In aquaculture, the choice and preparation of feed has a direct impact on the growth rate, health status and profitability of the fish. Among them, rapeseed cake, as a feed raw material rich in protein and essential amino acids, can further improve its nutritional value and utilization rate through scientific fermentation. Below, we will explain in detail the steps of rapeseed cake fermentation to make fish feed, and delve into the scientific principles and precautions.
First of all, we need to prepare the following materials: rapeseed cake, corn flour or other starchy substances (as fermentation substrates), starter culture (such as em bacteria, lactic acid bacteria, etc.). The choice and proportion of these materials have their scientific basis. Rapeseed cake is rich in protein and essential amino acids, but its fiber content is high, which is not easy for fish to digest and absorb. Therefore, we need to add the right amount of corn flour or other starches to reduce the cellulose content and improve the digestibility of the feed. The starter culture can promote the decomposition and transformation of nutrients in the feed, and improve the nutritional value and palatability of the feed.
Next, let's follow these steps:
The canola cake is dried and crushed into powder. The purpose of this step is to remove the moisture from the canola cake, making it easier to mix with other substances, and to increase the surface area, which favors the contact and action of the starter culture.
2.Add an appropriate amount of corn flour or other starchy substances to the rapeseed cake powder, generally in a ratio of 1:1 or 2:1 (rapeseed cake: corn flour). This ratio can be adjusted according to the actual situation and the needs of the fish.
3.Add water to the mixed powder and stir evenly, and the moisture is controlled at about 60%, that is, it can be held into a ball and can be naturally dispersed after being loosened. Moisture control is very important, too little will affect the fermentation effect, too much may cause the feed to be too moist and difficult to store.
4.Add starter culture, generally add 1-2 kg of starter culture per ton of feed. The choice of starter culture is determined according to the actual situation and needs, and the effect of different starter cultures may vary.
5.After stirring well, the feed is piled into piles, sealed with plastic film, kept at a temperature between 25-35, and the fermentation time is 3-5 days. In this process, the starter culture will break down the macromolecular substances in the feed to produce small molecule nutrients and organic acids, and at the same time produce a certain amount of heat to facilitate the fermentation process.
6.During the fermentation process, it is turned once a day to ensure that the fermentation is even. Stirring increases oxygen** and promotes the activity of fermentation bacteria while preventing local temperatures from becoming too high or humidity too high.
7.After the fermentation is completed, the feed will have a sour aroma, the color will change to dark brown, and the texture will be soft and easy to digest and absorb. These are all signs of successful fermentation.
8.Finally, the fermented feed is dried and stored in a cool, dry place away from direct sunlight and moisture. Drying can prevent the feed from becoming moldy and spoiling, and prolong the storage period.
During the operation, we need to pay attention to the following points:
1.Pay attention to ventilation during the fermentation process to avoid the production of harmful gases. Harmful gases such as carbon dioxide and ammonia are produced during the fermentation process, which can be harmful to fish and operators if not discharged in time.
2.The fermentation time should not be too long, otherwise it will lead to the loss of nutrients. Over-fermentation may cause some of the nutrients to be broken down or converted into forms that are not conducive to absorption by the fish.
3.Fermented feed should be used as soon as possible to avoid long-term storage leading to deterioration in quality. Fermented feed contains a large number of live bacteria and organic acids, and long-term storage may lead to an imbalance in the microflora, affecting the nutritional value and palatability of the feed.
In general, rapeseed cake fermentation to make fish feed is a scientific, environmentally friendly and economical feed processing method, through reasonable operation and management, can greatly improve the nutritional value and utilization rate of feed, improve the economic and environmental benefits of aquaculture. It is hoped that the interpretation and guidelines of this article can provide reference and help for the majority of farmers.