title: Milk production and composition from cows fed small amounts of fish oil with extruded soybeans.
abstract: Eight Holstein (189 +/- 57 DIM) and 4 Brown Swiss (126 +/- 49 DIM) multiparous cows were used in a replicated 4 x 4 Latin square with 28-d periods to determine the minimal dietary concentration of fish oil necessary to maximize milk conjugated linoleic acid (CLA) and vaccenic acid (VA). Treatments consisted of a control diet with a 50:50 ratio of forage to concentrate (dry matter basis), and 3 diets with 2% added fat consisting of 0.33% fish oil, 0.67% fish oil, and 1% fish oil with extruded soybeans providing the balance of added fat. Dry matter intake (23.1, 22.6, 22.8, and 22.9 kg/d, for control, low, medium, and high fish oil diets, respectively) was similar for all diets. Milk production (21.5, 23.7, 22.7, and 24.2 kg/d) was higher for cows fed the fat-supplemented diets vs. the control. Milk fat (4.42, 3.81, 3.80, and 4.03%) and true protein (3.71, 3.58, 3.54, and 3.55%) concentrations decreased when cows were fed diets containing supplemental fat. Concentration of milk cis-9,trans-11 CLA (0.55, 1.17, 1.03, and 1.19 g/100 g of fatty acids) was increased similarly by all diets containing supplemental fat. Milk VA (1.12, 2.47, 2.13, and 2.63 g/100 g of fatty acids) was increased most in milk from cows fed the low and high fish oil diets. Milk total n-3 fatty acids were increased (0.82, 0.96, 0.92, and 1.01 g/100 g of fatty acids) by all fat-supplemented diets. The low fish oil diet was as effective at increasing VA and CLA in milk as the high fish oil diet, showing that only low concentrations of dietary fish oil are necessary for increasing concentrations of VA and CLA in milk.
authors.affiliation: Dairy Science Department, South Dakota State University Brookings, South Dakota 57007-0647, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Whitlock
authors.forename: D J
authors.initials: DJ
authors.lastname: Schingoethe
authors.forename: A A
authors.initials: AA
authors.lastname: AbuGhazaleh
authors.forename: A R
authors.initials: AR
authors.lastname: Hippen
authors.forename: K F
authors.initials: KF
authors.lastname: Kalscheur
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D005227:Fatty Acids / Q000032:analysis* / Q000502:physiology; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage* / Q000494:pharmacology; D007774:Lactation / Q000187:drug effects; D044243:Linoleic Acids, Conjugated / Q000032:analysis / Q000502:physiology; D008892:Milk / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology; D009829:Oleic Acids / Q000032:analysis / Q000502:physiology; D013025:Glycine max / Q000737:chemistry / Q000502:physiology
chemical_list: D005227:Fatty Acids; D005395:Fish Oils; D044243:Linoleic Acids, Conjugated; D009829:Oleic Acids; C050413:11-octadecenoic acid