Stanton PhD Thesis final_docx - Atrium - University of Guelph

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NY) is a tiamilide compound, a subclass of macrolide long-acting antimicrobials. It is distinguished by maintaining therapeutic concentrations against pathogens commonly associated with BRD for up to 10 d (Nowakowski et al., 2004). Tulathromycin is approved for treatment and control of BRD in beef cattle and nonlactating dairy cattle. Tulathromycin has been shown to be effective in the treatment of BRD in 3- to 9-wk-old calves challenged with Mycoplasma bovis (Godinho et al., 2005, 2007). Oxytetracycline is a broad-spectrum tetracycline antibiotic that maintains therapeutic concentrations against pathogens associated with BRD for 3 d (Biomycin 200, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO). Oxytetracycline is approved for use in beef and dairy cattle. The hypothesis for this study was that administration of tulathromycin at a time of high risk of BRD would reduce the pathogen challenge and the risk of clinical respiratory disease in the weeks following a postweaning movement and housing change in dairy calves. 6.3 MATERIALS AND METHODS 6.3.1. Heifer Management and Housing This study was conducted at a commercial contract heifer raising facility in New York State. Enrollment in the study occurred between November 2006 and June 2007, with a total of 1,395 heifers being enrolled. Heifer calves arrived at the farm from 7 commercial dairy farms at 1 to 5 d of age. Upon arrival at the facility, each calf was processed according to a standard farm protocol and was then moved to individual housing in a naturally ventilated nursery barn or an outdoor hutch. The farm protocol included the identification of any congenital abnormalities, measurement of serum total protein, tail docking, and the collection of a tissue sample for the detection of persistent infection 137
with bovine viral diarrhea (BVD). Over the course of this study, no animal tested positive for BVD. Calves were vaccinated at 2 and 4 wk of age with an intramuscular modified live vaccine against infectious bovine rhinotracheitis, BVD type 1 and type 2, bovine respiratory syncytial virus, and parainfluenza-3 virus (Vista-5, Intervet Schering-Plough Animal Health, Boxmeer, the Netherlands). Preweaned calves were fed 4 L of milk replacer (Excel Calf Milk Replacer 26/18, Grober Nutrition, Cambridge, Ontario, Canada) twice daily and had access to ad libitum calf starter and water. Weaning from milk replacer was initiated at 5 wk and completed at 6 wk of age. Calves remained in their original individual housing for approximately 2 wk after weaning, at which time they were moved to group housing in the weaning barn and enrolled in the trial. Calves that were moved to group housing after 80 d of age were excluded from this trial. A schematic representation of the trial methods and events is shown in Figure 6.1. For the first 6 wk of the study, calves were housed in the weaning barn in groups of 8 to10 calves. For the initial 3 to 4 wk in the weaning barn, calves received dry hay and pelleted heifer grain ad libitum. Calves were then transitioned onto a TMR. After approximately 6 wk in the weaning barn, calves were moved to the transition barn and housed in groups of approximately 50 calves. 6.3.2 Study Treatments Before the start of the study, the farm had a pre-existing treatment protocol at movement. As such, the current study was designed as a positive control trial, with calves being assigned to treatment with tulathromycin (TUL) or the previously established oxytetracycline protocol (TET). Each calf was assigned to treatment group using a systematic random assignment method 138
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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
Page 97 and 98: Weight gain (kgs) first 7 days post
Page 99 and 100: The concept of separating stressors
Page 101 and 102: were bedded with straw. While house
Page 103 and 104: 4.2.5 Data Collection Calf starter
Page 105 and 106: 4.3 RESULTS enrolment. On average,
Page 107 and 108: 4.3 DISCUSSION There was no effect
Page 109 and 110: 4.4 REFERENCES Chua, B., E. Coenen,
Page 111 and 112: Steps per day 2500 2000 1500 1000 5
Page 113 and 114: Appendix 4.1: Scoring sheet used fo
Page 115 and 116: 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: efore entry into the milking herd 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 and 168: Table 6.5: Reasons for death loss a
Page 169 and 170: CHAPTER 7: THE IMPACT OF BOVINE RES
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
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Table 7.7: Producers primary reason
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Table 7.9: Effect of BRD60 on calvi
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Table 7.11: Distribution of heifers
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Figure 7.2: Difference in least squ
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Figure 7.4: Time to event analysis
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CHAPTER 8: CONCLUSIONS AND FUTURE R
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Heifers with poor post-weaning grow
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strategic antimicrobial use was met
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Specifically, How can disease sever
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Does transportation, initial social
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