IMPACT OF BIOTECHNOLOGY ON ANIMAL BREEDING AND GENETIC PROGRESS
1. IMPACT OF BIOTECHNOLOGY ON ANIMAL BREEDING AND GENETIC PROGRESS Animal breeding is a field related to a whole range of biotechnologies. The impact of a biotechnology can be measured by the influence it has on genetic progress. According to the type of biotechnology considered, different component of genetic progress may be affected: accuracy of prediction, generation interval, intensity of selection and genetic variance. The first type of biotechnologies affects the efficiency of male and female reproduction: artificial insemination, multiple ovulation, in-vitro-fertilization, ova pick-up, embryo-transfer, twining, sexing of semen and embryos cloning and selfing. The impact of these technologies is mainly in the enhanced distribution of superior germplasm and the selection intensity, but also in the accuracy obtained when testing animals. In the past, artificial insemination has been a very successful biotechnology, enhancing greatly the genetic progress. A secondary, negative, impact is that these biotechnologies affect indirectly genetic diversity and therefore reduce genetic variance.
2. A second group of biotechnologies that can improve determination of the genetic merit of animals is connected with the identification and using of quantitative or economical trait loci (QTL/ETL). Their main feature is the early availability in life, therefore allowing an earlier and more accurate selection. Two direction of research exists: detection of markers for the unknown QTL and direct use of potential candidate genes as QTL/ETL. These genes will have a major impact on animal breeding especially if they will be use in optimization of future breeding programs. A last type of biotechnologies are those with the ability to transform artificially DNA. The impact of these technologies is however still no very clear especially as gene expression and other issues remain unsolved. Biotechnology had, has and will have a major impact on animal breeding and genetic progress. To a certain extend animal breeding is a very promising field to use biotechnology as the past has already proven (Gengler N., Druet T. -2001).
3. HISTORY OF BIOTECHNOLOGIES USE IN LIVESTOCK ARTIFICIAL INSEMINATION biotechnology was among the first method with positive impact on genetic progress in animal populations. The first artificial insemination –scientifically mentioned - was made in 1779 by Italian monk Lazzaro Spallanzani, which inseminates a bitch with sperm, and he obtained three puppies. In England, in 1879 Heape made inseminations in mares with positive results. Other scientists like Hoffman or Ilia Ivanoff had great contributions in this field. Around 1899 and 1900, Russian scientist E.I. Ivanoff began conducting artificial insemination on cattle, horses, birds and sheep. He was first person recorded to have accomplished the first successful artificial insemination in cattle. Because Ivanoff was so successful at animal artificial insemination, by 1931, Russia bred approximately 19,800 cows. Now, artificial insemination is use all over the world in all animal species.
4. EMBRYO TRANSFER is another biotechnology, with the greatest influence on genetic progress in livestock populations, especially in cattle and horses, which have a low annual prolificacy and a very long distance between generations (cattle 5 years; horses 8-9 years). The first successful mammalian embryo transfer was performed in 1891 by Walter Heape in rabbits. The first bovine embryo transfer was recovered by Hartman, Lewis, Miller and Swett in 1930 at the Carnegie Laboratory of Embryology in Baltimore. In the 1950’s, embryo transfer technology in cattle expanded with the first successful transfer performed by Umbaugh and the first calf born through a joint effort by the USDA and the University of Wisconsin. Embryo transfer in food animals began in the 1930’s using sheep and goats, but it was not until the 1950’s that successful embryo transfers were reported in cattle and pigs by Jim Rowson at Cambridge, England. Until the 1970's progress was slow, with many ideas ending in failure. As non-surgical methods advanced through the efforts of Elsden, Hasler, Seidel and others, the commercial use of embryo transfer exploded. In 2002, over 25,000 (25 093) ET calves were registered in the United States.
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9. By dissection the result is 50-60% for each half of the embryo if the transfer is made at the same receptor female, which means that the pregnancy rate rich 120% from a single embryo. EMBRYO BIOPSY techniques also offer advantages to producers in knowing the sex of a calf prior to its implantation into a recipient. The procedure begins with a small sample of two to three cells aspirated from each embryo and a three hour DNA analysis to determine the sex. Normally, embryos collected in the morning from super ovulated donors can be "sexed" before noon the same day. Embryo biopsy
10. MICROINJECTION of a single sperm cell (spermatozoa) into oocytes is another reproductive technology using microsurgery that has tremendous potential for livestock production. The most advance biotechnology is CLONING . The term clone is derived from the Greek word for "twig, branch", referring to the process whereby a new plant can be created from a twig (Shmaefsky B. – 2006). Molecular cloning refers to the process of making multiple copies of a defined DNA sequence. Cloning is frequently used to amplify DNA fragments containing whole genes, but it can also be used to amplify any DNA sequence such as promoters, non-coding sequences and randomly fragmented DNA. Cloning of any DNA fragment essentially involves four steps: - Fragmentation - breaking apart a strand of DNA - Ligation - gluing together pieces of DNA in a desired sequence - Transfection - inserting the newly formed pieces of DNA into cells - Screening/selection - selecting out the cells that were successfully transfected
26. Comparing these two examples, we found that by using embryo transfer, the genetic progress is three times higher. The conclusion is that the embryo transfer lead to the increasing of the selection difference (S), and finally to a higher genetic progress (Δg).
