Doctoral Dissertations

Date of Award

3-1983

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

H.V. Shirley

Committee Members

R.L. Murphee, J.B. McLaren, R.S. Dotson

Abstract

Ochratoxin at levels of 0, 0.25, 0.5, 1, and 2 ppm (mg per kg feed) was fed to 280 S.C.W.L. hens for twelve weeks. Economic traits such as egg production, egg weight, egg quality, body weight, feed consumption, water consumption, urine and urate excretion, comb color, and mortality were studied. At the end of the test, twelve birds from each treatment were killed to observe macroscopical renal and liver changes. Liver weights were taken and kidney slides were made for histological examination. Analysis of variance was conducted for each trait and comparisons between treatment one, the control, and each of the other treatments were made.

All of the treated groups were lower than the control group in percent hen-day egg production, but differences were not statistically significant. Egg weights were reduced significantly (p≤.05) for the 2 ppm group during weeks 8 through 12 and for the 1 ppm group during weeks 11 and 12. The 0.5, 1, and 2 ppm levels of ochratoxin increased significantly (p≤.05) the percentages of egg blood and meat spots at 8 weeks of the experiment. All levels of ochratoxin reduced significantly the egg specific gravity score at the end of the experiment and the extent of reduction was proportional to the level of ochratoxin. The 0.5, 1, and 2 ppm levels of ochratoxin significantly reduced body weight at 4 weeks, but the highest body weight loss occurred at 12 weeks for the 1 and 2 ppm groups. Water consumption, mortality rate, and average liver weight were significantly increased (p≤.05) only in the hens receiving 2 ppm of ochratoxin.

There was no significant effect of any level of ochratoxin on egg Haugh units, feed consumption, or urine and urate excretion.

The 1 and 2 ppm ochratoxin groups were significantly lower than the control group in the percent of hens with red comb color (p≤.05) and had a lower number of birds with normal livers and kidneys. They were significantly higher than the control group in the percent of hens with pale comb color (p≤.05) and had a higher number of birds with abnormal livers and pale kidneys. Microscopical examination did not show clear histopathologic alterations in the kidneys.

Generally, it can be concluded that each trait studied was affected by some level of ochratoxin. Some traits were affected by 0.25 ppm ochratoxin and above, while other traits were not affected by even 2 ppm ochratoxin. Some symptoms of ochratoxicosis appeared early in the experiment, while other symptoms appeared only towards the end of the experiment. Some of the effects were proportional to the level of ochratoxin or became significant as the duration of exposure increased.

The effects of ochratoxin at levels used in this study on laying hens were generally not severe. These levels can be considered lower than the level required to produce acute ochratoxicosis.

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