Polymorphisms in the growth hormone (GH) gene that is associated with the growth rate of farmed fish have been the target of many breeding programmes. The present study aimed to identify single nucleotide polymorphisms (SNPs) in GH gene regions to evaluate the association of SNP variations with the growth rate of two Nile tilapia: Oreochromis niloticus (Linnaeus, 1758) strains. The targeted regions were amplified, sequenced, aligned and screened for the presence of SNPs; thereafter, performance tests were used to check for the association between SNPs and weight. Allele and genotype frequencies were estimated for each SNP and genotype. Genotype blocks or sets of SNP genotypes and frequencies were also estimated. Association between SNPs and growth rate was statistically evaluated using a univariate linear mixed model that included both fixed and random effects. A total of 10 SNPs were identified, nine in the proximal promoter and one located in the 5′ UTR, forming 10 genotype blocks. In all weight recordings, five genotype blocks were significantly associated with the highest weights. Single nucleotide polymorphisms 6‐10 were also found to be significantly associated with growth (p‐value < .05). Genotypes with higher additive genetic values for weight were identified in the Chitralada strain, suggesting a possible impact of these additive effects of the GH SNP genotype on the growth rate of Nile tilapia. These findings may be used as part of marker‐assisted selection in tilapia breeding programmes.
With the purpose of evaluating the changes and the degree of heterosis on performance and carcass traits of fish from the diallel crossing between Pacu and Tambaqui, four genetic groups were generated through hormonal induction: pacu, tambaqui, tambacu and paqui. For 196 days, 400 juveniles of each genetic group were stocked in a pond divided into four parts of equal size, one for each group. At the end of this period, when the fish weighed on average 1024 g (±115.52 g), 20 specimens of each genetic group were sampled, weighed, measured: head length; standard length; body height; and width; and also processed resulting in following body yield: viscera; carcass; head; fillet; rib; residue and skin yields. There was positive heterosis for body weight, viscera and skin yield and head measures and negative heterosis for carcass and filet yield and body width, indicating that the hybrids have better performance on weight gain, but are inferior in relation to the carcass conformation
-The objective of this study was to evaluate the morphometric growth and weight gain of strains of tilapia (Thai, Red, UFLA and Commercial) by nonlinear models. Initially, 500 male fingerlings of each strain, at 85 (Red and UFLA) and 86 (Thai and Commercial) days of age, were stocked separately in raceways with 56 m 3 . Twenty fish of each strain were randomly sampled, weighed and measured monthly. Five nonlinear models (Brody, von Bertalanffy, Gompertz, logistic and exponential) were tested, choosing one that best fit to the data. The variables studied were: weight, standard length (SL), head length (HL), height 1 (H1), height 2 (H2), height 3 (H3), first distance (D1), second distance (D2), first width (W1), second width (W2) and third width (W3). The exponential model had the best fit to weight and morphometric data, with the exception of W2, in which the best fitted model was von Bertalanffy. The convergence of the exponential model to data indicates that the cultivation period studied was not enough for the strains to reach maturity weight. The UFLA strain presented the lowest value for parameter "a" (initial weight estimate), 8.71 g, and the highest for parameter k (specific growth rate), 0.0127, when compared with other evaluated strains. However, the highest k of UFLA was not enough to overcome the final weight observed for the Commercial strain (603.1 g), which was higher than all other strains. Regarding the morphometric measurements, the UFLA strain also had the highest k for the variables SL, HL, HH, H1, H2, H3 and D2, and similar k to Commercial and Thai strains for the variables D1 and W3 respectively. The strains differ as to weight gain and morphometric growth.
The majority of tilapia farming is used for the production of fillets, resulting in the generation of waste that can be used to increase food stocks by producing minced fish. The aim of this study was to characterize and evaluate the viability of boiling and mechanical techniques for obtaining minced fish in relation to performance, physical-chemical and microbiological parameters and to reduce the waste generated in the process of filleting Nile tilapia. Based on performance outcomes, the mechanical technique proved to be 12% more efficient than the boiling one. The cost of the boiling technique was higher due to performance and operating costs. On both techniques microbiological alterations were not observed. Centesimal analysis results showed a difference in humidity between the techniques, which was expected due to loss of water during the boiling process, which possibly also affected protein levels. Dver all, the use of a deboning machine allied lower operating cost, better performance, quality and practicality. The debone machine technique it's feasible considering the large volume of waste generated daily on fish farms, which requires a speedy and effective disposal. Further, makes possible obtaining a nutritional raw material of high added-value and contributing to the reduction of environmental impacts.
Com o aumento da produção de tilápias em sistemas superintensivos, o número de casos de doenças bacterianas nesses peixes vem aumentando significativamente. O produtor acaba não encontrando meios de detecção e diagnósticos precisos para as doenças que acarretam na mortalidade de praticamente toda a produção. O uso indiscriminado de antibióticos e outras drogas têm selecionado espécies mais resistentes de microorganismos e o número de pesquisas sobre vacinas tem apresentado um crescimento significativo nos últimos anos, porém sem grandes sucessos. O manejo e a seleção de espécies de peixes mais resistentes vêm sendo usada como uma boa forma de prevenção de doenças bacterianas. Esta revisão objetivou-se em descrever sobre as principais bactérias encontradas peixes de agua doce no Brasil, mostrando suas principais características e estudos realizados.
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