novel approaches to expression and detection of oestrus in dairy cows

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Activity Units against date and time. This resulted in 12 activity readings daily, with peaks denoting oestrus (Figure 2.2). From the activity data oestrus could be determined by peaks on the graph (Figure 2.2) and numbered for each oestrus during the lactation. These were determined either by increases in activity, visual detection or both. All peaks after 25 days post partum were identified as oestrus since increases in activity before this could be due to cows re-entering the herd after solitary calving and establishing hierarchies, mixing with new herd mates and entering a new environment. Oestrus was identified as either recorded or not recorded. Recorded was defined as oestrus which was confirmed by the herdsmen and where mounting and standing behaviour had been observed. Any peaks that did not correspond to recorded oestruses from the farm database were included in analysis as unrecorded oestrus events. Unrecorded oestrus events as seen by an increase in activity, were used in the data analysis, and identified as showing no overt signs as recognised by the herdsmen. Any recurring oestrous cycles within 10 days were discounted from analysis as these may be due to management practices or general errors and hence not a true representation of the cyclical activity. 60 50 Activity Graph of Lactating Cow from Calving through to Pregnancy 1 2 3 40 30 20 iActivityAvg 10 0 06/02/2009 28/03/2009 17/05/2009 06/07/2009 25/08/2009 14/10/2009 Date and Time Figure 2.2 Graph of activity units plotted against date and time; initial peaks are due to entry into the herd post calving and the initial trough is due to calibration. Peaks 1, 2 & 3 correspond to oestrus, compared to the baseline average activity Two oestrous parameters per cow were determined to analyse for associations with cow factors. Strength was calculated as a percentage increase from average baseline activity (baseline calculated over a 4 day rolling average) at oestrus and the maximum activity at oestrus was determined to use as measurements of activity. An increase in activity at 52
oestrus was defined as 3 consecutive periods of increased activity compared with the baseline before the onset of increased activity. The smallest threshold for activity increase was 30% from baseline. Herd fertility records provided information on each oestrus, insemination and whether this resulted in pregnancy. General information about each cow, such as milk yield, was downloaded to the system during milking. All data were compiled into a database to identify associations between activity data for oestrous expression and cow factors such as age, stage of lactation, milk production and time of year when oestrus occurred, and whether conception was successful after AI. The data collected are presented in Table 2.1. 2.2.3 Statistical Analyses Statistical analysis was carried out using Genstat 15th edition (VSN International Ltd, Hemel Hempstead, UK). Activity data were analysed as generalized linear mixed models (GLMM) using the residual maximum likelihood (REML) procedure, with Poisson distribution and logarithmic link function. The model fitted fixed effects for days in milk (DIM), milk yield (all definitions; Table 2.1), parity (classified according to lactation number as 1, 2 and ≥3), oestrous number and time of year (classified as Jan-Mar, 1; Apr-Jun, 2; Jul-Sept, 3; Oct-Dec, 4), individually. For the random effects of the model, individual cows represented subjects to allow for multiple oestruses per cow. The significance of fixed effects was assessed by Wald tests. The resulting model was: Y ij = µ + V i + C j + ε ij where Y ij is activity at oestrus, the fixed part of the model consists of µ the overall mean, V i the effect of the individual variable (Table 2.1), C j the random effect of Cow, and ε ij the residual error. 53
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NOVEL APPROACHES TO EXPRESSION AND
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TABLE OF CONTENTS TABLE OF CONTENTS
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2.2.3 Statistical Analyses ........
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5.3 RESULTS .......................
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Furthermore, automated software was
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LIST OF FIGURES Figure 1.1 Hormonal
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LIST OF TABLES Table 1.1 Trends in
Page 15 and 16:
LIST OF ABBREVIATIONS ˚ ˚C μM 2D
Page 17 and 18: CHAPTER 1 - Introduction & Literatu
Page 19 and 20: the past 50 years and duration of o
Page 21 and 22: Oestrus growing follicle (Staigmill
Page 23 and 24: ecomes the main inhibitor of FSH an
Page 25 and 26: calf at 40-50 days post partum; inv
Page 27 and 28: al., 2006). However, aged sperm hav
Page 29 and 30: can occur within 2-3 days, but if t
Page 31 and 32: educes the incidence of problem cow
Page 33 and 34: oestradiol, the LH surge and ovulat
Page 35 and 36: The secondary signs of oestrus can
Page 37 and 38: There are also changes in normal be
Page 39 and 40: engage in more natural behaviours i
Page 41 and 42: 1983). Exact explanations and mecha
Page 43 and 44: 2006) and disruption of LH secretio
Page 45 and 46: 1.4.3.2 Milk Yield and Nutrition Di
Page 47 and 48: influence the ability of the ovary
Page 49 and 50: cyclicity can be delayed if dietary
Page 51 and 52: indication for the optimal time to
Page 53 and 54: calving), 3) pre-breeding heat date
Page 55 and 56: 1.5.2 Physiological Changes Physiol
Page 57 and 58: 1.5.2.3 Body and Milk Temperature T
Page 59 and 60: physical activity and stage of the
Page 61 and 62: caused by the general environment t
Page 63 and 64: may be gained. This is because data
Page 65 and 66: In summary the objective was to for
Page 67: diet, with concentrates at milking.
Page 71 and 72: The interaction between parity and
Page 73 and 74: individual oestrus was not signific
Page 75 and 76: Table 2.4 The effects of the intera
Page 77 and 78: (361 vs. 578 points, respectively,
Page 79 and 80: oestrous expression with increasing
Page 81 and 82: the blood (Sangsritavong et al., 20
Page 83 and 84: CHAPTER 3 - Single Nucleotide Polym
Page 85 and 86: population owing to previous select
Page 87 and 88: Table 3.1 Cont. Follicle Stimulatin
Page 89 and 90: 3.2.4 Sequencing of DNA in the Labo
Page 91 and 92: was achieved. PCR products were rem
Page 93 and 94: 3.4 DISCUSSION The objectives of th
Page 95 and 96: fertility and oestrous expression.
Page 97 and 98: CHAPTER 4 - Development of a Novel
Page 99 and 100: In summary UWB seems a good option
Page 101 and 102: Initial tests were carried out to i
Page 103 and 104: Therefore this demonstrates that X
Page 105 and 106: which is most important for achievi
Page 107 and 108: Figure 4.9 Horizontal - Vertical Di
Page 109 and 110: that UWB is matching the ‘truth
Page 111 and 112: mounting cow. For example height ch
Page 113 and 114: Backpack 1 st put on in AI stalls E
Page 115 and 116: Cows’ behaviour was assessed at 5
Page 117 and 118: or that the cows were in an area of
Page 119 and 120:
plane, but mostly in achieving high
Page 121 and 122:
Develop techniques for analysis of
Page 123 and 124:
in elastic silicone moulded over a
Page 125 and 126:
and time of mount, duration of moun
Page 127 and 128:
observed matched with increases in
Page 129 and 130:
5.3 RESULTS Results demonstrate pos
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Figure 5.2 Graph showing mounting b
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Table 5.1 Results from POC 2 showin
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Table 5.3 Efficiency and accuracy o
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oestrus and oestrus it is clear to
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P4 Concentration, ng/ml P4 Concentr
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Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Activity Activity Activity Activity
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5.4 DISCUSSION The aim of this work
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averaged 70% which was lower than t
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when the cows lie down, especially
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the level of oestrous activity was
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technology larger herds must be mon
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monitoring could also monitor non-l
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antennae which could affect accurac
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predispose cows to illness e.g. met
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CHAPTER 6 - Overall Discussion & Co
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oestrus, h 2 =0.27 (Lovendahl et al
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The final section of this thesis de
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ate. By using UWB in a commercial s
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provides an insight the potential o
Page 179 and 180:
BLOWEY, R. (2005) Factors associate
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ovine gonadotrophin releasing hormo
Page 183 and 184:
GINTHER, O. J., KOT, K., KULICK, L.
Page 185 and 186:
associated with embryonic survival
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ody condition at parturition on end
Page 189 and 190:
Signs in a 24-h Tie-Stalled Dairy H
Page 191 and 192:
SHERMAN, E. L., NKRUMAH, J. D., MUR
Page 193 and 194:
Influence of negative energy balanc
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