Growth response of the black tiger shrimp, Penaeus monodon fed diets containing different lupin cultivars

Over the last 10 years plant breeders have developed new cultivars of lupins which have largely replaced the cultivars that were studied in previous aquaculture feeds research. There was a need to establish whether the breeding programs had introduced changes into the new lupin cultivars that would affect the nutritional value of the kernel meal for shrimp. We have determined the performance of seven of the new cultivars of Lupinus angustifolius, when used to replace fish meal in diets for the black tiger shrimp, Penaeus monodon. The L. angustifolius cultivars examined in this study represent about 80% of Australia's current lupin production. We have also compared the performance of the new cultivars with that of solvent-extracted soybean meal. Three 50-day growth response experiments were carried out using an array of 100 L circular aquarium tanks in an open seawater system. Six replicate tanks each stocked with five juvenile shrimp were assigned to each treatment in complete randomised design experiments. Lupin kernel meal and solvent-extracted soybean meal were used to replace fish meal in the experimental diets on an iso-nitrogenous basis. The diets contained 454 g kg− 1 of crude protein (on a dry matter basis) in the first experiment and 420 g kg− 1 in the following experiments, with the plant proteins usually contributing 41.5% of the dietary protein. In all three experiments the growth rate of shrimp fed the diets containing lupin kernel meal or soybean meal was as good as, or better than, that obtained with the basal diet. Survival in all experiments was high (mean ∼ 90%). There was generally little difference between the allocated FCR of the basal diet and that of the lupin kernel meal or soybean meal diets. This study has demonstrated that lupin kernel meal can be used to replace at least 40% of the fish meal protein in diets for P. monodon, and that the new cultivars perform equally to solvent-extracted soybean meal when used on a protein-equivalent basis. From the growth response of the shrimp and the amino acid composition of the diets used in the experiments, it appears that the reported requirements of juvenile P. monodon for methionine may overestimate the true requirements. Further clarification of this issue is warranted as it is possible that formulators are restricting the inclusion level of lupins and soybean meal in shrimp feeds in order that they meet the reported requirement for methionine.