L18: Small Ruminant Theriogenology Pt.1 (Pozor) Flashcards
age rams reach puberty
6 mo. (as early as 3 mo, depending on breed)
age ewes reach puberty
5-7 mo. (as early as 3 mo, depending on breed)
age bucks reach puberty
6 mo.
age pigmy goats reach puberty
2-3 mo.
age does reach puberty
5-7 mo.
age of first breeding for sheep and goats
6-8 mo., or when 60-70% of mature BW
length of estrous cycle in sheep
17 days
length of estrous cycle in goats
21 days
duration of estrus in sheep
24-36 hrs
duration of estrus in goat
12-36hrs
time of ovulation in sheep
24-30 hrs from onset of estrus
time of ovulation in goats
30-36 hrs from onset of estrus
optimal breeding time for sheep
towards end of estrus
optimal breeding time for goats
at acceptance of buck (24 hrs) and again in 12 hrs
sheep/goats long or short day breeders?
short (~sep-jan); some breeds more seasonal than others
when is anovulatory season?
jan-june (after ovulatory season)
when is transitional season?
june-sep (before ovulatory season)
manipulations of the estrous cycle
- induction of estrus during transition or anovulatory season (goal = 3 pregnancies in 2 years)
- synchronization of estrus during ovulatory season
- increasing prolifacy (goal = homogenous crop of twins)
How to induce estrus during transition or anovulatory season?
- progestagen/progesterone impregnated vaginal devices
- eCG injection
- ram effect
- melatonin (tricks animal into thinking its dark outside)
- manipulating length of daylight
“hormone of darkness”
melatonin
-can advance breeding season by 4 weeks
how do progestagen/progesterone impregnated vaginal devices work?
- stops estrous cycle until everyone else “catches up” then take it out and will be synchronized
- mimic CL function
- note: progestagen is a synthetic substance that has similar effects as progesterone
- 2 examples of devices: intravaginal CIDR (approved), sponges with progestagens (not approved)
eCG
equine chorionic gonadotropin
- secreted by endometrial cups
- fx in fuminants: induces follicular growth**
- fx in horses: acts like LH to stimulate ovulation**
- can give an injection of it when trying to induce estrus during transition or anovulatory season
sheep/goat breeding management protocol
insert CIDR or sponge device, then remove 12-14d later and give eCG injection. Follow with one or multiple AI/matings 50-60 hrs later (DNK timings)
-CIDR or sponge in for shorter period of time in goats
What is a CIDR?
medicl silicone elastomer over a nylon core impregnated with natural progesterone
-approved for use in sheep
progestagen vaginal devices effect on submission rate, fertility, prolificacy. Can use with AI?
Can use with AI
sub. rate: +++
fertility: ++
prolificacy: +++
ram effect on submission rate, fertility, prolificacy. Can use with AI?
Don’t use with AI
sub. rate: +
fertility: +
prolificacy: +
Melatonin implant on submission rate, fertility, prolificacy. Can use with AI?
Don’t use with AI.
sub. rate: ++
fertility: ++
prolificacy: ++
Light control protocol of induction of estrus during transition or anovulatory season
8-12 wks of “long days” (16hrs of light) followed by 8-12 wks of “short days” (8 hrs of light)
-labor intensive - not practical!
Dow/Ewe anatomy
Ewe: 7 rings, tortuous
Doe: 5 rings, aligned
natural breeding male to female ratios
rams/ewes: 3-5/100 with 27 days together
bucks/dows: 3/100 with 32 days together
(these are for normal breeding w/o manipulation
AI methods***
1) Vaginal (highest + sperm)
2) Cervical
3) trans-cervical (difficult)
4) Laparoscopic
5) Intrauterine (lowest # sperm)
* decrease volume of sperm as you go deeper into the repro tract*
where are sperm naturally deposited?
urethral process
T/F: better to deposit sperm cervical than damage repro tract by trying to go through cervix
T
Pregnancy Dx: indirect methods
- return to estrus
- progesterone >1ng/ml
- *both are INDIRECT methods (could have been pregnant, lost it and have retained CL which is falsely elevating progesterone)
How many days for doe to return to estrus?
21d
How many days for ewe to return to estrus?
17
Pregnancy Dx: direct methods
US (transrectal/transabdominal around 30d)
Rads (>58d)
Ballotement (>100d gestation)
when can see cotyledons on transabdominal US?
> 30d
when do fetuses become difficult to count with US?
> 90d
Biomarkers for pregnancy Dx
BioPRYN (>30d)
Estrone sulfate (>50d) : used to check viability of fetus
Placentallactogene (>60d)
gestation length of ewes***
148d (CL dependent up to 60d, then depend on placenta progestagens >60d)
induction of labor in ewes
> 142d: glucocorticoids (dex)
-parturition occurs 36-48hrs later
gestation length of does***
150d (CL dependent throughout ENTIRE pregnancy)
induction in does
> 140d: glucocorticoids (dex)
-inconsistent timing of parturition
144d: prostaglandins (cloprostenol, dinoprost)
-parturition occurs 42-72 hrs later
Can use combo of dex then PGF: parturition occurs 32-36 hrs later
most commonly used and accurate method of pregnancy dx in SR**
US
