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EVALUATION OF BREED AND TEMPERAMENT EFFECTS ON COW REPRODUCTIVE TRAITS AND LONGEVITY IN A CROSSBRED CATTLE POPULATION
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The genetics of longevity in beef cattle production is a critical aspect of efficiency, thus making it an economically important trait. Variation in longevity has been observed between different breeds, and is dependent on individual animal reproductive performance amongst other traits. The effects of temperament on cow longevity has not been assessed before. The objective of this study is to evaluate the effects of breed type and temperament on longevity and reproductive traits in a predominantly Bos indicus x Bos taurus beef cow herd at the E. G. Morrison Brown Loam Research Station in central Mississippi. Cows (n = 1,285) involved in the study were categorized by breed type (i.e. > 0.25 and < 0.25 proportion Bos indicus influence) and temperament. Temperament categories were constructed based on exit velocity records (n = 747) and were distributed equally within 4 groups. The groups consisted of a categorization between 1 through 4, where most temperamental animals were placed in the 4th category and the most docile in the 1st temperament category. Calving and weaning records (n = 5,052) were utilized for evaluation of cow reproductive traits. Longevity data was analyzed using a threshold model with a probit function. Age category of the dam was a significant source of variation in calving rates (P < 0.001), weaning rates (P < 0.001), and 205-day weight (P < 0.001). Variation for breed effects within ages were significant (P < 0.005) in analysis of longevity. In conclusion, cows that were greater than or equal to a proportion of 0.25 Bos indicus background tended to remain productive at advanced ages, while cows of less than 0.25 Bos indicus influence were observed to leave the herd at a younger age. Temperament did not play a significant role in differences of longevity or reproductive traits within this study, but the inclusion of more temperament records could provide a more precise estimate.
Pena, Carlos Raul (2019). EVALUATION OF BREED AND TEMPERAMENT EFFECTS ON COW REPRODUCTIVE TRAITS AND LONGEVITY IN A CROSSBRED CATTLE POPULATION. Master's thesis, Texas A&M University. Available electronically from