rdf-syntax-grammar
mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Genetic analysis of reproductive performance of Rambouillet sheep
  name:
    name part: Snowder, Gary Douglas.
    role:
      role term: creator
  name:
    name part: Cartwright, T. C.
    role:
      role term: degree supervisor.
  name:
    name part: Shelton, J. Maurice
    role:
      role term: degree supervisor.
  name:
    name part: Dahm, Fred
    role:
      role term: degree committee member.
  name:
    name part: Long, C. R.
    role:
      role term: degree committee member.
  name:
    name part: Menzies, Carl
    role:
      role term: degree committee member.
  name:
    name part: Texas A & M University
    role:
      role term: degree granting institution.
  type of resource: text
  genre: bibliography
  genre: Academic theses
  origin info:
    place:
      place term: xx
    date issued: 1987
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: print
    extent: xi, 104 leaves : illustrations ; 29 cm
  abstract: Data from a purebred Rambouillet range flock between the years of 1919 and 1985 were analyzed to determine: the relationship of age, body weight, birth type, sex of natal twin on lamb and fleece production, and longevity; an accurate method of calculating the estimated breeding value (EBV) for reproduction of ewes with different production records. Genetically stable years for genetic parameters estimation were determined by ANOVA and testing for differences between years (P<.01). Data utilized for genetic parameter estimation included the years 1959 to 1985 with 6017 ewes mated to 293 rams. EBV was attained by modifying a standard EBV equation for repeated measures, improved by the use of repeatability and heritability estimates for number of lambs born within each age group. Heritability estimates increased linearly from age 2 to 7 yr (.30, SE =.10 to.64, SE =.20), except for age 5 yr (.41, SE =.08), suggesting an age or parity effect on gene expression. Frequency of multiple births increased between the ages of 2 and 6 yr (4.7 to 21.0%). Selection of twin born ewes over single born as breeding replacements was suggested by their higher frequency of multiple births (35.8 vs 33.6) and number of lambs born to age 8 yr (8.4 vs 8.0), without any significant negative effect on fleece weight (P<.01). No freemartin effects on twin born ewes were observed on pre- and postnatal growth for birth weight, fleece weight, number of lambs born and body weight (P<.05). Fleece weights decreased as the number of lambs reared increased: 4.2, 4.0, 3.9 and 3.8 kg for ewes with 0, 1, 2, 3 lambs, respectively. The genetic correlation between fleece weight and the average number of lambs born was $-.18$. The relationship of a ewe's body weight to lamb production was identified as curvilinear with lighter and extremely heavier ewes having lower rates of reproduction. A body weight range of 54.5 to 64.0 kg was found to have the highest frequency of multiple births and average number of lam…
  note: Typescript (photocopy).
  note: Vita.
  note: Ph. D. in Animal Breeding Texas A & M University 1987
  note: Includes bibliographical references (leaves 96-103).
  subject:
    topic: Sheep
    topic: Reproduction
  subject:
    topic: Sheep
    topic: Genetics
  subject:
    topic: Rambouillet sheep
  subject:
    topic: Major animal breeding
  identifier: http://hdl.handle.net/1969.1/Dissertations-754236
  identifier: http://proxy.library.tamu.edu/login
  related item:
    location:
      url: http://hdl.handle.net/1969.1/Dissertations-754236
  related item:
    location:
      url: http://proxy.library.tamu.edu/login
  record info:
    record content source: TXA
    record creation date: 881227
    record change date: 20190325092138.0
    record identifier: in00000741386
    language of cataloging:
      language term: eng