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First, determine the amount of feed The feed feeding technology, first to determine the amount of feed, both to meet the nutritional needs of fish growth, but can not be excessive, overfeed not only cause feed wastage, increase costs, and pollution of water quality, affect the fish Normal growth. Therefore, the determination of feed intake is an important part of feeding technology.
1. Determination of the amount of daily feeding: In the production, there are two methods to determine the amount of daily feeding: the annual feed distribution method and the feeding rate method. 1 Feed all year-round distribution method: First estimate the annual net output according to different culture methods such as ponds or cages, and then determine the feed coefficient of the used feed, estimate the total feed requirement for the whole year, and then according to the season, water temperature, water quality and the culture target The characteristics of growth, monthly, ten-day or even day-by-day distribution of feed. 2 Feeding rate method: The daily feeding amount is determined by referring to the feeding rate and the weight of the fish in the pond, (ie, the daily feeding amount = the weight feeding rate of the pond fish, and the weight of the fish in the pool can be calculated by sampling. In addition, according to the growth of the fish and the nutritional needs of each stage, the amount of daily feeding can be adjusted on the 7th or so, so as to better meet the growth needs of the fish.
2. Determination of feeding quantity: For some farmed fish that are unhurried or poorly acclimated, the average method is used to determine the amount of each feeding (ie: each feeding amount = daily feeding amount ). Better domestication of fish is generally rapid first, then eased until calm; first surface, after the bottom; first large fish, after the fish; first middle, after the surrounding. Each feeding should pay attention to observe the fish's feeding situation, when the water is calm, there is no obvious food rush, 80% of the fish has left or when there is no desire to feed in the surrounding roost, stop feeding, this is the so-called "80% full †That is, 80% of the farmed fish’s satiety, 80% is full, and 20% is not very full. Using this method to determine the amount of each feeding is more practical, it has the following advantages: (1) strong reliability. Due to errors in the fish stock sampling, the calculation error of the daily feeding amount may be caused. If the actual feeding amount differs from the daily feeding amount, the calculated feeding amount may be inaccurate. (2) Reduce feed loss. Grasping the principle of “80% fullness†feeding not only improves fish’s appetite, but also reduces feed loss and reduces breeding costs. (3) Improve feed digestion and absorption rate. The fish eats too much food, the absorption rate of feed nutrients is low, and digestion is not complete. If the amount fed is too small, the fish will continue to feed because of hunger, affecting the growth of the fish. The practice has proved that the "80% full" feed nutrient content digestion and absorption rate is better.
Second, the relationship between the amount of feed and water quality physical and chemical factors affect the fish feeding many factors, such as weak light, human activities. However, from the analysis of the physical and chemical environment of water quality, under the conditions of good water quality environment, the main factors affecting the fed amount are water temperature and dissolved oxygen.
1. Water temperature and feeding amount: Fish is a variable-temperature aquatic animal, and water temperature is one of the most important factors affecting energy metabolism of fish. In a certain range of water temperature, the energy metabolism of fish will increase with the increase of water temperature, and beyond this range, its metabolism will tend to decrease. For example, the feeding rate of carp (50g~100g) is at 15°C. 2.4%, 3.4% at 20°C, 4.8% at 25°C, and 6.8% at 30°C. Therefore, under the premise of grasping the basic feeding rate, the daily feeding amount should be increased or decreased according to the change of the water temperature. .
2. Dissolved oxygen and fed amount: The level of dissolved oxygen in the water directly affects the fish's food intake and digestion and absorption capacity. The dissolved oxygen content in water is high. The fish has high ingestion rate, high digestibility, fast growth, and high feed utilization rate. The dissolved oxygen content in water is low. Due to the physiological inadaptability of fish, the food intake and digestibility are reduced and consumed. More energy. Therefore, the growth is slow and the feed rate is low. According to the Soviet scholar B. Vlassov's determination of the relationship between dissolved oxygen and feed consumption of catfish, it can be seen that the feeding rate of fish increases with the amount of dissolved oxygen in the water.
Third, feeding frequency and feeding method
1. Number of feedings: The number of feedings refers to the number of feedings taken in one day after the feeding is determined on the same day. This is also related to feed utilization and fish growth. Feeding too frequently, the feed utilization rate is low; the frequency of feeding is small, and the amount of feed each time must be large, and the feed loss rate is also large. The frequency of feeding depends mainly on the developmental characteristics of the digestive organs of fish and the environmental conditions of feeding characteristics. In China, the main freshwater cultured fish are mostly fish of the family Euphorbia, and feeds are fed directly from the esophagus into the intestines for digestion. The amount of food that is contained at one time is far less than that of carnivorous stomach fish. Therefore, adopting multiple feedings for grass carp, head bream, squid, squid and other non-stomach fish will help improve digestion and absorption and improve feed efficiency. Usually, they are fed 4 to 5 times a day. Carnivorous fish The food has a good storage capacity, and the daily feeding amount should be controlled between 2 and 3 times. For the same species of fish, the frequency of feeding at the fry stage is more appropriate, followed by the fish species, and the amount of adult fish may be smaller; the nutritional value of the feed may be lower and the nutritional value may be more appropriate; the water temperature and dissolved oxygen are high. , can be more appropriate, and vice versa to reduce feeding or stop feeding.
2. Feeding methods: There are two kinds of artificial feeding and mechanical feeding. Generally, the artificial feeding needs to control the feeding speed. When feeding, it is necessary to grasp the two slow intermediate speeds, that is, when the feeding is started slowly, when the vast majority of fish have concentrated feeding, they are quickly fed, and when the fish feed tends to ease, most of the time When the fish is almost full, they need to slow-shoot. The feeding time is usually not less than 30 minutes. For artificial feeding of pond fish and cage fish, the amount of feeding can be controlled flexibly. Feeding can be done carefully and the feed efficiency is improved. But it is time-consuming and labor-intensive. Large water surface culture is best used mechanical feeding, that is, automatic feeding machine feeding, this method can be regular, quantitative, positioning, while having the advantages of saving time, labor, etc., but the use of mechanical feeding machine is not easy to grasp the feeding state, It is not possible to flexibly control the amount of feeding.
In the production of fish, the level of feed feeding technology directly affects the conversion rate of feed and the effect of breeding. Therefore, grasping the feeding technology using good feed is an important issue that can not be ignored, and is directly related to the economic benefits of breeding.