配方奶粉和母乳中结构脂质差异及其对婴幼儿生理功能的影响研究进展

母乳喂养和配方奶粉喂养婴儿的差异可以归因于母乳中多种成分在数量和质量上与配方奶粉的不同,特别是甘油三酯的结构和类型。本文基于国内外不同配方奶粉和母乳中结构脂质差异的研究现状,对两者结构脂质差异、消化与吸收过程、粪便排泄、脂肪酸代谢等作用分别进行了综述,并就不同结构脂质对婴幼儿生理健康的影响进行了总结归纳。     

Sialyloligosaccharides in human and bovine milk and in infant formulas: variations with the progression of lactation

Several lines of research support a role for human milk oligosaccharides in the defense of breast-fed infants against pathogens. Some ofthese oligosaccharides contain at least one moiety of sialic acid and are, thus, termed sialyloligosaccharides. These constitute a significant component (>1 g/L) of human milk. It is well established that milk composition varies among species, and previous reports have indicated that one ofthe differences between human and bovine milk is precisely their contents of sialyloligosaccharides. Because most infant formulas are manufactured with bovine milk components, it follows that formula-fed and breast-fed infants ingest dissimilar quantities of these carbohydrate structures. To ascertain these differences and their impact along lactation, the contents of oligosaccharide-bound sialic acids and major sialyloligosaccharides in samples of human and bovine milk (obtained at different lactation stages) were determined. In addition, infant formulas were assayed for their sialyloligosaccharide contents. Seven sialyloligosaccharides were identified in human milk; namely, 3'-sialyl-3-fucosyllactose and sialyllacto-N-tetraoses (a and b+c), the predominant structures at all lactation stages. Five sialyloligosaccharides were identified in bovine milk, of which 6'-sialyllactosamine and 3'-sialyllactose were the most abundant. In addition, sialyloligosaccharides in human and bovine milk decreased along lactation, and infant formulas did not contain significant amounts of sialyloligosaccharides. The results point to the general conclusion that regarding both qualitative and quantitative aspects, milk from humans and cows and infant formulas have different oligosaccharide contents. In this sense, bottle-fed infants are subject to reduced sialyloligosaccharide intake as compared to breast-fed infants.     

我国母乳脂肪和婴儿配方奶粉油脂研究现状

婴儿最理想的食品是母乳。我国对母乳脂肪的研究主要聚焦于母乳脂肪酸的分析研究,以及关注母乳中长链多不饱和脂肪酸(如AA和DHA)对婴儿健康的影响。国内婴儿配方奶粉油脂目前的设计也限于模仿母乳脂肪酸含量,而没有充分注意到母乳脂肪酸在甘三酯中的位置分布对婴儿消化吸收的重要影响,也没有注意到母乳中含有的脂肪酶能更好地促进消化吸收。综述了近年来国内外母乳脂肪和婴儿配方奶粉油脂研究现状,试图给婴儿配方奶粉企业提供一些参考。     

Phospholipids in Human Milk and Infant Formulas: Benefits and Needs for Correct Infant Nutrition

The composition of human milk has served as a basis for the development of infant formulas, which are used when breastfeeding is not possible. Among the human milk nutrients, 50% of the total energetic value corresponds to fat, with a high level of fatty acids and 0.2–2.0% present in the form of phospholipids (PLs). The PL contents and fatty acid distribution in PL species have been investigated as bioactive elements for the production of infant formulas, since they offer potential benefits for the optimum growth and health of the newborn infant. The differences in the amount of PLs and in fatty acid distribution in PL species between human milk and infant formulas can imply biologically significant differences for newborn infants fed with infant formulas versus human milk–mainly due to the greater proportion of sphingomyelin with respect to phosphatidylcholine in infant formulas. The limited information referred to the characterization of fatty acid distribution in PL species in infant formulas or in ingredients used to enrich them merits further research in order to obtain products with benefits similar to those of human milk in terms of infant growth, visual acuity, and neurological development. The present review establishes the scientific basis for helping to adjust formulations to the requirements of infant nutrition.     

Comprehensive analysis of fatty acids in human milk of four Asian countries

Human milk lipids provide not only energy but also indispensable bioactive components such as essential fatty acids. To establish the recommended daily intake value and guidelines for infant formula, a reference library of fatty acid composition has been generated from 4 Asian countries (South Korea, China, Vietnam, and Pakistan). Regardless of country, palmitic acid (C16:0), linoleic acid (C18:1), and linolenic acid (C18:2) were the 3 most abundant fatty acids in human milk and account for more than 75% of total fatty acids (total FA). However, there were several considerable differences between fatty acids, particularly n-3 and n-6 (omega-3 and omega-6) groups. Chinese mothers' milk had a high concentration of linoleic acid at 24.38 ± 10.02% of total FA, which may be due to maternal diet. Among the 4 countries, Pakistani mothers' milk contained a high amount of saturated fatty acid (56.83 ± 5.96% of total FA), and consequently, polyunsaturated fatty acids, including n-3 and n-6, were significantly lower than in other countries. It is noteworthy that docosahexaenoic acid (DHA) in Pakistani mothers' milk was 44.8 ± 33.3 mg/L, which is only 25 to 30% of the levels in the other 3 countries, suggesting the need for DHA supplementation for infants in Pakistan. Moreover, the ratio of n-6 to n-3 was also remarkably high in Pakistani mothers' milk (15.21 ± 4.96), being 1.4- to 1.7-fold higher than in other countries. The average DHA:ARA ratio in Asian human milk was 1.01 ± 0.79. Korean mothers' milk showed a high DHA:ARA ratio, with a value of 1.30 ± 0.98, but Pakistani mothers' milk had a significantly lower value (0.42 ± 0.12). The fatty acid compositions and anthropometric data of mother (body mass index, age) did not show any correlation. The obtained data might provide information about human milk compositions in the Asian region that could benefit from setting up recommended nutrient intake and infant formula for Asian babies.     

S100B Protein concentration in milk-formulas for preterm and term infants. Correlation with industrial preparation procedures

Human milk S100B protein possesses important neurotrophic properties. However, in some conditions human milk is substituted by milk formulas. The aims of the present study were: to assess S100B concentrations in milk formulas, to verify any differences in S100B levels between preterm and term infant formulas and to evaluate the impact of industrial preparation at predetermined phases on S100B content. Two different set of samples were tested: (i) commercial preterm (n = 36) and term (n = 36) infant milk formulas; ii) milk preterm (n = 10) and term infant (n = 10) formulas sampled at the following predetermined industrial preparation time points: skimmed cow milk (Time 0); after protein sources supplementation (Time 1); after pasteurization (Time 2); after spray-drying (Time 3). Our results showed that S100B concentration in preterm formulas were higher than in term ones (p < 0.01). In addition, S100B concentrations during industrial preparation showed a significant increase (p < 0.001) at Time 1 followed by a slight decrease (p > 0.05) at Time 2, whereas a significant (p < 0.001) dip was observed at Time 3. In conclusion, S100B showed a sufficient thermostability to resist pasteurization but not spry-drying. New feeding strategies in preterm and term infants are therefore warranted in order to preserve S100B protein during industrial preparation.     

市售婴幼儿配方乳粉中脂肪酸组成分析

对市售的10种不同品牌婴幼儿配方乳粉中脂肪酸组成进行了检测及分析。结果表明:共检出脂肪酸24种,不同品牌乳粉的脂肪酸组成及含量差别很大,棕榈酸含量介于14. 77%与35. 72%之间,亚油酸含量最高达27. 07%,最低仅有4. 68%,7种产品可检出DHA、AA,均未检出EPA;除了1种产品的亚油酸及α-亚麻酸含量偏低,其余脂肪酸含量均符合国家标准,检测结果与母乳之间仍存有差异。婴幼儿配方乳粉的脂肪酸仍需要进行优化以接近母乳来满足婴幼儿的营养需求。     

The effects of feeding fish oil on uterine secretion of PGF2alpha, milk composition, and metabolic status of periparturient Holstein cows

The objectives were to determine the effect of dietary fish oil (FO) on uterine secretion of PGF2alpha, milk production, milk composition, and metabolic status during the periparturient period. Holstein cows were assigned randomly to diets containing FO (n = 13) or olive oil (OO, n = 13). Cows were fed prepartum and postpartum diets that provided approximately 200 g/d from 21 d before the expected parturition until 21 d after parturition. The FO used contained 36% eicosapentaenoic acid (EPA, C20:5, n-3) and 28% docosahexaenoic acid (DHA, C22:6, n-3). Blood samples were obtained from 14 d before the due date until d 21 postpartum. A total of 6 FO and 8 OO cows without periparturient disorders were used in the statistical analyses of PGF2alpha-metabolite (PGFM) and metabolite concentrations. Length of prepartum feeding with OO or FO did not differ. Proportions of individual and total n-3 fatty acids were increased in caruncular tissue and milk of cows fed FO. The combined concentrations of EPA and DHA in caruncular tissue were correlated positively with the number of days supplemented with FO. Cows fed FO had reduced concentrations of plasma PGFM during the 60 h immediately after parturition compared with cows fed OO. Concentrations of prostaglandin H synthase-2 mRNA and protein in caruncular tissue were unaffected by diet. Production of milk and FCM were similar between cows fed the two oil diets. However, cows fed FO produced less milk fat. Feeding FO reduced plasma concentrations of glucose. Dietary fatty acids given during the periparturient period can reduce the uterine secretion of PGF2alpha in lactating dairy cows and alter the fatty acid profile of milk fat.     

Illumina技术研究不同喂养方式婴儿肠道菌群差异

目的:比较母乳喂养、混合喂养和人工喂养婴儿肠道微生物区系的差异,探讨喂养方式对婴儿肠道菌群的影响。方法:采用Illumina高通量测序技术对24份1～6个月内婴儿粪便中所有微生物的16SrRNA-V6区进行测序检测。结果:门水平上,3组均以Firmicutes和Proteobacteria为优势菌门;科水平上,Enterobacteriaceae在3组中均为优势菌,但在人工喂养组婴儿粪便菌群中所占的比例(50.82%)明显高于母乳喂养组(28.66%),混合喂养组为41.44%;Veillonellaceae和Bacteroidaceae在母乳喂养组婴儿粪便中是优势菌,相对丰度(21.42%和12.82%)明显高于混合喂养组(3.65%和4.32%)和人工喂养组(3.25%和0.04%);Bifidobacteriaceae在母乳喂养婴儿粪便中的数量仅占总菌数的8.16%,但高于混合喂养组(6.16%)和人工喂养组(1.48%)。结论:不同喂养方式婴儿肠道菌群存在明显差异,Illumina高通量测序技术为婴儿肠道菌群的研究提供了更加准确、科学的数据资源。     

脂肪酸鉴定及其在牦牛乳、牦牛肉品质分析中的应用

利用气相色谱-质谱对不同来源的牦牛乳、犏牛乳和牦牛肉脂肪酸组成及含量进行检测,以功能性脂肪酸含量为指标对牦牛乳和牦牛肉的品质进行评价。结果表明:牦牛乳、犏牛乳和牦牛肉中分别鉴定出47、46、37种脂肪酸;不同月份、海拔的牦牛乳中BCFA含量和n-6/n-3比值整体差异极显著(P <0.001),对比发现8月份采自3 500 m夏季牧场的牦牛乳品质最优;犏牛乳中富含多种功能性脂肪酸,接近牦牛乳脂肪酸组成;两种饲养方式(放牧和舍饲育肥)牦牛肉中功能性脂肪酸含量和n-6/n-3比值差异显著,放牧牦牛肉中DHA、DPA、EPA、BCFA等功能性脂肪酸含量均显著高于舍饲育肥牦牛肉,相较于舍饲育肥牦牛,放牧牦牛的牦牛肉品质更佳。     

摄食DHA-磷脂酰丝氨酸对发育期小鼠体组织DHA水平的影响

目的：比较研究断乳后干预二十二碳六烯酸-磷脂酰丝氨酸（docosahexaenoic acid-phosphatidylserine, DHA-PS）和DHA-甘油三酯（DHA-triglyceride,DHA-TG）对发育期ICR小鼠体组织DHA含量以及脂肪酸组成的影 响。方法：母鼠孕期及哺乳期喂饲n-3多不饱和脂肪酸（n-3 polyunsaturated fatty acids,n-3 PUFAs）缺乏饲料,子代 雄小鼠断乳后随机分为3 组,分别喂饲n-3 PUFAs缺乏饲料（n-3缺乏组）、DHA-TG饲料（DHA-TG组）、DHA-PS 饲料（DHA-PS组）,每组8 只,喂养2 周后检测小鼠脑皮质、精巢、肝脏、红细胞中脂肪酸组成和DHA含量。结 果：补充DHA-PS和DHA-TG可以使发育期小鼠各组织中DHA含量显著增加（P＜0.05）,二十二碳五烯酸和花生四 烯酸含量显著降低（P＜0.05）。DHA-TG组精巢中DHA含量明显高于DHA-PS组;DHA-PS组肝脏TG、磷脂和红细 胞中DHA水平显著高于DHA-TG组（P＜0.05）,而两组脑皮质DHA水平无显著性差异（P＞0.05）。结论：膳食补 充DHA-PS和DHA-TG均可明显提高发育期小鼠各组织中DHA水平,但二者的组织蓄积特性不同,DHA-PS可以更 高效地提高小鼠肝脏和红细胞中DHA水平。     

高通量测序技术研究不同喂养和分娩方式对不同月龄婴幼儿肠道菌群的影响

采用高通量测序技术分析比较54 份不同喂养方式（母乳、羊乳配方粉、牛乳配方粉）、不同分娩方式（顺产、剖宫产）和不同月龄（I段：0～6?个月、II段：6～12?个月、III段：12～36?个月）婴幼儿粪便样本,研究不同影响因素下婴幼儿肠道菌群的构成,尤其是羊乳配方粉对婴幼儿肠道构成的影响,分析肠道菌群的丰度及多样性,比较优势菌丰度,为婴儿配方食品的开发及婴幼儿科学喂养提供技术支撑。结果表明：在相同喂养方式、相同月龄的婴幼儿中,分娩方式对其肠道菌群影响不尽相同,I段顺产母乳喂养组中门水平Actinobacteria（放线菌门）、Firmicutes（厚壁菌门）、Bacteroidets（拟杆菌门）、Proteobacteria（变形菌门）的相对丰度分别为43.74%、25.48%、17.93%、9.71%;I段剖宫产母乳喂养组分别为40.83%、44.31%、3.81%、11.01%;II段顺产羊乳配方粉喂养组分别为41.44%、43.84%、8.38%、6.27%;II段剖宫产羊乳配方粉喂养组分别为60.76%、24.85%、8.66%、5.70%;III段顺产羊乳配方粉喂养组分别为26.58%、47.73%、24.07%、1.58%;III段剖宫产羊乳配方粉喂养组分别为34.77%、51.94%、11.10%、2.16%。在分娩方式相同且相同月龄的婴幼儿中,喂养羊乳配方粉的婴幼儿肠道菌群构成更为多样,且主要优势菌相对丰度更高,Actinobacteria在I段顺产羊乳配方粉喂养组中占62.98%,在I段顺产母乳喂养组中占43.74%;Bacteroidets在II段顺产羊乳配方粉喂养组中占43.84%,在II段顺产牛乳配方粉喂养组中占35.71%。对于相同分娩方式、相同喂养方式的婴幼儿,随着月龄的增长其肠道菌群构成存在显著差异（P＜0.05）,以II段婴幼儿肠道菌群更为多样,且Lactobacillales（乳杆菌目）较I、III段相对丰度更高,为差异显著的优势菌。本研究为婴幼儿的健康、代谢及相关疾病的防御提供参考依据。     

二十二碳六烯酸和花生四烯酸在婴儿配方奶粉中的应用

介绍了乳母中天然存在的两种不饱和脂肪酸二十二碳六烯酸（DHA）和花生四烯酸（AA）在婴儿生长发育中的作用及其在配方奶粉中强化对非母乳喂养婴儿营养的重要性。并介绍了各专家组织对DHA和AA在婴儿配方奶粉中补充的推荐及目前的应用情况。探讨了HDA和AA的两种来源，即天然来源和利用生物技术发酵生产。DHA和AA的天然来源主要是鱼油和蛋黄，而目前商业上大都利用生物技术以薇藻和真菌发酵生产DHA和AA。介绍了生物技术发酵生产DHA和AA的工艺，并讨论了发酵产品在婴儿配方奶粉中应用的安全性。     

泌乳期母乳脂肪酸变化及其多不饱和脂肪酸影响因素

采用气相色谱-质谱联用技术测定不同泌乳期母乳中脂肪酸的动态变化,并分析乳母血型、生育年龄、孕周、孕前身体质量指数（body mass index,BMI）、分娩方式和婴儿性别、胎次对成熟母乳中与婴儿生长发育直接相关的重要多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）,亚油酸（linoleic acid,LA）、α-亚麻酸（α-linolenic acid,ALA）、花生四烯酸（arachidonic acid,AA）,二十碳五烯酸（eicosapentaenoic acid,EPA）、二十二碳六烯酸（docosahexaenoic acid,DHA）相对含量的影响。结果显示,饱和脂肪酸（saturated fatty acid,SFA）含量在初乳和成熟乳间差异显著（P＜0.05）,单不饱和脂肪酸（monounsaturated fatty acid,MUFA）含量随着泌乳期的延长逐渐降低,但差异不显著（P＞0.05）,PUFA含量在各泌乳期无显著差异（P＞0.05）,AA、DHA含量随着泌乳期的延长逐渐降低,在初乳、过渡乳中含量差异均不显著（P＞0.05）,但均显著高于成熟乳中含量（P＜0.05）;母乳中LA含量与婴儿性别有关,ALA含量与乳母孕前BMI有关,母乳中AA、EPA含量与乳母血型有关,DHA含量与乳母孕前BMI、乳母血型有关,均具有统计学意义（P＜0.05）。     

Effects of breed and a concentrate or grass silage diet on beef quality in cattle of 3 ages. I: Animal performance, carcass quality and muscle fatty acid composition

An increase in the intake of the n-3 series polyunsaturated fatty acids (PUFA) is recommended by nutritionists for the human diet and beef is a significant source of these fatty acids. Enhancing the n-3 PUFA content of beef is important in view of the generally saturated nature of fatty acids in ruminant meats and the potentially negative effect this can have on human health. This study examined the effects of breed and diet on the fatty acid composition of beef M. longissimus. Ninety-six steers were used, 48 Aberdeen Angus cross (AA) and 48 Holstein-Friesian (HF). At 6months of age, 3 groups were identified, to be slaughtered at 14, 19 and 24months, respectively. Each group consisted of eight steers of each breed fed on a concentrate or a grass silage diet, rich in n-6 and n-3 PUFA, respectively. The intake of the concentrate diet was restricted so that steers of each breed grew at a similar rate on each diet. The early maturing AA produced heavier, fatter carcasses with better conformation. Animals fed grass silage had higher carcass fatness and conformation scores and higher levels of neutral lipid and total lipid in muscle than those fed concentrate. When all animals were pooled, a decline in PUFA% as total muscle lipid increased was evident. Feeding a grass silage diet rich in α-linolenic acid (18:3n-3) increased levels of this fatty acid in muscle neutral lipid by a factor of about 3.0 compared with the concentrate diet, as well as enhancing the synthesis of the n-3 series long-chain C20-22 PUFA in the phospholipid fraction, including docosahexaenoic acid (DHA, 22:6n-3). In contrast, both levels and proportions of linoleic acid (18:2n-6) and the n-6 series C20-22 PUFA were higher in animals fed the concentrate diet. The proportions of 18:1trans and conjugated linoleic acid (CLA) in muscle neutral lipid were higher in animals fed concentrate compared with silage in all 3 groups. This was partly due to increased consumption of 18:2n-6. The ratio of PUFA to saturated fatty acids (P:S) in muscle was reduced by feeding grass silage, partly as the result of increased fat deposition. However, the increase in levels of n-3 series fatty acids with silage-feeding resulted in beneficially low n-6:n-3 ratios in muscle in all age groups (approximately 1.2 compared with 12.0 in the concentrate diet). Subtle breed differences in PUFA amounts and proportions were noted. Holstein-Friesians had higher proportions of PUFA and higher P:S ratios compared with AA, partly due to a higher proportion of phospholipid in total lipid. In phospholipid itself, HF in the 19 and 24months groups had higher proportions of most n-3 PUFA. In all age groups the ratio of DHA to its precursor, 18:3n-3 was higher in HF.     

LONG CHAIN FATTY ACIDS IN HEALTH AND NUTRITION

The typical western diet which is low in long chain omega-3 fatty acids and high in long chain omega-6 fatty acids may not supply the appropriate balance for optimal metabolism. The imbalance is believed to cause a variety of disease symptoms ranging from cardiovascular disease, hypertension, inflammatory and auto-immune disorders, depression and disrupted neurological functions. In the area of cardiovascular disease new research on arrhythmias is exciting and shows that application of omega-3 fatty acids can produce rapid results. In addition omega-3 fatty acids are showing benefits in preventing restenosis following angioplasty in approximately half of the reported studies. Significant research in infant nutrition indicates that long chain polyunsaturated fatty acids are "conditionally essential" for growth and development. Adequate intake of docosahexaenoic acid (DHA) and arachidonic acid (AA) is critical during pregnancy, lactation and infancy for proper development of the fetus and infant. Premature babies are particularly at risk for inadequacies. Thus, many specialist groups are recommending that infant formulas include long chain fatty acids at levels matching breast milk. Recommendations by many academic and governmental bodies propose that daily intakes on long chain omega-3 fatty acids be increased as a step in reducing certain chronic diseases.     

母乳低聚糖的体内代谢与体外合成研究进展

母乳低聚糖（human milk oligosaccharides，HMOs）是母乳中独特的营养成分，结构复杂，种类繁多，不同的HMOs可能具有不同的功能。本文在HMOs的个体差异性、结构多样性与功能活性方面介绍了HMOs的最新研究进展，重点阐述了HMOs在人体内的代谢途径以及体外的合成途径，最后阐述了HMOs在婴儿配方粉中的应用现状，提出了研究及应用中面临的问题。HMOs的应用是婴儿配方奶粉发展中的重大突破，缩小了配方奶粉喂养儿在肠道菌群组成、免疫功能以及认知等方面上与母乳喂养儿的差距。HMOs的深入研究为新型婴儿配方奶粉的开发提供理论依据。     

True ileal amino acid digestibility of goat and cow milk infant formulas

Goat milk is used as an alternative to cow milk for the production of infant formulas. However, little is known about the protein quality and, specifically, about the digestible AA pattern of goat milk formulas compared with their cow milk counterparts. In this study, the true ileal AA digestibility of a goat milk infant formula was compared with a premium cow milk infant formula. The 3-wk-old piglet was used as a model for the 3-mo-old infant. Both milk formulas were prepared as described by the manufacturer, with titanium dioxide added as an indigestible marker. The formulas were fed to the piglets over a 2-wk trial period. Digesta from the terminal ileum were collected post euthanasia and analyzed for AA content, along with samples of the formulas. True AA digestibility was determined after correcting for endogenous AA loss at the terminal ileum of pigs fed an enzyme-hydrolyzed casein-based diet, followed by ultrafiltration (5,000 Da) of the digesta. Total urine and feces collection was also undertaken to determine the nitrogen retention from the diets. The true ileal AA digestibility was similar between the goat and cow milk infant formulas for all AA except Gly and Trp. There was no significant difference in the nitrogen retention of piglets fed the two different formulas. The goat milk infant formula and the premium cow milk infant formula were similar in terms of protein quality.     

婴幼儿配方奶粉强化DHA和AA的研究

近年来的研究表明DHA和AA对婴幼儿大脑和视力的正常发育有着重要的生理作用，在婴幼儿，特别是早产儿以及人工喂养的婴幼儿配方食品中添加DHA和AA十分必要。目前，婴幼儿配方奶粉强化DHA和AA已越来越受到世界各国的重视，许多国家已批准强化DHA和AA婴幼儿配方奶粉市场销售。不过，生产和摄取DHA和AA婴幼儿配方奶粉，需要考虑DHA和AA平衡以及摄取量，同时还应注意防止二者的氧化，以确保婴幼儿安全、有效地利用DHA和AA。     

Use of algae or algal oil rich in n-3 fatty acids as a feed supplement for dairy cattle

Fish oil is used as a ration additive to provide n-3 fatty acids to dairy cows. Fish do not synthesize n-3 fatty acids; they must consume microscopic algae or other algae-consuming fish. New technology allows for the production of algal biomass for use as a ration supplement for dairy cattle. Lipid encapsulation of the algal biomass protects n-3 fatty acids from biohydrogenation in the rumen and allows them to be available for absorption and utilization in the small intestine. Our objective was to examine the use of algal products as a source for n-3 fatty acids in milk. Four mid-lactation Holsteins were assigned to a 4×4 Latin square design. Their rations were supplemented with 1× or 0.5× rumen-protected (RP) algal biomass supplement, 1× RP algal oil supplement, or no supplement for 7 d. Supplements were lipid encapsulated (Balchem Corp., New Hampton, NY). The 1× supplements provided 29g/d of docosahexaenoic acid (DHA), and 0.5× provided half of this amount. Treatments were analyzed by orthogonal contrasts. Supplementing dairy rations with rumen-protected algal products did not affect feed intake, milk yield, or milk component yield. Short- and medium-chain fatty acid yields in milk were not influenced by supplements. Both 0.5× and 1× RP algae supplements increased daily milk fat yield of DHA (0.5 and 0.6±0.10g/d, respectively) compared with 1× RP oil (0.3±0.10g/d), but all supplements resulted in milk fat yields greater than that of the control (0.1±0.10g/d). Yield of trans-18:1 fatty acids in milk fat was also increased by supplementation. Trans-11 18:1 yield (13, 20, 27, and 15±3.0g/d for control, 0.5× RP algae, 1× RP algae, and 1× RP oil, respectively) was greater for supplements than for control. Concentration of DHA in the plasma lipid fraction on d 7 showed that the DHA concentration was greatest in plasma phospholipid. Rumen-protected algal biomass provided better DHA yield than algal oil. Feeding lipid-encapsulated algae supplements may increase n-3 content in milk fat without adversely affecting milk fat yield; however, preferential esterification of DHA into plasma phospholipid may limit its incorporation into milk fat.