American Journal of Clinical Nutrition, Vol 27, 1305-1312, Copyright © 1974 by The American Society for Clinical Nutrition, Inc.

Lactobacilli which attach to the crop epithelium of the fowl

¹ From the National Institute for Research in Dairying, Shinfield, Reading RG2 9AT, England

A population of lactobacilli closely associated with the squamous epithelial lining of the crop occurs in chickens. This association is established soon after hatching, persists throughout the life of the chicken and is unaffected by changes in diet or systems of rearing.

The attachment is mediated by a layer of carbohydrate outside the bacterial cell wall. The primary site of attachment is reinforced by filamentous projections extending from the surface of the bacterium to the crop epithelial cells.

The lactobacilli are antagonistic toward other bacteria as shown by the observation that elimination of lactobacilli from the crop results in an increase in coliforms. Attachment to the epithelium ensures that lactobacilli remain behind after the food passes on to the gizzard and in this way provides an inoculum for the incoming food so that the lactobacilli can quickly outgrow other bacteria and by creating an acid environment prevent colonization of the crop by these bacteria.

Conditions which tend to delay the establishment of lactobacilli in the crop would therefore lead to a derangement of the normal balance of the flora. Early establishment of lactobacilli in newly hatched chicks suggests that their growth rate might be improved by this practice.

The lactobacillus-chicken association would appear to be an example of symbiosis where the lactobacillus benefits by receiving nutrients from the diet and the host benefits by the maintenance of a nongrowth depressing microflora.