Enzymatic interesterification of tripalmitin with vegetable oil blends for formulation of caprine milk infant formula analogs

The structure of triacylglycerols in vegetable oil blends was enzymatically modified, and the blends were incorporated into skim caprine milk to produce goat milk-based infant formula analogs, homologous to human milk. A modified lipid containing palmitic, oleic, and linoleic acids, resembling the composition of human milk fat, was synthesized by enzymatic interesterification reactions between tripalmitin and a vegetable oil blend containing a 2.5:1.1:0.8 ratio of coconut, safflower, and soybean oils. A commercial sn-1,3-specific lipase obtained from Rhyzomucor miehei, Lipozyme RM IM, was used as the biocatalyst. The effects of substrate molar ratio and reaction time on the incorporation of palmitic, oleic, and linoleic acids at the sn-2 position of the triacylglycerols were investigated. The fatty acid composition and sn-2 position of the experimental formulas were analyzed using gas chromatography. Results showed that the highest incorporation of palmitic acid was obtained at 12 h of incubation at 55°C with a substrate molar ratio of 1:0.4 of tripalmitin to vegetable oil blend. However, the modified milk interesterified for 12 h at a 1:1 molar ratio had a greater resemblance to human milk compared with the other formulas. The level of oleic acid incorporation at the sn-2 position increased with the molar ratio of tripalmitin to vegetable oil blend. It was concluded that, unlike the original goat milk and other formulas, the formulated caprine milk with a molar ratio of 1:1 and a 12-h incubation was similar to the fatty acid composition of human milk.     

Composition and Oxidative Stability of a Structured Lipid from Amaranth Oil in a Milk-Based Infant Formula

ABSTRACT: Amaranth oil can be enzymatically modified to match breast milk fat analog requirements. We have developed a structured lipid (SL) from amaranth oil that, in combination with milk fat, delivers recommended amounts of docosahexaenoic acid (DHA) with palmitic acid specifically esterified at the sn-2 position of the triacylglycerol (TAG) backbone. The aim of this study was to study the final fatty acid (FA) contribution and oxidation stability of an infant formula prepared using the structured lipid DCAO (DHA-containing customized amaranth oil). DCAO was included as complementary fat in a “prototype” infant formula, and prepared in parallel with a “control” infant formula under the same processing conditions. The same ingredients but different complementary fat sources were used. A blend of the most commonly used vegetable oils (palm olein, soybean, coconut, and high-oleic sunflower oils) for infant formula was used instead of DCAO in the “control” formula. Additionally, “prototype” and “control” infant formulas were compared to a “commercial” product in terms of FA composition. The oxidative stability index (OSI) of the extracted fats from “prototype,”“control,” and “commercial” infant formulas were evaluated and compared to the OSI of the substrate fat replacers used. DCAO was the least stable compared to other fat analogs. The use of commercial antioxidants in DCAO containing products should prevent oxidation and therefore increase their stability.     

不同脂肪来源婴儿配方乳粉与母乳脂质组成的差异分析

研究4 种不同脂肪来源的婴儿配方乳粉与母乳在总脂肪酸、sn-2位脂肪酸及甘油三酯上的脂质组成差异。结果表明,从样品中共检测出27 种脂肪酸及87 种甘油三酯,与母乳相比,4 种婴儿配方乳粉含有更多的饱和脂肪酸,较少的多不饱和脂肪酸,且母乳中超过70%的饱和脂肪酸酯化在甘油三酯的sn-2位,而4 种婴儿配方乳粉甘油三酯sn-2位更多的被不饱和脂肪酸占据,尤其是植物油基IF1和IF2,sn-2位不饱和脂肪酸高达80%。在甘油三酯组成方面,母乳中1-油酸-2-棕榈酸-3-亚油酸甘油三酯、1,3-二油酸-2-棕榈酸甘油三酯及一些中长链甘油三酯显著高于4 种婴儿配方乳粉（P＜0.05）,而婴儿配方乳粉含有更多的三油酸甘油三酯、1-油酸-2,3-二亚油酸甘油三酯及一些中链甘油三酯（P＜0.05）,并且脂肪来源的不同会显著影响婴儿配方乳粉的脂质组成,同为植物油基的IF1和IF2具有更相似的甘油三酯、脂肪酸组成及分布,并与添加了乳脂成分的IF3和IF4形成明显区分,且牛乳/植物油混合基婴儿配方乳粉在整体脂质组成上更加接近母乳。最后,基于多变量分析,发现共有16 种甘油三酯可用于区分人乳和婴儿配方奶粉。本研究结果有助于研发更接近人乳的婴儿配方乳粉。     

Trends in fatty acids positional distribution in human colostrum, transitional, and mature milk

This study investigates the stereospecific distribution of fatty acids across the triacylglycerol molecules in breast milk obtained at three different periods of lactation. Fatty acids were distributed within the three sn-positions of the glycerol backbone in a highly specific pattern; the shorter fatty acids tend toward the sn-2 and sn-3 positions of the glycerol molecule, whereas the longer chain fatty acids are more in the sn-1 and sn-3 position. Significant differences in fatty acid composition occurred between lactation times, but factors affecting the fatty acids content do not alter their regiospecific fatty acyl profile, although the quantities in each position can be changed. This suggests that the fatty acids regiodistribution profile in human milk related to the optimal infant growth should be used as a standard for the preparation of infant formulas.     

我国市售婴儿配方乳粉油脂配料使用情况分析

目的:了解我国市售婴儿配方乳粉的油脂配料使用情况及脂肪酸提供情况,为提升婴儿配方乳粉的营养水平及制定产品相关标准提供参考。方法:多渠道收集婴儿配方乳粉标签信息,统计分析油脂配料的种类、组合、最高添加量构成比及标识含量,比较全脂乳产品与脱脂乳产品、牛乳基产品与羊乳基产品、高必需脂肪酸产品与全部产品间的差异。均数和率的比较分别采用t检验和卡方检验。结果:共纳入269个婴儿配方乳粉。配料表分析显示,85%的产品使用了4种及以上的油脂配料,葵花籽油和椰子油在全部产品中的添加率最高,分别为88%、76%。牛、羊乳基配方粉的油脂配料使用情况存在差异,牛乳基配方粉中脂肪、亚油酸及α-亚麻酸的标识含量略高于羊乳基配方粉(P<0.05)。脱脂乳配方粉中,棕榈油添加率为32%,显著高于全脂乳产品(P<0.05)。44例使用了棕榈油的产品中仅有4例强化了1,3-二油酸2-棕榈酸甘油三酯。结论:牛、羊乳基配方粉中的必需脂肪酸标识含量基本一致。现市售婴儿配方乳粉以多种油脂组合使用的方式,以尽可能模拟母乳脂肪酸模式,但有些油脂类原料使用的科学性还有待进一步研究。     

植物油在婴儿配方乳粉中的应用探讨

从婴儿配方乳粉在用的7种植物油(大豆油、玉米油、核桃油、葵花籽油、高油酸葵花籽油、棕榈油和椰子油)入手,通过检测植物油的脂肪酸含量,对亚油酸、亚麻酸和油酸等几个主要指标进行了分析,进而与3种新型植物油(双低菜籽油、米糠油和红花籽油)的脂肪酸组成进行了比较,对新型植物油在婴儿配方乳粉中的应用进行了探讨。     

Actual ratios of triacylglycerol positional isomers consisting of saturated and highly unsaturated fatty acids in fishes and marine mammals

The distribution of fatty acid species at the (sn-1, 3) position or the (sn-2) position of triacylglycerol (TAG) in natural fats and oils has already been analysed by many researchers and several interesting results have been reported. However, most of these reports only focused on the distribution of fatty acids at the or positions in TAG, and did not take account of the combination of fatty acids in the TAG, i.e., the TAG positional isomers. In this study, the actual ratios of TAG positional isomer pairs, consisting of palmitic acid and highly unsaturated fatty acid (HUFA) such as DHA or EPA, in fish and marine mammals were investigated using a high-performance liquid chromatography/atmospheric pressure chemical ionisation-mass spectrometry (HPLC/APCI-MS) system equipped with tandem jointed non-endcapped polymeric ODS columns. The results show that for combinations of DHA or EPA with two palmitic acids in the TAG of marine mammals, binding was almost all at the α position. In contrast, binding of DHA or EPA was mainly at the β position in fish. The preferred DHA and EPA positions in TAG were the same in the same marine mammal or fish. The binding position tendency of HUFA in TAG positional isomers consisting of two HUFAs and one palmitic acid was the same as that for combinations of one HUFA and two palmitic acids. These results were interpreted as showing that the preferred fatty acid species of sn-glycerol-3-phosphate acyltransferase and 1-acyl-sn-glycerol-3-phosphate acyltransferase in marine mammals are different to those in fish and other animals, or that diacylglycerol acyltransferase in marine mammals favours 1,2-dipalmitoyl-sn-glycerol formed from 1,2-dipalmitoyl-sn-glycerol-3-phosphatidate if HUFA is the reaction substrate.     

Treatment of milk fat with sn-2 specific Pseudozyma antarctica lipase A for targeted hydrolysis of saturated medium and long-chain fatty acids

Milk fat was treated with the sn-2 specific PAN-2 lipase from Pseudozyma antarctica with the aim of achieving selective removal of saturated fatty acids with chain lengths between C12 and C16, which are abundant at the sn-2 position. Hydrolysis was also carried out using the non-specific CRU-NS from Candida rugosa and the 1,3-specific TLA-1,3 from Thermomyces lanuginosus. PAN-2 treatment decreased the proportion of the target fatty acids considerably (content of 28%, w/w) and increased the proportion of unsaturated ones (content of 52%, w/w) at the degree of hydrolysis of 48% (mol/mol) in relation to the unhydrolysed substrate (47%, w/w, C12:0-C14:0 and 32%, w/w, unsaturated). The fatty acid distributions of the TLA-1,3 and CRU-NS treated samples were similar to untreated milk fat. The proportion of crystalline fat was smaller and the firmness lower in the PAN-2 treated milk fat samples than in the untreated milk fat at 5 °C.     

Enzymatic Synthesis of Refined Olive Oil‐Based Structured Lipid Containing Omega ‐3 and ‐6 Fatty Acids for Potential Application in Infant Formula

Structured lipids (SLs) containing palmitic, docosahexaenoic (DHA), and gamma‐linolenic (GLA) acids were produced using refined olive oil, tripalmitin, and ethyl esters of DHA single cell oil and GLA ethyl esters. Immobilized Lipozyme TL IM lipase was used as the biocatalyst. The SLs were characterized for fatty acid profile, triacylglycerol (TAG) molecular species, solid fat content, oxidative stability index, and melting and crystallization profiles and compared to physical blend of substrates, extracted fat from commercial infant formula (IFF), and milk fat. 49.28 mol% of palmitic acid was found at the sn‐2 position of SL TAG and total DHA and GLA composition were 0.73 and 5.00 mol%, respectively. The total oleic acid content was 36.13 mol% which was very close to the 30.49% present in commercial IFF. Comparable solid fat content profiles were also found between SLs and IFF. The SLs produced have potential for use in infant formulas.     

Dietary linseed supplementation affects the fatty acid composition of the sn-2 position of triglycerides in sheep milk

In the human intestine, lipids are absorbed as sn-2 monoglycerides (sn-2, also named β-position), produced mainly by pancreatic lipases, which hydrolysate the triglyceride molecule in positions 1 and 3 (sn-1,3, α-position). The fatty acids esterified in sn-2 are thus preferentially absorbed, which means that the bioavailability of a single fatty acid is affected by its position on the triglyceride. This experiment is carried out with the milk used to make cheese applied in a study with 42 human volunteers. In that study the authors detected an improvement in the blood lipid profile. The aim of the present study was to examine the effectiveness of this kind of cheese in improving human health by studying how linseed supplementation affects the milk fatty acid composition of the 3 different triglyceride positions and thus the fatty acid bioavailability. The sn-2 were obtained by reacting total milk lipids with swine pancreatic lipase. The milk came from 24 sheep fed a control diet and 24 sheep fed a diet containing 200 g of extruded linseed per day. The sn-2 were separated by thin-layer chromatography. The fatty acid composition of total lipids and sn-2 was obtained by a gas chromatography-flame ionization detector apparatus equipped with a high polar 100 m length capillary column. The bioavailability of the fatty acids was evaluated by a putative preferential intestinal absorption index (PPIAi), where PPIAi <0 indicated a disadvantageous nutritional condition and PPIAi >0 indicated a preferential intestinal absorption. With regard to the fatty acid composition of triglycerides, the linseed group showed a significantly higher content of both linolenic acid and rumenic acid compared with the control. As a consequence of linseed supplementation, the linolenic and rumenic acid content esterified in the β-position increased greatly. This was highlighted by the PPIAi. The results of the present study suggest that the linolenic acid and conjugated linoleic acid affinity for lyso-phosphatidic acid acyl-transferase increased with its tissue availability.     

不同乳基婴幼儿配方乳粉的理化性质和表面组成

为探究不同乳基对婴幼儿配方乳粉稳定性的影响,本研究对以牛乳和羊乳为基料制备的婴幼儿配方乳粉的水分质量分数和水分活度(water activity,a_w)、玻璃化转变温度(glass transition temperature,T_g)、乳糖结晶度、溶解度、色度、蛋白组成、总脂肪酸和表面游离脂肪酸组成等理化性质进行分析,用X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)仪对乳粉表面成分进行测定,并通过扫描电子显微镜(scanning electron microscopy,SEM)观察乳粉表面形貌。结果表明：羊乳婴幼儿配方乳粉具有较好的理化性质,与牛乳婴儿配方乳粉相比具有较低的水分质量分数、a_w、色度和T_g,而结晶度和溶解度接近,通过气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)对脂肪酸含量进行测定发现,牛乳和羊乳婴幼儿配方乳粉均表现出总脂肪酸中不饱和脂肪酸含量较高,表面游离脂肪酸中饱和脂肪酸含量较高的...     

Fatty acid distribution in triacylglycerols and phospholipids of broad beans (Vicia faba)

Fatty acid distribution of triacylglycerols (TAG) and phospholipids (PL) obtained from the four cultivars of broad beans (Vicia faba) was investigated. Total lipids extracted from the beans were separated by thin-layer chromatography into eight fractions. The major lipid components were TAG (47.7–50.1%) and PL (47.5–50.5%), while hydrocarbons, steryl esters, free fatty acids, diacylglycerols (1,3-DAG and 1,2-DAG) and monoacylglycerols were present in minor proportions (1.8–2.4%). The major PL components were phosphatidylcholine (56.4–58.4%), phosphatidylethanolamine (20.3–21.7%) and phosphatidylinositol (16.6–18.6%). Phosphatidylinositol was unique in that it had the highest saturated fatty acid content among the three PL. No significant differences (P > 0.05) in fatty acid distribution existed when the different cultivars were compared. The fatty acid distributions in the TAG were evident among the four cultivars: unsaturated fatty acids were predominantly concentrated in the sn−2 position, and saturated fatty acids primarily occupied the sn−1 or sn−3 position in the oils. These results could be useful to both consumers and producers for manufacture of traditional foods in Japan and elsewhere.     

Stereospecific analysis of triacylglycerols in camel (Camelus dromedarius) milk fat

In the lipid fraction of camel (Camelus dromedarius) milk the percentage of saturated fatty acids (SFAs) was 62.8% with a content of palmitic acid of 28.5%. The unsaturated fatty acid (UFA) fraction was dominated by oleic and palmitoleic acids. Enzyme digestion and chemical degradation methods were used to determine the intramolecular fatty acid (FA) composition and then the intermolecular FA distribution in the three sn-positions of the triacylglycerols of the camel milk. FAs showed a specific preference for a particular position: in all samples studied, SFAs were prevalently esterified in the sn-2 position, while UFAs occupied mainly the sn-1 and sn-3 position. As the carbon chain lengthened from 8 to 16 the percentages of SFAs decreased in the sn-2 position and increased in the outer positions. Such data indicated that the length of the carbon chain could be a discriminating factor in the acylation process of SFAs.     

Comparative analysis of the composition of the molecular forms of triglycerides in the fat of iwashi sardines and of traditional plant oils

A comparative analysis of molecular forms of triglycerides (MFTG) isolated from iwashi sardine fat and from certain routine vegetable oils (sunflower and corn oils) has shown that MFTG from iwashi fat considerably outnumber those from vegetable oils. Most triglycerides from ivasi fat contain polyunsaturated fatty acids (PUSFA) of p-3 series, and with the increase of the molecular mass the amount of PUSFA decreases insignificantly.     

Seasonal variation in the positional distribution of fatty acids in bovine milk fat

The aim of this study was to determine the seasonal variation in the positional distribution of fatty acids (FA) in bovine milk fat. Bovine milk samples were collected from May 2017 to April 2018 in the Netherlands, and the FA composition in the sn-2 position was determined by using sn-1(3)-selective transesterification of Candida antarctica lipase B. The majority of the FA showed significant variation at sn-2 and sn-1(3) positions between different seasons. The seasonal variation in sn-2 position was higher than the sn-1(3) positions. Parallel to the changes in the diet of the cows throughout a year, we observed an increase in blood-derived FA (i.e. C18:0, C18:1 cis-9) concentrations and a decrease in de novo–synthesized FA during summer. In winter, more saturated FA were esterified in sn-2 position of milk fat. Highest concentrations of palmitic acid, C16:0, was observed in sn-2 position in winter, whereas the amount of unsaturated FA at this position was highest in summer. These results showed that the FA compositions in different regiospecific positions changed due to season; however, the proportions of a specific FA within the 3 positions of the triacylglycerols in milk fat did not change upon seasonal variation.     

Spray‐Dried Structured Lipid Containing Long‐Chain Polyunsaturated Fatty Acids for Use in Infant Formulas

Human milk fat (HMF) analogs are structured lipids (SLs) modified to have palmitic acid content at the sn‐2 position of the triacylglycerol (TAG) and fatty acid composition comparable to HMF. Some of these SLs are also designed to incorporate long‐chain polyunsaturated fatty acids (LCPUFAs) because of their important role in infant development. In this study, Maillard reaction products (MRPs), obtained from heated whey protein isolates and corn syrup solids (CSS) solution, were used as encapsulants for microencapsulation of 2 enzymatically synthesized SLs for infant formula applications. The encapsulated SL powders were obtained through spray‐drying and evaluated in terms of their microencapsulation efficiency, chemical and physical properties, oxidative stability, and dispersibility. The microencapsulation efficiency of the SLs was 90%. Dispersibility test using particle size measurement demonstrated that these powders dispersed quickly into a homogeneous suspension. The encapsulated SL powders had low peroxide and thiobarbituric acid‐reactive substances values. Lower oxidative stability was obtained in the powder containing SL with a higher degree of unsaturation and a lower concentration of tocopherols. The results demonstrated that the degree of fatty acid unsaturation and concentration of endogenous antioxidant in starting oils influenced the oxidative stability of the encapsulated SLs.     

母乳中1,3-二不饱和脂肪酸-2-棕榈酸甘油三酯的组成及其功能特性研究进展

1,3-二不饱和脂肪酸-2-棕榈酸甘油三酯（UPU）是指甘油骨架的sn-1、sn-3位连接不饱和脂肪酸、sn-2位连接棕榈酸的一类甘油三酯的总称,其在母乳脂肪中含量最高,可为婴儿提供更加均衡的脂肪酸和甘油三酯,对婴儿生长发育有特殊的生理功能。为对开发新型母乳结构脂肪提供理论支持,系统介绍了不同国家、地区母乳脂肪中3种sn-2棕榈酸甘油三酯UPU、UPS、SPS的含量,我国成熟期母乳中UPU的组成和含量,从降低婴儿粪便硬度、促进脂肪和矿物质吸收、保护肠道健康,提供更多种类、比例更稳定均衡的脂肪酸等方面,论述了UPU的功能作用及其消化和吸收特性,另外对比了市售营养强化剂OPO与母乳中UPU组成的差异,通过分析提出LC-MS方法更适合婴儿配方奶粉中OPO含量的测定。     

Survey of the fatty acid composition of retail milk in the United States including regional and seasonal variations

Consumers are increasingly aware that food components have the potential to influence human health maintenance and disease prevention, and dietary fatty acids (FA) have been of special interest. It has been 25 years since the last survey of US milk FA composition, and during this interval substantial changes in dairy rations have occurred, including increased use of total mixed rations and byproduct feeds as well as the routine use of lipid and FA supplements. Furthermore, analytical procedures have improved allowing greater detail in the routine analysis of FA, especially trans FA. Our objective was to survey US milk fat and determine its FA composition. We obtained samples of fluid milk from 56 milk processing plants across the US every 3 mo for one year to capture seasonal and geographical variations. Processing plants were selected based on the criteria that they represented 50% or more of the fluid milk produced in that area. An overall summary of the milk fat analysis indicated that saturated fatty acids comprised 63.7% of total milk FA with palmitic and stearic acids representing the majority (44.1 and 18.3% of total saturated fatty acids, respectively). Unsaturated fatty acids were 33.2% of total milk FA with oleic acid predominating (71.0% of total unsaturated fatty acids). These values are comparable to those of the previous survey in 1984, considering differences in analytical techniques. Trans FA represented 3.2% of total FA, with vaccenic acid being the major trans isomer (46.5% of total trans FA). Cis-9, trans-11 18:2 conjugated linoleic acid represented 0.55% total milk FA, and the major n-3 FA (linolenic acid, 18:3) composed 0.38%. Analyses for seasonal and regional effects indicated statistical differences for some FA, but these were minor from an overall human nutrition perspective as the FA profile for all samples were numerically similar. Overall, the present study provides a valuable database for current FA composition of US fluid milk, and results demonstrate that the milk fatty acid profile is remarkably consistent across geographic regions and seasons from the perspective of human dietary intake of milk fat.     

婴幼儿配方奶粉及其配料油脂成分中有害酯类的污染差异分析

建立油脂和奶粉中3-氯丙醇酯、2-氯丙醇酯和缩水甘油酯的气相色谱-质谱检测方法,测定植物油脂及婴幼儿配方奶粉中的酯类污染物含量,并开展3 种有害酯类在不同种类油脂中的污染差异分析,以及与奶粉脂肪含量的相关性研究。婴幼儿配方奶粉常用植物油配料种类中,棕榈油是污染水平最高的油脂品种;其次是菜籽油、大豆油、玉米油和食用植物调和油;葵花籽油、椰子油、核桃油、亚麻籽油污染水平较低;1,3-二油酸-2-棕榈酸甘油三酯（1,3-dioleic acid-2-triglyceride palmitate,OPO）结构油脂、食用植物调合油（含OPO）污染水平最低。95 份婴幼儿配方奶粉中88.4%检出3-氯-1,2-丙二醇酯（3-monochloropropane-1,2-diol ester,3-MCPDE）,含量范围为ND～0.231 mg/kg,平均值0.070 4 mg/kg,中位值0.064 5 mg/kg;42.1%检出2-MCPDE,含量在ND～0.034 mg/kg之间;缩水甘油酯的检出率为2.1%,含量为ND～0.019 mg/kg。10.5%的奶粉样本中3-MCPDE含量超过欧盟0.125 mg/kg的限量值。奶粉中3 种酯类污染物总量与奶粉脂肪含量之间存在显著正相关,Pearson相关系数为0.453。为保护婴幼儿的安全,生产厂家应谨慎选择原料油脂,在确保营养健康的基础上尽可能降低婴幼儿配方奶粉中有害酯类的污染。     

Effect of plant oils and camelina expeller on milk fatty acid composition in lactating cows fed diets based on red clover silage

Five multiparous Finnish Ayrshire cows fed red clover silage-based diets were used in a 5 × 5 Latin square with 21-d experimental periods to evaluate the effects of various plant oils or camelina expeller on animal performance and milk fatty acid composition. Treatments consisted of 5 concentrate supplements containing no additional lipid (control), or 29 g/kg of lipid from rapeseed oil (RO), sunflower-seed oil (SFO), camelina-seed oil (CO), or camelina expeller (CE). Cows were offered red clover silage ad libitum and 12 kg/d of experimental concentrates. Treatments had no effect on silage or total dry matter intake, whole-tract digestibility coefficients, milk yield, or milk composition. Plant oils in the diet decreased short- and medium-chain saturated fatty acid (6:0-16:0) concentrations, including odd- and branched-chain fatty acids and enhanced milk fat 18:0 and 18-carbon unsaturated fatty acid content. Increases in the relative proportions of cis 18:1, trans 18:1, nonconjugated 18:2, conjugated linoleic acid (CLA), and polyunsaturated fatty acids in milk fat were dependent on the fatty acid composition of oils in the diet. Rapeseed oil in the diet was associated with the enrichment of trans 18:1 (Δ4, 6, 7, 8, and 9), cis-9 18:1, and trans-7,cis-9 CLA, SFO resulted in the highest concentrations of trans-5, trans-10, and trans-11 18:1, Δ9,11 CLA, Δ10,12 CLA, and 18:2n-6, whereas CO enhanced trans-13-16 18:1, Δ11,15 18:2, Δ12,15 18:2, cis-9,trans-13 18:2, Δ11,13 CLA, Δ12,14 CLA, Δ13,15 CLA, Δ9,11,15 18:3, and 18:3n-3. Relative to CO, CE resulted in lower 18:0 and cis-9 18:1 concentrations and higher proportions of trans-10 18:1, trans-11 18:1, cis-9,trans-11 CLA, cis-9,trans-13 18:2, and trans-11,cis-15 18:2. Comparison of milk fat composition responses to CO and CE suggest that the biohydrogenation of unsaturated 18-carbon fatty acids to 18:0 in the rumen was less complete for camelina lipid supplied as an expeller than as free oil. In conclusion, moderate amounts of plant oils in diets based on red clover silage had no adverse effects on silage dry matter intake, nutrient digestion, or milk production, but altered milk fat composition, with changes characterized as a decrease in saturated fatty acids, an increase in trans fatty acids, and enrichment of specific unsaturated fatty acids depending on the fatty acid composition of lipid supplements.