[Evaluation of the protein quality of meat flour from the tollo shark (Squalus acanthias)].

The protein quality of tollo flour evaluated by various biological methods, including digestibility, is reported. The product contained 91.52% crude protein and 69.86% true protein, the difference being non-protein nitrogen, mainly urea. Due to this reason the biological evaluations were carried out with different shark flour concentrations and evaluated at different lengths of time with each method. Diets containing 0, 3, 6, 9 and 12% shark flour were prepared and evaluated by the PER, NPR, and NGI methods. Casein was used as reference protein. The protein digestibility was 91.2%, not corrected for non-protein nitrogen. On this same basis, PER and NPR--at a protein level of 9.97% in the diet--were 2.58 and 2.05, respectively. The casein control diet gave a PER of 2.93 and an NPR of 4.52. NGI was calculated by using the non-protein diet, or without it, with values of 3.32 and 2.95, respectively. As expected, all values corrected for non-protein nitrogen were higher for protein digestibility. The differences were significant at the 5% level. Apparently, urea influenced negatively the biological evaluations. It can be concluded, therefore, that the tollo shark meat is of excellent quality.