The aquaculture sector plays a vital role in global food security, yet it grapples with significant challenges posed by infectious diseases. Piscine lactococcosis represents a major threat in rainbow trout farming, as it can lead to severe economic losses through increased mortality rates, decreased growth, and heightened vulnerability to additional pathogens. This situation complicates disease management approaches, affecting the sustainability and profitability of rainbow trout aquaculture.
The study investigates the changes in serum blood parameters in farmed rainbow trout (Oncorhynchus mykiss) during an outbreak of piscine lactococcosis caused by Lactococcus garvieae. Blood samples were collected for biochemical analysis, and the fish were screened for parasites and bacteria. DNA from the isolated bacterial colonies was subjected to PCR amplification and sequencing for identification. A total of thirteen biochemical parameters, including proteins, enzymes, lipids, chemicals, and minerals, were assessed in serum samples from both infected and healthy fish.
The findings demonstrate significant variations in the levels of these parameters during the outbreak, underscoring the effects of infections on the blood profiles of rainbow trout. Specifically, urea concentrations were higher in infected fish compared to healthy controls, with creatinine, phosphorus, and magnesium exhibiting similar patterns. Conversely, alanine aminotransferase and total protein levels were elevated in the control group. There were significant differences in chloride levels between the two groups, while iron concentrations were found to be higher in the controls and lower in the diseased fish. Other parameters did not show significant differences.
This study highlights considerable changes in serum blood parameters of rainbow trout during an outbreak of lactococcosis caused by L. garvieae. These alterations suggest that these parameters could serve as indicators for monitoring health status, stress levels, and aquaculture management. Ongoing monitoring can provide valuable insights into disease severity and overall fish health, assisting in the formulation of enhanced management strategies. The results contribute to a deeper understanding of the pathophysiology of piscine lactococcosis and the development of effective intervention measures for farmed rainbow trout.