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      • HARVEST
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      Sire verification in multi-sire breeding systems

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      DOMOLEWSKI-THESIS-2017.pdf (582.6Kb)
      Date
      2017-07-11
      Author
      Domolewski, Stacey Jo 1991-
      ORCID
      0000-0002-7693-6185
      Type
      Thesis
      Degree Level
      Masters
      Metadata
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      Abstract
      An experiment was conducted to evaluate using DNA parentage testing on commercial cow-calf operations using multi-sire breeding groups to determine the associations between various traits of bulls and number of calves sired. Four commercial Saskatchewan ranches with 7 breeding groups collaborated in this study, where all potential sires and progeny were sampled to determine the sire of each calf. Expected vs observed calf data were analyzed using Chi-square analysis. In all but 2 of the 7 breeding groups, it was determined that each bull sired a different (P<0.01) number of calves. Age of sire was found to effect (P<0.01) bull prolificacy or number of calves sired. A bull prolificacy index (BPI) was developed to compare which bulls are siring more or less than expected number of progeny. All bulls were required to pass a breeding soundness exam (BSE) before breeding season, therefore weak correlations were found between scrotal circumference (R2=0.04) or percent normal sperm (R2=0.13) and BPI values. No sire match ranged from 2-7% of calves tested. Testing only calves born in the 3rd week of calving, indicated that bulls could be assigned accurately to high or low prolificacy categories, but bulls with the fewest number of calves sired could not be detected. Economic models were developed to evaluate the value of adopting parentage testing on farm using a cost benefit analysis. The model showed bulls that sired more calves had a lower cost per calf sired. Based on the model, if bulls were siring < 25 calves it would be more economical to use AI in the breeding program. The model also determined that if one bull was causing increased dystocia rates in a herd, testing calves from difficult births to cull responsible bulls did provide an economic return on investment to the operation. There is potential to increase overall bull prolificacy in a herd and increase other economically important traits by using DNA parentage to aid in sire selection.
      Degree
      Master of Science (M.Sc.)
      Department
      Animal and Poultry Science
      Program
      Animal Science
      Supervisor
      Lardner , Bart A
      Committee
      Mutsvangwa, Tim; Buchanan, Fiona c; Campbell, John; Palmer, Colin
      Copyright Date
      June 2017
      URI
      http://hdl.handle.net/10388/7951
      Subject
      Bull prolificacy, DNA parentage, sire verification
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      • Graduate Theses and Dissertations
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