QUANTITATIVE EFFECTS OF PELLETING ON PERFORMANCE, GASTROINTESTINAL-TRACT AND BEHAVIOR OF MEAT-TYPE CHICKENS

1. In an attempt to quantify the effects of ''degree'' of pelleting, t wo experiments were conducted. Diets were prepared by mixing together a mash composed mainly of maize (experiment 1) or sorghum (experiment 2) with soft pellets, or soft pellets mixed with hard pellets. 2. The pelleting degrees (PDs) were as follows: 0 mash; 0.5 mixture of soft p ellets and mash 1 to 1; 1 soft pellets pelleted once; 1.5 mixture of s oft and hard pellets 1 to 1; 2 hard pellets pelleted twice. 3. In expe riment 2, the weight and length of the digestive organs were determine d as well as digestive enzyme activities. In both experiments, the beh aviour recorded was eating, standing, sitting and drinking. 4. Food in take and body weight gain were related to the degree of pelleting in a curvilinear manner. PD had a positive effect up to a peak (1 to 1.5 P D), after which its effect decreased. Food efficiency was not related to PD. In experiment 1, food efficiency of PDs 1 to 2 were superior to PDs 0 to 0.5 and in experiment 2, PDs 1.5 to 2 were superior to PD 0. 5. The relative weight of the gizzard was reduced by pelleting, where as pelleting increased the relative weight of abdominal fat. The conte nt of the crop was not affected by PD, whereas that of the proventricu lus was lowest in the PD 2 group. Gizzard content was inversely relate d to PD. Pelleting reduced the length of the jejunum and ileum: which were shortened by about 15% with PDs 1 to 2, as compared to PD 0. The weight/length ratio of the jejunum and ileum tended to increase with i ncreasing PD to a peak at PD 1.5, and to decrease thereafter. 6. Tryps in activity in the pancreas and amylase activity in the intestinal con tent were reduced by pelleting. 7. Chicks fed pelleted diets were less active: they 'sat' more and spent less time eating than their mash-fe d counterparts.