Lecture 2 and 3 Flashcards
What are examples of reproductive losses
- Oestrus behaviour
- Low ovulation rate
- Fertilisation failure
- Embryonic mortality
- Abortion
- Perinatal lamb losses
For fertility investigations what is examples of prospective
- Pre-joining: ewe - BCS, nutrition
- Pre-joining: ram - breeding soundness examination
- Harnesses/crayons during joining/after joining
- Mid-pregnancy: pregnancy testing and paddock surveillance
- Late pregnancy: flock examination
- Lambing: birthing issues and pick up dead lamb
- Marking: wet/dry ewes and count lambs
When is oestrus displayed
Every 16-17 days
What influences breeding season
Breed and age
How long does oestrus last
24 hours
What can affect oestrus
Stress and severe weather
What is the ram effect
Oestrus peaks between days 19-25 after introduction of ram
What is the intravaginal progestogen treatment and equine chorionic gonadotrophin
Progestogen-impregnated vaginal sponge
- Inserted in vagina for 12-14 days -> high progesterone levels -> when device removed -> collapse progesterone levels gonadotropin hormones increase -> oestrus occurs 36 hours later
eCG
- 250-1000 IU IM at time of sponge removal
How can you manipulate the onset of oestrus
- Ram effect
- Intravaginal progestogen treatment + chronic gonadotropin
- Photoperiod control (artificial day length manipulation)
- Melatonin (orally or implant)
What is ovulation influenced by
Time in the breeding season
Body weight and plane of nutrition
What the target condition score for joining
3
What is ovulation rate influenced by
Age Genetic factors Lucerne pasture Mycotoxins Pre-joining parasitic burdens of ewes
What is failure of fertility usually due to
Ram infertility Ewe infertility Other factors - Ram % - Choice of mating paddock - Length joining period
What is the most important factor in production
Nutrition
Why don’t you sheer animals prior to mating
The males don’t like the smell
What is an advantage of intravaginal progestogen treatment and equine chorionic gonadotrophin
Synchronisation of oestrus
Hormonal induction of oestrus outside breeding season
What is key to high lambing %
High ovulation rates are key
What is seen with a decreased condition score at joining
Decreased twins not necessarily lower pregnancy rates
When is time of joining
Determined by seasonal rainfall patterns
- Lambing needs to coincide with he time of the year when good quality fees is most likely to be available
When do merino rams perform well
At all times of the year
What is included in ram breeding soundness examination
- Check all rams 10-12 weeks prior to joining
- Pre-sale/post-purchase
- History
- TTTTT - teeth, toes, torso, testicle, tussle
- Semen quality and quantity is closely correlated with scrotal circumference
What are the 5 T
Teeth Toes Torso Testicle Tossle
What BCS should tams be at the start of joining
3.5 - 4
What is the purpose of ram breeding soundness examination
Identify those rams that are unsound for breeding
What can the scrotal circumference tell us
Age, breed, season, nutritional status
What to look for with the palpation of scrotum
Scrotal circumference Resilience/firmness Head and body epididymis Spermatic cord Scrotum itself
What are supplementary tests when ram breeding soundness examination
- Semen collection and evaluation
- Electro-ejaculation
- Artificial vagina
- Ultrasonographic examination genitalia
- Evaluation of libido
Conditions that may contribute to genital unsoundness in rams
Testes: degneration, atrophy, hypoplasia, cryptorchidism, monorchidism
Epididymis: epididmitis (brucella ovis, Actinobacillus seminis, Histophilus ovis)
Flystrike, footrot, parasite burdens, eye infections, brisket sores, arthritis, teeth problems
What bacteria causes pizzle rot
Corynebacterium renale
Who gets pizzle rot
Wethers -> grazing lush, clover-dominant pastures
What is pizzle rot
Maybe develop when bacteria are present and high concentration of urea in urine this causes bacteria to produce ammonia -> cytotoxic -> damages pizzle membranes and external skin
What are the clinical symptoms of pizzle rot
- Ammoniac smell
- Prepuce is typically swollen and oedematous
- Necrotic ulcer on skin near preputial opening; lesion often covered by scab
- Risk of secondary myiasis
How to treat pizzle rot
Restrict diet - move wethers to pasture with lower clover content
Flushing pizzle with mild antisepticum
Acidify urine - ammonium chloride in water
Sitting the pizzle in sever cases
How to prevent pizzle rot
- Ringing
- Restricted diet at certain times of the year
- Testosterone injections
What are the side effects of testosterone injections
Masculinisation, wool cuts increase, increase fibre diameter
How does testicular degeneration happen
Increased testicular temperature - Hot weather, any scrotal thickening, fever, septicaemia, over-fatness, excessive wool over scrotum
How to diagnose testicular degeneration
Physical examination and semen examination
How to treat testicular degeneration
Shear ram, provide cool conditions
How does ovine brucellosis affect sheep
The bacteria enter body though any mucous membrane -> local lymph node -> bacteraemia -> epididymis and accessory sex gland
How do sheep get ovine brucellosis
Venereal disease from infected semen
- Via the ewe’s vagina, joining a ewe that has recently been served by infected ram
- Ewes do not carry infection for long - do not carry infection from year to year
Homosexual activity
- Intranasal infection when rams sniff the vulva of ewes to detect those in oestrus
- Can also occur when infected ewes have recently lambed and are excreting organisms in the vaginal discharge
What are the clinical signs of ovine brucellosis
- Initially soft swelling in the tail of epididymis, may form granulomas or develop into abscesses-> epididymis is enlarged and hard
- Ram shows no sign of sickness
- Semen quality from infected rams may vary from aspermia to apparently normal
- Can be present in a flock for many years without being detected
- Sooner detected when small number of rams or low ram/ewe ratio
How to diagnose ovine brucellosis
- History
- Clinical examination - testicular palpation (tail epididymis)
- Blood serology
- Culture semen
- Microscopic examination fo semen
- Histopathology/bacteriology of genital tract
Is there a treatment for ovine brucellosis
No
How is ovine brucellosis eradicated
- Test and slaughter
- Total replacement
- Two flock system
How to prevent ovine brucellosis
- Buy rates from accredited brucellosis-free stock
- Do not buy rams from sale yards or clearing sales
- Do not borrow, lend, share rams
- maintain secure boundary fences
How does test and slaughter work
- All rams are palpated and blood tested -> all rams with lesions and/or positive blood test are slaughtered
- The remaining rams are re-tested at 3-4 weekly intervals until.a clear test is obtained
How does total replacement work
Selling all rams and replacing them with brucellosis-free rams
How does the two flock system work
Buy new rams and separate the, from infected ram flock. Infected ram flocks get smaller as rams get cast for age
What sort of bacteria is Actinobacillus seminis/Histophilus sommi
gram -ve
Where is Actinobacillus seminis/Histophilus sommi seen
Young rams following puberty
What are the clinical signs of Actinobacillus seminis/Histophilus sommi
May shoe systemic symptoms in association with acute epididymitis
Granuloma epididymis; atrophy testicle and flabby
What is Phyto-oestrogens know as
Clover disease
When does phyto-oestrogens occur
Occurs in medium to high rainfall areas of Australia, which grazing cultivars of subterranean clover and red clover with high formonentin content
What does photo-oestrogens cause
Temporary infertility
- When ewes are mashed on green osteogenic clover
- The cervical mucous increases in volume and becomes very watery
- impairs sperm transport through cervix
- Fertility returns to normal within a few weeks of removal from the pasture
Permanent infertility
-When ewes graze oestrogen clover pastures over consecutive years
- Permanent changes to epithelia of cervix and uterus
- Permanently reduced infertility
What is the major sign of clover disease
Decreased lambing %
