novel approaches to expression and detection of oestrus in dairy cows

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1.5.3.4 4sight 4sight is an optical electronic method of oestrus detection using digitised surveillance monitoring combined with optical electronic sensors, to recognise mounting behaviour and distinguish between primary and secondary mounting displays. Mounting and specific behaviour trigger a photosensitive beam which identifies the individual cows in oestrus through a preloaded database containing images of the 4 sides of each cow. A list formulates each day of cows that have been mounted, those that have mounted others, the time at which this behaviour occurred, an optimal time for AI and any cows not seen in oestrus for 21 days. In 2 trials 4sight has been reported to detect 100% of oestruses and correctly identify the 19 cows not cycling, and when used commercially heat detection was 90%, however conception rates were reportedly poor (Esslemont, 2006). 4sight overcomes the difficulties of visual detection, but does not account for cows not displaying overt oestrus but this system is advantageous because it will identify those cows which are eligible but have not shown oestrus. This method is efficient for oestrous detection and is accurate at detecting oestrus, although more trials on a number of herds will be needed to confirm the efficacy of this method. Esslemont (2006) calculated the benefits of 4sight and reported that the increase in profit/cow/year would be £86 and set to increase with the length of time using 4sight and improving detection. However, this does not take into account the initial cost of installation. 1.5.4 Genetic Selection The decline in dairy cow fertility resulting from genetic selection for milk yield ignoring other selection traits is well known; therefore genetic selection for fertility traits should also be possible. This, however, is not as easy, because fertility traits are widespread and largely influenced by external factors such as environment and management. By improving oestrous expression oestrous detection rates should also increase because it will be easier to identify cows in oestrus. Breeders can select for fertility traits from breeding values in the UK Fertility Index in which sires can be selected for breeding based on their daughter’s fertility. However, low heritability (h 2 =
may be gained. This is because data from daughters can only be recorded at the earliest 2 years following their first calving and further data collected at the 2 nd calving, making the bull 4 years of age before any breeding values are in place, when it will have subsequently bred with other cows (Flint et al., 2008). However, genetic selection for oestrous behaviour is not well defined and is often bypassed in relation to selection, except in Sweden where heat detection scores for oestrous symptoms are recorded as selection indices (Berglund, 2008). It has however, been reported that a link can be made between oestrous behaviour and genetic selection, reporting that days to first activity increase post partum, verified by pedometer data, was heritable h 2 =0.18, with repeatability of 0.18 indicating this trait is predominantly determined by genetics (Lovendahl and Chagunda, 2009) which is advantageous when selecting for oestrous behaviour. The heritability of duration and strength of oestrus were also determined, yet they were of low heritability: duration; 0.02 and strength; 0.04 (Lovendahl and Chagunda, 2009). Genetic selection for oestrous detection has also been reported in relation to hormonal factors associated with fertility; milk progesterone levels, GnRH response and metabolic hormone levels, which can all affect hormones in the oestrous cycle and oestradiol production to influence oestrous detection. These endocrine traits are less affected by management making heritability estimates more reliable. Milk progesterone measurements throughout the milk progesterone curve have been reported as heritable in defining the time to 1 st ovulation and commencement of luteal activity, h 2 =0.17 (Royal et al., 2002). The heritability of progesterone is similar to activity estimates of days to 1 st activity increase. In response to GnRH, LH and FSH are produced, which have a direct relationship with the production of oestradiol. By using the GnRH response of a bull’s progeny, fertility and oestrus activity can be predicted at an earlier age. The GnRH response, measured as concentration of LH has high heritability, h 2 =0.51 and data is available at 4-5 months in bulls, with the inclusion of heifers also in the Fertility Index (Royal et al., 2000b). Metabolic hormones; insulin, IGF-1 and GH (growth hormone) control the metabolites; FFA (free fatty acids) and glucose, and are all linked to ovarian function, thus can affect oestrous expression through GnRH pulses and steroidogenesis. The heritabilities of FFA, glucose 47
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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
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 and 58: 1.5.2.3 Body and Milk Temperature T
Page 59 and 60: physical activity and stage of the
Page 61: caused by the general environment t
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
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Backpack 1 st put on in AI stalls E
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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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Page 143 and 144:
Page 145 and 146:
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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
Page 191 and 192:
SHERMAN, E. L., NKRUMAH, J. D., MUR
Page 193 and 194:
Influence of negative energy balanc
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