Stanton PhD Thesis final_docx - Atrium - University of Guelph

List of Figures
Figure 2.1: Timeline describing trial milestones and behavioral observations, with average ages
(mean ± s.d.) at observation and measurements ........................................................................... 60
Figure 2.2: Method for behavioral scoring of the calves, conducted every other week .............. 61
Figure 2.3: Proportion of calves in each lethargy response category for the active diarrhea (n =
229) and healthy controls (n = 47) ................................................................................................ 62
Figure 3.1: The average number of steps per day (mean ± standard deviation ) by weight gain
category in the first week post-weaning for calves (n = 70) following weaning and relocation to a
novel environment. ....................................................................................................................... 82
Figure 3.2: The total lying duration per day (hours) (mean ± standard deviation ) for calves (n =
70) following weaning and relocation to a novel environment, and total lying duration per day by
weight gain category in the first week post-enrolment ................................................................. 83
Figure 3.3: The average number of lying bouts (mean ± standard deviation ) per day for calves
(n = 70) following weaning and relocation to a novel environment, and number of lying bouts
per day by weight gain category in the first week post-enrolment ............................................... 84
Figure 3.4: LSMEANS (±S.E.) of post-weaning weight gain for total lying duration by nursery
location interaction (P = 0.01) ...................................................................................................... 85
Figure 3.5: LSMEANS (±S.E.) of post-weaning weight gain for time at the bunk (% of total
observations) by nursery location interaction (P = 0.03), controlling for Day 0 weight, antibiotic
treatment, and pre-weaning calf starter intake, with random effects for group nested within group
size. ............................................................................................................................................... 86
Figure 4.1: Steps per day (Mean and 95% Confidence Interval ) for each of the time periods,
controlling for breed and age as fixed effects, replicate as a random effect and calf nested within
replicate and treatment as a repeated measure. ........................................................................... 100
Figure 4.2: LSMeans ( ± S.E.) of total daily lying time (hours), controlling for breed and age
with a random effect for replicate and calf nested within replicate and treatment. .................... 101
Figure 5.1: Images taken from farm prior to the start of the trial and used as guidelines to
identify ear droop. Shown: from left to right: Unilateral ear droop and ear droop with abnormal
head position ............................................................................................................................... 132
Figure 6.1: Timeline of trial events ............................................................................................ 157
Figure 7.1: Timeline of trial events ............................................................................................ 193
Figure 7.2: Difference in least squares means (± SE ) of the weight (kg) of heifers with BRD60 1
relative to calves without BRD60 at 5 time points at a commercial heifer raising facility,
controlling for birth weight, age at measurement and season with random effects for source farm
and weekly enrolment cohort. ..................................................................................................... 194
Figure 7.3: Differences of least squares means (± SE ) of the weight (kg) of heifers with no prior
history of bovine respiratory disease that received tulathromycin at study enrolment relative to
heifers that received oxytetracycline at study enrolment at entry at 5 time points at a commercial
heifer raising facility. The linear mixed models controlled for birth weight, age at measurement
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