Document Type

Dissertation - Open Access

Award Date

1978

Degree Name

Doctor of Philosophy (PhD)

Department

Animal Science

First Advisor

C.W. Carlson

Abstract

A series of eleven experiments was conducted with caged laying hens to study the effects of diet and strain on production and fat accumulation in the liver. In Experiments 1 to 4, a normal ad libitum feeding regime was used, while in Experiments 5 to 11, a force-feeding technique was used as a procedure to increase the incidence of FLHS. Four commercial hybrid strains and a straightbred SCWL (Regional Control) strain were utilized in this study. Choline supplementation at 1500 mg/kg of diet increased egg production from 1 to 11% while decreasing total liver lipid as much as 50%. Supplementation of biotin had little beneficial effect in preventing FLHS. The level of dietary protein affected egg production but had no effect on liver fat accumulation. When supplementing excess methionine in a low protein diet (14%) to increase the availability of methyl groups, a significant increase in total. liver lipid resulted (11 g). Increasing the level of added dietary fat resulted in no significant increases in liver lipids but rather produced a tendency for decreased liver size and lipid content. Corn, oats and wheat were used as primary carbohydrate sources to test for effects on FLHS. Conflicting results from feeding wheat as the only grain source resulted between two experiments. A highly significant decrease in total liver lipid occurred in a force-feeding regime, while no effect was observed between corn and wheat diets in an ad libitum experiment. Egg production averaged 10% less for hens fed oats as the only grain source as compared to those on a corn diet. However, a 50 to 75% decrease in total liver: lipids was also observed, suggesting that a factor in oats is necessary for normal lipid metabolism in laying hens. Results from two experiments using oat hulls and wheat bran indicate that these parts of oats and wheat, respectively, are not the factor responsible for the liver lipid lowering effect. The results of excessive energy intake by force-feeding suggest that total caloric consumption plays an important role in the incidence of FLHS. Force-feeding at levels from 114 to 162% of ad libitum fed hens resulted in three- to fivefold increases in total liver lipids and hemorrhage score. Large differences in liver lipids between strains suggest there is a difference in genetic susceptibility to FLHS. Histological observations verified that hens in normal egg production generally have high levels of liver lipid. Photomicrographs and electron micrographs suggest, however, that excessive liver lipid will lead to the presence of extracellular lipid and disarrangement of the hepatic nuclei and mitochondria, resulting in FLHS.

Library of Congress Subject Headings

Fatty liver syndrome of chickens
Poultry -- Feeding and feeds
Poultry -- Diseases

Format

application/pdf

Publisher

South Dakota State University

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