novel approaches to expression and detection of oestrus in dairy cows

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CHAPTER 2 – Effect of Cow Factors on Oestrous Expression 2.1 INTRODUCTION A main contributory factor to poor fertility in the dairy cow (Royal et al., 2000a;Butler, 2003) is poor oestrous expression; only 50% of cows are reported to show signs of standing to be mounted, the definite sign that a cow is in oestrus (Van Eerdenburg et al., 2002). Other measures of oestrus suggest that duration and intensity of oestrus has also decreased; only 8.5 standing events at oestrus and duration only lasting on average 7 hours in Holsteins (Dransfield et al., 1998). Associations have been found between parity (Macmillan et al., 1996) (Garnsworthy et al., 2008), seasonal variations (Critser et al., 1987) and milk yield (Royal et al., 2000a) and their effects on fertility. Previous work has recognised that oestrous expression can be influenced by cow factors, focussing on duration and intensity, and standing events (Van Eerdenburg et al., 1996;Peralta et al., 2005), but there have been few investigations into the effects of cow factors and their associations with activity at oestrus, measured by activity monitors. Emphasis should be placed on identifying cows at risk of poor oestrous expression. It is important to identify factors that affect oestrous expression in order to implement management systems for improvement of oestrous detection. This study investigated the effects of parity, time period of oestrus, oestrous number, days post partum and milk yield for their effects on activity. Associations between the activity increase on day of oestrus and probability of conception were also investigated. The aims of this study were to identify the effects of measurable cow factors on activity increases at oestrus. 2.2 MATERIALS AND METHODS 2.2.1 Animals Animals used in this study were 205 Holstein Friesian dairy cows housed at Nottingham University Dairy Centre. The lactating cows were kept indoors in groups of approximately 40. Housing consisted of a purpose built shed with 4 pens, which was well ventilated, with rubber matting, cubicles and shavings for comfort whilst lying. All cows were fed the same silage based 50
diet, with concentrates at milking. Cows were milked by 4 robotic milkers (Lely Astronaut A3 AMS units) voluntarily; visiting from 2 to 6 times per day. Oestrous detection was measured by activity monitors with data downloaded by infrared sensors, and by visual observation. Three full time staff were employed to work at the dairy unit, of which 2 were working at any one time. Cows were checked for signs of oestrus by the herdsperson first thing in the morning, at approximately 6am, and again in the evening, between 8pm and 10pm. However, this left a long period of time in which the cows were not monitored and could exhibit oestrous behaviour which could go undetected, if visual observation was the only method of detection. 2.2.2 Data Collection and Analyses Activity monitors were worn around the cows’ necks (Figure 2.1), measuring daily activity and identified increases which signalled that a cow was in oestrus. The cows wore Lely Qwes-HR Activity Tags which measured cow movement and movement intensity through a 3 dimensional accelerometer sensor which was expressed as a general activity index. Activity was expressed as counts from an instrument specific algorithm within the activity monitor, which is patented and undisclosed by the manufacturers. Data was recorded by a microprocessor and stored in the memory. Activity data were downloaded at milking from the cows’ transponder, which was read on entry to the robotic milker, but could also be downloaded from infrared identification units which were mounted in the barn. Activity data were downloaded at intervals throughout the day and split into activity units per 2 hour intervals. Figure 2.1 Example of a cow wearing a Lely-HR Tag activity monitor around her neck Activity data spanning 2 years (16.03.2008-11.02.2010) were collated from 205 cows, including 930 individual oestruses across different lactations and different stages of lactation. Activity data was analysed by plotting activity 51
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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: In summary the objective was to for
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
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or that the cows were in an area of
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plane, but mostly in achieving high
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Develop techniques for analysis of
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in elastic silicone moulded over a
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and time of mount, duration of moun
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observed matched with increases in
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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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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
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BLOWEY, R. (2005) Factors associate
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ovine gonadotrophin releasing hormo
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GINTHER, O. J., KOT, K., KULICK, L.
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associated with embryonic survival
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ody condition at parturition on end
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Signs in a 24-h Tie-Stalled Dairy H
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SHERMAN, E. L., NKRUMAH, J. D., MUR
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Influence of negative energy balanc
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