Feed additive enzymes Simple classification of feed enzymes:
1.endogenous enzymes, refers to the animal body can secrete digestive enzymes, the main function is to digest the nutrients in the feed used to improve the digestibility of feed; The digestive system of young animals is not perfect, and the digestive enzymes secreted by the body are insufficient. In particular, a large amount of endogenous enzymes should be added to the feed based on plant raw materials to solve the digestive problems. Endogenous enzymes generally refer to protease, amylase, lipase and so on.
2. Exogenous enzymes refer to the enzyme preparations that animals cannot secrete autonomously and must be added. The main function is to degrade the anti-nutrient factors of plant raw materials, non-starch polysaccharides that hinder the release of nutrients and react with the contact of endogenous enzymes, such as cell walls, and non-starch polysaccharides that bring negative effects; Common are phytase, xylanase, glucanase, cellulase, mannanase, galactosidase, etc.
3.functional enzymes, mainly use its catalytic function to achieve the processes and products we need, such as glucose oxidase, a brief overview is the catalytic process with glucose to consume oxygen, produce gluconic acid and hydrogen peroxide, Reduce the PH value of the gut, and use its strong oxidation to alleviate mycotoxin poisoning and protect the health of the digestive system, improve immunity and other functions; In addition, there are catalase, lysozyme and other related products, the specific function is not this unnecessary
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The production technology of big bunting fish fry
The broodstock can be selected either naturally or through artificial methods. The breeding season typically occurs between May and September, with the peak period falling in May and June. Female broodstock should weigh approximately 25 grams, and second-instar fish tend to produce more eggs. A well-developed female sex gland is indicated by a noticeably enlarged abdomen, large and rounded breasts. For males, a weight of around 20 grams is ideal, with elongated mastoid organs that extend beyond the tip of the head.
Broodstock with fully developed gonads can be used directly for spawning or placed in spawning pools or pipelines. Those with a gonad maturity level of 3 to 4 months are kept in holding pools and fed benthic diatoms collected from natural beaches. The pool depth should be between 20 to 30 cm, and half of the water should be changed daily to maintain optimal conditions.
Artificial induction of spawning often involves the use of oxytocin, such as human chorionic gonadotropin (HCG) and luteinizing hormone-releasing hormone analog (LHRH-A), either alone or in combination. These hormones are administered via injection into the pectoral or dorsal fin base. Females receive two injections, spaced 16 or 24 hours apart, while males receive a single dose, with the amount being half that of the females per gram of body weight.
When the water temperature is maintained at 22–24°C and salinity at 25–27 ‰, eggs mature within 24 hours after the second injection. High-dose HCG or a combination of HCG and LHRH-A yields the best results. Males are injected once and synchronized with the second shot of the females. After spawning, the fish are separated into male and female groups, and water is changed and aerated daily. At 19–21°C, the effect lasts 39–58 hours, while at 26–29°C, it takes 14–16 hours. Within 12 hours post-injection, females are regularly checked for egg development. If mature eggs are observed, the male testes are collected and used for semi-dry artificial insemination.
The process involves dissecting the ovary and placing the ovarian sac into a dry plastic container, or extracting the eggs without dissection. Male gonads are then crushed or cut into pieces and mixed with the eggs in the container. The ratio of females to males is 2:1. Fertilized eggs are then transferred to a bucket filled with clean seawater and evenly distributed over a pre-prepared sieve. The sieve is then hung in the hatching pond.
For artificial spawning pipelines, ceramic tubes of 10–20 cm in diameter are used, with removable upper and lower sections. These are placed in spawning tanks with a water depth of 20–25 cm. Broodstock with well-developed gonads are introduced into the pools, and they are fed benthic diatoms daily. Spawning usually occurs between midnight and dawn. Each morning, 2–3 pipelines are checked, and if spawning is detected, all eggs are moved to an incubation pool. More than 10,000 eggs can be obtained for further production. While artificial pipelines encourage pairing and natural spawning, the process is not highly concentrated, so multiple small nursery ponds are recommended. Raising the water temperature in the spawning pool has been shown to enhance gonad maturation and promote more concentrated spawning.
Eggs or spawning pipelines are directly hung in cement hatchery pools or placed in cages for incubation. Both methods achieve a high hatching rate, averaging 50–60%. During incubation, 50% of the water is replaced daily, or a gentle flow of fresh water is maintained throughout the day. The ideal incubation temperature ranges from 26–28°C, with a maximum limit of 30°C. Under conditions of 26.5–29.2°C and salinity of 25–27 ‰, larvae typically emerge after about 87 hours.
By the fourth day of hatching, most larvae have already broken free from their membranes. At this point, egg-catching nets and pipes can be removed. The hatched larvae can remain in the hatchery pond or be transferred to nursery ponds for further development.
Newly hatched larvae measure about 2.5 mm in length. Nursery ponds are stocked at a density of 5,000 fish per cubic meter. On the second day of hatching, the larvae begin to open, and by the fifth day, they reach a total length of 3.5–4 mm. The yolk sac is nearly gone, leaving only a small oil globule. There are 13 melanin spots along the ventral edge, and the larvae start feeding on the third day.
Rotifers are fed twice daily, with the quantity adjusted based on the current density in the pond. The rotifer concentration should be around 5 per milliliter. Around day 35, the larvae begin metamorphosis and enter the larval stage. Their scales become more defined, and 8 rows of horizontal melanin stripes appear along the sides and back. At this stage, Artemia nauplii should be introduced. From the late larval to early juvenile stage, their diet is primarily animal-based. By day 45, when the fish reach about 2 cm in length, they are transitioned to diatoms collected from mudflats. At this point, they can be moved out of the hatchery. Throughout the nursery phase, the water is sand-filtered seawater, with salinity adjusted using fresh water to maintain a specific gravity of 1.010–1.015. Aeration is gradually increased as the fish grow, and daily water changes range from 1/5 to 1/2 of the total volume.