Body yield and quality of fresh and post-freezing filet of Nile tilapia (Oreochromis niloticus) genetic groups.

The aim of this study was to evaluate the body yield and quality of fresh and post-freezing filet of male and female fish of inbred and non-inbred AquaAmérica genetic group and the hybrid between the AquaAmérica and Tilamax varieties. Forty fish (20 males and 20 females) of each genetic group were housed in four 48-m3 hapa net cages, getting 120 fish per cage. The fish were housed at 51 days of age and farmed for 269 days. Pre-slaughter weight was higher (P<0.05) in the AquaAmérica × Tilamax males (0.805±0.204 kg) than in the inbred AquaAmérica male (0.643±0.115 kg). Filet yield percentage was higher (P<0.05) in the AquaAmérica × Tilamax males (32.14±4.72%) than in the inbred AquaAmérica (28.15±2.67%) and non-inbred AquaAmérica (29.06±2.80%) males. Head and viscera yield percentages, pH, color values (L*, a* and b*), shear force, drip loss and cooking loss did not differ significantly between the genetic groups and sexes. Alterations in meat quality were observed after freezing. In conclusion, inbreeding in the AquaAmérica variety resulted in reduced slaughter weight for males; AquaAmérica × Tilamax males have a higher filet yield; and filet quality is not influenced by crossing, inbreeding, or sex, but is changed after freezing.

Weight and body yield of selectively bred tambaqui (Colossoma macropomum) farmed in different environments.

The objective of this study was to evaluate the weight and body yield of two families of selectively bred tambaqui farmed in different environments. Two families (FA and FB) were reared in the municipalities (environments) of Santo Antônio de Leverger (MT) and Campo Grande (MS) for 431 days. Pre-bleeding weight, body yield, and the interaction effect between families and environments on these traits were investigated. No interaction effect between the evaluated families and environments was detected on the evaluated traits. Pre-bleeding weight did not differ significantly between the families in MT (FA: 2,421.7g; FB: 2,478.0g) or in MS (FA: 1,138.7g; FB: 1,389.8g), but the fish from MT had a higher (P<0.05) pre-bleeding weight than those farmed in MS. The visceral fat yield (considering the two environments) was higher (P<0.05) in FB family (3.8%) than in FA family (3.3%).Fish from MS showed higher (P<0.05) offal yield (10.6%) and visceral fat yield (3.9%) but a lower clean-trunk yield (70.6%) than the tambaqui farmed in MT (offal: 7.7%; visceral fat: 3.1%; and clean trunk: 72.6%). In conclusion, the MT environment provides higher pre-bleeding weight and clean-trunk yield and lower offal and visceral-fat yields than the MS environment.