China Aquatic Products Channel reports that feeding frequency refers to the number of feedings per day. Nowadays, feeding frequency occupies a very important position in aquaculture production. Insufficient feeding times will reduce the growth performance of aquatic animals, increase mortality, and increase the number of feedings or feeding frequencies by increasing the growth performance, but also reduce the waste of feed. The feeding frequency also has a certain relationship with the type of aquatic animals, the size of aquatic animals, the composition of feed and the environment of the cultivated aquatic body.
<b>1. The influence of feeding frequency on growth performance</b>
At the same daily feeding rate, increasing the frequency of feeding can promote growth. Studies have shown that when the feeding frequency ranges from 0.5 to 2 times a day, the weight gain rate of the catfish is increasing. When the feeding level is 10%, the increase in feeding frequency leads to a significant increase in the specific growth rate of macroglobudge carp. However, when the amount of feeding is insufficient, and the nutrient and energy levels do not meet the needs of aquatic animal growth, excessive increase in feeding frequency will reduce the growth rate. At the feeding level of 5%, the specific growth rate decreases with the increase of feeding frequency, inhibiting its growth. When feeding with full food, the increase in feeding frequency can also play a certain role in promoting the growth of aquatic animals. When the feeding frequency increased from twice-daily feeding to 8 feedings per day, the specific growth rate of yellow croaker increased with the increase of feeding frequency, and the most suitable feeding frequency of yellow croaker was determined to be 8 feedings per day. However, when the number of feedings increased to 12, there was no significant increase in the specific growth rate and decreased. It can be seen that under the condition of full feeding, excessive feeding frequency will also limit the growth of aquatic animals. Therefore, finding an optimal feeding frequency is also particularly important for today's intensive farming models.
<b>2. The impact of feeding frequency on feed utilization</b> rate
Some studies have found that in the trial of raising bluefish at the feeding frequency of 1, 2, 3, 4 and 5 times per day under the same daily feeding rate, the feed efficiency increased significantly as the feeding frequency increased from 1 to 3 times per day, while the feeding frequency increased from 3 times a day to 5 times, and there was no significant difference in feed efficiency. Similar results have been reported in a large number of trials. From this point of view, under the condition of a certain amount of daily feeding, appropriately increasing the feeding frequency can enable aquatic animals to take up feed in a short period of time and reduce the dissolution loss of feed nutrients. However, when the frequency of feeding is increased excessively, due to the excessive frequency of feeding activities, the intestinal contents move faster, so that nutrients can not be well digested and absorbed, thereby reducing the utilization rate of feed.
<b>3. The effect of feeding frequency on body composition</b>
3.1 Protein
The effect of feeding frequency on the protein content of aquatic animals is similar to that of feeding levels, and the body protein content of Wuchang fish is not related to feeding frequency. Similar conclusions were found in studies of feeding frequencies of Russian sturgeon and tuantou bream. But some scholars have found different results, the body protein and fat content of yellow croaker increase with the increase of feeding frequency. This may be due to differences in the types and feeding methods of aquatic animals, which need to be further studied.
3.2 Fat
Under the condition of feeding volume, the body fat content of bluefish shows a downward trend with the increase of feeding frequency. This may be due to the fact that aquatic animals need to consume a certain amount of energy for feeding, and the low feeding frequency makes the aquatic animals less feeding activities and consumes less energy; on the contrary, the increase in feeding frequency will increase the energy consumed by aquatic animals, resulting in a decrease in fat content. Similar results were obtained in studies of the frequency of feeding of sea bass, which may be related to the similar feeding methods of the two. When feeding with full food, under a certain feeding frequency, the fat content of tuantou bream and Russian sturgeon showed an increasing trend with the increase of feeding frequency. From this point of view, under the appropriate feeding frequency conditions, the increase in feeding activities of aquatic animals makes the feed less dissolved in water, improves the utilization rate of feed, and increases the body fat content; and when the feeding frequency is excessive, the feeding activity of aquatic animals is reduced, and the energy consumed during the feeding process is increased, so the body fat content decreases.
3.3 Ash
Under the condition that the daily feeding amount is consistent and evenly distributed according to the number of feedings, the ash content of the bluefish body increases significantly with the increase of feeding frequency. This is due to the increase in feeding frequency, shortening the time for aquatic animals to complete feeding, reducing the dissolution of minerals in feed, increasing the intake of minerals by fish bodies, thereby increasing the accumulation of minerals in fish bodies. Under the condition of full feeding, the body ash content of Russian sturgeon, tuantou bream and Walter's yellow jaw fish is not affected by the frequency of feeding.
<b>4 Feeding methods</b>
At present, the main feeding methods can be divided into artificial feeding and timed quantitative automatic feeding. The advantage of artificial feeding is that the feeding status of aquatic animals can be observed at any time, and farmers can adjust the feeding amount in time through the feeding status of aquatic animals and environmental factors; the disadvantage is that it is time-consuming and laborious, and it is easy to cause feed waste and water pollution. The advantages of timed quantitative automated feeding are to save time and manpower, uniform feeding, reduce feed waste and reduce water pollution; the disadvantage is that it is impossible to observe the feeding status of aquatic animals at any time to flexibly adjust the feeding volume, and the feeding machine needs to be maintained regularly. Therefore, an automatic feeding machine that can adapt to the feeding habits of different aquatic animals should be designed and developed, so that intensive aquaculture can obtain the greatest economic benefits.
At present, the research on aquatic animal nutrition and feed mainly focuses on the nutritional needs of farmed animals, the development and utilization of new protein sources, nutrition and immunity, physiological metabolism, etc., and the research on feeding strategies involves very little. The study of feeding strategy, on the one hand, can achieve refined, standardized and digital management in actual aquaculture production, reduce feed waste and improve economic benefits; on the other hand, reduce the pollution of the water environment, and greatly improve the quality and safety of aquatic products. Therefore, in the case of strong support for the sustainable development of aquaculture, further exploration of feeding patterns and feeding strategies should be strengthened.