Enhancing the Proportions of Healthy Fatty Acids in Milk from Dairy Cows
Release of work delayed for one year.
Abstract
Enhancing the Proportions of Healthy Fatty Acids in Milk from Dairy Cows by Korie A.S. Nelson, Master of Science Utah State University, 2008 Major Professor: Randy Wiedmeier Department: Animal, Dairy, and Veterinary Sciences Twenty cows were used in a repeated measures, block design experiment for 9 wk to determine the effects of feeding partially ruminally inert calcium salts (Ca-salts) of fish oil (FO) and a general fatty acid (FA) supplement (EnerGII) at varying levels. The effects on cow health, milk components, composition of milk FA, and sensory evaluation of milk were evaluated. Cows in the 4 treatments were fed either a control diet of 57% forage and 43% concentrate mix with EnerGII fat supplement at 1.65% of diet DM (CTL) or EnerGII in basal diet was partially replaced with (a) 0.21% partially ruminally inert calcium salts (Ca-salts) of 71% fish oil (Ca-FO71) given at 0.41% DM (FH41); (b) 0.41% inert Ca-FO71 given at 0.83% DM (FH83); or (c) 0.83% inert Ca-FO 43% fish oil (Ca-FO43) given at 0.83% DM (FL). Cow health was not negatively affected by treatment diets. Treatment only significantly affected dry matter intake (DMI) and net energy of lactation (NEL), with FH83 having the lowest DMI. Week of trial significantly affected all milk components except protein percent, which did not change. Dry matter intake, milk yield, fat yield, fat percent, and protein yield demonstrated a net decrease over time. Lactose, solids, and somatic cell count all shared a net increase over time. iv Milk urea displayed no definitive trend over time. Content of conjugated linoleic acid (CLA) isomers C18:2 cis-9, trans-11 and trans-10, cis-12 combined over time was 0.54, 0.68, 1.18, and 0.82 g/100 g FA for CTL, FH41, FH83, and FL, respectively. Vaccenic acid (VA) C18:1 trans-11 content over time was 1.04, 1.51, 2.28, and 1.68 g/100 g FA; and total omega-3 FA content over time was 0.52, 0.76, 0.82, and 0.80 g/100 g FA for CTL, FH41, FH83, and FL, respectively. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels increased by as much as 6- and 2.7-fold, respectively, over CTL for the duration of the experiment. Although levels of EPA, DHA, VA, and CLA increased for treatments FH41, FH83, and FL over CTL, a trained sensory panel detected no difference in milk flavor between treatments with little or no intensity of off-flavors. Results suggest that feeding FO and EnerGII at varying levels enhanced CLA, VA, EPA, DHA, and total omega-3 FA in milk over the length of the experiment without negatively affecting cow health, milk composition, or flavor of milk. (84 pages)