A total of 205 Grey Leghorn chicks were hatched germfree for separate trials to determine the effects of Lactobacillus acidophilus treatment on pathogenic Salmonella typhimurium and Staphlococcus aureus. Prophylactic and therapeutic treatments with L. acidophilus were administered either before or after the pathogens were introduced. Prophylactic treatments significantly reduced chick mortality (P less than .01) and shedding of the pathogens (P less than .05). The L. acidophilus prophylactic treatments were also effective qualitatively in reducing the isolation of S. typhimurium and Staph. aureus from crop contents but not, to a great extent, from cecal or rectal contents of gnotobiotic chicks at postmortem. The average surface pH values for the crop, proventriculus, duodenum, cecum, and rectum for gnotobiotic chicks were 5.43, 5.02, 6.18, 6.56, and 6.71, respectively. The L. acidophilus treatments did not significantly affect surface pH of the various segments of the intestinal tract.

Chicks were hatched germfree in gnotobiotic isolators to determine the inhibitory effects of Lactobacillus acidophilus towards pathogeneic Escherichia coli in vivo. Twelve trials were conducted in two flexible film isolators utilizing a total of 221 chicks. One treatment consisted of inoculating 2-day-old chicks with L. acidophilus, then challenging with pathogenic E. coli with subsequent dosing with L. acidophilus. The other treatment consisted of challenging with the E. coli at 2 days of age, then subsequently dosing with L. acidophilus. Statistical analysis of the data showed initial dosing with L. acidophilus prevented excessive mortality when chicks were challenged with E. coli. Also, continued dosing with L. acidophilus lowered the pH in the crop, cecum, and rectum whether chicks were initially given L. acidophilus or E. coli. This strain of L. acidophilus was capable of competing with E. coli in the gut of gnotobiotic chicks.

The flow properties of different types of powder, with varying moisture contents, and the effects of adding small quantities of magnesium oxide, were measured. An explanation of the results in terms of adhesion by intermolecular forces and by the surface tension of moisture films is suggested.

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