Slaughter Yield and Weight of Body Segments in Rainbow Trout (Oncorhynchus Mykiss) Reared in two Different Growth Systems

Abstract

Slaughter yield is one of the most important indices of meat production, which in the current legislation, dealing with employment în quality classes and to establish the commercial value of fish or other animals. To make our research, were slaughtered by mechanical stunning, 25 rainbow trout (Oncorhynchus mykiss), from Fiad trout farm, Bistriţa-Năsăud County (M group), respectively 25 rainbow trout from an recirculating system arranged in Cluj-Napoca (E group). The average weight of the studied specimens was similar (228.96±1.21 g-M group, respectively 229.40±1.24 g-E group; d= -0.44 g, p>0.05). Slaughter yield obtained in the goup M was 89.23±0.05%, and in the group E 90.55±0.03%. Results showed that in gravimetric terms, the differences are insignificant between the two groups (d=3.43 g, p>0,05), but in percentage terms, the differences are negative and very significant (d=1.32%, p<0.001). In our opinion, this yields in good for both groups, and demonstrates that the biological material is valuable, and applied technology is optimal in both growth systems. In terms of weight of body segments, the results expressed significant differences for all elements studied, both in terms of gravity and percentage. Thus, if viscera (taken as a whole), the mean value of weight was 24.71±0.19 g (M group), respectively 21.67±0.12 g (E group), resulting a negative and very significant difference (d=3.04 g; p<0.001). In percentage terms, in M group the internal organs and the viscera represents 10.78±0.05% from the initial weight of fish, and in the case of E group, they were 9.44±0.03%, resulting a negative and very significant diferrence between the two groups (d=1.34%; p<0.001).