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10 Cards in this Set
• List 10 factors that can affect the expression of oestrous
behaviour in cows.
• The number of cows simultaneously in oestrus
• Type of housing and floor surface – reduced on slippery surfaces eg concrete
• Reduced in barn housing, wherever opportunities for interaction between cows are reduced (eg tethered or confined dairy cows in developing countries), concrete/slippery floors or very wet conditions
• Stress (a variety of stressors can impede oestrous behaviour and interfere with the development of a preovulatory LH surge)
• Lameness – decreases mounting activity
• Time of day – may be more frequent at night (especially in hot climates), less frequent when cows are hungry and released onto a fresh pasture
• Moving of animals: See more activity as the herd is moved and
interaction between cows is promoted
• Synchronisation method – eg if GnRH is used to induce ovulation most cows will not show oestrous behaviour, if oestrogen (eg oestradiol benzoate) is used to induce ovulation, most cows will show
oestrous behaviour. Why?
• Environmental temperature: Less frequent with extremes of
weather (eg 0OC<Temperature >30OC; high humidity + high
• Health – sick cows are less likely to demonstrate behavioural
• Nutrition and milk yield – cows experiencing greater negative
energy balance may have a less intense oestrus
• Age: - older cows tend to have shorter and less intense heats
• Breed – Bos indicus cattle are less likely to show behavioural
signs of oestrus in the presence of an observer (nervous
disposition), may have shorter & less intense heats, & may be
more likely to engage in riding behaviour at night/early in
morning, more prone to silent heats
“Kamar” device is:
a) A device used to correct uterine torsion in cows.
b) a rump mounted device that is used as an aid for the detection of oestrus.
c) a device that attaches to the leg of cows and monitors the
walking activity of cows.
d) a device that measures the electrical impedence of vaginal
secretions of cows.
e) a bench mounted machine that can be used to measure
concentrations of progesterone in milk or serum.
b) a rump mounted device that is used as an aid for the detection
Describe the use of aids for the detection of oestrus in cattle. For each aid that you list, describe some of the advantages and disadvantages of the aid for detecting oestrus
• Tail paint
– Available as liquid paint or aerosols (liquid paint is better than aerosols)
– Easy to use
– Apply in a strip, 10 cm long and 5 cm wide over base of tail
– Can be scored on a 0 to 5 scale for research
– Relatively cheap
– Needs to be reapplied approximately every 5 to 7 days
– With repeated application a thick crust of paint can build up, which can make it harder to rub off when in oestrus
rump mounted devices:
Pressure associated with mounting activates devices
Sensiti it in some in indic s
• Sensitivity can be high herds and Bos indicus herds
• Available as self adhesive, peel off backs or where you apply glue to the undersurface and then apply this to the cow
• Remove activated devices at the time of AI to avoid confusion
& environmental contamination
• False positives can be a problem in some herds or due to
rubbing on low lying branches, or if the time from application
to oestrus is greater than 1 to 2 weeks
• Glue can be messy to deal with
• Estrus alert devices
• Work like a “scratchie”. As a cow is mounted the top surface is removed revealing a fluorescent colour underneath
• Disadvantages: Cost, environmental contamination, difficult to apply to wet cows, need to be warmed when applied for glue to stick, can become warn over time and more difficult to interpret as
application to oestrus interval increases
• Radiotelemetry: HeatWatch
• Used in research and some dairy herds. Documents date, no. of
mounts, duration of mounts. Information relayed to a receiver
and then to a PC.
• Disadvantages: application of devices is time consuming, can
be rubbed off, require a lot of units for eg a seasonally calving
• Walking activity of cows peaks at oestrus, can be used to indicate oestrus
• Neck or leg anchored
• Newer devices can also record lying time and temperature
• Data is downloaded when cows walk through the dairy. Software is used to interpret the data. Thresholds can be altered in the software to change when the software will indicated that activity has changed to a
point where the cow may be in oestrus.
• Disadvantages: cost, changes in distances walked to the dairy can affect interpretation of data, false negatives and positives occur.
• Best used in conjunction with other oestrous detection aids.
• Concentrations of progesterone in plasma or milk can be used to document when cows are likely to be in oestrus.
• A high followed by a low
concentrations of P4 suggest that a cow has moved from dioestrus into pro-oestrus or oestrus
• In-line (within milk line) and on farm systems have now been developed so we are likely to see an increase in the use of this technology over the years.
• Disadvantages: cost of testing, delay in result if sent to a lab. Best interpreted with multiple samples.
Can be cows or steers, generally avoid young heifers.
• Safer than surgically modified bulls
• May be fitted with marking devices eg chin-ball harnesses
• Need to have a good temperament,
• Ratio: 1:30 to 1:50 (increase if synchronising oestrus (1:10 to 1:30))
• Consider rotating every 5 days or so in dairy herds
Hormonal stimulation methods:
– Testosterone enanthate 1 g sc Q14 days
– Synovex H implants (testosterone propionate & oestradiol benzoate) – 8 implants SC (1600 mg TP + 160 mg EB) + 0.5 g TE IM
+ 1.5 g TE SC (Spitzer and Chenoweth 1996). Oestradiol benzoate
injections (5 to 10 mg every 10 days – don’t do it forever as
oestrogen toxicity is always possible!)
• Oestradiol implants eg compudose (eg 2 implants) – no experimental
studies but theoretically should work
• Need to declare treated animals as having been treated with growth promotants when sold. Some treatments require frequent retreatment
vaginal mucus electrical resistance
• Probe is inserted in the vagina and electrical resistance is
• The lowest reading within a cow can coincide with oestrus
• Disadvantages: Labour intensive, requires multiple readings on a given cow to detect significant changes in ER
List the endocrinological characteristics of oestrus
• Progesterone: Low (<1 ng/mL – can be used to determine
accuracy of oestrous detection)
• Oestradiol: High
• LH: Increase in pulse frequency and amplitude culminating in an LH surge
• FSH: Increases coincident with the LH surge
You are asked to investigate reproductive performance in a seasonally calving dairy herd. During your assessment of the reproductive records you determine that 69% of eligible cows were submitted for AI within the first 3 weeks of the breeding season. What is the recommended percentage of eligible cows that should be submitted for AI within 3 weeks of the start of mating?
Seasonally calving herd target 3-week submission rate = 86%
Outline some of the potential causes for low submission rates to AI in the first 3 weeks of the breeding season
• Low submission rates in first 3 weeks of the breeding season could be due to: High prevalence of anoestrous cows, that is
cows not showing behavioural signs of oestrus, low sensitivity of detection of oestrus – this can be due to inappropriate or
inadequate use of oestrous detection aids, inadequate time spent detecting oestrus, being unfamiliar with how to detect
oestrus in cows or not knowing the signs of oestrus. Inadequate recording of data or identification of cows can also contribute
to low submission rates being recorded.
If you were to make some recommendations to improve submission rates how would you check to see if any improvements in submission
rates occurred and how might you determine if the cows that are being submitted for AI are actually in oestrus?
• Reviewing the herd records to determine if the proportion of cows that are available for AI which are being detected in oestrus
and inseminated has increased following implementation of any management change. This analysis can be divided into all of
the potential cows that are available for AI and it can be split by cows that are expected to be cycling.
• Construct a list of those cows who are non-pregnant, have been calved >6 weeks and who are ≥4 years of age before and after
the change in management. These cows have a higher probability that they will be undergoing oestrous cycles as they are more
likely to be under less nutritional stress than a younger cow who is still growing or a cow that has not been calved as long who
is more likely to be undergoing the transition between anoestrous and cycling post calving. Of the list of cows ≥4 years of age
and calved >6 weeks the percentage detected in oestrus should be increasing in this group of cows if the problem associated
with heat detection was due to inability to detect heat on the part of the farm management. If the problem is related to the cows,
eg low body weight and inadequate nutrition then the problem may still persist and further investigation may be required.
• An alternative or additional measure that could be used is to examine a group of cows that are non-pregnant and determine
which are ovulating (CL detected on an ovary). Monitor this group of animals to determine if they are detected in oestrus
following implimentation of the change in management.
How might you determine if the cows that are being submitted for AI are actually in oestrus?
• A milk or blood sample could be collected at the time of AI and tested for the concentration of progesterone. A low
concentration indicates that the cow would have either been in oestrus, pro-oestrus or anoestrus. A high concentration would
indicate that the cow was in dioestrus and would represent a false positive diagnosis.
• If a cows conceives to the AI that is given she was in oestrus – this can be determined by assessment of pregnancy rates
subsequent to AI.
• If the passage of the insemination pipette occurs easily and the cervix feels soft, compliant and representative of how a cervix
feels when cows are in oestrus
• If the cow shows signs of oestrus close to the time of AI – for example, place the cow in a yard with other cows that are in
oestrus. Observe the cow to see if she stands while being mounted.
• Look for secondary signs of oestrus, for example clear, thin mucus exiting from the vulva, fresh rub marks on pin bones and/or base of tail, swollen vulva etc.
What should a producer do when inseminating cows if they suspect that a cow may be in oestrus but information obtained from an oestrous detection aid does not provide sufficient information to indicate that the cow may or may not be in oestrus? What advice could you give them to try to increase the certainty as to whether the cow is, or is not in oestrus?
• Improve cow identification and record keeping
– This includes a record of who is pregnant and not pregnant, who is eligible for breeding, can the identity of cows be recorded correctly (a lot of mistakes/missed heats happen due to misreading ids or
poorly kept records)
• Spend time observing cow behaviour
– At least twice per day (early morning and late afternoon or at least 2 h after a feed), preferably more often (3 to 4 times per day)
– Start recording heats before mating begins, this elps you to know when to expect a cow to be in oestrus & which cows may be
• Place suspicious cows in with a group of oestrous cows
• Use heat detection aids
– Preferably use more than one system as no system is 100% & use of more than 1 system increases efficiency and accuracy
• Optimise nutrition and health
• Train staff
– Good heat detection skills and use of aids needs to be learnt
– Some properties have workers with special responsibilities for
• Consider synchronising oestrus where there is a significant problem
Compile a list of secondary signs that are associated with oestrus in
Definitive sign: Cow standing still while being mounted by another cow
• Attempting to mount other cows
• Mounting without standing
• Disoriented mounting
• Vulval mucus discharge (clear, thin mucus)
• Vulval swelling (not always apparent)
• Restlessness, (heads held high in dairy yard prior to milking)
• Sexually active groups: groups of cows engaging in mounting activity
• Aggressive behaviour, Butting, Lip curling (Flehmen reaction),
• Chin resting
• Increased ambulatory activity (detected with pedometers)
• Poor milk let down
• Rubbed pin bones or base of tail
• Oedematous vulva – occasionally observed, unreliable