Stanton PhD Thesis final_docx - Atrium - University of Guelph

The excluded source farm resulted in a loss of 3% of calves from the original database
(48/1393).
7.4 RESULTS
The weights and heights of calves upon entry to the six rearing barns are presented in
Table 7.2. Four heifers were not weighed or measured at one of the measurement time points
(transition barn (n = 1), grower barn 1 (n = 1) and grower barn 2 (n = 2)) and were excluded
from all analyses of ADG, weight and height that require the use of this data.
7.4.1 Average Daily Gain
Effects of BRD60 on ADG are presented in Table 7.3. BRD60 was associated with a 0.16
± 0.01 kg decrease in ADG in the weaning barn (P < 0.001). Similarly, BRD60 was associated
with reduced ADG in the Transition Barn and Grower Barn 1. Overall, BRD60 was associated
with a decrease in ADG between the weaning barn and the breeding of 0.03 ± 0.01 kg (P <
0.001).
An antimicrobial treatment and pBRD interaction was significant in the weaning and
transition barns, (P < 0.005 and P=0.05, respectively). The interaction between antimicrobial
treatment and pBRD did not have a significant effect on ADG in Grower Barn 1 or Grower Barn
2, (P = 0.51 and P = 0.25, respectively). In the weaning barn, calves without pBRD gained 0.97
± 0.01 kg/day and 0.86 ± 0.01 kg/day in the TUL and TET group, respectively (P < 0.001). In
the transition barn, calves without pBRD gained 0.98 ± 0.01 kg/day and 0.96 ± 0.01 kg/day in
the TUL and TET group, respectively, (P = 0.03). In calves with pBRD, antimicrobial treatment
had no effect on ADG, (P = 0.57).
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