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Estimation of variance components and heritability in populations affected by disease: lymphoid leukosis in chickens

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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.

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  1. Fadly AM, Okazaki W (1982) Studies of avian leukosis infection in chickens from a commercial breeder flock. Poult Sci 61:1055–1060

  2. Garwood VA, Okazaki W, Crittenden LB, Lowe PC (1981) Association of lymphoid leukosis virus and performance in a randombred layer population. Poult Sci 60:2619–2621

  3. Gavora JS, Spencer JL, Chambers JR (1982) Performance of meat-type chickens test-positive and -negative for lymphoid leukosis virus. Avian Pathol 11:29–38

  4. Gavora JS, Spencer JL, Gowe RS, Harris DL (1980) Lymphoid leukosis virus infection: effects on production and mortality and consequences in selection for high egg production. Poult Sci 59:2165–2178

  5. Gowe RS, Fairfull RW (1980) Performance of six long-term multi-trait selected Leghorn strains and three control strains, and a strain cross evaluation of the selected strains. In: Proc 1980 South Pacific Poultry Sci Conv, World Poultry Sci Ass, New Zealand Branch Auckland, New Zealand, pp 141–161

  6. Harris DL (1979) Genetic selection when egg transmission of lymphoid leukosis occurs. In: Proc 28th Nat Breeders’ Roundtable, Poultry Breeders of America (Mineographed), Memphis, Tenn, pp 131–146

  7. Maas HJL, de Boer FG, Groenendal JE (1982) Influence of age at inoculation with leukosis virus on egg production. Arch für Geflügelk 46:150–157

  8. Spencer JL, Gavora JS, Gowe RS (1980) Lymphoid leukosis virus; natural transmission and non-neoplastic effects. In: Essex M, Todava G, ZurHansen H (eds) Viruses in naturally occurring cancers. Cold Spring Harbor Publications, Cold Spring Harbor, pp 553–564

  9. Weyl KG, Dougherty RM (1977) The contact transmission of avian leukosis virus. J Natl Cancer Inst 58:1019–1025

  10. Witter RL, Calnek BW, Levine PO (1966) Influence of naturally occurring parental antibody on visceral lymphomatosis virus infection in chickens. Avian Dis 10:43–56

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Animal Research Centre Contribution No. 1011

Communicated by H. Aplanalp

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Gavora, J.S., Chesnais, J. & Spencer, J.L. Estimation of variance components and heritability in populations affected by disease: lymphoid leukosis in chickens. Theoret. Appl. Genetics 65, 317–322 (1983). https://doi.org/10.1007/BF00276571

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Key words

  • Disease
  • Lymphoid leukosis
  • Chickens
  • Variance
  • Heritability