A study has been made of the internal volume of the different parts of the alimentary tract of geese and fowls.
It has been shown that although the adult geese were two or three times as heavy as the adult fowls, the mean total gut capacity, exclusive of the crop, was proportionately less. Although the gizzard was much greater in weight than in the fowl, its capacity in proportion to body weight is only half that of the fowl, whilst the caeca are relatively even smaller. The distended oesophagus of the goose, which replaces the crop of the fowl, was at all times smaller relative to body weight.
The gut capacities of both chicks and goslings increased rapidly when they began to feed, and reached a maximum, relative to body weight, within the first fortnight after hatching. At 16 weeks, the capacity of the alimentary canal had almost the same relation to body weight as in the adult.
In both, the small intestine constitutes the major proportion of the volume in the adult, being 33–40% in the fowl and more than 50% in the goose.
Feeding a diet containing 21% crude fibre and supplemented with procaine penicillin G produced chicks with relatively greater gut capacities, and this effect was enhanced by the concurrent inclusion of procaine penicillin G, but where the fibre was reduced to 17·4%, the gut capacities were not significantly different, in relation to body weight, than in the control group.
Histological examination of the wall of the gut of chickens raised on different diets showed marked abrasion on high-fibre diets, and a much thinner intestinal wall in those birds receiving antibiotic.