Three sets of experimental tanks were used. Diets were combined so as to introduce either copra meal or acacia meal, plus troca meal. The major ingredients are tropical products, and were easy to collect in large quantites. The protein level was maintained at about 30%.

In the first experiment, it was found that a 40% copra meal diet resulted in a fair rate of growth. A higher level of copra meal brought about similar growth levels and a survival rate which was not significantly lower (analysis of variance). This result was checked and confirmed in a 400-m² pond.

In a second experiment, a diet composed of 40% acacia meal was tested on M. rosenbergii to find out whether the level of mimosine was toxic or not to the metabolism of this prawn, and to investigate the potentialities of this source of protein for the growth of M. rosenbergii. Two other typical herbivorous diets were used for comparison. No pathogenic signs were noticed. The survival rate was equivalent and an analysis of variance showed significant differences between the three diets: the 43.1.1.0. was the more efficient diet.

The introduction of acacia meal into a Macrobrachium diet seemed quite beneficial from several points of view (Ca/P ratio, protein quality and pigmentation of the animal). 1. (1) Regarding the mineral requirements of this species, it is pointed out that among the six diets tested the best growth rate was obtained with a Ca/P ratio above 1 in the diet. This underlines the importance of the mineral mixture.2. (2) Amino acid composition of the diet has to be as similar as possible to the shrimp muscle; the level of methionine is particularly important to the animal, and more essential than lysine which could be a limiting factor in the formulae without affecting the growth.3. (3) Leucaena meal contains a level of mimosine which is fairly normal and non-toxic for the freshwater prawn. In addition, the growth is very acceptable though a supplementation with troca meal seems quite suitable. Leaf protein contains a large quantity of β-carotene, which seems to bear some relation to the good pigmentation of the prawns after the feeding trial.

An analysis of variance shows a significantly higher growth rate (α < 5%) with the 40% acacia diet. This result has been confirmed in a larger-scale experiment. A 500-m² tank filled with 10 000 postlarvae has produced 130 kg in 7 months. Due to this result, the authors conclude that two tropical products are beneficial in the feeding of the freshwater prawn M. rosenbergii: copra meal, which is already in widespread use in animal nutrition, and a new one, acacia leaves, which has not yet been used in the feeding of aquatic animals.

Some other growth tests must be carried out in order to determine the influence of Ca/P ratio on the diet of M. rosenbergii, and the range of acceptance and the optimum level of acacia meal in the diet for enhancement of growth. Other combinations with acacia meal are to be tested.

Résumé

Plusieurs aliments composés ont été testés sur M. rosenbergii; ces aliments comportent en majeure partie des protéines d'origine végétale.

Les expériences de grossissement sont réalisées pendant 3 à 4 mois. Le tourteau de coprah apparaît tout à fait adéquat pour la croissance de M. rosenbergii. Et le niveau de tourteau de coprah peut atteindre 40$ (régime 25.1.1.0) à 60% sans affecter en rien la croissance des animaux.

Une autre source de protéines, les feuilles d'acacia Leucaena leucocephala semble fournir assez de composants nutritifs pour les post-larves. Une croissance convenable est observée avec 40% de farine d'acacia dans l'aliment.

Les résultats expérimentaux ont été confirmés à une plus grande échelle; dans des mares de 500 m², quelques 100 kg de crevettes d'eau douce ont été récoltés en utilisant les aliments 25.1.1.0 et 43.1.1.0.

Les besoins nutritionnels de M. rosenbergii sont assez importants en ce qui concerne la methionine tandis que la lysine ne représente pas un facteur limitant, en première approximation, à la croissance de cette espèce. Parmi les six aliments testés dans cette étude, la meilleure performance de croissance est obtenue avec un rapport Ca/P supérieur à 1; ceci reflète l'importance du mélange minéral dans l'aliment.

Enfin, la farine de feuilles de Leucaena contient une grande quantité de β-carotène qui serait responsable de la bonne pigmentation des crevettes en fin d'élevage.