| P.teira is a fish that is both ornamental and highly nutritious and economical.At present,the market demand for P.teira seedlings is increasing,but because of overfishing and immature artificial breeding technology,the market supply of seedlings is limited,which can no longer meet the market demand,which severely restricts the health of P.teira breeding industry.For sustainable development,there is an urgent need to carry out research on artificial breeding techniques for P.teira.It lacks perfect theoretical and practical research support in broodstock cultivation,fish egg hatching,seedling cultivation,and adult fish breeding.How to strengthen the nutrition of broodstock,cultivate high-quality fertilized eggs,increase hatchability,increase the survival rate of larvae,and control the phenomenon of larvae mutual residues are the problems faced by artificial breeding.This article started with the newly hatched larvae to study the changes of the digestive system during the post-embryonic development of the P.teira,observed and analyzed the development and changes of the digestive organs of the P.teira by HE staining and light microscope;The curve model of the growth process of fish and adult fish provides theoretical support for the conversion of artificially bred bait through the study of the occurrence and development of the digestive system,and the study of the growth process provides the basis for management and bait feeding strategies in the breeding process.The main results of this article are as follows:1 Histological studies on post-embryonic development of the digestive system of the P.teiraCollect the fertilized eggs of the P.teira brood stock.The fertilized eggs are hatched in a hatching net,and the larvae are raised in a high-position pond.The tissue section technology was used to observe the morphology and structure of the digestive tract of larvae 1-30 days after hatching.The results showed that the larvae were cultivated in outdoor high ponds,the water temperature was 27-30?,the salinity 30‰,and the dissolved oxygen 5.0-5.50mg/L,p H 8.2-8.4,ammonia nitrogen content <0.02mg/L,nitrite content <0.005 mg / L,the oral cavity of the larvae was closed for 1 day,its digestive tract was close to the abdominal wall and had not differentiated,and the volume of yolk sac Larger,HE stained dark red.The larvae were fed from the opening on the 4th day and entered a mixed period of endogenous nutrition and exogenous nutrition.The digestive tract communicates with the outside world,the yolk sac gradually decreases to disappear,and then the esophagus,stomach,and intestines are gradually differentiated into inherent components,and the function is gradually perfected.With the development of the digestive tract of 25-30 days larvae,the tissue structure is basically similar to that of adult fish.The digestive tract consists of a mucosal layer,a submucosal layer,a muscular layer and an outer membrane.The number of mucosal folds,mucosal epithelial cells,and gastric glands in the digestive tract is increasing among larvae,juveniles,and juveniles,indicating that the development of the digestive system of P.teira is related to the growth,morphology,and development of juveniles.Consumption of food,metabolism,and function are consistent,and its developmental stages are also compatible with the stages of the early developmental stages of the P.teira.2 Observation of the post-embryonic development of the P.teira skeletonFor larvae 1-30 days after hatching,10% neutral formalin was used for preservation.After processing the samples,the larvae were stained with the Alixinlan-Xisuhong staining method.The results showed that the total length of the newly hatched larvae of the P.teira was 2.75 ± 0.10 mm,and Mickel's jaw on the 2 day after hatching began Appears,indicating that bones are beginning to differentiate.The spine bones of the larvae did not begin to differentiate and the appendage bones did not appear 3 days after hatching.Only one spinal cord was tubular,and the larvae only relied on the spinal cord to support the body structure.The upper jaw began to differentiate in 4 day larvae(body length 3.3 ± 0.1 mm),and the same time,the outline of the bones became clearer.On the 7 day,the left and right tailstocks began to rise,and fuzzy fins began to appear,and the inferior tailbone appeared.At this stage,the inferior tailbone appeared as the first batch of tail bones.On 10 day larvae(body length 9.7 ± 0.1 mm),the tail rod bone has been formed here,at the same time the myeloid arch and vein arch on the tail spinal cord began to appear in the form of cartilage tissue.On 15 day(body length 13mm),the end of the tail bone of the larvae had been upturned,and the dorsal ribs,abdominal ribs,spinal spines,and spines of spines formed around this period.Segmented hard bone rings appeared at the front and back of the spine on the 23 dph,and juveniles began to ossify,and the medullary arch,venous arch,abdominal ribs,dorsal ribs,medullary spine,and vein spine all had hard bones at the base toward the distal end Into.On 30 dph,the larvae(28mm in length)have reached the juvenile stage.The pectoral fin,dorsal fin,ventral fin,anal fin,and all appendage fins are fully developed,the bone ossification is almost complete,and the larva metamorphosis is complete.3 Study on the growth curve model of P.teiraThe growth and development of fish usually have non-linear characteristics,and non-linear mathematical models can be used to describe their changing laws.In this study,the Logistic model,Gompertz model,and Bertalanffy model were used to fit the body length,height,full length,and body mass of the P.teira.The fits of full length and body weight are above 0.990,indicating that all three models can better simulate the growth curves of body height,body length,full length and body weight of finless finfish.However,considering the inflection point month age,inflection point weight,maximum monthly growth,and maximum growth,the Gompertz model of these three models has the best simulation of body height,length,full length,and weight,and the degree of fit(R2)They are 0.992,0.995,0.990,and 0.996,respectively.The limit growth(A)is 29.375,48.426,54.732,and 947.456.The inflection point month ages are 3.27,7.28,6.60,8.88,and the inflection point body weight or weight are 10.81,17.82,20.14,826.70,the limiting growth rates(K)were 0.210,0.119,0.129 and 0.220,respectively.This experiment reveals the growth and development rules and growth characteristics of the P.teira,and provides theoretical basis for the management and feeding strategies of the P.teira. |
PDF Full Text Request