Title page for ETD etd-08172009-214911

Type of Document Master's Thesis
Author Blevins, Sarah
URN etd-08172009-214911
Title Characterizing Compensatory Effects of Silymarin on Gossypol Toxicosis in Lines of Chickens Divergently Selected for Humoral Immune Response
Degree Master of Science
Department Animal and Poultry Sciences
Advisory Committee
Advisor Name Title
Lewis, Ronald M. Committee Chair
Blodgett, Dennis J. Committee Member
Ehrich, Marion F. Committee Member
Siegel, Paul B. Committee Member
  • Silymarin
  • Gossypol
  • Humoral Immunity
  • Chicken
Date of Defense 2009-08-04
Availability unrestricted
Feed costs are approximately 70% of total production cost for poultry producers.

Poultry diets in the United States generally consist of 2 grains: corn and soybean meal.

In recent years, the cost of these grains has dramatically increased. Due to these price

increases, producers seek alternative feeds that provide adequate nutrition, and are also

more affordable than “traditional” grains. Cottonseed meal is one alternative that is both

affordable and an excellent source of crude protein. However, cottonseed meal contains

gossypol, a pigment toxic to chickens.

This study had two main objectives. The first objective was to determine if

silymarin, an extract from milk thistle, could offset or prevent gossypol toxicosis. The

second objective was to determine if divergent selection for humoral immune response

would have an impact on the ability of the chicken to cope with gossypol toxicosis. Two

preliminary studies were conducted. One determined basal activities of liver

detoxification enzymes at various ages. The other determined concentrations of gossypol

and silymarin that should be added to the diet to elicit a response. The information

gathered from the second preliminary study was used to conduct the final experiment.

In the final experiment, chickens from each of 2 lines selected for humoral

immunity were exposed to diets containing gossypol, silymarin, gossypol and silymarin,

and a control. Humoral immunity had no impact on the ability of the chicken to cope

with gossypol toxicosis. Silymarin did not alleviate gossypol toxicosis. Future studies

will focus on using a lower gossypol concentration in the diet.

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