Cattle infertility 1+2 (Fertility, sub-fertility and infertility in the cow) Flashcards
What is a ‘sub-fertile’ cow?
one that fails to achieve its fertility target, or that of the herd/group
What is an infertile cow?
either a ‘sub-fertile’ cow or a sterile cow
Is cow fertility changing?
Yes - lactating cow fertility is decreasing, heifer fertility increasing, milk yield per lactation is increasing
What is the relationship between milk yield and fertility?
increasing mil yield –> decreased fertility
What are 4 broad causes of cattle sub-fertility?
structural
functional
management
infectious
What are signs of sub-fertility?
no observed oestrous
regular or irregular returns to oestrous (after service/AI)
abnormal vulval discharge
abortion and stillbrith
When should a cow cycle?
every 18-24 days unless pregnant or within 4-6 weeks post-partum
Reasons for no observed oestrous…
congenital abnormalities (ovarian aplasia/hypoplasia, freemartininism)
acyclical or anoestrous
ovarian cysts
no-limited behavioural signs of oestrous (known as a sub-oestrous or silent heat)
poor heat detection
Reasons for no observed oestrous in heifers
ovarian aplasia/hypoplasia - v rare - autosomal recessive gene with incomplete penetrance]
Freemartins (due to vascular fusion) - never cycle, small vestigial tract with no ovaries
Dx = by ‘test tube’ or ‘thermometer case’ into vagina (reaches 2-3cm in a freemartin, or about 10cm in a normal animal) and confirmed by karyotype testing
Outline freemartinism
92% heifers that are co-twins to bull calves are freemartins.
BE AWARE of single born female freemartins born where the bull calf has died after vascular fusion (i.e. common chorioallantoic sac, separate amnion)
What are the causes of no observed oestrous in COWS?
anoestrous or true acyclicity COD Persistent CL Pyometra + persistent CL sub-oestrous failure to detect oestrous
Causes of anoestrous of true acyclicity?
high mil yields inadequate nutrition (especially energy) poor BCS stress (lameness, intercurrent disease)
What are the clinical signs of anoestrous or true acyclicity?
rectal palpation shows involuted tract (ovaries feel small, smooth, flat)
ultrasound shows follicles <1.5cm, no CL
milk P4 at 10 day intervals is low (i.e. sequential)
How does inadequate nutrition influence fertility?
Inadequate nutrition –> reduced IGF-1 production –> this has 4 main effects:
HYPOTHALAMUS - low GnRH, decreased negative feedback to OE
PITUITARY - decreased LH and FSH secretion, decreased response to GnRH
OVARY - decreased granulosa proliferation and differentiation, decreased aromatase activity, decreased luteal activity and steroidogenesis
EMBRYO - decreased embryo growth, decreased IFNy production
How do you treat anoestrous or true acyclicity?
Wait until milk yield falls or cow returns to PEB: increase energy intake if possible
HORMONES: GnRH/analogue, PRID/CIDR +/- GnRH or eCG at a low dose (750 IU)
Better response if nutrition improved concurrently.
What do CIDR and PRID devices look like?
CIDR = y shaped PRID = spiral shape
What can be behind fluid-filled structures in bovine ovaries? 5
NORMAL: follicles or vacuolated CL
ABNORMAL: luteinised follicles, follicular and inactive cysts, luteal cysts
Describe a follicle:
feeling
size
Transient, dynamic, soft, fluctuant
Maximum 1.5-2cm diameter during or just after oestrous
<1.5cm diameter for rest of cycle
associated with normal cyclical acitivity
Describe a vacuolated CL:
feeling/appearance
occurence
same size as non-vacuolated CLs with ovulation point, identifiable with ultrasound vacuole disappears in pregnancy usually single occurs in about 25% ovulations associated with normal cyclical activity
Describe a luteinised follicle:
size
occurrence/when
<2.5cm diameter no sign of ovulation larger cavity than vacuolated CL usually single formed from anovulatory mature follicle occur early post-partum
Describe follicular and inactive cysts
appearance
when
soft, thin-walled (2.5cm diamter single or multiple one or both ovaries formed from anovulatory mature follicle low P4, cows are anoestorus
Describe luteal cysts:
appearance
when
Thick-walled (>3mm), fluid-filled structure, >2.5cm diamter
usually single
formed from anovulation of mature follicle
high P4, cows are anoestrous
What are the main differences between a mature follicle and ovarian cysts?
Mature follicle: 2.5cm, persists >10 days. (opinions vary about the presence or absence of a CL concurrently) –> aberrant reproductive function.
What do ovarian cysts develop from?
Develop from anovulatory Graafian follicles which instead of ovulating or regressing, the granulosa cell layer degenerates, with cessation of normal cyclical activity with the cow becomes either acyclical or nyphmaniacal
What is nyphomania?
where the cow shows persistent oestrous (several days) OR comes into oestrous every 7-8 days and this oestrous lasts longer than normal oestrous (i.e. >18 hours)
What are the different types of cyst? 3
TRUE FOLLICULAR: thin-walled, oestradiol-secreting
LUTEAL: thick-walled, progesterone-secreting
INACTIVE: thin-walled, functionally undifferentiated inactive (clinically similar to luteal cyst but structurally more similar to a true follicular cyst - i.e. thin-walled)
Which cyst type is associated with anoestrous? Why?
Luteal - because of P4 negative feedback
What do thin-walled follicular cysts result in?
acyclicity or, less frequently, nyphomania
What do thick-walled luteal or luteinised cysts result in?
acyclicity due to negative feedback of P4 on the anterior pituitary.
What is an increasing problem in high yielders?
acyclicity (rather than nyphomania)
What is normal follicular growth for a cow?
usually 2 follicular waves with the 3rd –> dominant follicle –> ovulation. This is a ‘3 wave follicular cycle’.
Some cows have a 2 wave follicular cycle. An even smaller % cows have a 4 wave follicular cycle.
Why does ovulation occur?
Mature dominant follicle –> increased secretion of oestradiol –> LH surge
Why do cysts occur - broad categories?
hypothalamic/pituitary causes
ovarian causes
What are hypothalamic/pituitary causes of cysts?
Due to failure of the normal pre-ovulatory LH surge after the end of the recovery period. This may be because of a lack of sensitivity of hypothalamic LH surge centre to oestradiol OR failure of GnRH release.
THUS IT IS A FAILURE OF OESTRADIOL TO ELICIT A NORMAL POSITIVE FEEDBACK STIMULATION OF LH SURGE.
What are ovarian causes of cysts
Reduced numbers of LH-Rs in granulosa cells of cysts (versus normal follicles).
OR
Low insulin and IGF-1 and NEB –> increased NEFAs which impair follicular cell proliferation and function.
What is this?
follicular (thin-walled) ovarian cyst
What is this?
luteal or luteinised (thick-walled) cyst
How can cysts be treated?
Prognosis?
Those that develop in the VWP (common for this to occur) –> regress spontaneuosly, no treatment needed
DON’T RUPTURE by squeezing transrectally
Luteal cysts - treat with PGF2a (–> luteolysis)
Follicular: GnRH or hCG (–>luteinisation), followed by PGF2a or CIDR/PRID for 10-12 days
Prognosis - recovery rate is good
When might you see a persistent CL? 2
High genetic merit cows of extended luteal phase
Uncertainty if it occurs without uterine infections
Occurs associated with pyometra (uterus changes interferes with luteolysin production)
How do you treat a persistent CL?
PGF2a (removes CL and opens cervix for pus to drain out in case of pyometra/infection)
When is oestrous not usually associated with overt behavioural signs?
first post-partum oestrous
What are signs of oestrous in cow?
Standing to be mounted (min 5 seconds) Head mounting other cows (learned behaviour?) clear vulval elastic mucus discharge bellowing if separated grouping of sexually active animals searches for other cows in heat for mounting restlessness not eating decreased milk yield
Why might oestrous not be detected?
COW PROBLEM - short oestrous, signs are covert PERSON PROBLEM (usually) - poor facilites, poor observational regimen
How often should cows be observed for oestrous?
at least 20-30 minutes, at least 3 times a day, not at milking time, especially between 9-10pm
How can you modify ovarian cyclical activity to implement TAI?
- 2 injections PGF2a 11 days apart with a single AI at 72-84 hours after second injection OR double AI at 72 and 96 hour OR 72 and 90 hour after 2nd injection
- PRID/CIDR for 7-9 days, PGF2a at 24 hour before removal, and double TAI at 48 and 72 hours OR single AI at 56 hours
Outline ‘Ovsynch’ - follicle wave synchrony
Day 0 - GnRH - synchronise new wave emergnece and accelerate follicular growth
Day 7 - PGF2a - luteolysis
Day 9 - GnRH - control time of ovulation
Day 10 - TAI
What is meant by double ovsynch?
Prior to Ovsynch programme, you do the traditional presynch:
PGF2a –> wait 14 days –> PGF2a –> wait 12 days –> start normal ovsynch: GnRH, wait 7 days, PGF2a, wait 48-56 hours, GnRH, wait a day, TAI)
For what reasons may a cow not calve after service/AI?
Oocyte not fertilised (10-15%)
Embryos die abortion, maceration, mummification, abortion
At what stage is organogenesis complete in the cow embryo?
day 42
What is an irregular return to oestrous?
Either > 24 days (late embryonic/early foetal death)
mistimed AI)
What are non-male reasons for fertilisation failure?
anovulation delayed ovulation incorrect TAI serving too early post-partum hormonal deficiencies an dimbalance structural defects of tubular genital tract preventing sperm and oocyte meeting infection of genital tract and endometritis nutritional deficiencies and imbalances stress
When does a cow ovulate?
About 12 hours after end of oestrous (unique amongst domestic mammals)
What are causes of early and late embryonic death?
Luteal deficiency and hormonal imbalance
uterine infection with specific embryopathic microorganisms
Infection with opportunist pathogens and endometritis
nutritional deficiencies/excesses
genetic factors
heat and other stressors
How do you treat luteal deficiency and hormonal imbalances?
difficult to diagnose
some success with P4 supplementation using PRID/CIDR
hCG for 4-9 days post A causes accessory CL formation
List some embryopathic microorganisms
Campylobacter foetus Tritrichomonas foetus Mycoplasma, ureaplasma and acholeplasma BVDV IBR BTV Chlamydophila psittaci
What is a repeat breeder cow?
a cow that has returned to oestrous (not become pregnant) after AI/natural service at normal or extended interval on 3 or 4 consecutive occasions
What is an empirical approach to treating a repeat breeder cow?
- change sire if used repeatedly
- use semen from bull with good fertility (high non-return rates)
- insemminate at normal time AND 24 hours later
- nCG or HnRH at time of first AI
- 11-12 days after AI, GnRH analogue (Buserelin) IM
- 11-12 days after AI consider using PRID/CIDR
What effect may infectious agents have on heifer/cow fertility?
Prevent fertilisation
Early embryonic death
Late embryonic death
Abortion/stillbirth/weak calves
How can you diagnosie sunclinical endometritis?
only way is by taking an endometrial biopsy
Define metritis
infection and inflammation across all uterine wall layers (myometrium, endometrium and serosal layer)
List predisposing factors for endometritis
long/short gestation lenght RFM (commonest cause) parity milk yield dystocia and trauma (2nd commonest cause) hygiene season intercurrent disease nutrition early or delayed return to oestrous
Diagnosis for endometritis
VAGINAL EXAM ESSENTIAL: dry wipe, clean glove: character, volume and smell
SCORE FOR SEVERITY - MUCUS CHARACTER (0-3) and ODOUR (normal = 0, fetid =3)
BACTERIOLOGY - very difficult
List some frequent cases of endometritis
Truperella (Arcanobacterium) pyogenes Prevotella spp E. coli Fusobacterium necrophorum Fusobacterium nucleatum
List some rare causes of endometritis
Acinetobacter spp Bacillus licheniformis Enterococcus faecalis Haemophilus somnus Mannheimia haemolytica Pasteurella mutlocida Peptosptreptoccous spp S. aurues Strep. uberis
How do you treat endometritis? 3
CL PRESENT: PGF2a
NO CL: Metricure = intrauterine cephalosporin
CHRONIC LESIONS: fail to respond to treatment, may consider Pevidene iodine
Define abortion
expulsion of one or more calves < 271 days after service or AI, either dead or live for < 24 hours
Define stillbirth
birth of a dead calf at term (272-273 days)
List some non-infectious causes of abortion/stillbirth
Genetics (chromosome/ developmental abnormalities)
Endocrine deficiencies/excesses
Toxicity
Heat stress
Misuse of therapeutics (corticosteroinds, PGs)
Stillbirth: dystocia
What was the most common infectious cause of bovine fetopathy in 2013?
Neospora
List infectious causes of bovine fetopathy
(IN ORDER OF 2013 frequency) Neospora Bacillus licheniformis S. dublin Trueperella pyogenes Schallenberg Listeria spp Other fungi BVD Campylobacter Leptospira
How often is a specific cause of a fetopathy identified?
2006 - 19.3% submissions ID
2013 - 13.7 % submissions ID
Sheep: 40-50% submissions ID
When does Brucella abortus cause abortion?
6-9 months
When do Leptospira species cause abortion?
6-9 months
When does Campylobacter fetus (venerealis) cause abortion?
5-7 months
When does Tritchomonas fetus cause abortion?
5 months
When do Salmonella spp cause abortion?
variable time, usually 7 months
When does Trueperella (Arcanobacter) pyogenes cause abortion?
sporadic and variable time
Which infectious causes of abortion are venereal? 2
Campylobacter fetus (venerealis) Tritrichomonas foetus
When can Mycobacterium tuberculosis cause abortion?
any stage
When can fungi (Aspergillus, Absidia, Mortiella spp, mucoralis group) cause abortion?
from 4 months to term
When does Bacillus licheniformis cause abortion?
sporadic late abotions
When Can IBR-IPV virus cause abortion?
4-7 months (n.b. venereal)
When can BVDV cause abortion?
any stage (n.b. venereal)
When can Neospora caninum cause abortion?
late abortions
What is IPV?
Infectious pustular vaginitis (a clinical sign of BoHV-1)
What are two possible clinical signs of BoHV-1?
IBR and IPV
