans,trans isomers, and a substantial loss of total underivatized conjugated dienes. Other catalysts such as the trimethylsilyldiazomethane produced additional peaks of unidentified artifacts. The analysis of CLAFFA appears to provide more accurate quantification of CLA isomers in commercial and biological samples.     

Preparation of alcohols from cyclic fatty acids

Saturated C_18- and C₂₀-cyclic alcohols have been prepared by catalytic hydrogenation of methyl esters from cyclized linseed monomeric acids, purified saturated C₁₈-cyclic acids, ethylene adduct of conjugated soybean fatty acids, and ethylene adduct of conjugated octadecadienoic acids. The cyclic alcohols have also been prepared from free acids of crude cyclic linseed, cyclic linseed monomeric, and ethylene adduct of 9,11,t,t,-octadecadienoic. Conversion of esters and acids was 88–99% by hydroxyl determination; by gas-liquid chromatographic analysis, almost quantitative Hydrogenations were carried out with 10%, by weight, copper chromite catalyst, an initial hydrogen pressure of 2,100 psi, and a temperature of 280C for 3–5 hr. Preliminary evaluations indicate that saturated C_18- and C₂₀-cyclic alcohols have a potential use in cosmetic formulations. Presented AOCS meeting in Minneapolis, Minn., 1963. No. Utiliz. Res. & Dev. Div., ARS, USDA.     

Trans fatty acids in Canadian margarines: Recent trends

The fatty acid composition and the trans fatty acid content of the top-selling 109 Canadian margarines were determined by a combined capillary gas-liquid chromatography/infrared spectroscopy method. The 109 brands accounted for 68% of the margarine brands sold in Canada and represented 74% of the market share. The mean level of total trans content in tub margarines (n=79) was 18.8% (g/100 g fatty acids) and ranged from 0.9 to 46.4%. The most frequent occurrence of trans in tub margarines was in the 15–20% range; 48 of the 79 tub brands were in this range but seven brands contained more than 40% trans. The trans content of hard margarines (n=30) ranged from 16.3 to 43.7% and the mean value was 34.3%. In 20 of the 109 brands, the levels of trans,trans isomers of linoleic acid exceeded the maximum level of 1% recommended for Canadian margarines. The levels of cis,trans/trans,cis isomers of linoleic acid were also high; 78 brands contained more than 1% and in 16 brands, the levels were in the 6–7% range. Linoleic acid content in the 109 brands ranged from 1.0 to 45.2% and averaged 18.3%. In 33 samples, linoleic acid was below the level of 5% recommended by an ad hoc committee of Health Canada. Moreover, in these, the total trans content exceeded 30%, and trans polyunsaturated fatty acid level was greater than 5%. There were eight margarines prepared from nonhydrogenated fat and their total trans content was below 2.5%. From the trans content and market share of each of the margarine brands, the average intake of trans fatty acids from margarine was estimated as 0.96 g/person/d. The intake of trans fatty acids in Canada from various sources was previously estimated by us as 8.4 g/person/d. Thus it is suggested that only 11% of the dietary trans fatty acids are supplied by margarines and the majority of trans fatty acids in the Canadian diet is derived from hidden fats in fast foods and bakery products.     

Oxygenated fatty acids of oil from sunflower seeds after prolonged storage

Chemical analysis of a number of sunflower (Helianthus annuus) seed oil samples revealed a low and variable percentage of hydrogen bromide-reactive material. To characterize the compounds responsible for this reactivity, oil was extracted from selected introductions from Uruguay, Turkey, and Yugoslavia that had been subjected to prolonged storage. Two epoxy fatty acids and two conjugated dienolic acids were isolated from the methyl esters derived from these sunflower seed oils by using a combination of column chromatography and countercurrent distribution. The epoxy acids arecis-9,10-epoxystearic acid (0.5%) andcis-9,10-epoxy-cis-12-octadecenoic (coronaric) acid (2.2%). Characterization of the dienols revealed that they are 9-hydroxy-trans-10,cis-12-octadecadienoic acid (1.2%) and 13-hydroxy-cis-9,trans-11-octadecadienoic acid (1.3%). Fresher seed of some of these introductions contained less of the oxygenated components. Oil from recently produced seed of selected high-oil Russian sunflower varieties, including some currently grown in the United States, contained no more than trace amounts of oxygenated acids. Though the relative contributions of genetic and environmental factors toward genesis of oxygenated acids are not established, increase of those acids in some sunflower lines as a result of storage has been demonstrated. Presented at the AOCS-AACC Joint Meeting, Washington, D. C., April 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Reactions of conjugated fatty acids. VIII. Dibasic acids by hydrogenation and oxidative cleavage

Summary Conjugated linoleic acid can be hydrogenated as sodium soap in an aqueous or ethylene glycol solution with commercial nickel catalysts. Under suitable conditions the acid is reduced predominantly to monounsaturated acids with only a slight increase in saturated acids. An alkali-conjugation reaction mixture may be hydrogenated without isolating the conjugated acids. One set of conditions found suitable for hydrogenation is as follows: 10 g. of conjugated linoleic acid, 7 g. of sodium hydroxide, 250 ml. of water, and 0.05 g. of nickel placed under 40 p.s.i. hydrogen pressure and heated at 140°C. for 1 hour. Acids prepared from this reaction mixture have an iodine value of about 90. Oxidation and chromatographic analyses of the resultant dibasic acids indicate that with alkali-conjugated linoleic acid, 1,2, 1,4, and 3,4 addition of hydrogen take place with equal ease. The reduced acids contain 66%trans acids. Withtrans,trans conjugated linoleic acid, 1,4 addition takes place to a greater extent that 1,2 and 3,4 addition, and the reduced acids are allrans. Presented at the fall meeting, American Oil Chemists' Society, Cincinnati, O., September 30–October 2, 1957. Part VII is in press, Journal of Organic Chemistry.     

Reactions of conjugated fatty acids. VI. Selenium catalysis,a method for preparing diels-alder adducts from cis,trans-octadecadienoic acid

Summary Adducts of dienophiles and alkali-conjugated safflower fatty acids containing conjugated linoleic acid in thecis,trans form were prepared by heating the reactants in the presence of selenium as a catalyst. The products appeared to be identical to those prepared fromtrans,trans conjugated linoleic acid so that isomerization ofcis-trans totrans,trans acids is eliminated as a separate step. Although yields of pure product were lower than desired because of difficulties in removing selenium, yields of crude adducts ranged from 64–82%. The adducts obtained could be epoxidized with hydrogen peroxide and an ion-exchange resin as catalyst in 80–93% yield or with peracetic acid in 89–98% yield. Presented at the meeting of the American Oil Chemists' Society, Cincinnati. O. September 30–October 2, 1957.     

Vicinally unsaturated hydroxy acids in seed oils

Summary The interference of certain unsaturated hydroxy acids in the Durbetaki method of epoxide determination has been demonstrated. The concentrations of these constituents were determined concurrently with those of epoxy components by measurement of the near infrared spectra of samples before and after treatment with anhydrous ethereal hydrogen chloride. The individual hydroxy esters were separated and isolated from samples of mixed esters by thinlayer chromatography. GLC of these esters resulted in their alteration to conjugated trienoates and gave proof of their conjugated diene hydroxyl structure. Thin-layer chromatographic and infrared studies verified theTrans-trans diene unsaturation of the acid fromDimorphotheca aurantiaca oil and showed that the other hydroxy compounds examined have acistrans diene system. These data suggest that the seed oils ofArtemisia absinthium, Calliandra eriophylla, Balanites aegyptica, Cosmos bipinnatus, and Helianthus annuus contain 9-hydroxy-trans-10-cis-12- and 13-hydroxy-cis-9-trans-11-octadecadienoic acids. Supported by grants from The Hormel Foundation and the National Institutes of Health (Research Grant No. H-3559), and presented in part at the 33rd fall meeting, American Oil Chemists’ Society, Los Angeles, Calif., September 28–30, 1959. Fulbright Scholar to the Hormel Institute, 1958–1960.     

13C nuclear magnetic resonance spectroscopic analysis of seed oils containing conjugated unsaturated acids

¹³C Nuclear magnetic resonance spectroscopy has been used in a nondestructive investigation of conjugated unsaturated acids in seed oil triacylglycerols. Spectra of seven seed oils, fromPunica granatum, Cucurbita palmata, Jacaranda mimosifolia, Centranthus ruber, Catalpa bignonioides, Chilopsis linearis andCalendula officinalis, containing among them six isomeric trienoic acids,cis,trans,cis- andtrans,trans,cis-8,10,12-,cis,trans,cis-, cis,trans,trans-, trans,trans,cis- andtrans,trans,trans-9,11,13-octadecatrienoic acids, and of the oil ofImpatiens balsamina containingcis,trans,trans,cis-9,11,13,15-octadecatetraenoic acid, have been examined. Structures of component acids were derived from shifts of double bond carbons and of carbons close to the double bond systems. Compositions of the oils were obtained from signal intensities. Results were similar to those obtained by older methods. Only oil ofCentranthus ruber contained more than one major conjugated acid; bothcis,trans,trans- andtrans,trans,trans-9,11,13-octadecatrienoic acids were found. The latter acid is now thought to occur naturally. Presented in part at the International Society for Fat Research/American Oil Chemists' Society World Congress, New York, 1980. NRCC no. 20405.     

Fatty acids of cows' milk. A. Techniques employed in supplementing gas-liquid chromatography for identification of fatty acids

Milk fat methyl esters were subjected to distillation and silicic acid column chromatography to provide fractions of less complexity for gas-liquid chromatographic analysis. It was still necessary however to employ supplemental techniques for identification. Chromatograms were obtained with polyester columns of different polarity on all the fractions and necessary reference samples. While many of the components were identified in the usual way by plots of relative retention time versus number of carbon atoms, iodine values for total unsaturation and ultraviolet spectrophotometry for conjugated and nonconjugated polyunsaturated acids were essential for positive identification of some components. Similarly, examination by infrared spectrophotometry confirmed the presence or absence of conjugated diene ascis-trans, trans-trans or both. Isolatedtrans or terminal double bonds were also determined in this way. Gas-liquid chromatograms of some fractions showed incompletely resolved peaks attributable to the presence of methyl esters of odd-carbon atom, branched-chain, and unsaturated acids. Hydrogenation and rechromatographing provided more positive determination of the structure of these components. Further confirmation of identity of some peaks on the chromatogram was achieved by collection of the appropriate fractions and examination of the collected material. At least 60 fatty acids were identified, including several not previously reported, such as odd-numbered carbon chain length monoethenoid acids from C₁₅ to C₂₃. Presented at the 53rd Meeting of the American Oil Chemists' Society, October 17–19, 1960, New York. Eastern Utilization Research and Development Division, Agricultural Research Service, United States Department of Agriculture.     

OxygenatedTrans-3-olefinic acids in aStenachaenium seed oil

Interesting differences were found in oils from two samples ofStenachaenium macrocephalum (Compositae) seed with dissimilar storage histories. One contained significant amounts of epoxy acids (6.5%) and hydroxy conjugated dienoic acids (5.6%), but the other contained no more than 1% of these oxygenated acids. Characterization of components in the former oil established that the principal epoxy acid (4.0%) is the previously unknowncis-9, 10-epoxy-trans-3,cis-12-octadecadienoic acid. The conjugated dienols include two additional new acids with Δ3 unsaturation (2.5%): 9-hydroxy-trans-3,-trans-10,cis-12-octadecatrienoic and 13-hydroxy-trans-3,cis-9,trans-11-octadecatrienoic acoids. The nonoxygenated acids, except for the large amount (40%) oftrans-3,cis-9,cis-12-octadecatrienoic, are those that commonly occur in seed oils. Presented at the AOCS Meeting, San Francisco, April 1969. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Phosphorus derivatives of fatty acids. The addition of dialkyl phosphonates to unsaturated acids and the synthesis of some 11-dialkylphosphonoundecanoamides

A series of dialkylphosphonoundecanoic acids and 9(10)-dialkylphosphonostearic acids was prepared by the addition of dialkylphosphonates to 10-undecenoic acid and oleic acid under free radical conditions in 58–66% yield. The phosphonates used were: dimethyl, diethyl, di-n-butyl, di-n-hexyl and di-2-ethylhexyl. All of the products are colorless, odorless, thermally stable liquids, insoluble in water and soluble in organic solvents. The dialkylphosphonoundecanoic acids were converted into the corresponding acid chlorides by reaction with oxalyl chloride. The acid chlorides were then converted into the corresponding amides by addition of ammonia. All of the amides are white waxy solids except the 2-ethylhexyl derivative which is a high-boiling liquid. Two of the dialkylphosphonoundecanoic acids were converted into the N-decyl substituted amides by heating withn-decylamine. The N-n-decyl-11-dialkylphosphonoundecanoamides are white waxy solids. Presented at the AOCS Meeting, New Orleans, 1964.     

Gas chromatography-mass spectrometry of methyl esters of unsaturated oxygenated fatty acids

Silylation of hydroxyl groups in methyl esters of unsaturated hydroxy acids provides compounds that give mass spectra which can be readily interpreted, whereas spectra of underivatized esters are extremely difficult to evaluate. The relationship of the double bond(s) to the trimethylsiloxy (TMS) group results in specific mass spectral patterns. In esters that have the TMS group separated from the double bond by one methylene group, the ions caused byα-cleavage at the TMS group on the side closest to the olefinic group are much more abundant than those produced fromα-cleavage on the other side of the TMS group. In esters that have the TMS group and the double bond separated by two methylene groups,α-cleavage ions are approximately equal. When the TMS group and the double bond are allylic, no fragmentation results between them. Cleavage does occur on either side of this system, and those ions resulting from cleavage alpha to the TMS group are in greatest abundance. Silylation of esters that have a conjugated diene or ene-yne system adjacent to a hydroxyl group also gives derivatives amenable to gas chromatographymass spectrometry. In these esters, large peaks are observed that arise fromα-cleavage at the TMS group and at the other end of the olefinic system. No fragmentation between the TMS group and the sites of unsaturation occurs. Unsaturated epoxy methyl esters produce spectra difficult to interpret. When the epoxide is converted to methoxy-hydroxy derivatives by BF₃-methanol, the spectrum locates the position of the epoxide group. Silylation of the hydroxyl group produces a compound that gives a less complicated spectrum which also locates the original epoxy group. Mass spectrometry of a series of unsaturated keto-esters, without derivatization, provides spectra that are easily interpretable. Presented at the AOCS Meeting, Los Angeles, April 1972. N. Market. Nutr. Res. Div., ARS, USDA.     

Methyl punicate,Alpha andBeta eleostearate.Cis,trans isomerism and structure

Methyl esters ofbeta eleostearic,alpha eleostearic, and punicic acids have been isomerized with iodine and light to the same equilibrium mixture of 64%beta, 33%alpha, and 2.6% punicate structures. The course of isomerization is in agreement with the following structures:trans, trans, trans forbeta; cis, trans, trans foralpha; andcis, trans, cis for punicate, in agreement with structures provenvia synthesis by Crombie and Jackson. There is some theoretical and experimental evidence that the center double bond of this type of conjugated triene isomerizes less readily than the outer double bonds. Paper No. 253, Journal Series, General Mills Inc., Central Research.     

Measurement oftrans and other isomeric unsaturated fatty acids in butterand margarine

A procedure is described for gas liquid chromatographic determination of cis andtrans isomers of unsaturated fatty acids after fractionation of the saturated, monenoic, dienoic, and polyenoic fatty acid methyl esters by argentation thin layer chromatography. To test its reliability, the procedure was used for quantitative measurement of transisomers of unsaturated fatty acids in a known mixture of simple triglycerides containing saturated fatty acids from 4:0 to 24:0 andcis andtrans isomers of 14:1. 16:1, 18:1, and 18:2. Results of the analyses of five margarine and five butter samples are presented, together with results of infrared spectrophotometric analyses fortrans fatty acid concentrations, ultraviolet spectrophotometric analyses for conjugated fatty acid concentrations, and enzymatic analyses forcis-cis-methylene interrupted fatty acid concentrations. The combined argentation thin layer and gas Chromatographic procedure is suitable for determination of the principal fatty acids in complex food lipids such as milk fat.     

Polymerization of allyl esters derived from long-chain fatty acids and palm olein

Allyl esters of palm olein, palmitic, and oleic acids were synthesized by transesterification and esterification methods using KOH and absolute H₂SO₄ as catalysts, respectively. Three allyl esters, namely, allyl palmitate, allyl epoxystearate, and epoxidized allyl ester of palm olein, were successfully polymerized in the presence of t-butyl perbenzoate at 120°C to obtain oligomers with the average number of backbone atoms approximately equal to the number of skeletal atoms of the long-dangling side chains. The kinetic data of polymerization were conformed to the rate equation proposed by other workers. No oxirane cleavage was detected during the chain reaction. The melting behavior of these comb-shaped polymers was compared with that of their respective allylic monomers. The polymer of epoxidized allyl ester of palm olein exhibits a glass transition temperature at 204.4 K. The critical molecular weights of the polymers of allyl esters investigated are predicted to be not lower than 10⁴.     

Characterization of fatty acid isomers in dehydrated castor oil by gas chromatography and gas chromatography-mass spectrometry techniques

Fatty acid isomers present in dehydrated castor oil were analyzed by gas chromatography and gas chromatography-mass spectrometry (GC-MS) of their dimethyl oxazoline derivatives. Conjugated linoleic acid 9,11 and 10,12 isomers were identified by GC based on equivalent chainlengths. Segmental peak analysis of GC-MS total ion chromatogram mass fragmentation pattern revealed the presence of 7,9 and 8,10 conjugated linoleic acids along with 9,11 and 10,12 conjugated linoleic acids. Interestingly, a reverse elution of trans,trans-conjugated linoleic acids was observed, viz. 10,12 was followed by 9,11, which was in turn followed by the 8,10 and 7,9 isomers. The observed reverse order of elution was in contrast to the conventional elution pattern of both nonconjugated and conjugated cis,cis-, cis,trans- and trans,cis-isomers.     

Synthesis of fatty acid esters from acid oils using lipase B from Candida antarctica

Esterification of corn and sunflower acid oils with straight‐ and branched‐chain alcohols were conducted using lipase B from Candida antarctica (Novozym 435) in n‐hexane. Sunflower acid oil consisted of 55.6% free fatty acids and 24.7% triacylglycerols, while the free fatty acids and triacylglycerols contents of corn acid oil were 75.3% and 8.6%, respectively. After 1.5 h of methanolysis of sunflower acid oil, the highest fatty acid methyl ester content (63.6%) was obtained at 40 °C and the total fatty acid/methanol molar ratio was 1/1, using 15% enzyme based on acid oil weight. The conversion of both acid oils with straight‐ and branched‐chain alcohols was not significantly affected by the chain length of the alcohols. However, the lowest fatty acid methyl ester content (50%) was obtained in the reaction of corn acid oil with methanol. Sunflower acid oil was converted to fatty acid esters using primer alcohols such as n‐propanol, i‐ and n‐butanol, n‐amylalcohols, n‐octanol, and a mixture of amylalcohol isomers, resulting in a fatty acid ester content of about 70% at 40 °C.     

Plasticizing properties of esters of monohydric alcohols and tall oil fatty acids

Tall oil fatty acid esters prepared as intermediates in an epoxy ester plasticizer program were similarly evaluated as low-temp plasticizers in polyvinyl chloride resins. Performance characteristics as primary and secondary plasticizers in polyvinyl sheeting and extruded tapes were determined on esters from methyl to heptadecyl tallate. Results indicate that these materials impart low-temp properties which would make them of value as low-cost plasticizers in extruded and molded products where light and heat stability are not primary factors.     

trans fatty acids. 4. Effects on fatty acid composition of colostrum and milk

trans Isometric fatty acids of partially hydrogenated fish oil (PHFO) consist oftrans 20∶1 andtrans 22∶1 in addition to thetrans isomers of 18∶1, which are abundant in hydrogenated vegetable oils, such as in partially hydrogenated soybean oil (PHSBO). The effects of dietarytrans fatty acids in PHFO and PHSBO on the fatty acid composition of milk were studied at 0 (colostrum) and 21 dayspostpartum in sows. The dietary fats were PHFO (28%trans), or PHSBO (36%trans) and lard. Sunflower seed oil (4%) was added to each diet. The fats were fed from three weeks of age throughout the lactation period of Experiment 1. In Experiment 2 PHFO or “fully” hydrogenated fish oil (HFO) (19%trans), in comparison with coconut oil (CF) (0%trans), was fed with two levels of dietary linoleic acid, 1 and 2.7% from conception throughout the lactation period. Feedingtrans-containing fats led to secretion oftrans fatty acids in the milk lipids. Levels oftrans 18∶1 andtrans 20∶1 in milk lipids, as percentages of totalcis+trans 18∶1 andcis+trans 20∶1, respectively, were about 60% of that of the dietary fats, with no significant differences between PHFO and PHSBO. The levels were similar for colostrum and milk. Feeding HFO gave relatively lesstrans 18∶1 andtrans 20∶1 fatty acids in milk lipids than did PHFO and PHSBO. Only low levels ofcis+trans 22∶1 were found in milk lipids. Feedingtrans-containing fat had no consistent effects on the level of polyenoic fatty acids but reduced the level of saturated fatty acids and increased the level ofcis+trans monoenoic fatty acids. Increasing the dietary level of linoleic acid had no effect on the secretion oftrans fatty acids but increased the level of linoleic acid in milk. The overall conclusion was that the effect of dietary fats containingtrans fatty acids on the fat content and the fatty acid composition of colostrum and milk in sows were moderate to minor.