novel approaches to expression and detection of oestrus in dairy cows

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influenced by other factors such as cysts and ulcerous inflammations and the continuous sampling needed to determine the changes in resistance, which can cause irritation of the reproductive tract resulting in inflammation which will both hinder results and cause discomfort (Firk et al., 2002). The animal’s temperament, positioning of the probe and nutritional (mineral) imbalance can also alter resistance (Rorie et al., 2002). Vaginal mucus resistance as a measure of oestrous detection is impractical but could be overcome by implants continuously recording resistance and plotting the results to observe changes over time. 1.5.2.5 Rectal Palpation and Ultrasonography Rectal palpation and ultrasonography are used to evaluate ovarian activity and diagnose the stage of the oestrous cycle. Rectal palpation is used to detect the presence of the corpus luteum. Ultrasound is used to determine which ovary the growing follicle is situated on by measuring the diameter, then once a preovulatory follicle is obvious the ovary can be monitored at intervals to determine the time of ovulation, which is when the follicle disappears, for AI (Roelofs et al., 2005). These techniques can also be used to detect silent heats, rectal palpation with 69.7% accuracy and ultrasonography 89.0% accuracy (Zdunczyk et al., 2009). However these techniques can be time consuming and impractical as a method of oestrous detection, and must be carried out by either a veterinarian, which is costly, or a skilled stockperson (Foote, 1975). 1.5.3 Automated Technologies Automated technologies are advantageous for oestrous detection because they monitor cows for oestrus 24 hours a day continuously requiring little input from the herdsman. Most electronic technologies fulfil the criteria set out by Senger (1994), for the ‘ideal’ system of oestrous detection. Although automated methods of detection are efficient they lack accuracy at detecting oestrus when compared to frequent visual observations and error rates are often increased. Automated methods must also be accurate at detecting signs of oestrus that are related to ovulation in order to correctly time AI to improve conception rates. 1.5.3.1 Pedometers and Activity Monitors Pedometry and activity monitoring detect changes in the physical activity of the cow through motion sensing analysis. The relationship between 42
physical activity and stage of the oestrous cycle was first documented by Farris (1954), before confirmation by Kiddy (1976) reporting that cows are approximately 2 to 4 times more active when in oestrus compared to when they were not. Activity is measured by a mercury switch in the pedometer/ activity monitor which is turned on or off by cow movement. The device is fixed around the neck or leg of the cow and data downloaded at milking on entry to the parlour or by infrared sensors around the barn and analysed automatically. When activity increases above a threshold level or significantly from the baseline a cow is said to be in oestrus and this is flagged up automatically for further attention and submission for AI (Firk et al., 2002). There are significant activity increases on the day of oestrus than on any other day (Schofield et al., 1991), although it has been said that activity increases linearly and gradually from 72 to 16 hours before oestrus and from 16 hours to oestrus activity increases rapidly (Arney et al., 1994). It is also reported that a marked increase in activity occurs 4 hours before peak oestrus allowing for optimal timing of AI (Nebel et al., 2000). Activity is an accurate method of oestrous detection as At-Taras and Spahr (2001) reported activity corresponded most closely to standing behaviour. Secchiari et al., (1998) also confirmed the relationship between activity increase, time of insemination and successful conception. Yet this relies upon the frequency of activity records per day. The efficiency of recordings determined by activity are in the range of 60 to 100% combined from several studies (Senger, 1994), mostly averaging 80-90% accuracy (Firk et al., 2002;Lehrer et al., 1992). Some studies even achieved 100% accuracy (Arney et al., 1994;Schofield et al., 1991). Low values for accuracy arise from false positives; technical faults and loss of devices, but also the severity of activity increase. When the increase in activity is bigger (4 fold compared to 2 fold) and duration of sustained activity is longer (approximately 4 hours), detection becomes more efficient and accurate (Rorie et al., 2002), as a clear distinction between non oestrus and oestrus can be made. Error rate has been reported between 17 and 55% in a range of studies (Firk et al., 2002) due to routine management tasks causing an increase in activity. However, activity monitoring is an efficient method of oestrous detection, more so than visual detection because continuous monitoring of data provides a reliable signal for the onset of oestrus. It is also economical, although not 43
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NOVEL APPROACHES TO EXPRESSION AND
Page 3 and 4:
TABLE OF CONTENTS TABLE OF CONTENTS
Page 5 and 6:
2.2.3 Statistical Analyses ........
Page 7 and 8: 5.3 RESULTS .......................
Page 9 and 10: Furthermore, automated software was
Page 11 and 12: LIST OF FIGURES Figure 1.1 Hormonal
Page 13 and 14: 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: 1.5.2.3 Body and Milk Temperature T
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 and 68: diet, with concentrates at milking.
Page 69 and 70: oestrus was defined as 3 consecutiv
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
Page 131 and 132:
Figure 5.2 Graph showing mounting b
Page 133 and 134:
Table 5.1 Results from POC 2 showin
Page 135 and 136:
Table 5.3 Efficiency and accuracy o
Page 137 and 138:
oestrus and oestrus it is clear to
Page 139 and 140:
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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Page 151 and 152:
Page 153 and 154:
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
Page 159 and 160:
the level of oestrous activity was
Page 161 and 162:
technology larger herds must be mon
Page 163 and 164:
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
Page 169 and 170:
CHAPTER 6 - Overall Discussion & Co
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oestrus, h 2 =0.27 (Lovendahl et al
Page 173 and 174:
The final section of this thesis de
Page 175 and 176:
ate. By using UWB in a commercial s
Page 177 and 178:
provides an insight the potential o
Page 179 and 180:
BLOWEY, R. (2005) Factors associate
Page 181 and 182:
ovine gonadotrophin releasing hormo
Page 183 and 184:
GINTHER, O. J., KOT, K., KULICK, L.
Page 185 and 186:
associated with embryonic survival
Page 187 and 188:
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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