Stanton PhD Thesis final_docx - Atrium - University of Guelph

The human approach test used in this study is based on the knowledge that these milk-fed
calves rely on humans for feed and as such will likely have positive associations with a
stationary person. For this reason, it is highly probable that calves will rapidly approach a
stationary observer. A previous study showed that at 17 days of age calves that were hand reared
without additional positive human contact approached within 1 meter of an observer in an
average of 12 seconds (Jago et al. 1999). It was hypothesized that failure to approach an observer
by calves in this age group would be an indicator of a decreased interest in the environment,
which has previously been associated with sickness behavior (Hart 1988; Dantzer & Kelley,
2007).
2.2.3 Disease Recordings and Weight Gain
All disease treatment events were recorded daily by barn staff. The standard farm practice
was to first record all treatments on standardized paper forms and later enter the data into a farm
management computer program (DairyComp 305, Valley Agriculture Software Inc., Tulare,
CA). Standardized definitions were used for the most common diseases. Neonatal diarrhea
complex was defined as “feces soft and does not hold form”. Non-specific fever was defined as
“dull and listless with a rectal temperature above 39.5 o C”, and was distinct from the definition
for respiratory disease, which was “rectal temperature above 39.5 o C, together with elevated
respiratory rate, nasal discharge or cough”. Neonatal calf diarrhea complex was the most
commonly treated disease with 84% of calves treated at a median age of 10 days. Only 4%
(27/788) of calves were never treated for disease. Failure of passive transfer was determined
based on serum total protein < 5.4 g/dL (Tyler et al. 1998). Failure of passive transfer was
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