Impact of feeds on developement of the digestive system of burbot (Lota lota Linnaeus, 1758) reared in aquaculture

Abstract

U ovom radu analiziran je utjecaj prehrane na razvoj probavila mlađi manjića (Lota lota Linnaeus, 1758) uzgojenih u recirkulacijskom sustavu akvakulture. Prehrana ličinki manjića temelji se na hranjenju živim organizmima, najčešće račićima artemijama, nakon čega se prelazi na hranjenje umjetnom hranom. Cilj ovog istraživanja je utvrditi razlike u razvoju probavila mlađi manjića uzgojenih u akvakulturi s obzirom na razdoblje prelaska na umjetnu, suhu hranu. Promjene u prehrani kao prelazak sa žive na umjetnu hranu mogu uzrokovati visoku smrtnost među jedinkama.U radu su analizirani histološki preparati poprečnog presjeka stražnjeg crijeva u 72 ličinke manjića uzgojenih u mrjestilištu edukacijsko-istraživačkog postrojenja AQUA-ERF iz Zele, Belgija. Uzorkovane jedinke bile su podijeljene u dvije skupine s obzirom na početak prehrane umjetnom hranom: 1) u 6. tjednu života i 2) u 8. tjednu života. Histološki preparati su obojani kombinacijom hematoksilina i eozina, te selektivnom metodom za vrčaste stanice kombinacijom perjodne kiseline i Schiffovog reagensa (PAS) te alcijanskim modrilom (AB). Mjerene su dužina i težina tijela, površina sluznice i visina epitela te je kvantitativno određen udio vrčastih stanica po površini sluznice i udio AB i PAS pozitivnih vrčastih stanica. Masa i težina tijela, površina sluznice, visina epitela, udio vrčastih stanica i AB vrčastih stanica pozitivno su korelirali sa starošću ličinki u obje istraživane skupine. Ličinke koje su prešle na umjetnu hranu u 8. tjednu života bile su bolje prilagođene novom načinu prehrane na što ukazuju kvantitativne histološke analize probavila,te povećani somatski rast analiziranih jedinki manjića.This study describes impacts of feeds on development of the digestive system of burbot larvae (Lota lota Linnaeus, 1758) reared in recirculatory systems in aquaculture. The larvae diet starts with feeding larvae living prey and after they switch to manufactured diet which affects the mortality rate. Because of it, the aim of this experiment was determinate the period of weaning start, considering the development of the digestive system. In this study, histological sections of the posterior gut from 72 burbot larvae reared in hatchery in education and research facility from Zele, Belgium were analysed. Sampled larvae were divided into two groups: one group started weaning process in 6th week of life, where the second one started weaning in 8th week of life. The sections were stained with hematoxilin and eosine, combined periodic acid and Schiff reagens (PAS) and alcian blue (AB). The whole body length, wet body weight, the mucosa surface and epithelia height were measured, and goblet cells per mucosa and AB and PAS positive goblet cells were counted. Whole body length, wet body weight, the mucosa surface and epithelia height, count of goblet cells per mucosa measured and count of AB and PAS positive goblet cells positively correlated with the larvae age in both groups. The larvae that started with early weaning in 8th week showed a better growth in length and weight