Romero, Natasha Elizabeth (2008-12). Evaluation of traits associated with bucking bull performance and behavior. Master's Thesis.
Video and industry data were used to assess the inter-relationships of aggression,
delivery, coat color, year of birth, number of outs, buckoff percent and score in rodeo
bulls. An evaluation of laterality based on observations of how the individual animals
were loaded into chutes at 11 bull riding events showed 63% left-handed delivery and
37% right-handed delivery across all observations (n = 525). There was a similar
distribution for aggressiveness (based on whether or not the bull charged after the rider
dismounted) with 64% of bulls being non-aggressive and 36% of bulls being aggressive.
Significant linear relationships existed between score and number of outs and
score and buckoff percentage indicating that experience impacted performance. The
correlation between number of outs and buckoff percentage was low to moderate (0.06
to 0.30), depending upon the subset of data evaluated.
The r-square value for the analysis of score among all bulls was 0.14; however,
the r-square value in the subset of bulls with known sires with more than one son was
0.68 when sire was included in the model. Similar increases in r-square values were
observed for 2006 average score, career average score, buckoff percentage, and career buckoff percentage, indicating important genetic influences on these traits and/or their
Investigations into the relationship between performance and aggression may
help bucking stock producers improve the selection criteria they use. The current trend
within the industry is for several breeders to breed 'hot' or flighty, nervous cattle to
achieve higher performing offspring. Given that there was no association between
aggression and score based on chi-square test, aggression may be removed from the
criteria for using certain animals for breeding purposes. Based on results from this
work, if bucking stock breeders want to make genetic changes in these traits,
documentation of pedigree information is vital.