Fate of salmonellas in the alimentary tract of chicks pre-treated with a mature caecal microflora to increase colonization resistance.
Oral challenge with a strain of Salmonella kedougou, resistant to nalidixic acid, gave a time-course for salmonella survival in the alimentary tract of chicks pre-treated with a caecal culture from an eight-week-old bird to increase colonization resistance. In untreated, control chicks, salmonella colonization of the caeca resulted in counts of greater than 10(6)/g within 48 h and a mean generation time of 1.6 h. With treated birds, however, the salmonellas failed to multiply in the caeca and decreased to a low level over a 48-h period, thus suggesting a mainly bacteriostatic effect. Pre-treatment of chicks with the caecal culture also reduced the proportion of salmonella-positive crop samples. Growth of the salmonella in a feed-slurry system resembling moistened crop contents occurred rapidly at 37 degrees C but was prevented by addition of the treatment culture, a decline in numbers coinciding with Lactobacillus populations of ca 10(9)/g and a pH value of 5.5. Incorporation of a feed decontaminant, 1% formic acid (pH 4.0), rapidly eliminated both salmonellas and organisms added from the treatment culture.
Impey
C S
CS
Agricultural and Food Research Council, Institute of Food Research--Bristol Laboratory, Langford, UK.
Mead
G C
GC
D000818:Animals; D002432:Cecum / Q000382:microbiology*; D002645:Chickens / Q000382:microbiology*; D004064:Digestive System / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D005516:Food Microbiology; D007778:Lactobacillus; D011201:Poultry Diseases / Q000517:prevention & control; D012475:Salmonella / Q000254:growth & development*; D012481:Salmonella Infections, Animal / Q000517:prevention & control