Large Animal - Fertility Flashcards
(158 cards)
1
Q
What is a fertile cow?
A
A cow that meets the fertility criteria established for the herd/unit
2
Q
What is the fertility criteria of a cow in a herd that calves all-year-round?
A
Has to calve every 12 months
3
Q
What is the fertility criteria for a cow in a herd with a tight seasonal calving pattern?
A
Calving within a certain time period to match availability of pasture
4
Q
What is a sub-fertile cow?
A
One that fails to achieve its fertility target, or that of the herd or group
5
Q
What is an infertile cow?
A
Sometimes considered a sub-fertile cow but sometimes considered a sterile cow
6
Q
What is a sterile cow?
A
Cow that is incapable of becoming pregnant no matter how long a period she is given
7
Q
What are the four causes of sub-fertility described as traditionally?
A
Structural causes
Functional causes
Management causes
Infectious agents
8
Q
What is it simpler to consider causes of sub-fertility from?
A
The presenting clinical signs observed by stockperson or veterinarian
9
Q
What are the signs of sub-fertility?
A
No observed oestrus
Regular or irregular returns to oestrus after service
Presence of abnormal vulval discharge
Abortion and stillbirth
10
Q
How often will a cow come into oestrus if not pregnant or 4-6 weeks post-partum?
A
Every 18-24 days
11
Q
What is the commonest cause of no observed oestrus in heifers?
A
Congenital abnormalities - ovarian aplasia/hypoplasia, freemartinism
12
Q
What are the causes for no observed oestrus in dairy cattle?
A
Congenital abnormalities Acyclical or anoestrus Ovarian cysts Persistent corpus luteum Pyometra with persistent CL Cyclical ovarian activity occurring but no behavioural signs Showing signs but not being detected
13
Q
What percentage of co-twin heifers to bull calves are freemartins?
A
92%
14
Q
What are freemartin cows?
A
Heifers that never cycle
Small vestigial tract with no ovaries
Diagnosed as calves by test tube or thermometer case test
Confirmed by karyotyping
15
Q
What are the causes of anoestrus or true acyclicity?
A
High milk yields
Inadequate feeding - especially energy
Poor BCS
Stress - lameness, intercurrent disease
16
Q
What would a clinical examination show with anoestrus or acyclicity?
A
Rectal palpation - involuted tract, ovaries feel small, smooth and flat
Ultrasound - follicles <1.5cm, no CL
Milk progesterone - intervals low at day 10
17
Q
How can inadequte nutrition affect fertility?
A
Through reduced IGF-1 production - hypothalamus (decreased GnRH secretion, decreased +ve feedback to embryo), pituitary (decreased LH and FSH secretion, decreased response to GnRH), ovary (decreased granulosa proliferation and differentiation, decreased LH/FSH supported steroidogenesis, decreased aromatase activity, decreased luteal activity and steroidogenesis), embryo (decreased embryo growth, decreased IFN-tau production)
18
Q
How can anoestrus or true acyclicity be treated?
A
Wait until milk yield falls or cow returns to positive energy balance
Increase energy intake if possible
Hormonal treatment - GnRH or analogue, progesterone/progestagens (PRID), controlled internal drug release (CIDR) alone or with GnRH or eCG at low dose rate
Better response to hormones if nutrition improved concurrently
19
Q
What are the two normal structures present in bovine ovaries?
A
Follicles
Vacuolated CL
20
Q
Describe normal follicles in the bovine ovary
A
Transient, dynamic, soft, fluctuant structures
1.5-2.0cm in diameter during or just after oestrus
<1.5cm diameter during rest of cycle
Associated with normal cyclical activity
21
Q
Describe a vacuolated CL in a bovine ovary
A
Same size as non-vacuolated CL Ovulation point identifiable with ultrasound Vacuole disappears during pregnancy Usually single Occurs in about 25% of ovulations Associated with normal cyclical activity
22
Q
What are three abnormal structures within a bovine ovary?
A
Luteinised follicles
Follicular and inactive cysts
Luteal cysts
23
Q
Describe luteinised follicles in a bovine ovary
A
<2.5cm in diameter No sign of ovulation Larger cavit than vacuolated CL Usually single Formed from anovulatory mature follicle
24
Q
Describe follicular and inactive cysts in a bovine ovary
A
Soft, thin walled fulid filled structure >2.5cm diameter Single or multiple One or both ovaries Formed from anovulatory mature follicle
25
Describe luteal cysts in bovine ovaries
Thick walled fluid filled structure
>2.5cm in diameter
Usually single
Formed from anovulation of mature follicle
26
What are ovarian cysts?
Fluid filled structures on the ovaries
>2.5cm diameter
Persist for longer than 10 days
Result in aberrant reproductive function
27
How are ovarian cysts formed?
Develop from anovulatory Graafian follicles
Granulosa layer degenerates
Normal cyclical activity cessates
Cow becomes either acyclical or nymphomaniacal
28
What are the three types of cysts?
True follicular cyst - thin walled, oestradiol secreting follicular cyst
Luteal cyst - thick walled, progesterone secreting luteal cyst
Inactive cyst - thin walled, functionally undifferentiated inactive cyst
29
What do thin walled follicular cysts result in?
Acyclicity
| Nymphomania - less frequently
30
What do thick walled luteal cysts result in?
Acyclicity - negative feedback of progesterone on anterior pituitary
31
What causes ovulation of the dominant follicle?
LH surge
| Induced by increased secretion of oestradiol by mature dominant follicle
32
Why do cysts occur?
Normally LH surge absent or attenuated after calving (recovery period)
Failure of the pre-ovulatory LH surge after the end of the recovery period
33
What occurs post-calving in the hypothalamus? How can this cause a failure of the LH surge?
Progressive restoration of hypothalamic response to oestradiol
Produces LH surge due to - lack of sensitivity to oestradiol, failure of GnRH release
LH surge fails when oestradiol fails to elicit a normal positive feedback stimulation of LH surge
34
What are the ovarian causes of cysts?
Reduced numbers of LH receptors in granulosa cells of cysts
Low insulin, IGF-1 and negative energy balance cause greater non-esterified fatty acids
These impair follicular cell proliferation and function
35
With cysts developed in the immediate postpartum period what needs to be done?
Nothing - generally regress spontaneously, do not need treatment
36
What should not be done with ovarian cysts?
Rupture by squeezing transrectally
37
How should ovarian cysts be treated?
Luteal cysts - PGF2alpha
| Follicular cysts - GnRH or hCG, cause luteinisation, follow with PGF2alpha or CIDR/PRID for 10-12 days
38
What is the recovery rate for ovarian cyst treatment?
Good
39
How can persistent CL occur?
Associated with pyometra
Pathological changes to uterus interfere with luteolysin production
CL persists
40
How should persistent CL be treated?
PGF2alpha
41
What are the signs of oestrus in the cow?
```
Restlessness
Not eating
Reduced milk yield
Searches for other cows in oestrus to elicit mounting
Grouping of sexually active cows
Bellowing if separated
Clear vulval elastic mucus discharge
Head mounting other cows
Standing to be mounted for at least 5 seconds
```
42
What is the usual cause of oestrus not being detected?
Person problem - poor facilities, poor observational regimen
43
How often should cows be examined for oestrus?
At least 3 times a day for 20-30 minutes - not at milking times, undisturbed
44
What can be used to help with oestrus detection?
Detection aids
| Synchronise oestrus with AI
45
What are some examples of oestrus-detection aids?
KaMaR, Beacon, Estrotect heat mount detector, tail paint
Pedometers
Changes in vaginal impedence
CCTV
Sequential milk progesterone assays
Abolish detection - oestrus-synchronisation
46
What are the two main ways of modifying normal ovarian cyclical activity?
PGF2alpha injections - two injections 11 days apart, single AI at 72-84 hours after 2nd injection, double AI at 72 and 96 hours
PRID or CIDR - insert for 7-9 days, PGF2alpha injected 24 hours before removal, double fixed-time AI at 48 and 72 hours, or single AI at 56 hours
47
What are the reasons for a cow not calving after service/AI?
Oocytes not fertilised - 10-15%
Embryos die under 13 days - 15-20%
Embryos die between 13-42 days - 10%
Foetal death after 42 days - 5%
48
What four things can foetal death after 42 days result in?
Abortion
Maceration
Mummification
Abortion
49
What is a regular return to oestrus?
Interval between service and return is 18-24 days
| Due to either fertilisation failure or early embryonic death
50
What is an irregular return to oestrus?
Interval between service and return is greater than 24 days
Cause is late embryonic or foetal death
Interval of less than 18 days means oestrus not correctly identifies - mistimed AI
51
What are the causes of fertilisation that aren't due to bull or poor semen?
```
Anovulation
Delayed ovulation
Incorrect timing of AI
Serving too early postpartum
Hormonal deficiencies or imbalance
Structural defects of tubular genital tract
Infection of genital tract and endometritis
Nutritional deficiencies or imbalances
Stress
```
52
What are the causes of early and late embryonic death?
Luteal deficiency
Hormonal imbalance
Uterine infection with specific microorganisms
Infection with opportunist pathogens and endometritis
Nutritional deficiencies and excesses
Genetic factors
Heat and other stressors
53
Describe the diagnosis and treatment of luteal deficiency/hormonal imbalance
Difficult to diagnose
Some success with P4 supplementation (PRID or CIDR)
hCG 4-9 days post AI can cause accessory CL formation
54
What is an unlikely cause of embryonic death in the absence of clinical signs? How would you treat it?
Opportunist pathogens and endometritis
| Treat as for endometritis
55
What are the sseven specific embryopathic micro-organisms?
```
Campylobacter fetus
Tritrichomonas fetus
Mycoplasma, ureaplasma and acholeplasma
BVDV
Infectious bovine rhinotracheitis (IBR)
Blue tongue virus
Chlamydophila psittaci
```
56
What is a repeat breeded cow?
Cow returned to oestrus at normal or extended intervals on three or four consecutive occasions
57
How does pregnancy rate trend with milk yield?
The higher the milk yield the lower the pregnancy rate
58
Describe the empirical approach to treating the repeat breeder cow
```
Change sire if used repeatedly
Natural service if possible
Use semen from bull with good fertility
Inseminate at normal time and 24 hours later
hCG or GnRH at time of first AI
11-12 days after AI give GnRH analogue
11-12 days after consider PRID or CIDR
```
59
What does the effect of infectious agents on fertility depend upon?
Reproductive process where it exerts its effect
60
What are the effects of infectious agents on fertility?
Prevent fertilisation - return to oestrus at normal interval
Cause early embryonic death - return to oestrus at normal interval
Cause late embryonic death - return to oestrus after extended interval
Cause abortion, still birth or weakly calves
61
What are the predisposing factors for endometritis?
```
Longer/shorter gestation length
Retained foetal membranes
Parity
Increased milk yield
Dystocia
Trauma
Hygiene
Season of the year
Intercurrent disease
Nutrition
Early or delayed return to oestrus
```
62
How can endometritis be diagnosed?
Vaginal examination essential - character, volume, smell
Scoring for severity
Bacteriology very difficult
63
What are frequent bacterial causes of endometritis?
```
Trueperella pyogenes
Prevotella species
E. coli
Fusobacterium necrophorum
Fusobacterium nucleatum
```
64
What are bacteria that rarely cause endometritis?
```
Acinetobacter species
Bacillus licheniformis
Enterococcus faecalis
Haemophilus somnus
Mannheimia haemolytica
Pasturella multocida
Peptostreptococcus species
Staphylococcus aureus
Streptococcus uberis
```
65
Describe the general treatment for endometritis
CL present - PGF
No CL - Metricure (intrauterine cephalosporin)
Chronic lesions/failure to respond to treatment - Pevidene iodine possibly
66
What is the difference between abortion and stillbirth?
Abortion is expulsion of one or more calves less than 271 days after service that are dead within 24 hours
Stillbirth is the birth of a dead calf at term
67
What are non-infectious causes of abortion/stillbirth?
Genetic factors - chromosomal, developmental
Endocrine deficiencies/excesses
Toxic substances
Heat stress
Misuse of substances - corticosteroids, PGs
Dystocia - stillbirth only
68
What are the infectious agents that cause the most abortions/stillbirths?
Neospora
Bacillus licheniformis
Salmonella dublin
69
What are the infectious causes of abortion and when do they cause abortion?
Brucella abortus: 6-9 months
Leptospira spp.: 6-9 months
Listeria monocytogenes: 6-9 months
Campylobacter fetus: 5-7 months
Tritrichomonas fetus: 5 months
Salmonella spp.: variable time, usually 7 months
Trueperella pyogenes: sporadic and variable time
Mycobacterium tuberculosis: any stage
Fungi (Aspergillus, Absidia, Mortiella spp.): from 4 months to term
Bacillus licheniformis: sporadic late abortions
Neospora caninum: late abortions
IBR-IPV virus: 4-7 months
BVDV: any stage
70
Describe the five point cycle that should be carried out when monitoring herd fertility
```
Plan and set objectives
Set targets
Monitor progress
Periodic evaluation
Advice and recommendations
```
71
What calving interval should we be aiming for?
One calf per cow per year - 365 days
72
Why do we want to maximise the calving interval at 365 days?
Maximise milk production - making the interval longer would reduce milk yield as spends less time milking
73
What do targets for herd fertility need to be?
Achievable
74
What is the gestation period of a cow?
9 months - 283 days
75
What can vary a gestation period of cows?
Breed
76
Why can't we get a cow pregnant immediately after calving?
Needs to start cycling again
77
How many days post-calving should a cow start cycling?
42 days
78
What can cause a cow to not cycle again after 42 days?
```
Poor BCS
Retained foetal membranes
Traumatic calving
Milk fever
Mastitis
Nutritional problems
Fatty liver
```
79
When should a cow expel her foetal membranes?
Within 24 hours
80
How many days do we usually have to get a cow pregnant?
43 days
81
How many times is it possible to serve a cow if we want a maximal calving interval?
Twice - 21 day cycle
82
What is the target mean number of days between calving and first service?
65 days
83
What is the target mean number of days between calving and conception?
85 days
84
What is the difference between a calving index and calving interval?
Index is average of all cows calving intervals
85
What is the target conception rate at first service?
60%
86
What is the target conception rate for all services?
55%
87
What is the main thing that can affect the voluntary waiting period in cattle?
Management techniques - feeding, exercise, hygiene etc.
88
What things can affect the calving to first service period?
Voluntary waiting period
Post partum problems
Return of ovarian cyclicity
Oestrus detection
89
Why is the timing of first service critical?
Too soon after calving lower pregnancy rates
| Too late prolongs calving interval
90
What are the two ways of measuring timing of first service?
Mean interval between calving and first service over a time period
First service submission rate
91
What are the problems with calving to first serving interval?
Cows not served missed out
Large spread not seen - early and late cows cancel out
Unusual VWP can affect number
92
What is the submission rate?
Percent of cows that get served within 24 days of earliest service date
93
What submission rate would be good between days 50 to 74 days?
85%
94
How long is a cow often in heat for?
Actually 8-15 hours
| Stands only for 20-30 minutes
95
What are the key targets between calving to conception?
Detecting oestrus effectively
| Good pregnancy rate
96
How can we detect oestrus detection accuracy?
Milk sample at time of AI
| Test for low progesterone (5 or less)
97
What should milk progesterone be at the time of oestrus?
Low - less than 5
98
What percent of cows should be in calf 120 days post calving?
More than 64%
99
What percentage of cows should not be in calf 210 days post calving?
Less than 7%
100
What are the two groups of cows that should be examined for fertility?
Problem animals
| Any cow not seen bulling at 50-55 days
101
What three records should we check on a fertility examination?
Key indices
Oestrus detection
Pregnancy rates
102
What four things should a routine visit contain?
Regular visits
Examination of animals
Examination of records
Advice
103
What does the profitability of a sheep enterprise depend on?
Reproductive performance of the flock
104
What two things can be used to measure fertility in ewes?
Percent barren
| Percent pregnant
105
What is fecundity in ewes?
Number of lambs born per pregnancy
106
What is the survival rate in ewe fertility?
Number of lambs that survive to weaning
107
What is the lambing percentage?
Number of lambs reared/weaned/sold per 100 ewes put to ram
108
What causes an increase in single lambs resulting in a poor lambing percentage?
Poor ovulation rate
109
What causes an increase in barren ewes resulting in poor lambing percentages?
Poor conception rate
| High embryonic/foetal loss
110
What causes a decrease in ewes rearing a lamb resulting in a poor lambing percentage?
High abortion/stillbirth/death
111
What should we compare measurements of reproductive performance to?
Previous performance
| MLC Flockplan records for local area/breed
112
What should be established when measuring reproductive performance of ewes?
True output - consider breed, season, environment
113
What are the four main causes of poor reproductive performance in ewes?
Poor ovulation rate
Poor conception rate
High embryonic/foetal loss
Abortion/still birth/perinatal loss
114
What four factors affect ovulation rate in ewes?
BCS
Season
Age
Genotype/breed
115
How do low and very high BCS affect lambing percentage?
Cause: decreased ovulation, decreased conception rate, increased embryonic loss, decreased lamb birth weight, decreased colostrum production
116
What things can affect the conception rate?
```
Season
Reproductive tract abnormalities
Fertilisation failure
Phyto-oestrogens
Stress
Male infertility
```
117
How does the season affect conception rate?
Very early or late breeding in season results in poor conception rate
Difference in length of season between breeds
All animals may not be cyclic
Possibility of short cycles
Irregularity in cyclicity
118
What days can a high environmental temperature have an effect on fertilisation in sheep?
14-47 days
119
What nutritional factor can have an effect on fertilisation in ewes?
Clover-rich pastures - cause to fail
120
What are phyto-oestrogens?
Oestrogen-like compounds produced by plants - lucerene, red clover
121
How do phyto-oestrogens decrease conception?
Change cervical mucus and sperm transport
122
What is hydrometra?
Accumulation of aseptic fluid in uterus
| Persistent corpus luteum present
123
What are the reasons for a hydrometra?
Lack of conception
Early embryonic death
Genetic predisposition
Artificially bred
124
What is the treatment for hydrometra?
PGF2alpha
| Ocytocin
125
What are the causes of early embryonic death in ewes?
Asynchrony - between embryonic development and timing of P4 rise
Dietary intake - overfeeding inversely related to progesterone concentrations
Age - uterine environment, ovum
Mineral deficiencies - selenium and iodine
Infection - toxoplasma, border disease virus
126
What are the two causes of late foetal death in ewes?
Overfeeding in early pregnancy - placental insufficiency
| Underfeeding in late pregnancy - higher demand due to increased foetal growth rate
127
What are the three most common causes of late foetal death in ewes?
Chlamydophila abortus
Toxoplasmosis
Campylobacter
128
What are the five causes of perinatal mortality?
Still birth
Disease - watery mouth, viral diarrhoea, Toxoplasmosis, Chlamydophila
Trauma
Mineral deficiency
Starvation/exposure - poor mothering, mis-mothering
129
How can an investigation into poor scanning percentage be defined in a sheep flock?
Targets vs breed/age
Group differences
Scanning records - more barren or less ovulation
Current time of the year
130
What should be taken from a history for a poor scanning percentage sheep flock?
Mating - Age/breed/background, nutrition and BCS at mating, Ram use, other problems
Early pregnancy - nutrition, stress, EED
Late pregnancy - nutrition, abortions/vaginal discharges
131
What does the clinical examination depend upon when investigating poor fertility in a sheep flock?
Investigation
| Circumstances
132
What three things can be evaluated/examined when investigating poor fertility in a sheep flock?
BCS and nutrition
Male fertility
Aborted foetuses/placenta/ewes
133
Why would we carry out an investigation of male fertility?
Pre/Post-purchase
Pre-mating
Response to reproductive problem
Insurance certificates
134
What number of bulls are generally unsound?
2-4 out of every 10
135
When would you investigate male fertility?
6-8 weeks pre-mating
| As soon as possibleif a reproductive problem
136
What four things should always be done when evaluating male fertility?
Clinical history
Physical examination
Genital examination
Interpretation of results
137
What three things are optional when investigating male fertility?
Semen evaluation
Mating ability/libido
Other tests if required
138
What four things should be collected on a clinical history for male infertility?
General animal information
Past performance
Illness/lameness
Future use
139
What should be looked for generally on a male infertility physical exam?
Abnormalities affecting animal - now, in future
| Clinical significance of abnormalities
140
What three things are generally checked on the physical examination in male infertility problems?
Feet
Body condition
Teeth
141
Describe what should be looked for on a genital examination of the male
External scrotal lesions - scrotal mange in rams, external wounds
Systematic evaluation of contents
Consider - size, tone/consistency, lesions/symmetry
Inspection of prepuce and penis
Rectal - bulls
142
What is testicular tone a good indicator of?
Sperm output
Breeding soundness
SHould feel like a "flexed bicep"
143
What two lesions could be felt upon genital examination?
Epididymo-orchitis
| Epididymitis
144
What two ways can lesions occur in themale genitalia?
Infectious - penetrating wounds, haematogenous, retrograde infection
Iatrogenic - following vasectomy
145
What lesion can occur in the scrotal lymph node?
Caseous lymphadenitis - rams
146
What does the method of semen collection depend on?
Species
Equipment
Expertise
147
Describe semen assessment
```
Gross assessment
Motility
Morphology - number normal, number abnormal
Presence of white blood cells
Bacterial culture
Concentration
```
148
What is it very useful to assess with mating ability/libido in males?
Ability to mount
Ability to mate
Penile abnormalities
Leg or back injuries
149
What may libido be influenced by?
Age
Shyness
Place in hierarchy
150
What can be used to assess libido during mating?
Mating harnesses
151
What other tests can be performed to test male fertility?
Blood testing - BVD antigen, Brucella ovis
Preputial wash - Trichomonas fetus, Campylobacter fetus venerealis
Bacterial culture of semen
152
What are the classifications for male fertility?
Sound or satisfactory
Temporarily unsound or classification deferred
Unsound or unsatisfactory
153
What terms should not be used to evaluate male fertility?
Fertile or infertile
154
What are the ages of sexual maturity for goats, sheep, pigs, cows, horses and alpacas?
```
Goats: 4-8 months
Pigs: 6-8 months
Sheep: 6-15 months
Cows: 7-18 months
Horses: 12-24 months
Alpacas: 14-24 months
```
155
What are the average gestation lengths for goats, sheep, pigs, cows, horses and alpacas?
```
Goats: 150 days
Sheep: 145 days
Pigs: 114 days
Cows: 280 days
Horses: 330 days
Alpacas: 343 days
```
156
What are the most common indications for semen evaluation?
Animals where semen is collected for AI
Animals for export
Investigating poor reproductive performance
Abnormality detected on clinical examination
Part of pre-sale or pre-breeding soundness exam with high stakes
Checking rams/bulls are infertile folwing vasectomy
157
What are the options for semen collection?
Artificial vagina - stallions, bulls and rams
Electro-ejaculation - production animals and wildlife species
Manual stimulation - dogs and pigs
158
What are the routinely evaluated parameters for semen evaluation?
Gross examination and concentration
Sperm motility
Sperm morphology
