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  • 1
    Electronic Resource
    Electronic Resource
    Lymphoma induced by herpesvirus: Resistance associated with a major histocompatibility gene (1976)
    Springer
    Immunogenetics 3 (1976), S. 401-407 
    Details
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Studies with crosses of inbred chicken lines demonstrate that resistance to Marek's disease, a herpesvirus-induced lymphoma of chickens, is associated with an allele (B 21) of the major histocompatibility locus (theB locus). TheB 21 allele is thus the first genetic marker for resistance to herpesvirus-induced neoplastic disease, and our studies suggest the means whereby similar associations might be found in man.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01576971
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  • 2
    Electronic Resource
    Electronic Resource
    Genetic selection in presence of pathogens such as the lymphoid leukosis virus: computer simulation (1984)
    Springer
    Theoretical and applied genetics 68 (1984), S. 397-413 
    Details
    ISSN: 1432-2242
    Keywords: Quantitative genetics ; Selection response ; Chickens ; Lymphoid leukosis ; Egg production ; Computer simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A computer model was developed to simulate the population dynamics involved when selection is for a trait influenced by the presence of a pathogen in addition to quantitative genetic factors. The lymphoid leukosis virus is such a pathogen, when selection is for egg production in chickens. It is transmitted congenitally from dam to offspring and horizontally from one individual to another. For these simulations, individual selection for high performance in the trait influenced by the pathogen was more effective than family selection for removing infected individuals from populations. The resulting reduction in the incidence of infected individuals in following generations made the overall response to individual selection greater than for family selection. However, the virus would remain in most populations due to horizontal transmission to individuals which later transmit the virus to their offspring. These horizontally infected individuals would not be eliminated in the selection process because their egg production was assumed to be less reduced than that of congenitally infected birds. These simulation results seem to mimic certain experimental results which heretofore have been difficult to explain since they were not consistent with quantitative genetic theoretical expectations from selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254807
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and parameters of new populations of meat-type chickens (1984)
    Springer
    Theoretical and applied genetics 69 (1984), S. 23-30 
    Details
    ISSN: 1432-2242
    Keywords: Meat-type chickens ; Synthetic populations ; Parameters ; Broiler traits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sire and dam populations of meat-type chickens were developed at the Animal Research Centre, Ottawa to provide unselected control populations suitable for modern broiler research, estimate genetic parameters of broiler traits, and initiate selection experiments. The populations were synthesized from 16 commercial broiler parent stocks (nine sire and seven dam stocks) during two generations of crossbreeding and one generation of random mating. The estimated genetic contribution per stock to the respective population ranged from 8.3 to 16.7% for autosomal genes, from 5.5 to 17.8% for genes on Z chromosomes, and from 0 to 25.0% for genes on W chromosomes. Genetic differences among the original stocks had not been fully diffused among individuals within the populations at the time parameters were estimated. Consequently, genetic parameter estimates are probably slightly biased. Estimated heritabilities of broiler traits in these populations were generally high, 0.39 to 0.63. Hence, rapid genetic change of these traits is possible. The genetic correlation between 28 to 49 day feed efficiency and corresponding weight gain was 0.69 and between feed efficiency and abdominal fat percentage was -0.68. Increasing body weight gain, improving feed efficiency and reducing abdominal fatness of broilers by selection appears feasible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00262532
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  • 4
    Electronic Resource
    Electronic Resource
    Incidence of endogenous viral genes in two strains of white leghorn chickens selected for egg production and susceptibility or resistance to Marek's disease (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 26-32 
    Details
    ISSN: 1432-2242
    Keywords: Egglayers ; Marek's disease resistance ; Egg production ; Endogeneous viral genes ; Group specific antigen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Endogenous viral (ev) genes related to the avian leukosis virus were classified in two differentially selected strains of Leghorns in order to investigate whether such genes affect production traits. Strain K had been selected for resistance to Marek's disease (MD) and for high egg production and egg weight, whereas strain S had been selected only for MD susceptibility. Except that founders of strain K included a few commercial birds, both strains were derived from a common genetic base. DNA restriction fragment length analyses of 110 strain K and 94 strain S birds revealed the presence of 8 different ev-genes, 6 of which were identical to previously identified loci. This result was confirmed by assays for group specific antigen (gs-antigen), the product of the gag region of the ev-genes. The levels of gs-antigen in the birds closely followed what had been predicted from data obtained from previously described ev-genes. Both strains had a similar average number of ev-genes per bird (3.5 and 3.2 for strains S and K, respectively). However, strain K carried only five different ev-genes while strain S carried seven. Four of these loci were present in both strains. Among the ev-genes absent or occurring less frequently in strain K were those that code either for infectious endogenous virus (ev-10 and possibly ev-19) or for the internal viral gag-proteins (ev-3). Only those ev-genes which are transcriptionally silent or which code for the viral envelope gene were present in increased frequencies in strain K. The results indicate that selection for egg traits and/or Marek's disease resistance reduces the frequency of ev-genes which produce endogenous virus or the viral gag-proteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00292311
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  • 5
    Electronic Resource
    Electronic Resource
    DNA fingerprinting: a tool for determining genetic distances between strains of poultry (1989)
    Springer
    Theoretical and applied genetics 77 (1989), S. 669-672 
    Details
    ISSN: 1432-2242
    Keywords: DNA fingerprinting ; Poultry ; Inheritance ; Inbreeding ; Genetic distance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary DNA fingerprinting, a technique based on the detection of hypervariable minisatellite regions in DNA restriction fragments, was tested for its applicability to conduct population genetics in poultry. Using MspI digestion and phage M13 DNA as a probe, between 25 and 35 minisatellite-containing DNA fragments were observed per bird. Comparison of the banding pattern of offspring with their parents revealed that the bands were inherited as stable genetic traits. The variability of the DNA fingerprinting pattern was reduced in inbred strains. DNA fingerprints of chickens from five well-defined populations of known genetic relationships were analyzed and indices of genetic distances were computed. They correctly reflected the history of these strains, indicating that DNA fingerprinting may be a powerful tool to characterize genetic relationships between different breeding populations of the same species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261241
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  • 6
    Electronic Resource
    Electronic Resource
    Age changes in genetic and environmental variation in laying hens (1984)
    Springer
    Theoretical and applied genetics 67 (1984), S. 391-401 
    Details
    ISSN: 1432-2242
    Keywords: Age changes ; Egg production and quality ; Genetic and environmental factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Effects of age on the genetic and environmental variation of egg production, egg weight and egg quality were investigated in two populations of laying hens. The first part of the study was based on data from a crossbred population in Sweden that allowed the estimation of sire and residual but not of dam variance components. Sire, dam and residual components of variance were estimated in the second part of the study that used data from eight generations of two unselected control and four high egg production-selected Canadian strains of chickens. — Although the data did not allow a clear-cut separation of the various genetic and environmental variance components, the results indicated that new genetic variation appeared parallel to an increase in the environmental variation with age of the birds. This was interpreted as a suggestion that the deteriorating process of aging impaired the organism's ability to cope with environmental conditions and this resulted in the observed increase in environmental variation. The simultaneous increase of the genetic variation was caused by the turning on of new genes in order to induce reactions counteracting the effects of aging. Alternatively, reduced accuracy of DNA transcription in older birds may cause impairment of the functional efficiency of metabolic systems thus increasing environmental variation parallell to an increase of genetic “error variation”.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263399
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  • 7
    Electronic Resource
    Electronic Resource
    Estimation of variance components and heritability in populations affected by disease: lymphoid leukosis in chickens (1983)
    Springer
    Theoretical and applied genetics 65 (1983), S. 317-322 
    Details
    ISSN: 1432-2242
    Keywords: Disease ; Lymphoid leukosis ; Chickens ; Variance ; Heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effects of disease, particularly when congenitally transmitted, on variance components and heritability were studied. Observations on lymphoid leukosis, a congenitally transmitted, viral disease of chickens, were used as the basis of the considerations but the results are deemed applicable to other situations where a population is similarly affected by a disease or another factor resulting in alteration of performance. The numbers of pullets tested for lymphoid leukosis virus (LLV) shedding into eggs were 1785 in 1976 and 1699 in 1977. A comparison of the distribution of LLV shedders (approximately 8% of the birds tested) among sire and dam families with its binomial expectations supported earlier reports that only dams play a role in congenital transmission of LLV. The effects of LLV infection on variance components and heritability were assessed in the 1976 data by comparing estimates from both LLV-shedders and nonshedders (population A) with estimates from nonshedders only (population B). Sire variances for age at first egg, number of eggs per hen housed, egg production rate, and egg weight were 3 to 18% greater in population A compared to population B. The corresponding differences in dam variances were generally larger (5 to 48%) while relative differences in individual variances were small (1 to 10%). Total phenotypic variances for the traits were 2 to 13% larger in population A than B. Corresponding changes in percent sire heritability ranged from −1 to 6%, and in dam heritability from −2 to 12%. The significance of these effects was not established with certainty due to standard errors of the estimates (9 to 13%). The study pointed out the need to consider possible effects of agents such as LLV on designing breeding plans, experiments and in data analyses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276571
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  • 8
    Electronic Resource
    Electronic Resource
    Practical and ethical considerations of agricultural research assistance for the Third World (1989)
    Springer
    Journal of agricultural and environmental ethics 2 (1989), S. 307-322 
    Details
    ISSN: 1573-322X
    Keywords: Agriculture ; research ; Third World ; ethics ; biotechnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Philosophy
    Notes: Abstract The right to eat and to an adequate standard of living for everyone motivates agricultural research assistance to developing countries with the primary objective of assuring sufficient food supply. This article focuses on aspects of food production and related agricultural research with specific examples from animal production. It discusses ethics of agricultural research in light of the utilitarian theory and compares livestock production in developing and developed countries. Major reasons for low outputs of animal production in developing countries are identified, and the potential for increasing the productivity of original, extensive production systems is evaluated. The article reviews the current status of biotechnology in developing countries and discusses several advanced animal technologies. The conclusions emphasize the need to involve local professionals in all phases of research and technology transfer in developing countries, avoidance of research that may worsen the situation of the recipients, sustainability of production systems, and the need for detailed assessment of potential impacts of technology on recipients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01826809
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