Histological evaluation of soya bean-induced enteritis in Atlantic salmon (Salmo salar L.): Quantitative image analysis vs. semi-quantitative visual scoring

• A novel histological assessment system based upon image analysis, was described and evaluated.
• This analytical methodology can evaluate the extent of morphological changes occurring in the distal intestine of Atlantic salmon following dietary modulation.
• Such tool can be conducted with minimal user-interaction, thus allowing rapid and objective assessment of continuous variables per histological frame analysed.
• This method shown excellent reproducibility and accuracy performance levels, when compared to analogous well-established semi-quantitative assessments.
• This approach can provide a viable alternative to a pathologist's manual scoring, being more practical and time-efficient.

This paper describes a first broad-scale application of quantitative image analysis to the assessment of nutritionally-induced soya bean enteritis in farmed Atlantic salmon. It employs a novel multivariate approach for the histomorphometric analysis of biopsy samples and directly compares the prognostic value of such a quantitative approach against that of a semi-quantitative visual scoring system.This study provides evidence that most of the quantitative indices selected, perform equally well when compared to analogous semi-quantitative descriptive parameters normally used to assess soya bean-induced enteritis seen in Atlantic salmon. The high reproducibility and accuracy of this approach indicate that image analysis can provide a useful and reliable method for the quantification of SB-induced enteritis and by extension, for other facets of gut plasticity/histopathology. Other characteristics of this approach, such as rapidity, simplicity and adaptability similarly favour the use of image analysis, and are particularly useful where less experienced interpreters are performing the analysis. The quantitative assessment system outlined here, clearly identifies soya bean-associated enteropathy in experimental fish, and may thus be recommended for evaluation of related variations in salmon intestinal histomorphology.