novel approaches to expression and detection of oestrus in dairy cows

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Fertility in dairy cows is defined as ‘the ability of the animal to conceive and maintain pregnancy if served at the appropriate time in relation to ovulation’ (Darwash et al., 1997a). Infertility can be caused by failure to initiate oestrous cycles, failure to express oestrus, poor detection of oestrus, failure to ovulate, inadequate corpus luteum function and poor support of embryo development. However, the cause of infertility can be multifactorial (Roche, 2006); associated with the inclusion of Holstein genetics for increased milk production (Royal et al., 2002), influenced by nutrition, production diseases and management (Lucy, 2001). Because of the broad nature of infertility, it is difficult to treat, but since subfertility is the highest economic cost to the dairy industry (Royal et al., 2000a) and erodes the efficiency and profitability of the industry through increased calving intervals and missed reproductive targets there are many gains to be had. Culling for infertility costs the industry through the need for more replacement cows, extra labour for oestrous detection, more inseminations to get cows in calf, extra semen straws and technicians to artificially inseminate and veterinary costs all reducing the net profit per cow and decreasing herd profitability (Roche, 2006). Involuntary culling means more cows are required for the same units of milk to be produced and more non-productive cows are needed as replacements. These extra animals, for no increase in output, require more resources, feed, fertiliser and fossil fuels, at extra cost, and result in greater pollutant emissions; methane, ammonia, nitrate and nitrous oxide which have negative effects on the environment (Garnsworthy et al., 2008). Therefore the cost of infertility is diverse and of major importance. A significant part of the fertility problem is detection of oestrus which results in one of the biggest economic losses (Peralta et al., 2005). Oestrous detection rates have declined, associated with the decline in fertility with average herd detection rates currently 50% according to the latest DairyCo figures (DairyCo, 2009). Less than 50% of cows in the herd are detected in standing oestrus (Van Eerdenburg et al., 2002), which is the definitive and most accurate sign that a cow is in oestrus (Orihuela, 2000). This correlates strongly with timing of ovulation as oestrus is the overt expression for the physiological, internal mechanism of ovulation (Roelofs et al., 2010). Furthermore, the number of silent heats, especially associated with high producing cows, has increased (Harrison et al., 1990) and hence it is not surprising that fewer cows are detected in oestrus. The number of cows standing to be mounted has declined from 80 to 50% over 2
the past 50 years and duration of oestrus has declined from 15 to 5 hours (Dobson et al., 2008). Intensity and duration of oestrus have also declined, to 8.5 standing events on average and Holsteins are reported to average only 7 hours duration of oestrus (Dransfield et al., 1998). It is also reported that the duration of secondary symptoms decreases with reduced standing time (Yoshida and Nakao, 2005). Therefore, coupled with increasing herd sizes (see Table 1.1) and less labour, it is becoming much harder to detect oestrus. Visual observation has been previously used for detection of oestrus, although accurate this method is time consuming and impractical (Lehrer et al., 1992). Current focus is centred on automated technologies which vary in detection rate from 80 to 90% but are coupled with high error rates between 17 and 55% (Firk et al., 2002). There are many methods of oestrous detection with different detection efficiencies and accuracies reviewed by Firk et al., (2002) and Roelofs et al., (2010), yet none have succeeded in increasing oestrous detection rates. Undetected and falsely detected oestrus is costly due to missed and untimely inseminations, caused by extended calving intervals, reduced milk and calf production potential, replacement heifers and semen costs for infertile inseminations (Lehrer et al., 1992). Therefore, emphasis in research needs to focus on efficient and accurate detection of oestrous behaviour and detection of oestrus in relation to the timing of insemination, relative to ovulation. Expression of oestrus and effective methods of oestrous detection are of great importance to the efficiency and profitability of the dairy industry, because conception rate is strongly influenced by oestrous detection rate (Roelofs et al., 2010). Detection of oestrus allows for insemination at an optimal time coinciding with ovulation, increasing probability of fertilisation with viable sperm and oocyte. Currently since a 40% conception rate is achieved (Royal et al., 2000a), combined with only 50% oestrous detection rates (DairyCo, 2009), only 20% of all ovulations result in pregnancy. Strategies to improve oestrous detection rate can help arrest the fertility decline and increase pregnancy rates contributing to the sustainability of the dairy industry. 3
Page 1 and 2: 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: CHAPTER 1 - Introduction & Literatu
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 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
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Activity Activity Activity Activity
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
5.4 DISCUSSION The aim of this work
Page 155 and 156:
averaged 70% which was lower than t
Page 157 and 158:
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
Page 165 and 166:
antennae which could affect accurac
Page 167 and 168:
predispose cows to illness e.g. met
Page 169 and 170:
CHAPTER 6 - Overall Discussion & Co
Page 171 and 172:
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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novel approaches to expression and detection of oestrus in dairy cows

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