Niloticus Strains Research Articles

Performance of Oreochromis niloticus and Oreochromis andersonii in controlled laboratory conditions in Zambia

In the present study, two hatchery strains of Oreochromis niloticus and two of O. andersonii sourced from different hatcheries in Zambia were subjected to the same feeding and management regimes in a controlled indoor tank environment. All strains were stocked at a mean weight of 2.1 ± 0.01 g and harvested after 175 days. Mean final body weight at harvest for the two O. andersonii groups was 65.2 ± 31.5 g and 73.8 ± 38.5 g, which was significantly (P < 0.05) lower than those for the two O. niloticus groups at 178.5 ± 74.7 g and 187.8 ± 73.6 g. There was no significant difference in body weight at harvest between hatchery strains within either species. The mean specific growth rate (SGR) and the daily growth coefficients (DGC) had similar patterns with the O. niloticus strains DGC values more than one and half times those of O. andersonii. The high survival values within all groups (range 86–96 %), their good condition factor index values (range 3.2–3.5) and lack of significant differences between species indicated the experimental conditions were suitable for both species and provided a valid test of their relative growth. Food conversion ratios (FCRs) for O. niloticus of 1.22 ± 0.11 and 1.07 ± 0.05 were significantly (P < 0.05) better than for O. andersonii of 1.81 ± 0.10 and 1.84 ± 0.18. The experiment provided rare well-controlled data comparing the growth performance of these species and different hatchery strains in Zambia, as a contribution to better informing investment decisions for the aquaculture industry there and in Southern Africa.

Genetic Variability of Nile Tilapia Strains as Determined by Microsatellite DNA Markers

AbstractThe main purpose of the present study was to investigate the genetic variability of Nile Tilapia Oreochromis niloticus strains by using microsatellite DNA markers and to compare these data with those previously obtained with single‐nucleotide polymorphisms (SNPs). Five mixed‐sex strains and four YY‐male strains were analyzed. All nine microsatellite loci were polymorphic; the number of unique alleles per locus varied from 6 at UNH216 to 33 at UNH880. Strong correspondence was observed between the level of expected heterozygosity (He) or observed heterozygosity and the number of alleles per locus (A) or the number of private alleles. Strains with high levels of heterozygosity typically had higher values of A and the presence of private alleles. In general, mixed‐sex strains had higher genetic variability than YY‐male strains. Four mixed‐sex strains (GIFT, Ismailia Canal, LSA hybrid, and Miami) had the highest level of genetic variability, with mean He ranging from 0.630 to 0.798 and mean A ranging from 5.11 to 9.78. Three YY‐male strains (Fishgen YY Dark–Group 2, Fishgen YY Red, and Til‐Aqua YY) had low genetic variability, with mean He ranging from 0.282 to 0.367 and mean A ranging from 1.89 to 3.56. All investigated strains demonstrated low values of the inbreeding coefficient FIS (from –0.266 to 0.014), suggesting that mating of closely related individuals is being avoided during maintenance of these strains. Pairwise genetic differentiation index FST values had a broad range (from 0.0915 to 0.6063), indicating different levels of genetic differentiation between strains. A dendrogram constructed according to shared allele distance showed the existence of two distinct clusters among strains. The present data on genetic variability of Nile Tilapia strains demonstrated substantial similarity with data from a previous study of SNPs in the same populations.

Evaluation of growth, sex (male proportion; sexual dimorphism), and color segregation in four cross combinations of different strains of XX female and YY male Nile Tilapia

AbstractFour cross combinations of different YY male and female Nile Tilapia Oreochromis niloticus strains were evaluated for growth, sex, and color segregation. Red color parental strains included blotched phenotypes. The Genetically Improved Farmed Tilapia (GIFT) was the only dark (wild‐type) color parental strain. Fish of the same age and cross were stocked in three replicate tanks for four crosses in one recirculating system for 167 days. Data recorded included feed consumed, body weight, total length, color, sex, and fillet weight. YY males crossed with GIFT females (Cross 2) exhibited superior growth that was significantly different (p &lt; .05) to other three crosses. Male proportions were 79–100%. Only YY males crossed with the LSA female strain (Cross 4) yielded 100% males, but, Cross 4's productivity was inferior to that of Cross 2. Body weight advantage of males over females was 28.7–84.2%. Color segregation indicated that red color trait in Nile Tilapia is autosomal dominant, and black patch coverage was variable. This study showed that different parental strain combinations clearly impact productivity traits, and that YY male technology combined with crossbreeding provide the opportunity for genetic improvement and development of commercially beneficial superior traits in Nile Tilapia.

A duplication of the Anti-Müllerian hormone gene is associated with genetic sex determination of different Oreochromis niloticus strains.

Sex determination (SD) mechanisms are ancient and conserved, yet much diversity is exhibited in primary sex-determining signals that trigger male or female development. In O. niloticus, SD is associated with a male-specific locus on linkage group (LG) 23 which harbors the Y-linked Anti-Müllerian hormone (amh) gene, and a truncated duplication, denoted amhΔy. We have evaluated the possible role of identified indels and SNPs in the amh gene on SD, based on conservation in different O. niloticus strains. A fluorescent assay for the detection of a 5 bp insertion in amhΔy exon VI, efficiently discriminated between XX, XY, and YY genotypes. Concordance rate between amhΔy and sex varied in six Oreochromis strains, from 100% (Ghana) through 90% (Swansea) to 85% (Thai-Chitralada). The association of amhΔy with sex was found to be conserved in all tested O. niloticus strains, and thus supports its key role in SD. However, the previously identified missense SNP (C/T) in amh exon II was found only in the Swansea strain, thus excluding its candidacy for the causal variation of SD across all strains. Effects of markers on LGs 1, 3, and 23 (amhΔy) fully explained sex distribution in one Thai-Chitralada family (R2 = 1.0), whereas in another family only the major effect of LG23 (amhΔy) was significant (R2 = 0.37). Thus, amhΔy on LG23 is associated with genetic SD, either as a single causal gene in different O. niloticus strains, or in combination with segregating genes on LGs 1 and 3 in the Thai-Chitralada hybrid strain.

Single‐Nucleotide Polymorphism Discovery and Genetic Variation in YY‐Male and Mixed‐Sex Strains of Nile Tilapia Available in the United States

AbstractThe present study was focused on the discovery of single‐nucleotide polymorphisms (SNPs) and measuring genetic variation in three YY‐male and five mixed‐sex Nile Tilapia Oreochromis niloticus strains, which are available in the United States. We performed restriction site‐associated DNA sequencing for SNP discovery and genotyping. Overall, 31,813 SNPs were identified and used to measure both intra‐ and interstrain genetic variation. Mean expected heterozygosity (He) ranged from a low of 0.084 in the Miami YY strain to a high of 0.222 in the Miami mixed‐sex strain. Two of the three YY groups (Miami YY and Fishgen YY Red) had the lowest He values (0.084 and 0.085, respectively) and the second‐ and third‐lowest observed heterozygosity (Ho) values (both Ho = 0.107). The number of private alleles varied from 90 to 3,795 in different strains and tended to increase with increasing He. Inbreeding, as measured by FIS, was found to be low in all populations, ranging from −0.060 ± 0.004 (mean ± SE) in the Fishgen YY Dark strain to 0.04 ± 0.0093 in the GIFT (Genetically Improved Farmed Tilapia) strain; this indicates that the analyzed strains are currently being maintained with approximately random mating of individuals. Genetic differentiation between populations, as measured by pairwise FST, ranged from little differentiation (FST = 0.06 for the Ismailia Canal and GIFT strains) to strong differentiation (FST = 0.32 for the Miami YY and Lake Manzala strains). The discovered SNPs and quantification of genetic variation can be used for parentage determination and high‐throughput pedigree reconstruction as well as for determining the optimal interstrain crosses to achieve heterosis.

Performance of Nile tilapia Oreochromis niloticus strains in Brazil: a comparison with Philippine strain

ABSTRACT The aim of this study was to evaluate the performance of three Nile tilapia strains in Brazil compared to Genomar Supreme™ Generation 24 from the Philippines. Tilapia fingerlings, male population, of approximately 8 g which were cultivated in water recirculation systems containing 0.5 m3 tanks, density of 60 fish m−3, with four replicates (tanks). The fish will be fed three times a day with the same commercial feed for each particular growth phase according to biomass in each tank. Five fish from each tank were sampled at the start and 60th, 120th, 180th and 240th days of cultivation. They were determined the weight gain, feed conversion and homogeneity of batch in each period. The Gompertz model given by was fit and it was calculated the absolute and relative growth rate. The weight and age at inflection point were calculated too. The improvement programme from Genomar in the Philippines brings tilapia strain with better growth rate and performance when compared with the one commercialized in Brazil. This Philippine strain constitutes an important potential to improve tilapia farm in Brazil. However, the use of this genetics needs to be accomplished in this country.

Intestinal proteome response to salinity stress in three tilapiine spp

Chronic salinity stress is likely to have significant impacts on organismal performance, especially near the upper bounds of the Critical Salinity maximum (CSmax), the “zone of resistance”. Some euryhaline fish species maintain stable internal osmolality over great salinity ranges, while close relatives tolerate much narrower ranges. Greater tolerance ranges have also been linked to reduced growth under optimum conditions. For example, breeding for improved growth rates in the tilapia species Oreochromis niloticus has inadvertently resulted in decreased tolerance to hypersaline water conditions. To examine changes in growth and stress tolerance at the cellular and tissue levels, high salinity acclimation challenges were conducted for three cichlid species, including the previously mentioned O. niloticus with reduced salinity tolerance, wild‐type (WT) O. mossambicus which exhibit tolerance to salt concentrations greater than seawater, and WT Astatotilapia burtoni which exhibit low salinity tolerance similar in range to the O. niloticus strain. Three intestinal sections were sampled from salinity‐challenged fish at 90% CSmax, and from control fish maintained in freshwater, and used to establish a standardized data‐independent acquisition (DIA) assay for label‐free quantitative proteomics for a large number of proteins in each species. Spectral libraries created by data‐dependent acquisition (DDA) and annotated using multiple search engines were used for DIA assay construction. Skyline and a sample training set were used for automated and manual assay curation to select and validate reproducible transitions and proteotypic peptides for protein quantitation. Salinity effects on intestinal protein expression patterns in each species were statistically evaluated and corresponding protein sets analyzed for gene ontology enrichment. The resulting data on salinity‐dependent intestinal proteome dynamics provide insight into biochemical processes controlling growth and stress tolerance.Support or Funding InformationFunded by BARD and NSF Grant IOS‐1355098This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Growth Performance of Three Nile Tilapia (&lt;i&gt;Oreochromis niloticus&lt;/i&gt; L., 1758) Populations in Pond System

A 120 days study was conducted to evaluate the growth performances of juvenile Oreochromis niloticus from different lakes (Chamo, Tana and Hashengie) in pond culture system. Fingerlings of average weights 16.7, 15 and 16.9 g for O. niloticus from Lake Chamo, Lake Tana and Lake Hshengie, respectively were stocked at stocking density of 2 fish/m 2 with three replicates each. The treatment groups were fed formulated feed with 29% crude protein at 5% of their body weight per day. Final mean weight of Nile tilapia was highest ( p <0.05) for Lake Chamo (59.6 g) followed by Lake Hashengie (46 g) and Lake Tana (39.4). Daily growth rate (0.4 g per day), Specific growth rate (1.1% per day) and Food conversion ratio (2.5) of O. niloticus from Lake Chamo were significantly ( p <0.05) different from O. niloticus of Lake Tana and Lake Hashengie. On the other hand, O. niloticus from Lake Tana and Lake Hashengie had 0.2 g per day and 0.8% per day daily growth rate and specific growth rate, respectively. O. niloticus from Lake Hashengie was also significantly ( p <0.05) higher in its final mean weight (46 g) and mean weight gain (29.1 g) than O. niloticus from Lake Tana. On the other hand, there was no significant difference ( p <0.05) in the Specific Groth Rate and Food conversion ratio between O. niloticus of Lake Tana and Lake Hashengie. In conclusion, the result of the present study revealed that O. niloticus strain from Lake Chamo showed better growth performance compared to those from Lake Tana and Lake Hashengie. Based on the current result, we recommended O. niloticus strain from Lake Chamo can be considered for tilapia stocking and also for further strain selection programs.

Single nucleotide polymorphisms in the growth hormone gene ofOreochromis niloticusand their association with growth performance

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.

Strain performance of tilapia in freshwater prawn polyculture

Production performance of two tilapia (Oreochromis niloticus) strain viz. Chitralada and GIFT (Genetically Improved Farmed Tilapia) in fish-prawn polyculture system was compared, and possible effect of tilapia inclusion in freshwater prawn (Macrobrachium rosenbergii) culture was evaluated in 120 days of grow-out phase. There were three treatments, i.e. only freshwater prawn as control (T1), prawn + Chitralada (T2), and prawn + GIFT (T3) with three replications of each. Stocking densities for prawn juvenile was 30,000 ha-1 in all the treatments and for both tilapia strains were 10,000 ha-1. Floating feed containing 28% protein for tilapia and pelleted sinking feed for prawn were provided twice daily at a rate of 10-5% bw adjusted after each month of sampling. Water transparency was significantly lower (P&lt;0.05) in treatment T1 with significantly higher chlorophyll-? content that increased with progression of time. Along with, plankton abundance was significantly higher (P&lt;0.05) in T1 indicating prawn-tilapia mixed culture is better than traditional single species culture of prawn in terms of water quality management. Average individual weight, final weight, survival and production of prawn did not differ significantly (P&gt;0.05) among the treatments. In case of tilapia, average individual weight was significantly higher in Chitralada (254.22 g) than that of GIFT (201.52 g). However, survival of GIFT was significantly higher (92.50%) than that of Chitralada (65.83%). Gross and net production of tilapia did not vary significantly. It was concluded that prawn-tilapia mixed culture is advantageous over traditional mono culture regarding production augmentation, and tilapia inclusion improving water quality.J. Bangladesh Agril. Univ. 14(1): 127-134, June 2016

The development of genetically improved red tilapia lines through the backcross breeding of two Oreochromis niloticus strains

In order to develop a crossbred of Oreochromis niloticus with a high growth rate and coloration, a backcross breeding program was developed using Red-Stirling and Chitralada strains with 50%, 75%, and 87.5% of genic proportion to Chitralada. Seven genetic groups were obtained from Chitralada (C) and Red-Stirling (R): the hybrids F1, fish-female Red-Stirling×fish-male Chitralada (RC), and its reciprocal (CR), and the backcross breeding (BB1), fish-female CR×fish-male Chitralada (CR×C), and its reciprocal (C×CR) and BB2 [C(C×CR)]. Growth curves were adjusted using an exponential model for females and males. The curves show a distinct difference among genetic groups and between genders based on the backcross breddingapproach. The best ranking for red females was observed in BB1 [C×(CR)]. The gain observed is due to the action of a genetic additive effect of Chitralada (42.90g), a maternal effect of Chitralada (41.48g), and a non-additive effect, which is attributed to paternal heterosis (11.41g). While the best ranking for red males was found in BB2, The observed gain may be attributed to an additive genetic effect of Chitralada (74.04g) and maternal effect of Chitralada (57.68g). Survival among females was average. Among males, a higher mortality in the Red-Stirling group was observed compared to the other groups. These results indicate that the backcross breeding program can be used to develop genetic lines of red tilapia for further genetic breeding programs mainly exploring paternal heterosis to produce dams. Statement of relevanceThe present study proposes a breeding methodology based in robust statistical analysis to develop genetically lines of red tilapia.

Genotype by environment interaction for harvest weight, growth rate and shape between monosex and mixed sex Nile tilapia (Oreochromis niloticus)

In Kenya, Nile tilapia (Oreochromis niloticus) is mostly grown in ponds. To avoid excessive reproduction and stunted growth, fingerlings are treated with methyl-testosterone to make all-male populations (monosex). For a national breeding programme that aims to provide genetically improved broodstock to hatcheries that supply monosex fry to smallholder pond farmers, it is important to assess the genetic correlation (rg) for traits between the mixed sex breeding candidates from the breeding nucleus and monosex production fish. The purpose of the study was to estimate genetic parameters for harvest weight (HW), daily growth coefficient (DGC) and body shape and investigate genotype by environment interaction (G×E) for these traits between mixed sex and monosex populations. Forty-eight sires and 76 dams from the F2 generation of a local O. niloticus strain, kept at Sagana Aquaculture Research Station, Kenya were used to produce 76 full-sib families. Mixed sex fry (3days old) from each full sib family were divided into two groups of 50 individuals each. One group (monosex) was fed a diet treated with methyl-testosterone to induce sex reversal while the other group (mixed sex) was reared on a control diet. After hapa rearing, tagging and weighing, fish were randomly divided and stocked in six earthen ponds, three for mixed sex and three for monosex fish. After 5months, fish were harvested, photographed and weighed. Genetic parameter estimates for HW, DGC, and shape were obtained on 2105 fish. Heritability estimates for HW, DGC and shape were 0.21±0.03, 0.26±0.04 and 0.12±0.03 for mixed sex respectively. Genetic correlations for HW between monosex and mixed sex was 0.74±0.14, suggesting low G×E. The corresponding rg for DGC and shape were lower; 0.59±0.10, and −0.19±0.11, respectively, denoting the presence of G×E. It is concluded that G×E between the mixed sex nucleus and monosex production fish is important, and that a breeding programme for Nile tilapia needs to include production performance from monosex siblings. Statement of relevanceFirst study that reports estimates for Genotype by treatment interaction between hormone treated monosex Nile tilapia and mixed sex Nile tilapia, and discusses the consequences for nucleus breeding programmes.

Prolactin I Microsatellite as Genetic Markers for Characterization of Five Oreochromis Tilapia Species and Two Oreochromis Niloticus Strains

Hybrid tilapia is a major aquaculture food fish species in developing countries. The development of molecular markers to characterize and trace tilapia species is necessary to improve tilapia quality and enhance the competitive advantage of the aquaculture industry. Microsatellite markers have been suggested to assist breeding, species identification, and traceability system for tilapia. We used six microsatellites markers located within growth-related genes to discriminate between several tilapia species. We found that a combination of two microsatellites markers located within the proximal promoter of the prolactin I (PRL I) gene, PRL I-MS01 and PRL I-MS02, were able to discriminate between five Oreochromis tilapia species (O. mossambicus, O. aureus, O. niloticus, O. hornorum and O. spilurus) and two O. niloticus strains that exhibit the distinctive growth traits. Furthermore, we found that PRL I-MS01 microsatellite marker was able to trace parental origin of hybrid tilapia. Thus, this marker is a potentially beneficial tool for a tilapia traceability system. We conclude that the GT tandem repeats in PRL I-MS01 and CA tandem repeats in PRL I-MS02 are useful genetic markers to characterize diverse tilapia species, assist in the genetic tracing and conventional breeding of superior strains and strengthen the management of the tilapia aquaculture industry. There was strong relationship between the cold and both temperature at death and cumulative degree hours represented by negative correlation coefficient for all tested fish. There was no correlation between cold tolerance and fish size for all tested fish. The cooling degree hours were significantly different between the selected and non-selected O. niloticus (P<0.005). The selected O. aureus exhibited greater cold tolerance than the non-selected and death began at 14.1°C, while non-selected occurred at 15.2°C.

Evaluation of Nile tilapia strains cultivated in cages under different feeding programmes

The objective of this study was to evaluate the performance of three Nile tilapia Oreochromis niloticus strains cultivated in cages and subjected to different feeding programmes. Initially, 31,200 Nile tilapia juveniles with an average weight of 61.15 g were distributed in 48 cages. Two genetically improved strains were used together with one from the Fish Culture Section of Universidade Federal de Lavras (UFLA). The fish were subjected to four feeding programmes, consisting of different levels of crude protein (CP) in diets provided at different stages of cultivation. There was no interaction effect of the strain and feeding programme for most variables. The UFLA strain presented the highest weight gain, but with greatest lack of uniformity at the end of cultivation. The feeding programme with diets containing 36%, 32% and 28% CP, consecutively, promoted the highest weight gain and highest final biomass. The UFLA strain has great growth potential, justifying the development of a breeding programme for this strain. Crude protein levels below 36% for tilapias between 60 and 170 g and below 32% for tilapias between 170 and 700 g worsen fish performance.

Comparative Studies on the Growth Performance of Four Juvenile &lt;i&gt;Oreochromis niloticus&lt;/i&gt; L., (1758) Strains in Pond Culture, Ethiopia

This study was conducted to investigate and compare the growth performance of four juvenile Oreochromis niloticus strains in pond culture. The fish having an average body length of 9.18 cm and weight of 12.48 g were collected from Hawassa, Ziway, Koka, and Hora lakes. They were stocked in triplicate in 5.0 m × 5.0 m × 1.5 m concrete earthen ponds in 1 m water depth. The stocking density was 2 fish/m 2 . The fish were fed 3% of their body weight per day manually, twice a day with locally available feed having 23% crude protein. The results showed that the Koka strain had the best strain and had significantly (p < 0.05) higher final mean body weight (FMBW), mean body weight gain (MBWG), specific growth rate (SGR) and gross fish yield (GFY) than the Ziway and the Hora strains, but not from the Hawassa strain. The Koka stain had the best feed conversion ratio (FCR) with slightly higher Fulton’s condition factors (FCF). However, statistical analysis showed that there was no significant difference in FCF and FCR among the four strains. Except for the Ziway strain, all the strains revealed an isomeric growth pattern. The overall conclusion is that growth performance between the four strains of Oreochromis niloticus was significantly different and thus, it is crucial to select the right strain for aquaculture purpose. However, further research may still be needed to compare more strains from different Ethiopian lakes to evaluate the genetic potential for Oreochromis niloticus breeding program.

Polimorfismo no gene GH1-PstI associado a características corporais de linhagens de tilápia-do-nilo

O objetivo deste trabalho foi determinar a associação de polimorfismos no gene do hormônio crescimento GH1 às características corporais, em linhagens de tilápia-do-nilo (Oreochromis niloticus). Foram coletados fragmentos da nadadeira caudal de exemplares das linhagens, aos cinco meses de idade, para as análises de "polymerase chain reaction-restriction fragment lenght polymorphism" (PCR-RFLP). Foram realizadas as seguintes mensurações: comprimento total, comprimento padrão, altura, largura e comprimento da cabeça. Realizou-se a amplificação de um fragmento com 652 pb do gene GH1, com subsequente restrição com a enzima PstI. Para a análise de associação do marcador molecular com as características quantitativas, utilizou-se o procedimento GLM do SAS. O polimorfismo descrito para o íntron 1, do gene GH1 da tilápia-do-nilo, apresentou correlação significativa com o comprimento total, comprimento padrão, altura e largura corporal. Foi verificado que o genótipo PstI+/- está associado ao melhor crescimento, independentemente da linhagem. A associação verificada pode ter ocorrido em razão do efeito direto da regulação do próprio gene GH.

Desempenho de três linhagens de tilápia submetidas ao tratamento com 17-α-metiltestosterona em condições ambientais não controladas

Este estudo foi realizado para descrever o efeito da reversão sexual de linhagens de tilápia sobre as taxas de sobrevivência, o crescimento e o percentual de machos fenotípicos em condições ambientais variáveis. Foram utilizadas duas linhagens de Oreochromis niloticus (tilápia-do-nilo comum e tailandesa) e uma híbrida Oreochromis sp (vermelha), que receberam o hormônio masculinizante 17-α-metiltestosterona incorporado à ração (60 mg/kg) durante os primeiros 30 dias de vida. Aos 90 dias de idade, a taxa de sobrevivência da tilápia-do-nilo comum superou a da tilápia tailandesa em 39,00% e da tilápia vermelha em 22,70%, enquanto a taxa instantânea de crescimento foi similar nas linhagens comum e tailandesa e significativamente inferior na linhagem vermelha. O percentual de machos, de acordo com o exame de gônadas, decresceu na seguinte ordem: tilápia-do-nilo comum, tailandesa e vermelha. Em situações de oscilação de temperatura, a linhagem comum tem maior desempenho produtivo, mas são necessários estudos para comprovação da pureza genética e análise do manejo reprodutivo de linhagens de tilápia.

A YY-male Oreochromis niloticus strain developed from an exceptional mitotic gynogenetic male and growth performance testing of genetically all-male progenies

A YY-male Oreochromis niloticus strain developed from an exceptional mitotic gynogenetic male and growth performance testing of genetically all-male progenies

Genetic structure of domestic and natural populations of the Nile tilapia, Oreochromis niloticus in Burkina Faso, West Africa

The present study is part of an aquaculture developmental program held in Burkina Faso. The final aim is to generate a genetic selection program for an Oreochromis niloticus strain presenting good performances in both growth and reproduction. A characterization of the genetic diversity within and between wild and domestic populations was performed using Restricted Fragment Length Polymorphism (RFLP) of the mitochondrial DNA (mtDNA). Muscle or fins were sampled from 142 individuals in 7 different sites on the 3 main hydro-graphic basins of Burkina Faso (Comoe, Volta and Niger). DNA was extracted using a commercial kit (Promega). The fragment Nd-5/6 (2 500 bp) of mtDNA was amplified by PCR using primers C-GLU and C-LEU3. The amplified products were then digested using one of the six following restriction enzymes: AluI, HaeIII, HinfI, HpaII, RsaI, and Taq I. Haplotype frequencies of the mtDNA per population were calculated from the mtDNA data. When using TaqI, we obtained 4 haplotypes in the basin of Comoe, 3 in that of Volta and only one in the basin of Niger. While the haplotype B is fixed in the Niger basin and the haplotype C dominants in the Comoe basin, haplotype A is only found in the Volta basin. Within the Volta basin, we observed differences in the C haplotype frequencies when we compared the domesticated Bazega population with the wild population of Bama. The populations of Bazega could have been introgressed by those coming from Kompienga as the frequency of haplotype C is higher in the Kompienga population, also visible in the Bazega population. It appears that some individuals of Kompienga population are also maintained in the same rearing station of Bazega. This distribution revealed heterogeneity of the Oreochromis niloticus populations of Burkina Faso. A larger number of individuals are being analysed presently with Taq I in order to validate these results. Further studies will consider the possible association of these genetic population differences, with growth and reproduction performances. (Texte integral)

Comparative growth performance of two Nile tilapia (Chitralada and Red-Stirling), their crosses and the Israeli tetra hybrid ND-56

Growth performance of two Oreochromis niloticus strains, Chitralada and Red-Stirling, their reciprocal crossbred and the Israeli tetra-hybrid ND-56 were assessed in net cages under on-farming conditions. Throughout 268 days of grow-out, the strains were weighed monthly and mortality, feed consumption and water quality were recorded. Ten rigid net cages (1.5 x 1.5 x 1.7 m) immersed in a 10 ha reservoir were linearly arranged near the reservoir outlet following a completely randomized design with two replicates for each treatment (strain). Each cage was stocked with 459 fish (120 fish m(-3)) and fed twice daily to apparent satiation with a commercial tilapia diet following the recommended feeding program. The final mean weights were higher for Chitralada (557.20 g) and the reciprocal crossbreds (522.95, 496.40 g) than those of Red-Stirling (421.90 g). All treatments outperformed the ND-56 tetra hybrid. Daily growth showed statistical differences between Chitralada (2.04 g) and Red-Stirling (1.52 g) but they were statistically the same when compared with the reciprocal crossbreds (1.90, 1.80 g). The relative growth ratios showed the same trend observed in the results for daily growth. The mean survival rate was 98%. The overall growth rate showed that crossbred performed as well as the parental lines. All crossbred progeny presented red colouration with variable pattern of black marks corroborating the dominant inheritance of the red trait in Red-Stirling strain.