Monitoring the reproductive status of dairy cows using cow-side oestrus detection technologies
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Date
31/07/2021Item status
Restricted AccessEmbargo end date
31/07/2022Author
Muasa, Bridgit Syombua
Metadata
Abstract
Reproductive failure remains one of the main reasons for culling in dairy herds
worldwide. Prolonged inter-calving periods occasioned by failure or delay in
conceiving reduces the lifetime productivity of the cows and increases the herd
replacement rate. The postpartum open state is a critical stage for the mature
dairy cow that determines its future productivity. The ability of the postpartum
cow to return to cyclicity, express oestrus, conceive when inseminated, and
carry the pregnancy to term within a prescribed period, assures a cow’s
productivity and its chances of remaining in the herd. One of the key activities
in the management of the postpartum dairy cow is oestrous detection. Oestrus
is defined as a recurring period of sexual receptivity and fertility in female
mammals. Successful conception requires that oestrus be detected accurately
and cows that are identified to be in oestrus inseminated at the right time, in
relation to ovulation.
The goal of this thesis was to evaluate and compare the degree of agreement,
effectiveness and robustness of three cow-side oestrous detection tools
(ODTs) in three production and climatic conditions. The three ODTs selected
for investigation were CowAlert®, (IceRobotics, UK), a cow activity monitoring
platform, Estrotect™ (Rockway Inc, USA), a scratch card-based mount
detector and P4 Rapid (Ridgeway Sciences, UK), a lateral flow technique
based on milk Progesterone. Three experiments were carried out, one each in
a large-scale farm in a temperate region, a large-scale farm in the tropics and
small-holder farms in the tropics. The purpose of the different production
environments was to understand how the effectiveness and robustness of the
ODTs changed with each production environment. The expectation was that
at the end of the study recommendations would be made on which of the tested
ODT was best suited for that production environment.
The first experiment was carried out Scotland’s Rural College’s (SRUC) Dairy
Research and Innovation Centre in Dumfries, UK. This served as the large-scale farm in a temperate region. In this experiment, the three ODTs were
evaluated for their degree of agreement, effectiveness and robustness.
Degree of agreement was evaluated by carrying out a Cochran’s Q test, the
effectiveness evaluated through sensitivity analysis while the robustness was
evaluated by carrying out the sensitivity analysis on groups of cows
categorised according to their body condition and locomotion scores, milk
yield(Kg), weight(kg), days in milk and parity. The ODTs were applied
concurrently to the cows to allow for accurate comparison. All three ODTs did
not agree in their ability to detect oestrus . P4 Rapid had the highest
effectiveness as measured by the sensitivity (0.86 (0.79, 0.90)) in detecting
oestrous followed by CowAlert® (0.50(0.43, 0.58) then Estrotect™ (0.31 (0.24
, 0.37)). The body condition and locomotion scores, milk yield and weight did
not influence the effectiveness of the ODTs. For all three ODTs there was a
statistically significant difference in their effectiveness when cows were
grouped in their different parities and between P4 Rapid and both CowAlert®
and Estrotect™ when the cows were grouped in their days in milk. A closer
examination at the influence of parity on the effectiveness showed that P4
Rapid was statistically significantly different to Estrotect™ in all parities
recorded but only statistically significantly different to CowAlert® in cows from
parity four and higher. For the days in milk, there was a statistically significant
difference in the effectiveness between P4 Rapid and both CowAlert® and
Estrotect™ in cows up to 60 days in milk. For this production system P4 Rapid
was deemed the most effective and robust while Estrotect™ was found to be
the least effective.
The second experiment followed the same experimental design as the first one
and was carried out in College of Agriculture and Veterinary Sciences (CAVS),
University of Nairobi (UON) dairy farm in Kenya. This served as the large-scale
farm in a tropical environment. In this experiment, P4 Rapid did not agree with
either CowAlert® or Estrotect™ in its effectiveness in detecting oestrus.
However, CowAlert® and Estrotect™ agreed in their effectiveness in detecting
oestrus. P4 Rapid had the highest effectiveness as measured by the sensitivity
(0.98(0.94,1.0)). In contrast to the first experiment Estrotect™ had the next
highest sensitivity (0.26(0.19, 0.34)) while CowAlert® had the least sensitivity
at (0.2(0.14,0.28)). However, in this experiment both CowAlert® and
Estrotect™ had a sensitivity of less than 30%. In deviation from the first
experiment, only the parity had an influence on the effectiveness of the ODTs.
For this production system P4 Rapid was deemed the most effective and
robust while CowAlert® was found to be the least effective. However, there
were certain drawbacks associated with the use of Estrotect™ as it allowed for
potentially infective ticks to burrow under the strip, providing a haven for them
against acaricides. While detecting oestrus is an important management
activity, it is prudent that it is not done at the expense of the health of the cows.
The third experiment was set in the tropics with 34 small-holder farms. Based
on the information collected in the first two experiments, the experimental
design was different from the first two experiments. With the small-holder
farms, the first objective was to evaluate the reproductive status monitoring
practices in use, with a focus on oestrous detection and pregnancy diagnosis.
All the farms sampled used visual observation to detect signs of oestrus prior
to insemination and their absence (non-return to oestrus) as an indicator of
conception. None of the farms sampled had used an ODT prior to this study.
The second objective was to evaluate the performance P4 Rapid and
CowAlert® in detecting oestrus both at insemination and as an indicator of
non-conception up to 24 days following insemination when compared with
visual oestrous detection. P4 Rapid was found to be the most effective in
detecting oestrus during insemination and non-oestrus up to 24 days post
insemination.
In conclusion, P4 Rapid was consistently the most sensitive in detecting an
oestrous event in the three production systems tested. This is likely because
P4 Rapid is a direct measure of an intrinsic parameter, progesterone.
Progesterone concentration has a distinct pattern as the cows moves though
the oestrous cycle and has been used successfully to identify ovulation and
thus signifying that oestrus occurred. However, both CowAlert® and
Estrotect™ occur in response to elevated levels of Oestrogen and not direct
measures of an intrinsic parameter. Increased activity can also occur outside
oestrus for the case of CowAlert® and for Estrotect a scratched strip is not an
indicator of mounting activity. This study proved particularly useful for small-holder farms where there was little documented use of ODTs. A natural
progression of this work would be to investigate the economic implication of
adoption of P4 Rapid as a oestrous detection tool by large and small-holder
farms.