How to judge the quality of pellet feed for fish?
At present, there are many manufacturers of pellet feed for fish, with various varieties, good and bad, and there are many manufacturers of pellet feed for fish, with various varieties, good and bad, and the relevant salespersons praise the products of their respective manufacturers as perfect. For such a wide variety of fish pellet feeds, in addition to sending them to the competent authorities to appraise their quality, the quality of fish pellet feeds should be judged mainly from five aspects: "seeing, smelling, twisting, soaking, and chewing". Now we will introduce the simple method. as follows:
Look at the color: Fish pellet feed is made of several main raw materials such as fish meal, soybean meal, cotton meal, rapeseed meal, secondary meal, meat and bone meal, etc. To a certain extent, the color of the finished product can reflect the amount of raw materials used. For example, if there are more fish meal and soybean meal, the color of the fish material will be slightly yellow; when there is more miscellaneous meal, the color of the material will be dark red;
Look at the particle size: fish feed is a pellet formed after being processed by a pelletizing process. By observing the particle size, the ratio of the original particles, the fineness of the original particles, the degree of uniformity of tempering, the granulation process, and the selection of the ring die can be judged. The particle size surface of high-quality fish feed is uniform and smooth, the section is neat, the length is 1.5-2 times the diameter, and the pulverization rate is not more than 1%; Caused by the following reasons: (1) raw material crushing fineness is not enough, (2) raw material ratio is unreasonable, (3) uneven tempering, (4) improper selection of ring die, (5) improper adjustment of cutter distance, etc.
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Look at the gloss: The surface of the pellets of high-quality fish feed is smooth, uniform and shiny. This kind of feed has good palatability, storage resistance and high utilization rate. Poor quality fish feed has a rough and dull surface. The above phenomenon is mainly caused by the following reasons: (1) the crushing fineness of the raw materials is not enough, (2) the granulation process is improperly compressed, (3) the feed oil is not added enough and so on.
Look at the submersion speed: When feeding granular fish feed, it is necessary to ensure that the feed has a certain buoyancy and submersion speed. The fish feeds on the upper surface of the water body, which not only saves feed but also facilitates observation of fish feeding. Generally, fish feed should be guaranteed to float on the water surface for 3 to 4 seconds. If the water sinks too fast, the fish will not have time to feed, which will cause waste; if the floating time is too long, it proves that the feed contains more crude fiber and the quality is poor.
Pellet fish feed is made by mixing various raw materials and then quenching and curing with steam. After the raw material is matured, it will emit a unique aroma. Grab a freshly opened bag of feed and smell it in front of your nose. If you find a musty bitter taste, burnt taste, artificial fishy smell, raw fish meal and raw flour taste, it means that there are the following problems in the processing process
(1) Poor quality of raw materials,
(2) Excessive water content and deterioration during storage,
(3) The tempering temperature is not suitable and so on.
Fish feed needs to be handled many times from production to feeding, and it is objectively required to have a certain mechanical strength. Under normal circumstances, it is enough to twist it with your fingers for a few times, but it should not be too hard. If it breaks after a twist, it means that the feed is not hard enough, and the pulverization rate during handling is high, which is easy to cause waste of feed; if the hardness is too large, the palatability is poor, which affects the movement of the feed in the digestive tract and easily causes fish enteritis. .
Put the feed into the water to soak, on the one hand, you can check whether the physical properties of the feed can meet the needs of the fish digestive tract. On the other hand, the rough composition of its raw materials can also be analyzed. The specific method is to pick up a handful of feed and put it into the water, and observe the time for the feed to disperse. Generally, the feed will completely disperse after 3-5 minutes. If the time for the feed to disperse is too short, it will easily cause the digestive tract of the fish to swell and affect its food intake. ; The feeding time is too long, which affects the intestinal peristalsis of the fish and is not conducive to the digestion and absorption of the fish.
Although the fish feed is swallowed, the taste is the main factor affecting its feeding behavior. Through the touch and taste of our mouth, we can feel the hardness of the lower particles and whether there is peculiar smell, whether the feed has deteriorated, whether the feed is mixed with impurities such as sand, soil and so on.
The feeding rate is affected by water temperature, fish weight, dissolved oxygen and other factors.
(1) Temperature The change of water temperature affects the metabolic intensity of fish, and thus also affects the food intake of fish. Generally, the feeding amount increases with the increase of temperature within the suitable temperature range.
(2) Fish body weight The fish grows and the body weight increases, and the feeding amount is required to increase, while the feeding rate decreases, because the fish feed consumption is negatively correlated with the fish body weight.
(3) Oxygen-dissolved fish have vigorous feeding in water with high dissolved oxygen, high digestibility, fast growth, and high feed efficiency;
(4) Types of fish Different types of fish have different digestion and utilization rates of their feeds, and their food intake is also different. The feeding amount of herbivorous fish is high, omnivorous fish is in the middle, and carnivorous fish is low.