Stanton PhD Thesis final_docx - Atrium - University of Guelph

CHAPTER 4: EVALUATION OF A GRADUATED WEANING PRACTICE ON
BEHAVIOR AND PERFORMANCE OF DAIRY CALVES
4.1 INTRODUCTION
Weaning and relocation to group housing is considered to be a time of great stress for
dairy calves. The majority of milk-fed calves in the United States are individually housed, and
stress associated with weaning and moving to group housing at weaning can result in increased
susceptibility of calves to bovine respiratory disease complex (BRD) (McGuirk, 2008). This
increased risk of BRD has been attributed to the many changes occurring at this time including
nutritional, environmental, and social stress, as well as increased exposure to pathogens
(McGuirk, 2008). It has been suggested that separating challenges including vaccination,
dehorning, nutritional changes, as well as moving to new social and physical environments could
reduce susceptibility to clinical disease (Quigley, 1996). One recommendation is to pre-condition
calves by mixing them into small groups after they have been weaned, but before they are moved
into group housing in a novel environment. Comparisons of the responses of pair-housed calves
with those of individually housed calves indicate that pair-housed calves had lower heart rates
during transportation (Lensink et al., 2001) and during the week of weaning did not experience a
growth check in contrast to individually housed calves (Chua et al., 2002). However, in these
studies, calves were paired for longer than 6 weeks. For managers that house calves individually
during the pre-weaning period, preconditioning may require additional space in the nursery to
house calves for longer periods of time. Therefore, for economic and practical reasons it is
important to determine if housing calves in groups for shorter periods of time (e.g. one week)
prior to movement to a new facility will be beneficial for health or growth.
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