Design of fish breeding programs (original) (raw)
Related papers
Selective breeding in fish and conservation of genetic resources for aquaculture
Reproduction in Domestic Animals
To satisfy increasing demands for fish as food, progress must occur towards greater aquaculture productivity whilst retaining the wild and farmed genetic resources that underpin global fish production. We review the main selection methods that have been developed for genetic improvement in aquaculture, and discuss their virtues and shortcomings. Examples of the application of mass, cohort, within family, and combined between-family and within-family selection are given. In addition, we review the manner in which fish genetic resources can be lost at the intra-specific, species and ecosystem levels and discuss options to best prevent this. We illustrate that fundamental principles of genetic management are common in the implementation of both selective breeding and conservation programmes, and should be emphasized in capacity development efforts. We highlight the value of applied genetics approaches for increasing aquaculture productivity and the conservation of fish genetic resources.
Toward the Genetic Improvement of Feed Conversion Efficiency in Fish
Journal of the World Aquaculture Society, 2003
Feed conversion efficiency (FCE) is the effectiveness with which feed is converted to saleable fish product. Feed costs are a major input to aquaculture production systems, and genetic improvement in FCE may therefore have an important influence on profitability. FCE is usually expressed by a composite measure that combines feed intake and growth rate. The two most common measures are feed conversion ratio (feed intake/weight gain over a specified time interval) and its inverse, feed efficiency. Feed conversion ratio and feed efficiency are measures of gross FCE, because they do not distinguish between the separate energy requirements of growth and maintenance. There is abundant evidence of substantial genetic variation in FCE and its component traits in terrestrial livestock species and, although data are few, the same is likely for cultured fish species. The major problems with selecting from this variation to genetically improve FCE in fish species are: 0 It appears impractical to measure feed intake on individual fish, so that family mean data We do not know the optimal time period over which to test fish for FCE. 0 We do not know the genetic correlations between FCE under apparent satiation or re-If these problems can be overcome, selection to improve FCE might be best achieved by measuring feed intake of growing animals, and by utilizing genetic correlations that are likely to exist between feed intake and other production traits to develop a weighted selection index. must be used. stricted intake conditions, or between FCE at different times in the production cycle.
Recent advances in animal breeding theory and its possible application in aquaculture
SUMMARY - The genetic change of the population mean of a quantitative trait is the outcome of the action of two antagonistic forces: artificial or natural selection and genetic drift. The latter may generate inbreeding depression and erosion of the genetic variance, both for production and fitness traits. Inbreeding changes are cumulative and inversely proportional to the effective population size. To keep undesirable inbreeding effects in check, a minimum number of selected parents larger than that required to produce the desired offspring number should be used. Moreover, the variability of selection response is also inversely proportional to the effective size. Thus, a reasonable chance of success of achieving some response can only be attained by further increasing the effective size. In parallel, the magnitude of short-term selection response depends linearly on the accuracy of selection. Efficient selection methods rely on the use of family information through BLUP evaluation. ...
Aquaculture, 2014
When setting up a breeding program for fish, an optimal breeding scheme is sought, and especially the number of families to use is a pivot parameter in this regard. This simulation study tests a range of probable number of families, with the use of two different methods for implementation of optimum contribution procedures in fish: one based on individual quotas and one with family quotas. Schemes are compared at the same prescribed rate of inbreeding. The breeding goal consisted of two correlated traits, one that could be measured on all selection candidates, the second only on full-sibs. The number of families ranged from 50 to 400, whereas the number of offspring per full-sib family was fixed at 50. Average genetic gain for generations 5 to 15 was used for comparing the schemes, and the rate of inbreeding per generation was restricted to 1%. The individual-based method gave the overall highest genetic gain, but the superiority for this method was most evident for the breeding schemes with a high number of families. The biggest difference between the two methods tested stems from the fact that the family-based method furnished a relatively larger proportion of the gain on the first trait; measurable only on the informants. For the individual-based method, this trait had negative or almost no gain when the genetic correlation was negative. The study also showed that although the total gain did not differ too much, the choice of method could highly influence the specific gain in each of the two traits. It is concluded that for the parameters and assumptions used in this study, the optimal number of families for both methods are likely to be around 200 to 300 if economic considerations are also included.
Genetic improvement programs for aquaculture species
Proceedings of the British Society of Animal Science
The high yields obtained in agriculture rely heavily on the use of domesticated and genetically improved breeds and varieties. Until quite recently this has not been the case for most farmed aquaculture species that, in the genetic sense, are still much closer to the wild state than are the major terrestrial animals and food crops. Less than 10 % of the total world aquaculture production is based on improved strains. Due to a growing human population and a decline in production from capture fisheries, there is therefore a great disparity between the need for increased aquaculture production and the genetic quality of the strains available to meet that need. Moreover, full benefits of investments in management improvements (feed and feeding practices, control of diseases, etc.) can only be obtained through the use of genetically improved animals.
Methods of Selection Using the Quantitative Genetics in Aquaculture-A Short Review
Efficient breeding programs can contribute significantly to the development of fish farming by reducing production costs, improving the resistance of farmed organisms to disease, improving food use and product quality. Unfortunately, less than 20% of the world's inland fish production comes from genetically improved stocks. In breeding programs for these fish (and also from other origins or species), three strategies can be applied: selection, crosses and hybridizations, and chromosome manipulation. Selection was poorly applied in inland fishes, being restricted mainly in trout, carp and tilapia. The most common selection goals in fish breeding programs include growth rate, feed conversion, disease resistance and survival, quality and meat yields. Three selection methods have already been applied to this animal group: individual selection, selection between and within families and the combined selection. The first one was the most practiced, but usually entails a rapid increase in inbreeding rates. The second method, used for low heritability traits or those that require animal sacrifice for measurement, may result in increased inbreeding when the selection is made between families or be less efficient when animals are selected in all families. The combined selection associates the individual information of the animal and its relatives. It is expected that the dissemination and use of these tools in fish farming will increase considerably in the coming years given the history of their low (even traditional) uses and that gains in productivity will improve the efficiency of the use of natural resources (water and land) needed for which may contribute to the growing need for animal protein for human consumption.
A novel breeding design to produce genetically protected homogenous fish populations for on-growing
Aquaculture Research, 2013
We present a novel KING breeding design to produce genetically protected homogeneous fish material for commercial producers from a breeding nucleus. KING F2-production population is established from the nucleus, first through full-sib mating within two unrelated high-quality families to produce inbred F1-progeny and then resolving the inbreeding in F2 through mating of the unrelated F1-individuals. Owing to a small number of founders and the inbred F1-parents, the remaining additive genetic variance is 37.5% of the original. This restricts the use of F2-progeny to establish new breeding programmes, thereby protecting the genetic material of the nucleus. The theoretical calculations show that a concomitant decrease of phenotypic variance is possible. However, the reduction is considerable only for traits with high heritability (h 2 > 0.50). The method was tested with rainbow trout. The results revealed that the mean body weight of the KINGprogeny was similar, but, surprisingly, phenotypic variation (especially due to residual variance) was higher compared with either their outbred control group or the nucleus breeding population. Although further evaluation of this breeding design is needed, the results suggest that while genetic protection is achieved, the efficiency of the method to reduce phenotypic variation is limited for economically important traits with lowto-moderate heritability.
Aquaculture, 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.