Ask about the taste of feed. Good agricultural feed should have pure fishy smell. Some inferior feeds are added with high-concentration essence to cover up the musty smell, so some feeds are not delicious even if they are particularly fragrant.
Look at feed uniformity. The high-quality feed of regular manufacturers is very evenly mixed, and there will be no polarization, while the inferior feed is difficult to ensure the feed quality. It is easy to see the difference from the different positions of each package of feed.
The demand of fish and trout for protein varies with the temperature. When the water temperature is high, the content of protein in feed should be appropriately increased. Delong and Haval (1958) pointed out that the demand of salmon for protein was 40% at 8.3℃ and 55% at 14.4℃. The optimum requirement of protein was 45% measured by the experiment of eels in Xinjing (1972). Sin( 1973) has worked out the protein requirement of carp feed with different specifications, among which the requirement of protein for fingerling is 43-47%, and that of protein for fingerling and juvenile is 37-42%. The protein requirement of adult fish and parent fish is 28 ~ 32%. The optimum protein requirement of catfish is 35% at 20℃ and 40% at 25℃.
The demand of fish for protein and protein changes with the change of temperature. When the water temperature is high, the content of protein in feed should be appropriately increased. Delons and Haver( 1055) pointed out that at 8.3℃, the demand of salmon for protein was 4. Intestines, 14.4℃ requires 55 intestines. According to the experiment of eels in Nengshui and xin jing (1972), the optimum requirement of protein is 45 intestines.
Look at the packaging label. The packaging of regular manufacturers should be beautiful and neat, with clear address, telephone number and suitable varieties. The industrial and commercial departments have trademarks, and the upper right corner of registered trademarks has the R mark.
Look at the date of production. Although some feeds are high-quality feeds produced by regular manufacturers, if the shelf life is exceeded, the feed will inevitably deteriorate, and the titer of vitamins and other nutrients will also decrease, which will affect the feeding effect. Pay attention when buying, and it is best to use up the feed at one time.