This study was conducted to determine if a relationship exists between
temperament, stress response, and the shedding of Escerhichia coli O157:H7. Cattle (n
= 150) were evaluated for disposition and stress response before shipping to the feeding
operation, upon arrival at the feedlot, at approximately 70d on feed, and prior to
transport to the harvesting facility. Chute and pen scores, as well as serum cortisol
concentrations, were measured in order to assess individual temperament and stress
response. A temperament index was created to classify cattle as Excitable, Intermediate,
or Calm. The presence of E. coli O157:H7 was determined by rectal swabs on the live
cattle and swabs of colons collected postmortem at the processing facility. As expected,
variables for pre-shipment temperament index, exit velocity, pen score, arrival and midpoint
exit velocity, and mid-point cortisol concentrations differed (P < 0.05) greatly
between temperament groups. However, pre-shipment chute scores and cortisol
concentration, as well as arrival and final cortisol concentrations differed (P < 0.05) only
for Excitable cattle compared to both Calm and Intermediate groups. The percentage of
cattle shedding the pathogen at arrival was approximately equal between temperament
groups. When sampled before shipment to the processing facility, a higher proportion (P
= 0.03) of cattle displaying Calm temperaments shed E. coli O157:H7 than the other groups. Results from postmortem colon samples exhibited a similar trend. When the
results from all four sampling periods were pooled, the Calm cattle had a greater
numerical percentage test positive for E. coli O157:H7. However, the pooled frequency
distribution is largely dictated by the results of the final sampling time. Based on these
results, it appears that Excitable cattle are not more likely to shed E. coli O157:H7. In
fact, it seems that Calm cattle may be equally or more susceptible to shed at later points
in the feeding period. However, it is important to note that a relatively small number of
the samples tested positive for E. coli O157:H7, thus, potentially causing dramatic
changes in the distributions.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4436 |
| Date | 30 October 2006 |
| Creators | Schuehle, Celeste Elaine |
| Contributors | Savell, Jeffrey W. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 231948 bytes, electronic, application/pdf, born digital |
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