title: Modifying milk fat composition of dairy cows to enhance fatty acids beneficial to human health.
abstract: There is increased consumer awareness that foods contain microcomponents that may have beneficial effects on health maintenance and disease prevention. In milk fat these functional food components include EPA, DHA, and CLA. The opportunity to enhance the content of these FA in milk has improved as a result of recent advances that have better defined the interrelationships between rumen fermentation, lipid metabolism, and milk fat synthesis. Dietary lipids undergo extensive hydrolysis and biohydrogenation in the rumen. Milk fat is predominantly TG, and de novo FA synthesis and the uptake of circulating FA contribute nearly equal amounts (molar basis) to the FA in milk fat. Transfer of dietary EPA and DHA to milk fat is very low (<4%); this is, to a large extent, related to their extensive biohydrogenation in the rumen, and also partly due to the fact that they are not transported in the plasma lipid fractions that serve as major mammary sources of FA uptake (TG and nonesterified FA). Milk contains over 20 isomers of CLA but the predominant one is cis-9,trans-11 (75-90% of total CLA). Biomedical studies with animal models have shown that this isomer has anticarcinogenic and anti-atherogenic activities. cis-9,trans-11-CLA is produced as an intermediate in the rumen biohydrogenation of linoleic acid but not of linolenic acid. However, it is only a transient intermediate, and the major source of milk fat CLA is from endogenous synthesis. Vaccenic acid, produced as a rumen biohydrogenation intermediate from both linoleic acid and linolenic acid, is the substrate, and delta9-desaturase in the mammary gland and other tissues catalyzes the reaction. Diet can markedly affect milk fat CLA content, and there are also substantial differences among individual cows. Thus, strategies to enhance milk fat CLA involve increasing rumen outflow of vaccenic acid and increasing delta9-desaturase activity, and through these, several-fold increases in the content of CLA in milk fat can be routinely achieved. Overall, concentrations of CLA, and to a lesser extent EPA and DHA, can be significantly enhanced through the use of diet formulation and nutritional management of dairy cows.
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Adam L
authors.initials: AL
authors.lastname: Lock
authors.forename: Dale E
authors.initials: DE
authors.lastname: Bauman
mesh_terms: D000818:Animals; D002417:Cattle; D005227:Fatty Acids / Q000032:analysis* / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology*; D005260:Female; D006017:Glycolipids / Q000737:chemistry; D006023:Glycoproteins / Q000737:chemistry; D006262:Health; D006801:Humans; D019787:Linoleic Acid / Q000494:pharmacology*; D066292:Lipid Droplets; D008892:Milk / Q000737:chemistry*
chemical_list: D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D006017:Glycolipids; D006023:Glycoproteins; C110367:milk fat globule; D019787:Linoleic Acid
references.citation: J Dairy Sci. 1999 Dec;82(12):2737-45
references.pmid: 10629821
references.citation: J Dairy Sci. 2005 Feb;88(2):489-98
references.pmid: 15653514
references.citation: J Dairy Sci. 2003 Aug;86(8):2568-76
references.pmid: 12939080
references.citation: Am J Clin Nutr. 1999 Sep;70(3 Suppl):560S-569S
references.pmid: 10479232
references.citation: Br J Nutr. 2004 Apr;91(4):539-50
references.pmid: 15035681
references.citation: Am J Clin Nutr. 2002 Sep;76(3):504-10
references.pmid: 12197992
references.citation: J Nutr. 1999 Aug;129(8):1579-84
references.pmid: 10419994
references.citation: J Dairy Sci. 2004 Mar;87(3):645-51
references.pmid: 15202649
references.citation: J Dairy Sci. 2003 Jan;86(1):70-7
references.pmid: 12613850
references.citation: J Dairy Res. 1972 Feb;39(1):167-82
references.pmid: 5044765
references.citation: J Dairy Sci. 2004 Feb;87(2):369-78
references.pmid: 14762080
references.citation: J Dairy Res. 2002 Nov;69(4):511-20
references.pmid: 12463689
references.citation: J Dairy Sci. 1980 Jan;63(1):1-14
references.pmid: 6989864
references.citation: J Nutr. 2004 Oct;134(10 ):2698-704
references.pmid: 15465769
references.citation: J Dairy Sci. 1997 Sep;80(9):2204-12
references.pmid: 9313166
references.citation: Biochem J. 1939 Oct;33(10):1635-8
references.pmid: 16747077
references.citation: J Mammary Gland Biol Neoplasia. 2003 Jan;8(1):103-18
references.pmid: 14587866
references.citation: J Dairy Sci. 2003 Aug;86(8):2588-97
references.pmid: 12939083
references.citation: Lipids. 2002 Jul;37(7):681-8
references.pmid: 12216839
references.citation: Lipids. 2003 Jun;38(6):657-64
references.pmid: 12934676
references.citation: J Dairy Sci. 2000 Nov;83(11):2422-5
references.pmid: 11104258
references.citation: Am J Clin Nutr. 2000 Jan;71(1 Suppl):171S-5S
references.pmid: 10617967
references.citation: Annu Rev Nutr. 2004;24:597-615
references.pmid: 15189133
references.citation: J Dairy Sci. 1993 Jun;76(6):1753-71
references.pmid: 8326036
references.citation: J Dairy Sci. 1998 Jun;81(6):1630-6
references.pmid: 9684170
references.citation: J Nutr. 1999 Nov;129(11):2048-54
references.pmid: 10539783
references.citation: Annu Rev Nutr. 2002;22:505-31
references.pmid: 12055356
references.citation: Lipids. 1998 Aug;33(8):803-9
references.pmid: 9727611
references.citation: J Dairy Sci. 1999 Oct;82(10):2146-56
references.pmid: 10531600
references.citation: J Dairy Sci. 2001 Feb;84(2):345-53
references.pmid: 11233018
references.citation: J Nutr. 2003 Sep;133(9):2893-900
references.pmid: 12949384
references.citation: J Dairy Sci. 2004 May;87(5):1196-202
references.pmid: 15290967
references.citation: J Dairy Sci. 2000 Nov;83(11):2564-73
references.pmid: 11104276
references.citation: J Dairy Sci. 2004 Apr;87(4):1047-50
references.pmid: 15259240
references.citation: J Dairy Sci. 2001 Mar;84(3):680-90
references.pmid: 11286421
references.citation: J Dairy Sci. 2002 Feb;85(2):295-350
references.pmid: 11913692
references.citation: J Dairy Sci. 2003 Nov;86(11):3648-60
references.pmid: 14672195
references.citation: J Dairy Sci. 2002 Sep;85(9):2164-72
references.pmid: 12362448
references.citation: J Dairy Sci. 2003 Mar;86(3):944-53
references.pmid: 12703631
references.citation: J Nutr. 1999 Dec;129(12):2135-42
references.pmid: 10573540
references.citation: J Nutr. 2001 May;131(5):1548-54
references.pmid: 11340114
references.citation: J Dairy Sci. 1993 Dec;76(12):3851-63
references.pmid: 8132891
references.citation: J Dairy Sci. 2002 Jan;85(1):234-43
references.pmid: 11860116
references.citation: J Dairy Sci. 2001 Oct;84(10):2295-301
references.pmid: 11699461
references.citation: Br J Nutr. 1997 Jul;78 Suppl 1:S15-35
references.pmid: 9292772
references.citation: Lipids. 1992 Aug;27(8):629-31
references.pmid: 1406074
references.citation: J Nutr. 1999 Jul;129(7 Suppl):1395S-7S
references.pmid: 10395605
references.citation: Lipids. 1998 Aug;33(8):835
references.pmid: 9727617
references.citation: J Dairy Sci. 2001 Jul;84(7):1607-9
references.pmid: 11467809
references.citation: J Nutr. 2003 Nov;133(11 Suppl 2):3875S-4061S
references.pmid: 14714275
references.citation: Am J Clin Nutr. 2004 Jun;79(6):935-45
references.pmid: 15159222
references.citation: Br J Nutr. 2004 Feb;91(2):271-8
references.pmid: 14756913
references.citation: J Dairy Sci. 2001 Oct;84(10):2144-51
references.pmid: 11699444
references.citation: J Nutr. 2002 Jun;132(6):1235-41
references.pmid: 12042439
references.citation: J Dairy Sci. 1991 Sep;74(9):3244-57
references.pmid: 1779073
references.citation: J Nutr. 2001 Jun;131(6):1764-9
references.pmid: 11385065
references.citation: J Dairy Sci. 2002 Jul;85(7):1764-6
references.pmid: 12201527
references.citation: J Dairy Sci. 2000 May;83(5):1016-27
references.pmid: 10821577
references.citation: Annu Rev Nutr. 2003;23:203-27
references.pmid: 12626693