Small Ruminant Reproduction Management Flashcards
What does it mean when they say sheep are seasonally polyestrus?
They are short day breeders
-Breeding period depends on photoperiod, food, breed, presence of make, breeding system and physiologic state
What is secreted by the pineal gland during darkness that influences the gonadotropin releasing hormone and HPG feedback loop?
Melatonin - increase gnrh and makes them cycle
What factors influence SR reaching puberty?
Age, nutrition, season, breed, exposure to make
When do the following go into puberty?
Rams/Buck:
Doe:
Ewe:
Ram: 4-6m
Doe: 6-8m (pygmy 3m)
Ewe: 6-9m
When should we breed SR?
Once they reach 60-70% adult body weight
Why are SR hard to AI breed?
6-7 cartilaginous rings
What is the average estrus cycle for sheep and goats?
Sheep 17d
Goat 21d
(short cycle beginning and end or postpartum)
How many follicular waves do SR have?
3-4 = hard to synchronize
How long after the Lh surge does ovulation occur?
20-26hrs
What are signs of estrus in SR?
Swollen vulva, mucous discharge turning cloudy, tail flagging, mounting/immobilization reflex
How long does estrus last for SR?
Sheep: 30-36hr
Goat: 24-48hr
Why do we manipulate the estrous cycle in SR?
Max milk, meat through year (cornell star)
How do we manipulate the cycle in SR?
Adapted nutrition
Photoperiod manipulation (artificial light, melatonin)
Hormonal treatment - most not approved
Male effect
Combo
What is adapted nutrition?
Flushing before breeding - increase energy increase ovulation and kidding rate
-best response if marginal BCS
-2 week pre-breed up to 2-3 week into breeding season
What BCS should males have entering breeding season?
3-4/5
-Will lose lots breeding
-Need energy and protein supplement 4-6 week prior to breeding
-Don’t over condition or effect semen quality
How do you manipulate the photoperiod?
Alter light or melatonin implants
What hormones can be used in sheep and goats?
None are labeled so all extra label use
Prostaglandin - Lyse Cl
-Single or double injection 11-12 days apart, estrus 24-72hr, must be cycling
Progestin: mimic luteal phase, estrus 24-96hr after withdrawal (CIDR)
eCG/PMSG: FSH like activity - stimulate ovulation
GnRH Agonist: Act on anterior pituitary to stimulate LH/FSH activity
What are some synch protocols?
Day 1: PGF
Day 8: GnRH
Day 15: PGF
Day 18: TAI and GnRH
How do you bring a ewe in to synch when its out of season?
-Progestin >14d + PG600 24-48hr before progestin removal
-AI lighting - mimic long day 60d then short 60d
-Melatonin
What is the ratio of ram to eve and buck to doe for natural breeding?
Ram:Ewe: 1:30-50
Buck:Doe: 1:50
What is a teaser male? Why do we use them?
Help to dected female in heat - use AI
Teasing Harness
Vasectomized
Epididectomized
Where is the site of semen deposit in ewes?
Vagina
What type of semen should you use in SR and with what technique?
Fresh - AI in sheep tortuous cervix
Frozen - only Lap AI sheep
Goat AI - in vagina fine
Where do you go for transcervical AI?
Through external os
For Lap AI where is the semen being deposited?
Left horn uterus if can - but split between both sides
How do you embryo flush a ewe?
Surgically - scrub, exteriorize, make hole and use tomcat cath to flush up and collect in dish
What is the average gestation for sheep and goats?
Sheep: 145-150 days
Goats: 147-155 days
When does the embryo enter the uterus and when is MRP?
Enter uterus on day 4
MRP D12-13
When does the embryo implant?
D16
When does it become an aminotic vesicle?
D20
How is pregnancy maintained in a sheep and goats?
Sheep: CL up to day 60-70 when placental progestins take over
Goat: CL dependent
Why do we do pregnancy detection?
Tell if breeding successful, any infertility issues, health problems, need to cull, see how many
Help with nutritional management, know preg tox risk, dystocia considerations
How and when do you preform Pregnancy diagnosis?
Transrectal ultrasound >20d
Transabdominal ultrasound >30d(fetal sex 55-70d
Radiograph >70d - very accurate for number of kids
Where does the probe go for transabdominal ultrasound?
Left fold of flank
What do you see on ultrasound based on day of pregnancy?
D21
D25-35
D30-40
D40-90
>50
D21: Placentomes - small echongenic area
D25-35: see embryo better- hyperechoic, amnion
D30-40: C shaped placentomes
D40-90: Placematone, umbilical cord, fetus
>D50: Fetus begin to resemble lamb/kid
>90 hard to count fetus - ballotment useful
What kind of placenta do sheep have?
Cotylendonary synepitheliochorial
What is the best way to fetal age?
Crown to rump length
What should you ask the owner to do before ultrasounding?
fast 12hr food, 4hr water
When should you ultrasound to say yes/no preg?
When to gestation age or # fetus?
40day after ram/bock removed or last possible date of breeding
50-55d, count 90d
How much fetal growth occurs in last 6 weeks?
70%
-Good nutrition needed to prevent preg diseases - concentrate and best hay
