Stanton PhD Thesis final_docx - Atrium - University of Guelph

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Appendix 7.1: Daily minimum and maximum temperature at the Rochester, New York weather station, located approximately 65 km from study site, by season. 40 30 20 10 0 -10 -20 Reference Season Season 2 Season 3 Bach, A. 2011. Associations between several aspects of heifer development and dairy cow survivability to second lactation. J. Dairy Sci. 94:1052-1057. 197 Max TemperatureC Min TemperatureC
CHAPTER 8: CONCLUSIONS AND FUTURE RESEARCH 8.1 GENERAL DISCUSSION There are many challenges associated with rearing healthy dairy heifer calves that can result in high mortality rates and welfare problems. Multidisciplinary approaches of evaluating management practices, identifying animals at risk of disease, and quantifying the impact of diseases are valuable tools for improving calf welfare and productivity. High mortality rates in dairy calves are important concerns for producers, due to the monetary costs of calf loss, the welfare costs to animals during illness and convalescence, and the impact of mortality and calf suffering on public perception of the dairy industry. Two diseases are primarily responsible for mortality in neonatal dairy calves: neonatal calf diarrhea complex (diarrhea) and bovine respiratory disease complex (BRD). These diseases are responsible for 79% of the deaths in milk fed calves and 59% of the deaths in weaned dairy calves (USDA, 2007). To reduce the impact of these two diseases, new and improved methods of disease identification and animal management are needed. The three main areas of focus of this doctoral thesis are the use of behavior to identify animals at risk of disease, group level management of disease risk, and identification of long-term impacts of BRD. Animal diseases have many negative impacts on animal welfare and production (Chapter 1). The early identification of animals at risk of disease allows for interventions either through reducing or eliminating risk factors. Examples include altering weaning management practices (Chapter 4), or in the absence of controllable risks, such as poor weather, administering a prophylactic antibiotic (Chapter 5 and 6). Even if risk factors are reduced, some disease still occurs. Therefore, to improve recovery and reduce welfare impacts, early identification of 198
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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
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feedlots (Van Donkersgoed, 1992). I
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protocol included the identificatio
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(cases) and two calves closest in a
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No statistical analysis was perform
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5.4.3 Growth Three calves returned
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5.4.4 Testing for Mycoplasma Of the
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may be an early sign of respiratory
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small number of unilateral ear droo
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evaluated for efficacy and carefull
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5.6 REFERENCES Biddle, M. K., L. K.
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USDA. 2007. Dairy 2007, part II: Ch
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Table 5.2: Incidence and median age
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Table 5.4: Breakdown of the number
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Figure 5. 5.1: 1: Images taken from
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6.1 ABSTRACT Bovine respiratory dis
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efore entry into the milking herd o
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with bovine viral diarrhea (BVD). O
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6.3.3 Outcome Measures All calves w
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tests, or multiple partial F-tests,
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The effect of treatment on height a
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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
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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
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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: Figure 7.4: Time to event analysis
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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