Stanton PhD Thesis final_docx - Atrium - University of Guelph

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Figure 6.1: Timeline of trial events 157
CHAPTER 7: THE IMPACT OF BOVINE RESPIRATORY DISEASE AND A PREVENTATIVE ANTIBIOTIC TREATMENT ON GROWTH, SURVIVAL, AGE AT FIRST CALVING, AND PRODUCTIVITY HEIFERS 7. 1 ABSTRACT Bovine respiratory disease complex (BRD) is a common disease in weaned dairy calves that incurs economic and welfare costs. This study was an extension of a randomized clinical trial in which a single injection of tulathromycin (TUL) or oxytetracycline (TET) was administered at first movement to group housing for the prevention of BRD in the 60 days following antimicrobial treatment (BRD60). Calves treated with TUL were 0.5 times (95% CI: 0.4 to 0.7) as likely to be treated for BRD60 as calves treated with TET. The objectives of the current study were to evaluate the long-term effects of BRD and antibiotic treatment on growth of heifers until breeding age, age at first calving, incidence of dystocia, milk production and mortality prior to first calving and mortality prior to 120 days in milk. Body weight and average daily gain were analyzed using generalized linear mixed models (Proc Mixed, SAS) controlling for source farm and enrolment cohort as random effects. Survival to calving and calving prior to 25 months were analyzed using mixed models with binary distribution and logit link function (Proc GLIMMIX) in SAS (Version 9.1). A p-value of less than 0.05 was considered to be statistically significant. At entry to the breeding barn (382 days of age) calves that experience BRD60 weighed 16.0 ± 2.3 kg less than calves that did not. For TET and TUL calves, calves without BRD60 were 3.4 {Confidence Interval: 2.2-5.2} and 1.7 {CI:1.0-2.9} times more likely to survive to first calving compared to BRD60 calves, respectively. BRD60 calves were 0.6 (95% CI: 0.4-0.8) times as likely to calve before 25 months of age and 1.5 (95% CI: 1.1-2.2) times more likely to have a calving ease score ≥ 2 at their first calving. BRD may affect first test 158
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AN EVALUATION OF THE IMPACT OF MANA
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differences in weight gain or calf
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3.2.2 Experimental Study Design 68
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7.4.5 Culling and mortality prior t
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Table 6.5: Reasons for death loss a
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and season as fixed effects and for
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, which requires that “all calves
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ehaviour of dams challenged with LP
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In cattle, early disease detection
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increased rest and decreased appeti
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1.4.2 Nutritional Stressors Dairy c
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humans, the metabolic rate increase
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Without human intervention, calves
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average group size of three or four
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al., 2004). Group composition and g
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first is the addition of antibiotic
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viral diarrhea virus (BVDV) bovine
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1.7 CONCLUSION AND THESIS OBJECTIVE
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Buhman, M. J., L. J. Perino, M. L.
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Hemsworth, P. H., G. J. Coleman, J.
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Schein, M. W. and M. H. Fohrman. 19
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Waltner-Toews, D., S. W. Martin and
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ehavioural observations ( Borderas,
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and had access to ad libitum calf s
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may indicate abdominal discomfort,
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identified in 5% (40/788) of calves
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of diarrhea in calves on this farm
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The most common response to the vig
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at any observation period. For this
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3 was associated with lower ADG rel
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of heifers to allow them to calve a
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2.5 REFERENCES Al-Chaer, E. D. & Tr
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Panivivat, R., Kegley, E. B., Penni
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Table 2.2: List of exclusions used
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Table 2.4: The lsmeans ± S.E. of t
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Figure 2.1: Timeline describing tri
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Proportion of calves performing beh
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in a lower rate of vocalizations an
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sites. During the summer months bot
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treatment and weight gain category.
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pre-weaning calf starter intake, an
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Calves spent a total of 13 ± 6 (me
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calves were still allowed access to
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It was hypothesized that the more t
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calves to consume sufficient calf s
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Table 3.1: Descriptive list of obse
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Number of steps per day 7000 6000 5
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Number of lying bouts per day 35 30
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Weight gain (kgs) first 7 days post
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The concept of separating stressors
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were bedded with straw. While house
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4.2.5 Data Collection Calf starter
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4.3 RESULTS enrolment. On average,
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4.3 DISCUSSION There was no effect
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4.4 REFERENCES Chua, B., E. Coenen,
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Steps per day 2500 2000 1500 1000 5
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Appendix 4.1: Scoring sheet used fo
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positive for M. bovis and 4 differe
Page 117 and 118: feedlots (Van Donkersgoed, 1992). I
Page 119 and 120: protocol included the identificatio
Page 121 and 122: (cases) and two calves closest in a
Page 123 and 124: No statistical analysis was perform
Page 125 and 126: 5.4.3 Growth Three calves returned
Page 127 and 128: 5.4.4 Testing for Mycoplasma Of the
Page 129 and 130: may be an early sign of respiratory
Page 131 and 132: small number of unilateral ear droo
Page 133 and 134: evaluated for efficacy and carefull
Page 135 and 136: 5.6 REFERENCES Biddle, M. K., L. K.
Page 137 and 138: USDA. 2007. Dairy 2007, part II: Ch
Page 139 and 140: Table 5.2: Incidence and median age
Page 141 and 142: Table 5.4: Breakdown of the number
Page 143 and 144: Figure 5. 5.1: 1: Images taken from
Page 145 and 146: 6.1 ABSTRACT Bovine respiratory dis
Page 147 and 148: efore entry into the milking herd o
Page 149 and 150: with bovine viral diarrhea (BVD). O
Page 151 and 152: 6.3.3 Outcome Measures All calves w
Page 153 and 154: tests, or multiple partial F-tests,
Page 155 and 156: The effect of treatment on height a
Page 157 and 158: this study involved continuing with
Page 159 and 160: is important to emphasize that the
Page 161 and 162: 6.7 REFERENCES J. Carroll and N.E.
Page 163 and 164: Table 6.1: Disease variables consid
Page 165 and 166: Table 6.3: Least squares means ( ±
Page 167: Table 6.5: Reasons for death loss a
Page 171 and 172: 7.2 INTRODUCTION Bovine respiratory
Page 173 and 174: days following study enrolment than
Page 175 and 176: Age at First Calving Since age at f
Page 177 and 178: (Weaning, Transition, Grower 1, Gro
Page 179 and 180: The excluded source farm resulted i
Page 181 and 182: of calves with BRD60 survived to fi
Page 183 and 184: 7.4.8 Milk Production First Test Da
Page 185 and 186: BRD before 6 months of age decrease
Page 187 and 188: BRD following movement to group hou
Page 189 and 190: calves with BRD60 were 1.5 (95% CI:
Page 191 and 192: 7.7 REFERENCES Correa, M. T., C. R.
Page 193 and 194: Table 7.1: Calving Ease Scoring Sys
Page 195 and 196: Table 7.3: Least-square means (± S
Page 197 and 198: Table 7.5: Proportion of calves sur
Page 199 and 200: Table 7.7: Producers primary reason
Page 201 and 202: Table 7.9: Effect of BRD60 on calvi
Page 203 and 204: Table 7.11: Distribution of heifers
Page 205 and 206: Figure 7.2: Difference in least squ
Page 207 and 208: Figure 7.4: Time to event analysis
Page 209 and 210: CHAPTER 8: CONCLUSIONS AND FUTURE R
Page 211 and 212: Heifers with poor post-weaning grow
Page 213 and 214: strategic antimicrobial use was met
Page 215 and 216: Specifically, How can disease sever
Page 217 and 218: Does transportation, initial social
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Stanton PhD Thesis final_docx - Atrium - University of Guelph

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