[Food value of spiruline algae for growth of the broiler-type chicken].

Five trials were carried out during the growth (0-8 weeks) of the broiler type chicken. The weight increase was always depressed when spiruline algae replaced traditional protein sources (soybean meal, fish meal, ...) in a complete and well balanced diet (trials 1 and 2). The delay in growth was small and non significant for 5 p. 100 or less of spirulines in the diet. However, for the highest levels of spirulines the delay in growth was more pronounced, especially during the starting period (0-4 weeks): live weight gain was reduced from 16 and 26 per cent for the spirulines levels of 20 and 30 p. 100. Different methods (live weight gain, balance technique, body analysis) were used for the determination of the protein and energy efficiencies. Spirulines were fed at different levels, either added to a protein free diet (trial 3), or included with other protein sources in complete diets (trial 4). Both protein and energy efficiencies were reduced when the spiruline level increased. Thus, the protein efficiency of the spirulines was found to be similar to that of the other traditional protein sources (soybean, fish,...) for a level lower than 10 p. 100. In contrast, it was reduced (--20 p. 100) when more than 20 p. 100 of algae were included in the diet. The average metabolizable energy was 2,487 kcal per kilogram when 20 and 30 p. 100 of algae were added in the protein free diet. In the complete diets, this value was found to be smaller or greater according to the level of spirulines, 30 p. 100 reduced and 5 p. 100 increased the energy value. The poor digestibility of some glucidic fraction in the algae seems responsible for the low energy value and for the reduced growth performance. The addition of a glycolytic enzyme to the diet failed to improve the performance (trial 5).