Energy and protein retention in holoxenic, axenic and gnotoxenic chickens monoassociated with Lactobacillus spp.

1. Axenic, holoxenic and monoxenic chickens (strains LEM 220 or LEM 206 of lactobacilli isolated from the crop of the cockerel) were fed ad libitum on semi-purified diets containing 180 or 200 g protein and 30 g long (LCD) or short (SCD) chain dextrins/kg. Energy and protein retentions were determined from 0 to 3 weeks of age by carcass analysis. 2. Energy retained as a proportion of gross energy intake was only influenced by the microflora in birds receiving 180 g protein/kg and nitrogen retention followed a similar pattern, but differences were less marked: total flora always depressed retentions, but in monoxenic birds the action of the microflora varied with changes in the carbohydrate composition of the diet, the lowest retentions occurring when the diet contained carbohydrates (SCD) which allowed rapid lactate production in the crop.