Taiwan.- As the demand for fishmeal increases, prices have also risen in lockstep year by year. In order to lower feed cost and seek sustainable operations in the industry, the Fisheries Research Institute, Council of Agriculture is actively engaged in the development of replacing fishmeal with protein sources and conducting relevant research into enhancing the utilization of vegetable protein.
Subsequent achievements have effectively improved groupers’ utilization rate of an alternative protein source for fishmeal, reduced the usage of fishmeal by as much as 70%, lowered feed production cost by 10%, cut the additional proportion of fishmeal in feed, and at the same time enriched the meat quality and flavor of grouper, so as to make the grouper aquaculture industry more competitive on the global market.
Fisheries Research Institute stated that alternative protein sources of fishmeal are mainly byproducts of livestock processing and insects. The byproduct of livestock processing is mainly chicken powder, with a high content of protein (above 50%) and grease (9-15%), but a low content of limiting amino acid, such as lysine and methionine. The content and quality of the insect powder’s protein are approximate to or higher than that of quality fishmeal. Currently, the insect protein sources of silkworm chrysalis and fly maggots are widely available, and the added effect of replacing fishmeal with them can be applied to feeding different aquatic livestock. However, the yield is limited. For types of vegetable protein, soy protein is a common raw material. Its protein content is high, and it is easily digestible. However, it has the problem of low lysine and methionine contents.
Fisheries Research Institute pointed out that groupers are a carnivorous economic aquaculture species, with demand for as high as 45% protein in the feed. The proportion of replaceable feed fishmeal with single vegetable protein is about 20-40%. If the proportion can be increased, then the feed utilization will drop, resulting in inferior growth of fishes. The content and quality of feed protein are also related to the meat quality of fishes, except for affecting the growth of aquaculture fishes. Feeds with comparatively poor quality of protein not only can increase the fat content of fish meat, but also may reduce its quality.
The low-fishmeal grouper feed developed by the Fisheries Research Institute mixes black-water gadfly powder, soy protein, and chicken powder at different proportions into compound fishmeal to replace protein sources according to nutrient composition, digestion rate, and price and uses different forms of methionine to balance the necessary amino acid in the feed. With feed additives consisting of enriched nutrients and flavorful materials, the groupers’ utilization of this alternative protein source of fishmeal can be effectively improved, and the additional proportion of fishmeal in feed can decrease, so as to lower the production cost of feed and improve the income of aquaculture farmers of groupers.
