An analysis of refractometry as a method of determining blood total protein concentration in the American lobsterHomarus americanus(Milne Edwards)

Abstract

Given the high unit value of live American lobsters (Homarus americanus), a non-destructive field method to assess physiological state is desirable during out-of-water transport conditions. This study compared an Uricon® specific gravity refractometer, with a commercial veterinary blood analyser (Vet-Test), as a method for determining the blood total protein concentration in live, out-of-water individuals. Regression analysis of R2 = 0.8641 (n = 64) was observed in determination of blood total protein concentration, y = 0.0036x + 1.0163 where x is the protein concentration in mg dL−1 in Vet-Test. Our results (R2 = 0.864, SE ± 0.003) support the results (R2 = 0.985) of the previous study conducted by Leavitt & Bayer (1977) in which serum total protein was compared with the refractometric method. We therefore confirm that the refractometric method can be used as a reliable method to indicate health of a lobster by measuring the blood total protein concentration. The results show good correlation between the protein concentrations observed using the refractometric method and a Vet-Test blood chemistry analyser. anova analysis was significant between the protein refractometer and the Vet-Test (P < 0.05). Although protein concentration units obtained from both methods were different the results followed the same trends. Refractometry as a method is reliable to determine blood total protein concentrations in the American lobster. Consequently, a refractometric method can be used directly by commercial growers and distributors to assess responses to holding facility conditions and to feeding regimes. Whole blood protein concentrations may provide more information than serum protein concentrations as measured in the study of Leavitt & Bayer (1977).