Feeding technology of rainbow trout pellet feed

Water, species and bait are the basic conditions of fishery production. In order to obtain better feeding effect and reduce the cost of fish culture, we should pay attention to the following problems: 1. The shape, structure and specification of feed are very important for fish to accept or reject certain food. Feed pellet size affects not only palatability but also digestibility. Therefore, the selection of pellet feed size should be suitable for each growth stage of fish swallowing. The fish is very large and the feed is too small, so the fish is not easy to eat and sink to the bottom of the pond; on the contrary, the feed particles fed by the fish are very large, and the feed is swallowed by unfavorable fish and dissolved in the water, so the utilization rate of such feed is low. In rainbow trout feed, fry less than 12 grams can be fed with 0.3-2.2 mm pellets according to their individual size, while those with 12-60 grams can choose 2.2-3.2 mm in diameter and 3 in length. The individuals with a particle size of 4 mm can be fed with a particle size of 3.5 mm and a length of 4 mm for individuals of 60 to 195 grams, and individuals with a particle size of 5 mm and a length of 6 mm to 8 mm can be fed for more than 195 grams. 2. The amount of dissolved oxygen in water has a great influence on the feeding, digestion and absorption of fish and the growth of fish. The content of dissolved oxygen in water is low, the appetite of fish is poor, the digestion and absorption rate of feed is low, the growth rate is slow, and the feed coefficient is high. Rainbow trout has exuberant metabolism, good growth and high feed utilization when dissolved oxygen is more than 9 mg / L. When it is less than 5 mg / L, the respiratory rate increases. When it is lower than 4.3 mg / L, the floating head appears and does not feed. Therefore, when feeding, we should pay attention to the change of dissolved oxygen in the water, low dissolved oxygen in the water, fish floating head, do not feed, wait for the change of dissolved oxygen in the water before feeding. In rainbow trout feeding, hypoxia generally occurs in the rear fish pond in series, so we should pay attention to the stocking density of the rear fish pond, which should be lower than that of the front fish pond. In addition, sewage should be discharged in time to maintain good water quality. 3. Pay attention to the change of water temperature. The survival water temperature of rainbow trout was 25 ℃, and the optimum water temperature for growth was 16 ℃, which was lower than 8 ℃ or higher than 20 ℃. The rainbow trout had anorexia and slow growth, and stopped feeding when it exceeded 24 ℃. In the actual production, if there are conditions for D, pumping well water in high temperature season and heating up spring water in winter to keep the temperature of pool water at 16-18 ℃ can greatly improve the weight gain rate and feed utilization rate of rainbow trout. 4. the expert behavior restricts the feeding of rainbow trout. The adverse effects of size and invasiveness on feeding are common in rainbow trout farms. The aggressive fish in the farmed population (such as large fish) will affect the appetite or food intake of small fish, thus affecting their growth. Only when the big fish are full and scattered, can the small fish eat. Increasing the feeding times or dispersing the feeding r evenly is helpful for the feeding of small fish. In addition, rainbow trout species were screened once a month because of their uneven growth, and different specifications were selected and fed respectively to facilitate their growth and improve feed utilization. 5. The daily feeding amount should be appropriate. If the feeding amount is too low, the fish will be in a state of semi-hunger and slow growth and development; if the feeding amount is too high, not only the feed utilization rate will be low, but also the water quality will be corrupted and diseases will be breed. The appropriate feeding rate is the guarantee of the fastest growth rate and the highest feed conversion efficiency of fish. The daily feeding amount is expressed by the feeding rate, that is, the feed is calculated as the percentage of the dry weight of the feed to the body weight of the feeding fish. The feeding rate is different with different feed quality, different growth stages and different water temperature. When the protein content of rainbow trout juvenile pellet is 45%, 3.7% is calculated at 14 ℃, 4.3% at 16 ℃, 1.8% at 14 ℃ and 2.1% at 16 ℃, which can meet the nutritional needs of normal growth of rainbow trout. Rainbow trout culture, its weight will increase, according to the weight gain, timely adjust the amount of feeding. The weight of the fish was measured 3 times a month and the feeding amount was adjusted 3 times a month, and the feeding amount was adjusted every 15 days in the adult stage. 6. The feeding time should be fixed and the feeding times should be appropriate. Regular feeding can keep the fish full for a certain number of times a day, and its growth, assimilation efficiency and feed conversion rate will maintain a high level. Too many feeding times will result in incomplete digestion and reduce feed utilization rate; if the feeding times are too small, the amount of each feeding must be very large, and the feed loss will be serious. The high nutritional value of feed can be appropriately less, and the lower nutritional value can be more appropriate. When the water temperature and dissolved oxygen are high, it can be more appropriately, otherwise it will be less or stop feeding. Rainbow trout were fed 4 times a day in the fry stage, 3 times in the fry stage, and 2 times in the adult and parent fish. Feed twice a day, preferably at 9: 10 a.m., 16: 17 p.m., 3 times a day at 8: 9 a.m., 12: 13 p.m., 17: 18 p.m., 4 times a day, and evenly set up 4 feeds between 8: 10 a.m. and 18:00. 7. Pay attention to the feeding speed, be patient and meticulous, and pay attention to the method when feeding. When feeding, you should put the feed into the water bit by bit at a certain frequency each time. Do not put the feed into the water at once, which will cause the feed to be dissolved. In the rainbow trout study, it was found that the feeding intake was large at the beginning, and then decreased rapidly to stop eating. Therefore, the duration of each feeding of rainbow trout should not be too long or too short, too long feed will sink to the bottom and the feed utilization rate is low; too short, most fish are not yet 80% full. The duration of each feeding of rainbow trout should be 15-20 minutes. Do not feed moldy and deteriorated feed.