biotechnology assignment n
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Bahir Dar University College of Agriculture Bahir Dar University College of Agriculture and Environmental Sciencesand Environmental Sciences
Department of Animal Genetics and BreedingDepartment of Animal Genetics and Breeding
GENETIC BASIS OF DISEASE RESISTANCE (GBDR):
in relation to Ethiopian Indigenous cattle breeds
Assemu Tesfa Assemu Tesfa
(([email protected]@yahoo.com))
(Andassa Livestock Research Center)(Andassa Livestock Research Center)
June, 2013June, 2013
INTRODUCTION INTRODUCTION
Animal health and well being have become increasingly important issues for animal producers and consumers.
Decrease profitability of animal production (Jovanović, 2009).
The development of genome resources and technologies allow for identification of several host resistance genes
Pathogens are ubiquitous and have a significant impact on their hosts’ fitness and survival fitness and survival ((Roger and Larry, 985).
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Intro…Intro…
Members of a given species are not all equally susceptible to infectious diseases
The genetic basis of variation in resistance is evident from observations on breed differences
(Example: Indigenous VS Exotic breeds)
Aim: Aim: to prepare and present about genetic bases of disease resistance in the livestock
sector.
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The concepts of GBDRThe concepts of GBDR
Disease have two directional impact,
In animals direct effect and
Cost for medication to treat it
Works done on genetic base, selection of disease resistance breeds
for improvement of production and productivity.
According to a study in Evolution, resistance to certain infectious diseases is inheritance (Science Daily, 2007)
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The The concepts… concepts…
It had indicated, diseases rarely occur in all members of animal populations exposed to pathogens (Whitelaw and Sang, 2005) (miss all pop.)
Disease is of multifactorial and interactive b/n
two genomes (the host and the pathogen) and
the environment.
Resistance to disease is Resistance to disease is because of interactions because of interactions and need multiple genes and need multiple genes at different loci.at different loci.
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The concepts…Genetic bases of disease resistance varies.
Example;
Salmonella pullorum and coccidian parasites in poultry;
Brucella suis in swine;
Virus responsible for myxomatosis in Rabbits;
Trypanosomes and tick infestations in cattle;
Gastrointestinal (GI) nematodes in sheep;
Within specious goats better than sheep for footrot fungus (FAO, 2002).
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The concepts…Resistance to pathogens
encompasses resistance due to:
Impenetrable barriers,(skin got enzymes, acids and even helpful Bacteria) (Bagley, 1997).
Absence of appropriate receptors for binding and penetration of cellular membranes,
Failure to survive after entering the host,
Inability to replicate in the host,
Killing and elimination by host defense mechanisms
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1) N'Dama resist trypanosomosis 1) N'Dama resist trypanosomosis (Mattioli et al., 1998; Murray et al., 1990). Because:
genetic bases VS blood Immune system, (Mattioli 2000) serum antibody levels (Joan Lunney, 2011).
immune proteins that are associated with anti-disease responses (e.g., cytokines, such as anti-viral interferons).
2) Malaria VS sickle cell anemia 2) Malaria VS sickle cell anemia heterozygous sickle-cell anaemics (sickle
shaped & normal RBCs)
the protozoan is unable to live inside the sickle red blood cell
due to the fibres formed from the mutation, shorter life span (Wikipedia, the free encyclopedia.htm)
Selection of animals for GBDR Selection of animals for GBDR From a genetic perspective, understanding the natural,natural,
innateinnate, and acquired immune systems is crucial in developing selection programs for disease resistance (Bagley, 1997).
Exotic breeds,High production
Low D+ resistance
Simple Simple observations or observations or using using genetic genetic
markers markers
Selected for breeding based
on their resistance or
tolerance
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Markers: Example: Pigs
SNP chips (Mapping and understanding the expression
level)
Selection of animals….Selection of animals…. In dairy cattle,
Selection programs to mastitis resistance, because have correlation with production traits.
Chicken breeders, Selection program to avian lymphoid leucosis complex and Marek’s disease (Alison Van Eenennaam, 2012).
Genetic selection programs aimed at increasing the economic value increasing the economic value
Ignoring disease resistance during selection may result in lower economic returns (David Shalhevet and H. Rex Gaskins, 1998).
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Significance of GBDR Significance of GBDR Enhanced disease
resistance or tolerance will lead to:
Reduced need for inputs (especially drugs), and
Beneficial to low-input agricultural systems in developing countries.
Increased productivity, specially; dairy dairy VSVS mastitismastitis
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But now thanks for But now thanks for biotechnologybiotechnology….. transgene for ….. transgene for
disease resistance. disease resistance.
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Opportunities for EthiopiaOpportunities for Ethiopia Is a home of various indigenous cattle (livestock),
genetically resistance
Example: Sheko, Horro…. Fogera
Focus had better given for the breeds in hand and better policies for implementation and monitoring strategies
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