HETEROSIS RETENTION AND INTER-BREED RECOMBINATION AMONG NONALLELIC GENES ASSOCIATED WITH CROSSBREEDING AND SYNTHESIS OF BREEDS | ||||
| Egyptian Journal of Sheep and Goats Sciences | ||||
| Article 7, Volume 5, Issue 1, April 2010, Page 1-48 PDF (533.05 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/ejsgs.2010.27078 | ||||
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| Author | ||||
| J. N. B. Shrestha | ||||
| Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, P.O. Box 90 - Lennoxville Station, 2000 College Street, Sherbrooke, Québec, Canada J1M 1Z3. | ||||
| Abstract | ||||
| ABSTRACT Systematic crossbreeding and newly developed synthetic populations based on complementary breeds of exotic and/or indigenous origin, in conjunction with selection for specific objectives among economically important traits has consistently expedited rapid genetic improvement of production efficiency along with the income and profitability of the livestock and poultry enterprises. The breakdown of desirable combinations of segregating alleles inherited from many of the parental breeds during crossbreeding or the development of synthetic populations could lead to loss of desirable morphological characteristics and production performance. This may be attributed to the inter-breed recombination among non-allelic genes (epistasis) decreasing the proportion of retained heterosis, both direct and maternal. In addition to recombination loss, selection over subsequent generations increase the loss of within breed variability, decrease effective population size and hasten the rate of inbreeding. Research results on recombination loss in the parents and their offspring have often been conflicting. Precise estimates require large numbers of breeds and their crosses independent of environmental influence. The objective of the present study is to discuss crossbreeding strategies capable of retaining heterosis in the following generations while enhancing genetic merit of parents and their offspring. | ||||
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