Bovine reproduction Flashcards
John Cavalieri
Explain why oestrus would be synchronised in cattle ?
What is the purpose of synchronising oestrus
- faciliatates the use of AI, thus improving genetic gain
- facilitates the use of ET by synchronising embryo transfer recipients
- improves ease of oestrous detection (shorter period of time)
- Improves oestrous detection (easier when a large number of animals are in oestrus simultaneously)
- shorten calving to conception intervals + increase lactation length
- synchronises partuition
- may reduce the number of bulls required
- can increase the number of replacement heifers
Describe the potential disadvantages of synchronising oestrus ?
Synchronisation of oestrus
- cost (the largest impediment)
- organisational and logistic skills
- requires appropriate handling and AI facilities
- often requires cattle to be handled multiple times to implement treatments
- conceptions rates could be reduced with some protocols
Owners expectations may be unrealistic - you need to brief owners very carefully.
Describe the characteristics of an ideal oestrous synchronisation protocol ?
Characteristics of an ideal oestrous synchronisation protocol
- Easy and cheap to implement
- Precise synchronistaion of oestrus and ovulation in cattle
- produces a high response rate when initiated at any stage of the oestrous cycle and also in animals not undergoing oestrous cycles
- eliminates the need for detection of behavioural oestrus enabling fixed time AI
- achieves normal fertility
- no unacceptable milk or tissue residues
Describe the physiological requirements to achieve precise synchrony of oestrous and ovulation in cattle ?
Physiological requirements for synchronisation of oestrous in cattle
- Synchronise a decline in plasma concentrations of progesterone / or exogenous progestogen
- Synchronise follicular development ( to ensure follicles are at a similar stage of development at the end of the synchronistaion period) new wave emergence
- Synchronise a preovulatory LH surge (Ensure the follicles which ovulate have normal fertility)
- Ensure concentrations of progesterone following synchronised oestrous are normal
Why is it important to synchronise follicular development ?
The importance of synchronisation of new wave emergence
Foolicles too small
- if ovulation is induced while the follicles in some are too small they may not ovulate, or may produce a small CL which will secrete less progesterone
- Follicles are too large
- if the follicles are too old synchronisation of ovulation may occur but fertility will decline due to ovulation of aged oocytes.
Describe how we can stimulate a new wave emergence ?
Two methods too synchronise new wave emergence
Treatment of oestrodiol and progesterone at the same time
- atresia of growing follicles
- synchronous new wave emergence (3-4 days later) occurs
Cows treated with GnRH
- ovulation or luteinising of growing follicles
- new CL formation
- synchronous new wave emergence (1-2 days later)
Describe the mechanism of action of oestrogen and progesterone treatment in cows ?
Synchronisation of new wave emergence
Treat cows with progesterine and oestrogen at the same time
- atresia of growing follicles
- synchronous new wave emergence
Mechanism
- ATRESIA through decrease in GnRH support for existing growing follicles (FSH and LH) by negative feedback of oestrogen
- allows a new wave to emerge due to increasing conc of FSH at emergence
Describe the mechanism of action GnRH treatment at the start of a synchronisation protocol in cows ?
Cows treated GnRH at the start of synchronisation protocol
- ovulation or luteinisation of growing follicles
- new CL formation
- synchronous new wave emergence (1-2 days later)
This terminates the growth of existing growing follicles by inducing them to ovulate or luteinise.
Effective in follicles > 10mm in diameter
How long after treatment with oestrodiol benzoate or GnRH is new wave emergence expected ?
New wave emergence occurs
Oestrodiol benzoate 3-4 days later
GnRH 1-2 days later
Describe why oestrodiol treatment should be avoided in lactating dairy cows or beef herds ?
Why shouldn’t we exceed 1mg oestrodiol benzoate ?
Oestrodiol benzoate and oestrodiol cypionate
Oestrodiol is not permitted in lactating dairy cows or beef cattle properties accredited with the European union.
May be used in non lactating dairy heifers and beef properties not accredited with the EU.
Why not use >1mg treatment of oestrodiol benzoate
- a dose of oestrodiol benzoate exceeding 1mg may cause a reduction in pregnancy rate
Describe synchronisation strategies which utilise P4 ?
The importance of P4
At the end of treatment synchronise a decline in P4
This can be done via two methods
- PGF2A
- Remove exogenous source of progesterone/ progestogen
Before growing follicles can progress to the point where oestrus and ovulation occurs concentration of P4 must decline.
P4 has inhibitory effects on GnRH and thus the LH surge
Describe the dose for use in a 500kg heifer for GnRH and oestrodiol benzoate ?
After synchronistaion of the follicular phase, describe how you would induce ovulation ?
Inducing ovulation through an LH surge after synchronised follicular phase (NOT always done)
Administer oestrogen in the absence of P4
Administer GnRH
Administer eCG
(eCG is less reliable may increase twinning, has mostly a FSH effect increasing follicular development which can then produce enough oestrogen to stimulate an LH surge).
What is the purpose of synchronising ovulation during a synchronised pro-oestrous ?
Purpose
(pro oestrous - stage of rapid follicular development)
- Improve synchrony of ovulation
- Increase the probability that ovulation will occur in animals that are at risk of not ovulating (eg anoestrous cows or perpubertal heifers).
- To enable fixed time insemination (closer to the expected time of ovulation)
Explain the different Lh profiles that occur following administration of EB compared to ECP, and when each drug is administered in relation to removal of a progesterone releasing intravaginal device ?
OB vrs OCP
Rule of thumb ovulation occurs
- 24hrs post administration of GnRH
- 48hrs following administration of ODB
- 72 hrs after administration of OCP
eg if OB is administerd 24hr after removing a p releasing device and OCP at the time of removal - you will plan fixed time AI at a similar time 48-56 hr after removal of inserts.
When should AI be carried out after treatment with GnRH, OB and OCP ?
State when PGF2A is effective in causing in causing leuteolysis in cows and heifers ?
PGF2A is effective in most cows and heifers;
Intramuscular injection cloprostenol
In cows - day 7 to 18 of cycle
Heifers - Day 5-18 of cycle
Outline the MOA underlining a PG program ?
PG programs
PG cloprostenol are administered via intramuscular injection to cause luteolysis and a decline in progesterone concentrations.
Interval from PG injection to oestrus depends upon the stage of the oestrous cycle
- mature follicle time to oestrus short
- immature time to oestrous is long
- dominant follicle will undergo atresia and take even longer
Describe the advantages and disadvantages of a PG program in cattle ?
PG program
Advantages
- cheap
- variety of treatment programs to meet needs
- normal fertility
Disadvantages
- only effective in animals with a CL of appropriate age
- ineffective anoestrus (non cycling cows)
- can cause abortion (pregnent cows < 5months)
- health and safety issues (respiratory problems, human abortions
- wide pattern of onset of oestrus.
Outline a single PG and double PG protocol ?
PG protocol
one shot 5-7 days
two shot PG 1 (detection of oestrous), PG 2 (detection of oestrous) 14 days apart
The beneifit of a two shot protocol
- immature follicles will mature to respond to the second injection
- mature follicles respond to first injection
- a two shot protocol is more likley to be able to obtain oestrous in the whole herd
What precautions should you observe when using PGF2A or its synthetic analogues to synchronise oestrous in cattle ?
PG programs
- good pregnnacy detection in cattle (avoid injecting pregnnat cows <5months may cause abortion)
- human safety (respiratory difficultys, abortion)
Describe the mechanism of action for progesterone synchronization protocols ?
Progesterone protocols
(cue mate and CIDR)
Treatment duration 5-10 days
Increase circulating conc of progesterone (or progesterone like hormone)
- removal of devices synchronises a decline in in P4 and all animal theoretically enter the follicilar phase of the cycle
- induce anoestrous cows into cycling
- ovulation can not occur when there are high levels of circulating progesterone
- sensitizes hypothalamus to oestrogen
Describe how you could go about disinfection of CIDR or Cue mate devices ?
Outline this protocol ?
Outline this protocol
- EB + progesterone
new wave emergence synchronises follicular growth - PG = luteinisation
Removes endogenous sources of PG, with synchronous removal of the IVD removing artificial progeserone source.
Source of progesterone must be removed to allow ovulation to take place.
(monitor cows for detection of oestrus) - EB Estrodiol benzoate
Stimulates ovulation to occur 24hrs later so that timed AI may occur on day nine.
Describe the use of Melengesterol acetate (MGA) ?
Review Questions
- Cue mate
- progesterone
- 5-10 days (commonly 5-7 days)
- oestrogen or GnRH to synchronise new wave emergence
- PG or GnRH to induce luteolysis
- Yes - the sponges can be removed and replaced to ensure adequate amounts of progesterone are released
Describe the positives of an GnRH synch protocol ?
GnRH based protocol
- simple
- some effect in non cycling cows
- intermediate cost
- conception rates can be low “higher risk)
- proportion of cows displaying heat is lower
- more applicable where heat detection is a problem
- better pregnancy rates when used in conjunction with a progesterone releasing intra vaginal insert
- not recommended for heifers (reduced pregnancy rates
Describe an Ovsynch protocol ?
What is presynchrony before Ovsynch ?
Presynchrony
two shot PG 14 day interval
Single PG injection then detecting heat for three days prior to ovsynch
double ovsynch
Describe some indications for using Ovsynch ?
Be able to describe the behavioural signs associated with oestrus ?
Behavioural signs of oestrous
Definitive
Standing to be mounted
Secondary signs of oestrus
- sniffing, rubbing
- mounting
- flehman response
- vulva swelling and thin mucous discharge from vagina
- restlessness
- chin resting
- poor milk let down
- rubbed pin bones or base of tail
Describe the endocrinological charateristics of oestrus ?
Endocinology of oestrus
High oestrogen
High LH
Fsh Increases
Progesterone low < 1ng/ml
Oestrus; describe efficiency (sensitivity) and how the positive predictive value is calculated ?
Oestrus
Sensitivity = % of oestrus periods detected that occured in a given time
N detected in oestrus / those in oestrus X 100 =
Positive predictive value
Probability that a test is correct, IE is the cow truly in heat
correct detections / number of correct + false detections X 100 =
List factors affecting the behavioural signs of oestrus in cows ?
What affects the behavioural signs of oestrus in cows
- Environment
- slippery wet surface
- cow interactions reduced (small numbers)
- stress
- moving animals, more activity and interaction during movement
- climate extremes
- health
- milk yeild
- age
- breed (Bos indicus less intensive oestrus)
- synchronisation method GnRH
Describe and identify a variety of aids ?
Aids used to detect heat
- tail paint
- marking crayons L20cm, 5cm wide
- Kamar (pressure detection)
- Estrostat devices “scratchie”
- pedometers
- concentration of progesterone (within milking line)
- hormone treated detector animals
- surgically modified animals (vasectomy, penile deviation, penile fixation)
- electrical resistance of vaginal mucous
Be able to describe your approach to investigation situations of suboptimal oestrus detection in herds ?
Suboptimal oestrous detection
Seasonal 3 week submission rate =86%
Year round 80 day submission rate = 73%
If submission rates are low investigate accuracy of heat detection
Potential causes low submission rates
- cow identification
- < time spent obsering
- poor training of staff
- small groups of cows
can consider synchronisation of oestrous in problem groups
Describe the position of a calf during the birthing process ?
Position
The relation of the dorsum of the foetus in longitudinal presentation, or the head in tranverse position to the quadrants of the maternal pelvis.
There are four quadrants
- sacrum
- right ileum
- pubis
- left ileum
There fore the possible positions of the calf could be described as
Dorsosacral - normal presentation
Dorsopubic
right / left dorsoilial
right / left cephaloilial
Describe the presentation of a calf during partuition ?
Presentation
- Longitudinal
- transverse
- cranial or caudal in the longitudinal position
- dorsal or ventral in a transverse presentation
- (ventrotransverse or dorsotransverse)
Normal = cranial, longitudinal
Describe how you can describe the posture of a calf during partuition ?
Posture
Relation of the foetal extremities (head, neck and limbs) to its own body.
limbs - flexed, relaxed
head - retained, right or left above or below the foetus
Describe position through the three Ps
posture, position, presentation
Describe the normal presentation of a calf through the three Ps ?
Three Ps
(posture, position and presentation)
Cranial longitudinal presentation
dorsosacral position
with the head, neck and forelimbs extended
Describe the position of this calf during partuition ?
3PS postion, presentation and posture
Cranial longitudinal presentation
Dorso sacral position
forelimbs extended with head and neck flexed
Describe this malpresentation of the foal ?
Malpresentation of the foal
remember the three Ps
position = caudal longitudinal
presentation = dorsosacral
position = hindlimbs are bilaterally flexed
Describe what aetiology of the cow could lead to ineffective labour ?
Aetiology ineffective labour
- incomplete dilation of the cervix
- uterine inertia
- uterine rupture
- constriction of vulva, vestibule and vagina
- deformities of the birth canal
Describe possible causes of uterine rupture ?
Potential causes of uterine rupture
- emphysematous foetus
- hydrops allantois (excessive allantoic fluid)
- uterine adhesions prior to pregnancy
- excessive traction
- retropulsion of foetus
- often involve the greater curvature of the pregnant horn
Signs of partuition may cease due to ineffective labour
Describe how you would go about treating a foetopelvic disproportion ?
Treatment foetopelvic disproportion
Viability of dam eg down paralysis consider uthanasia
- copious lubricant
- correct malpresentation
- traction + possible foetotomy or C section
- epidural may be indicated for pain relief during delivery
- potential for episiotomy
Potential for hip lock can occur following delivery of the cranial part of the foetus
What is an episiotomy ?
Episiotomy
Indicated large head small vulva
Administer a epidural
incise 11 and 1 oclock location avoiding the anus
- one incision may be adequate
Closure
2 chromic cat gt using continuous suture pattern
begin anterior end of mucosal wound towards mucutaneous junction (avoid vaginal mucosa)
Identify this malposition?
Carpal flexion
one foot and head may be presented at the vulva
Describe how you would go about correction of carpal flexion ?
Correction of carpal flexion
Repel foetus and the shoulder of displaced limb
- grasp metacarpus
- while cupping the hoof flex affected forelimb so the carpus moves up into the pelvis and the carpus can be extened (elevate carpal joint)
- correct one limb at a atime
- rope snare may also be used attached distal to the fetlock
If manipulation is not possible consider foetotomy
When presented with the malpresentation carpal flexion describe foetotomy ?
Carpal flexion and foetotomy
Once successful manipulation is not possible
Foetotomy cut at the distal row of the carpal bones
- this allows an anchor point for obstetrical ropes and chains
- proximal cut exposes sharp carpus bones which may lacerate the cows uterus/ vagina
Identify this malpresentation and describe its correction ?
Incomplete elbow extension “elbow lock”
Identify
- presentation of both hooves and head
- muzle overlies fetlocks
Correction
- repel while applying longitudinal and dorsomedial traction to the forelimb
- aim elevate the elbow above the pelvic inlet allowing extension of the forelimb
Identify this malpresentation ?
Should flexion
Identified
via incomplete extension of forelimbs
swollen toungue and head
Describe how you could go about correcting the malpresentation of shoulder flexion ?
Correction of shoulder flexion
First check viability of foetus
- clean perineal area
- apply epidural
- place a snare on the head so it may be retreived after repulsion
- crab humerus and convert to carpal flexion
- correct as for carpal flexion.
Kuhn’s crutch
If foetus is dead may remove head and front limb for ease of removal
Identify this malpresentation and describe how you could correct it ?
Foot nape posture
one or both forelimbs lie on top of the head or neck.
risk to lacerate the vaginal wall.
Correction
- repel foetus
- grasp fetlock, move it laterally and ventrally
- place lateral to the head
- raise head
Identify this malpresentation ?
Dicplacement of the head
(lateral, dorsal or ventral deviation)
- can be associated with foetal wry neck congenital curvature
Correct of lateral deviation
This may be difficult in the mare and some cows
- repel foetus
- if muzzle can not be grasped grab an ear, orbits, or place a finger into the corner of the mouth
- rope snare applied to the jaw
- pull head into the pelvic canal
- if not possible removal of the head with foetotomy wire
Identify this malpresentation ?
Hock flexion
CS: tail may protude from the vulva or felxed hocks may be felt
If only one hock flexed the other leg may extend through the vagina.
Describe how you could correct hock flexion ?
Correction of hock flexion
Repel the foetus by applying pressure to the perineal area
- Kuhn’s crutch
- grasp metatarsus and push into the pelvic cavity
- grasp the hoof in palm (protect the uterus) elevate and direct hoof laterally into the pelvic cavity
- use a diagonal (extra room)
- once both limbs are extended diagnostic traction may be applied
Identify this malpresentation ?
Bilateral hip flexion
(breech presentation)
The signs
foetus does not engage the cervic (no dilation)
- prolonged second stage labour
- restless elevated tail
- blood presence at the vulva
Upon rectal palpation detect tail but no limbs
Describe how you would go about a correction of bilateral hip flexion ?
Bilateral hip flexion
A difficult correction
- repel foetus cranially by applying pressure to the perineal area
- Kuhn’s crutch
- grasp stifle draw caudally
- convert hip flexion to hock flexion
- correct as for hock flexion
If this fails consider foetotomy cut to remove hindleg (ensure removal of femoral head)
Identify this malpresentation ?
Caudal presentation
Signs
- soles of feet face dorsally
- tail presence
- apply diagnostic traction and execute delivery if indicated
Consider caesarian if traction dose not resolve as foetal viability is compromised caudally
compression of umbilical cord
Identify and describe correction of this malpresentation ?
Ventrovertical or dog sitting position
all four legs presented and head
+ unproductive straining
+ hindlegs maybe palpated on the pelvic brim
Correction
- repel hindlegs cranially
- then apply traction to front legs and head
- use snare rope and chains
may also use a roll over method
if not possible consider foetotomy or caesarian
Describe how you would correct a transverse dorsal presentation ?
Transverse dorsal presentation
This is impossible to correct - caesarian
- nothing for physician to grasp
- no stimulation of cervix (no dilation)
- poor dilation of birth canal
- may also pass a foetotomy wire around the trunk (if possible and cut)
How could multiple pregnancies cause dystocia ?
Multiple pregnancies = dystocia
Dystocia arises due to
- overstrech (uterine inertia)
- simultaneous presentation (too wide)
- malposition
- identification of fore and hindlimbs in birth canal, count the number of joints
To correct repel one foetus and apply traction to the other
- administer oxytocin post delivery to stimulate involution
Identify this foetal abnormality ?
Perosomus elumbus
Ageness of lumbosacral spine
abnormal development of hind legs
- hindlimbs often rigid
As a clinician what would indicate to you that a foetotomy is needed ?
A foetotomy is required when
Can avoid a caesarian in lactating/valuable cow where surgery would have significant recovery and withheld period.
- foetus is dead
- emphysenatous foetus
- relatively oversized foetus
- abnormal presentation, position or posture that can not be corrected
- congenital abnormalities
- incomplete cervical dilation
- hip lock and dead foetus
When selecting cases for foetotomy - choose cows that are able to stand, bright and alert with an intact uterus
Describe the cuts that are required for a classical foetotomy (cranial presentation) ?
A classical foetotomy require 6 cuts, 7 pieces
- removal of head
- removal both forelimbs (2 cuts)
- cut of foetal trunk (2 cuts)
- bisection of the pelvis
Aim to only remove what is necessary to enable delivery.
Describe what cuts are required to carry out a modified foetotomy (cranial presentation) ?
Modified foetotomy
modified foetotomy involves 3 cuts
- removal of head and one front leg
- evisceration of the thorax and abdomen (cutting of foetal ribs and collapse of thorax)
- bisection of pelvis
Describe the process for amputation of the head in foetal foetotomy ?
Amputation of the head
- chains, rope, eye hooks anchor the head and both forelimbs
- often the first cut when the calf is in a cranial position
- place loop of wire well behind the ears
- head of foetotome held ventral to the calf’s head
Avoid this cut in emphysematous foetuses to preserve the head and neck as anchor points
Describe the process of removing a foreleg with a foetotome ?
Removal of a foreleg
Head of foetotome is located dorsal and caudal to the scapular
- anchor temporarily to digits while moving the head of foetotome is advanced (wire placed between the claws
- once the foetotome is placed release the wire to lie medially
Describe the modified technique of removing the head and one forelimb ?
Modified head and forelimb
- wire is looped around neck and head of foetotome dorsal and caudal of the scapular
- removes one foreleg and head in a single cut
- exposure of the thoracic inlet enables evisceration of the foetus if needed
- may use a cutting hook for the ribs
Describe the process of division of the trunk with a foetotome ?
Tranverse division of the trunk
First cut
Usually a single cut carried out as close to the foetal pelvis as possible (makes bisection easier)
Used once head and forelimb are removed if further foetal reduction is required
- 2/3 along the chest
- stump is anchored to the foetotome
- mid thoracic area
- rarely needed to complete two cuts
Second cut
- directed transversely just cranial to the ileum
