Abstract
Skim-milk and lactose supplements in the diet were recommended by Beach and Davis 1 as affording a considerable degree of protection against coccidiosis in poultry. The explanation of the claimed benefits was the production of an abnormal degree of acidity in the caeca of the birds, which in turn injured or destroyed the sporozoite or merozoite stages of the parasites. Since the rat is a favorable host for the study of a coccidian infection, an experiment was planned in which one series of hosts received the regular growing ration made up to 40% with skim-milk beginning 4 days before the date of the first infection and continuing throughout the experiment, and another series received its regular ration without skim-milk. Infection was accomplished by forced feeding of from 1,500 to 3,000 oocysts of Eimeria miyairii daily for 4 or 5 successive days. The counts of the oocysts eliminated in the fecal pellets were taken as the index of the infection intensity. Seventeen rats on the skim-milk diet eliminated from 94 to 376 million oocysts each; mean, 203.24 millions. Sixteen controls on the regular diet eliminated from 72 to 464 million oocysts each; mean, 237.25 millions. The difference in the means divided by the standard deviation of the difference (34.01 ÷ √737.25 + 381.334) was 1.02, a nonsignificant value. Through the kindness of Dr. Donald Starr of the Chemistry Department it was possible to determine the pH of the entire content of the small intestine of some of the rats at the end of the experiment. The values for 3 rats on the milk diet were 6.92, 6.74, and 7.28; for 3 controls, 6.60, 6.75, and 6.48. It is evident that the skim-milk diet did not produce an abnormally acid condition in the small intestine of the rat, and that the parasite population was not reduced by the diet.
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