Date of Award:

5-2012

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Committee Chair(s)

Daren P. Cornforth

Committee

Daren P. Cornforth

Committee

Robert E. Ward

Committee

Silvana Martini

Committee

Korry J. Hintze

Committee

Jennifer W. MacAdam

Abstract

There is currently much interest in increasing health benefits from consuming nutritious food, including beef. Plant secondary compounds (PSC) such as tannins or saponins in various forages have an influence on animal nutrition and health, depending on the type of PSC and the amount consumed. However, relatively little is known about effects of PSC on meat color, flavor, and nutritional value. Thus, additional information is needed to better understand and to develop new animal feeding regimes for optimum animal growth, meat flavor, and meat nutritional quality.

In the first study, grain- vs. pasture-fed beef rib steaks were evaluated. The objective was to examine meat characteristics as affected by cattle diet; and to examine the relationship between meat volatiles during heating with meat sensory profile, as determined in a separate study. Ribs from pasture-fed animals had much lower fat content, more omega-3 polyunsaturated fatty acids and conjugated linoleic acid than grain-fed beef. Pasture-fed beef also had lower measures of oxidation during retail storage and higher antioxidant capacity. Both diets also influenced the chemical volatile profiles of cooked meat and were distinctively associated with consumer sensory descriptors. Grain beef had higher levels of hexanal, 1-octen-3-ol, 2,3-octandione, and 2,6-bis (1,1-dimethylethyl)-4-ethyl-phenol, uniquely associated with umami and juicy flavors. In the second study, beef finished with two pasture-finishing models, tall fescue-alfalfa (containing PSC saponins) vs. tall fescue-sainfoin (containing PSC tannins), were compared. Meat characteristics were not different between the two legume diets, indicating that sainfoin was comparable to alfalfa as a cattle forage. However, more information is needed regarding rate of weight gain and other production factors for cattle finished on sainfoin pastures.

Metabolomics is the study of the complete set of small molecules produced in a tissue such as muscle during metabolism of carbohydrates, lipids, peptides, or nucleotides. There is limited information about metabolomics of meat animals, i.e., how diet affects the genetic machinery and meat chemistry. In a third study, lambs (infected with red stomach worm larvae) were fed different purified PSC's to determine possible anti-parasitic effects (companion study) and metabolomics profile in lamb loin muscle using a gas chromatography/mass spectroscopy technique. Diet treatments included dried beet pulp supplemented with tannins or saponins, given in single ration or as choice of them. Carbohydrate metabolites were higher in animals fed tannin diets. Cholesterol levels were lower in saponin groups, in agreement with many previous studies reporting cholesterol lowering activity of saponins in mammals.

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Comments

This work made publicly available electronically on September 20, 2012.

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