Gjerde B.,Nofima |
Gjerde B.,Norwegian University of Life Sciences |
Mengistu S.B.,Norwegian University of Life Sciences |
Mengistu S.B.,Hawassa University |
And 4 more authors.
Aquaculture | Year: 2012
With the objective of how to best improve fillet weight in Nile tilapia (Oreochromis niloticus) through selection round and gutted body weight and fillet weight were recorded at harvest over four generations (G0, G1, G2 and G3) and from which the following traits were derived: Fillet yield (fillet weight×100/round weight), non-edible part of the fish (NEP=round weight-fillet weight), and non-meat part of the gutted weight (NMP=gutted weight-fillet weight). The round weight was recorded on 42,795 offspring of 327 sires and 422 dams, and the other traits on a random sample of 3361 of the offspring of 277 sires and 359 dams. The fish were reared in net-cages in a lake or in earthen ponds. Selection was performed for harvest weight and fillet yield with an equal relative economic weight (50%) on each trait. The heritabilities for round, gutted and fillet weight, NEP and NMP were all moderate (0.16-0.19) and lower for fillet yield (0.06). The effect common to full-sibs (c 2) accounted for a large proportion of the phenotypic variance for all traits (0.11-0.19). The genetic correlation between round weight of fish reared in cages and in ponds was unity (1.00), indicating no genotype by environment interaction for this trait. The genetic correlations between round, gutted and fillet weights were all close to unity, as were the genetic correlations of round and fillet weight with the calculated traits NEP and NMP. The close to unity genetic correlation between round body weight and fillet weight indicates that genetic improvement of one of the traits without achieving a proportional genetic change in the other is difficult or even impossible. This implies that improvement of fillet yield through direct selection is difficult to achieve. Still, based on the current results, fillet yield is expected to increase with increasing body weight, both genetically and phenotypically. However, if increased growth leads to harvest at a younger age rather than higher weight, response in fillet yield may not be observed. Improvement of fillet weight can be obtained through selection for increased round body weight, a more efficient strategy as the trait can be recorded on live breeding candidates and as higher economic weight can be put on this trait instead of on fillet yield. © 2012 Elsevier B.V.
Genetic improvement of tilapias in China: Genetic parameters and selection responses in fillet traits of Nile tilapia (Oreochromis niloticus) after six generations of multi-trait selection for growth and fillet yield
Thodesen J.,Akvaforsk |
Rye M.,Akvaforsk |
Wang Y.-X.,Hainan Progift Aqua Technology Co. |
Bentsen H.B.,Nofima Marin. P.O. Box 5010 |
Aquaculture | Year: 2012
Genetic parameters and selection responses were obtained for fillet weight and fillet yield of Progift Nile tilapia (Oreochromis niloticus) in China after six generations of multi-trait selection for growth and fillet yield. A total of 9619 test fish representing 687 full-sib families in six generations (G 1-G 6) of Nile tilapia originating from the GIFT breed were sacrificed to record skin-on fillet weights. Some of these skin-on fillets were further processed by skinning (5971 test fish) and trimming (4633 test fish) to allow calculations of three estimates of fillet yield (based on skin-on, skinned and trimmed fillets). Recorded fillet weights were positively influenced by body weight and negatively influenced by age at recording. The heritability (h 2) of skin-on fillet weight showed large variation in magnitude between generations (range of 0.00-0.45), but was of medium magnitude (0.30) when analyzing all data combined. The h 2 of fillet yield, which varied between 0.08 and 0.30 in different generations, was relatively stable (0.17-0.23) for different estimates of fillet yield when analyzing across all generations. Including all data, the effects common to full-sibs (c 2) accounted for 8% and 1-2% of the total phenotypic variance, respectively, for skin-on fillet weight and different estimates of fillet yield. The genetic correlations between different estimates of fillet yield were all very high (0.95-0.97 when analyzing all data) showing that it is sufficient to select based on skin-on fillet yield. The genetic correlation between skin-on fillet weight and body weight at harvest was also very high (0.97), while that between fillet yield and fillet weight was of moderate magnitude (0.33). The genetic correlation between fillet yield and body weight at harvest was not significantly different from zero. Genetic trend analysis based on all data predicted accumulated selection responses of 121g (1.87 phenotypic standard deviation units) larger skin-on fillet weight and 1.2%-units higher skin-on fillet yield after six generations of multi-trait selection. It is concluded that the ongoing program in China has resulted in considerable genetic improvement of fillet weight, and that genetic changes of fillet yield is a much slower process (0.2%-units per generation). Implications for commercial selective breeding programs are discussed. © 2012 Elsevier B.V.
Genetic improvement of tilapias in China: Genetic parameters and selection responses in growth of Nile tilapia (Oreochromis niloticus) after six generations of multi-trait selection for growth and fillet yield
Thodesen Da-Yong Ma J.,Akvaforsk |
Rye M.,Akvaforsk |
Wang Y.-X.,Hainan Progift Aqua Technology Co. |
Yang K.-S.,Hainan Progift Aqua Technology Co. |
And 2 more authors.
Aquaculture | Year: 2011
Genetic parameters and selection responses were obtained for growth of Progift Nile tilapia (Oreochromis niloticus) in China after six generations of multi-trait selection. About 64,000 tagged fingerlings representing 787 full-sib families in seven generations of Nile tilapia originating from the GIFT breed were tested in freshwater earthen ponds, floating cages in reservoirs and a brackish water earthen pond in Guangdong and Hainan Provinces of China. Individual body weight was recorded on 25,000 of these at the expected time of sexual maturation and 50,000 at harvest to estimate genetic parameters for growth rate. Heritability (h 2) estimates for body weight showed large variation in magnitude (0.00-0.52) when analyzing data from each test environment and generation separately. Estimates obtained in floating cages and a brackish water pond was comparable or lower in magnitude than those obtained in freshwater earthen ponds. The h 2 estimates for body weight at harvest became more stable (range 0.13-0.20) when data from previous generations were included in the analysis. Including all data, the effect common to full-sibs (c 2) accounted for 10% of the total phenotypic variance for body weight at harvest. Genetic correlation between growth recorded at expected time of sexual maturation and at harvest was 0.8, but seemed to decrease in later generations. The genetic correlations between growth in freshwater earthen ponds and other test environments were of similar magnitude. Breeding candidates in the base population (G 0) were ranked according to their individual breeding values for growth (recorded as body weight at harvest), while those in later generations (G 1-G 5) were ranked according to a selection index including individual breeding values for growth and family breeding values for fillet yield. The selection response for growth was, on average, 11.4% per generation of selection (range 7.4-18.7%) when estimated based on control groups representing the parental generations. A genetic trend analysis based on all data (h 2=0.20, c 2=0.10) predicted an accumulated selection response of more than 200g and an average selection response of 8.0% per generation of selection when using the LS mean of the G 0 as a base line for the comparison. The average inbreeding coefficient (F) was estimated to be 5.0% after six generations of selection. The results are discussed in a practical context of developing selective breeding programs for tilapias and it is concluded that the ongoing selective breeding of Nile tilapia in China has resulted in considerable genetic improvement of growth (60-90% larger body weight at harvest) after six generations of multi-trait selection. © 2011 Elsevier B.V.
Gjerde B.,Nofima Marin |
Odegard J.,Nofima Marin |
Aquaculture | Year: 2011
The magnitude of the genetic variation in the susceptibility of Atlantic salmon to Lepeophtheirus salmonis was estimated through a controlled infestation test of 2206 individually tagged post-smolts of 154 full-sib families, i.e. the offspring of 78 sires and 154 dams. The infestation test took place in two replicated tanks with seawater. On average 74 and 36 copepodids per fish were added to tanks 1 and 2, respectively. The number of sessile lice (chalimus II-II stage) per fish (LC) was counted ten days after infestation at which the average body weight of the fish was 260g in each of the two tanks. The average LC per fish was 27.1 (SD=16.4) and 13.9 (SD=13.2) in tanks 1 and 2, respectively while the lice density per fish, calculated as LD=LC/Body weight2/3, was 0.66 (SD=0.38) and 0.34 (SD=0.29). Observed LC was found to increase with increasing body weight, while LD was seemingly independent of body weight. These relationships explain the lower heritability for LD (0.26±0.05) than for LC (0.33±0.05), and a genetic correlation between LC and LD (rg=0.89±0.03) different from unity. The magnitude of the heritability estimate for LD together with the large phenotypic variation of the trait, and a genetic correlation close to unity between LD in the two replicated tanks, shows that there is substantial additive genetic variation in resistance to L. salmonis in Atlantic salmon, and thus a great potential for increasing the resistance through selective breeding. The genetic correlation between LD and harvest body weight recorded on two subsamples of sibs of the lice infected fish reared at two farms was close to and not significantly different from zero (0.06±0.12 and -0.13±0.11). Hence, the increasing lice problem in the salmon industry during the last years is most likely caused by other factors than the selection that has been practised for increased growth rate over the last 3-4 decades. © 2011.
Gjedrem T.,Akvaforsk |
Reviews in Aquaculture | Year: 2016
The aquaculture sector is significantly behind plant and farm animal production in applying selective breeding, in spite of the fact that it has been suggested that the world aquaculture production could be doubled in 13 years if breeding programmes were supplying stocks for the farmed species. It is estimated that as late as in 2010, only 8.2% of the world's total aquaculture production was based on material developed in selective breeding programmes. Reported estimates of genetic gain per generation for a key trait like growth rate average 13%, implying that the animal's potential for growth can be doubled in a time span of only six generations of selection, as demonstrated for major farmed species like Atlantic salmon and Nile tilapia. Likewise are reported genetic gains for improved disease resistance generally very high. This study offers an updated review of published estimates on genetic gains for a range of traits in aquaculture species. Results are highly encouraging and demonstrate a substantial potential for genetic improvement in aquatic productions, in particular for traits such as growth rate and resistance to diseases. © 2016 Wiley Publishing Asia Pty Ltd.
Gjedrem T.,Nofima |
Gjedrem T.,Akvaforsk |
Robinson N.,Nofima |
Aquaculture | Year: 2012
Aquaculture is the fastest growing food production industry, and the vast majority of aquaculture products are derived from Asia. The quantity of aquaculture products directly consumed is now greater than that resulting from conventional fisheries. The nutritional value of aquatic products compares favourably with meat from farm animals because they are rich in micronutrients and contain high levels of healthy omega-3 fatty acids. Compared with farm animals, fish are more efficient converters of energy and protein. If the aquaculture sector continues to expand at its current rate, production will reach 132. million tonnes of fish and shellfish and 43. million tonnes of seaweed in 2020. Future potential for marine aquaculture production can be estimated based on the length of coastline, and for freshwater aquaculture from available land area in different countries. The average marine production in 2005 was 103. tonnes per km coastline, varying from 0 to 1721 (China). Freshwater aquaculture production in 2005 averaged 0.17. tonnes/ha, varying from 0 to close to 6. tonnes per ha (Bangladesh), also indicating potential to dramatically increase freshwater aquaculture output. Simple estimations indicate potential for a 20-fold increase in world aquaculture production. Limits imposed by the availability of feed resources would be lessened by growing more herbivorous species and by using more of genetically improved stocks.Aquaculture generally trails far behind plant and farm animal industries in utilizing selective breeding as a tool to improve the biological efficiency of production. It is estimated that at present less than 10% of aquaculture production is based on genetically improved stocks, despite the fact that annual genetic gains reported for aquatic species are substantially higher than that of farm animals. With an average genetic gain in growth rate of 12.5% per generation, production may be dramatically increased if genetically improved animals are used. Importantly, animals selected for faster growth have also been shown to have improved feed conversion and higher survival, implying that increased use of selectively bred stocks leads to better utilization of limited resources such as feed, labour, water, and available land and sea areas. © 2012 Elsevier B.V.
Aquaculture | Year: 2012
It has been exciting to follow the rapid development of aquaculture production in Norway, and internationally, since 1971. As an animal breeder I am particularly impressed with the genetic gain obtained for growth rate, and also for disease resistance in several aquatic species, which is five to six times higher than what has been achieved in terrestrial farm animals. This is illustrated in five selected projects I have been involved in. The sad story is, however, that only less than 10% of the world's aquaculture production is based on genetically improved stocks. The big challenge for the future is to develop more selective breeding programs for existing and new emerging aquaculture species in order to increase the production of this nutritious food source and to improve the efficiency of the use of feed, water, land and labor resources. © 2012 Elsevier B.V..
Pike T.W.,University of Glasgow |
Bjerkeng B.,Akvaforsk |
Blount J.D.,University of Exeter |
Lindstrom J.,University of Glasgow |
Metcalfe N.B.,University of Glasgow
Functional Ecology | Year: 2011
1.Carotenoid-based signals typically vary in both the total concentration of carotenoids deposited and the relative quantities of different constituent carotenoids. As these constituents often have differing spectral properties, the relative and absolute concentrations of different carotenoids deposited in a signal can significantly affect the spectrum of light reflected. A critical but rarely tested assumption of hypotheses concerning the information content of carotenoid-based signals is that their colour directly reveals the concentration and composition of constituent carotenoids to intended recipients. Most previous studies have attempted to address this question using either photographic techniques or by analysing recorded reflectance spectra, neither of which take into account the specific properties of the receiver's visual system. 2.Here, we use psychophysical models of the visual system of three-spined sticklebacks (Gasterosteus aculeatus) to estimate their sensitivity to variation in the concentration and relative abundance of constituent carotenoids of males' carotenoid-based sexual signals. 3.We demonstrate that sticklebacks are acutely sensitive to variation in both the total concentration of carotenoids in the signal and the relative proportion of its constituents, and that the accuracy of these assessments is largely unaffected by the presence or absence of ultraviolet radiation in the illuminant. We discuss these findings in relation to the evolution, maintenance and information content of carotenoid-based sexual signals. © 2010 The Authors. Functional Ecology © 2010 British Ecological Society.
Skagemo V.,Nofima Marine |
Skagemo V.,Norwegian University of Life Sciences |
Sonesson A.K.,Nofima Marine |
Meuwissen T.H.E.,Norwegian University of Life Sciences |
Aquaculture | Year: 2010
We studied a typical breeding nucleus with dissemination of genetic material directly from the nucleus to the grow-out level by stochastic simulation. Profits could be increased through production and dissemination of specialised stocks suited for specific production environments or markets. Truncation selection of 50 sires and 200 dams (trunc ♂2.5% ♀10%) and of 5 sires and 25 dams (trunc ♂0.25% ♀1.25%) were compared to random selection of 50 sires and 200 dams (rand ♂2.5% ♀10%). Higher profit was obtained for all truncation selection schemes as compared to random selection, and increasing with decreasing proportion selected. By optimising the selection of parents, which are used for dissemination from the nucleus to the grow-out, instead of using randomly selected nucleus parents, an additional response corresponding of approximately 1.5 generations of selection in the nucleus was achieved. The effect of the correlation between the nucleus breeding goal and the breeding objective of the grow-out was that profit was highest when the correlation was high. With a negative genetic correlation between the traits, profit was still high if the trait with the highest heritability (i.e. the trait measured on candidate itself) had the highest economic value. The range of ΔF in the 7th generation in the nucleus was [- 0.0075-0.0269] with SD equal to 0.0056. The average over all the replicates was 0.0095. This study showed that selection of specialised stocks for specific breeding objectives from the nucleus to the grow-out level will give the grow-out producers a direct and extra genetic improvement and that selecting breeders in the nucleus for dissemination gives also more flexibility for a final product, by adapting economic weights for each grow-out producer. © 2010 Elsevier B.V. All rights reserved.
Sahoo P.K.,Indian Central Institute of Freshwater Aquaculture |
Rauta P.R.,Indian Central Institute of Freshwater Aquaculture |
Mohanty B.R.,Indian Central Institute of Freshwater Aquaculture |
Mahapatra K.D.,Indian Central Institute of Freshwater Aquaculture |
And 3 more authors.
Fish and Shellfish Immunology | Year: 2011
Selection for disease resistance in fish may be performed directly on basis of survival data obtained in controlled challenge trials, or indirectly using information from immunological or molecular markers linked to differential survival. In the present study, several key innate immune parameters were measured in aeromoniasis resistant and susceptible lines of rohu Labeo rohita to assess their suitability as immune markers for use in indirect selection for increased resistance. Experimental infection with Aeromonas hydrophila (9.55 × 10 6 cfu g -1 fish) through the intraperitoneal route produced higher survival in the resistant line (73.33%) as compared to the susceptible line (16.67%). Blood and liver tissue samples from both lines were collected to study some of the innate immune parameters and immune-related gene expression. The respiratory burst activity of blood phagocytes, serum myeloperoxidase activity and ceruloplasmin level were significantly (p < 0.05) higher in the resistant line compared to the susceptible line. Lower level of blood glucose and serum natural haemolysin titre were marked in the resistant line as compared to the susceptible line. No significant difference was measured in total serum protein concentration, antiprotease activity and bacterial agglutinin level between two lines, while the expression of transferrin, complement factor C3 and TLR 22-like transcripts were significantly (P < 0.05) higher in liver samples of the susceptible line. However, no such difference was found in β 2-microglobulin and lysozyme gene expression between lines. The study demonstrated the possibility of using some of the investigated innate immune parameters as indirect marker traits for selection for improved resistance to aeromoniasis in rohu. © 2011 Elsevier Ltd.