Determinação de desempenho zootécnico e morfometria de linhagens de tambaqui (Colossoma macropomum) melhorados geneticamente

Abstract

The genetic improvement of tambaqui Colossoma macropomum aims to boost the production of this species in the country, as it was developed to increase the growth rate of this fish. The objective of this work was to evaluate the zootechnical performance and morphometric characteristics of 3 genetically improved tambaqui strains in relation to unimproved fish and to analyze the impact of genetic improvement on the 122 days of breeding time for the production of 500g average weight curumim tambaqui. The juveniles used for this study come from the mating of 6 breeders (3 males and 3 females) of the AquaBrasil Genetic Improvement Program that formed the treatments (strains A, B and C) for the control group unimproved breeders. A total of 160 juveniles were identified by microchips, 40 fish from each improved strain and 40 unimproved fish (control). A total of 160 juveniles were identified by microchips, 40 fish from each improved strain and 40 unimproved fish (control). They were housed in a 600 m² excavated pond with a density of 0.26 fish. m². The juveniles started the experiment with an average weight of 58.08 ± 24.44g and total length of 17.73 ± 1.72 cm. They were fed commercial diet with crude protein levels that decreased each month: 36, 32 and 28%, being fed twice a day (8:00 and 17:00 hours), the dietary rate ranged from 7-2% of the diet biomass. Monthly biometrics were performed to obtain weight and body measurements such as total length, pattern, head length, height and body width. Data were subjected to analysis of variance and Tukey test (5%). The survival rate was 100%. Line B presented the lowest average for weight gain (808, 70g), differing from lines A (873.73g), C (886.41g) and control (875.45g), which did not differ from each other. Fishes of strain C showed the highest average for specific growth rate (2.52%) showing a higher growth. For morphometric characteristics, line B obtained the lowest body conformation, but presented difference for the morphometric ratio body width / standard length, however it was the same as line C, which presented the best body conformation and the largest relationship between head length and standard length. Even with these differences, the 3 improved tambaqui strains, as well as the unimproved fish, exceeded the established weight of 500g in 122 days of rearing. However, for the continuation of the Tambaqui Genetic Improvement Program in Amazonas, we suggest the use of C strain fish that showed better results among the improved strains.