Effects of lactococcus lactis and bacillus sp. on hatchery performance of Rainbow trout (oncorhynchus mykiss) eggs until larval stage

Abstract

In this study, the effect of Lactococcus lactis and Bacillus sp. (Gram-positive bacteria) on survival rates of rainbow trout (Oncorhynchus mykiss) from egg to larval stage was investigated. In addition, the effects of bacteria on the blue sac syndrome in the fry stage of fish and basic water quality criteria were also noted. Bacteria were applied by immersion method to healthy-eyed eggs during the incubation period. Two bacteria and the control group were examined in a duplicated plan. The highest survival rate was 92.5% observed in the Bacillus sp. group (L. lactis; 70% and control; 45%). The lowest survival rates in all groups were observed during the alevin stage. It was found that the amount of nitrite in the water decreased in the bacteria-applied groups, and it was determined that the effects of blue sac syndrome (caused by the pathogen A. hydrophila) were suppressed in the Bacillus sp. group.

Bu çalışmada Lactococcus lactis ve Bacillus sp. (Gram-pozitif bakteri) uygulamasının gökkuşağı alabalığının (Oncorhynchus mykiss) yumurtadan larva dönemine kadar yaşama oranları araştırıldı. Ayrıca çalışmada balıkların yavru aşamasında mavi kese hastalığı üzerine bakterilerin etkileri ve temel su kalitesi kriterleri de not edilmiştir. Bakteriler kuluçka döneminde sağlıklı gözlü yumurtalara daldırma yöntemiyle uygulandı. İki bakteri ve kontrol grubu, iki tekerrürlü deneme planında incelendi. En yüksek hayatta kalma oranı Bacillus sp. grubunda (L. lactis; %70 ve kontrol; %45) %92.5 ile gözlendi. Tüm gruplarda en düşük hayatta kalma oranları alevin döneminde gözlendi. Bakteri uygulanan gruplarda sudaki nitrit miktarının azaldığı, Bacillus sp. grubunda ise mavi kese sendromunun (patojen etken A. hydrophila) etkilerinin baskılandığı belirlendi