Sheep Goat Repro Flashcards
when are the periods we can manipulate the estrous cycle
in season - sync females to cycle as group
out of season - force cycling to start, sync group
transitional period - advance start of breeding season, sync as group
who has a longer season, goats or sheep
goats
in season sync: use ________ injection during ________ season
prostaglandin injection (estrumate or lutalyse) breeding season
why: must be a functional CL for be responsive to prostaglandin; needs to be at least 5 days after standing heat (ie. during diestrus) to respond
what is the length of estrus and diestrus in sheep and goats
estrus 2-3 days for both
diestrus 10 for sheep, 14 for goats
in season sync: what is the 2 dose program for prostaglandin
- give flock prostaglandin dose and repeat 11 days later to sync up, so that if bred on same day lambing will occur within 7 day span
- about 3/4 of flock will respond to a dose of prostaglandin on any given day, during diestrus when the CL has had time to develop; 1/4 will not be effective
- all will respond to second dose
in season sync: what are 2 methods for supplying external progesterone
CIDR controlled intravaginal drug release
MGA melengesterol acetate feed additive
in season sync: what is the purpose of supplying external progesterone
provides high levels of progesterone, preventing the decrease in progesterone that initiates estrus (heat cycle is blocked)
in season sync: how long does external progesterone need to be supplied in order to sync
needs to be in for at least 10-18 days sheep /12-18 days goat bc you don’t know where animal is in their heat cycle when you give it, and so you can pull in manageable numbers before introducing males (12-24 hours later)
pros and cons of melengesterol acetate
cost effective, but need to ensure consistent intake and has inconsistent estrus and conception rates, so CIDR is more popular because more reliable
why is out of season sync used?
give at least 3 pros and 1 con
pros:
lamb out of season to access high market rates
efficient use of labour and facilities
generic selection for ability to breed out of season
keep replacement labs from ewes that lamb out of season
cons:
difficult to get adequate conception rates and profligacy, and may cost more to synchronize
how do you sync animals during non-breeding season using drugs?
add progesterone for at least 7-9 days so that follicles (that at the time lack any activity) will develop into almost normal follicles
then PMSG used to cause ovulation in the non breeding season; 50-70% of the flock will ovulate
how do you sync out of season flock using manipulation of day length?
a. expose to long a light-tight barn, expose to long day light for 8-12 weeks, then short day length for 8-12 weeks (minimum 8 hours shorter), which mimics natural days getting shorter so ewes cycle; rams must be exposed also
b. new alternative: lights on for 23 hours for 8-12 weeks, then 17 hours or less and after 55 days of that shorter day length introduce the males for breeding
during transitional period (within 6 weeks of normal start of season) what procedure can. be used to advance the normal breeding season
ram/buck effect: keep females away form males for 60 days prior, then introduce vasectomized teaser for 2 weeks, then remove and replace with intact males
in a traditional breeding program, flock is bred in _____ and lambing is in ______
fall; spring
(this is when there is highest natural profligacy and is ideal time to utilize AI and ET)
why consider combining out of season breeding with a spring birthing flock
multiple lambings per year to spread out the work of lambing over the year, spread out income from sales of lambs/kids, and better use of facilities and labour
what are some pros and cons of accelerated lambing systems (an advanced breeding program)
(this involves having each female give birth every 7-8 months)
pros: cash flow more consistent, increase in lambs/ew/yearm but usually decrease in lambs/lambing
cons: requires selection for seasonal breeds, needs very high management skills and good facilities, need high nutrition all year
in accelerated lambing systems, how often does lambing occur
3 lambings in 2 years (every 8 months)
or 5 lambing in 3 years (every 7.2 months, Cornell Star model)
what is preferred method of pregnancy diagnosis
transabdominal ultrasound (can US at about 40 days)
why is pregnancy diagnosis important
remove open ewes/does
market open ewe lambs
sort into feeding groups
manage lambing/kidding time
besides ultrasound, how can open ewes be found?
if in season, use teaser male with marker harness (marks open ones)
how often should BSE be performed on males, and what does it involve?
all males every year
health and breeding hx, BCS and conformation, scrotal measurement and palpation, examination of penis and sheath, semen collection and evaluation
what are two kinds of artificial insemination
cervical or laparoscopic
what are some benefits of using AI
rapid dissemination of genetics from elite sires
use genetics not otherwise available (import frozen semen)
maintain biosecurity and health status of flock
use ram/buck in many females in many flocks
increase rate of genetic gain
what are some benefits of using embryo transfer
rapid increase of genetics from elite females
many more offspring than would naturally produce
access genetics otherwise unavailable
increase rate of genetic gain
increase number of saleable offspring for rapid ROI
make use of genetically less valuable ewes as recipients for elite embryos
what are the average conception results for cervical AI, fresh semen, versus laparoscopic AI, frozen semen
cervical AI, fresh semen slightly Lowe, 50-60%
laparoscopic AI, frozen semen 60-70%
how many average transferable embryos are collected in in sheep and goats?
depends on breed
eg. Dorper 4-6, Charolais and il de france 6-8, Romano and East Friedan and goats 10-12
what are average conception rates for fresh vs frozen embryo transfer
fresh: 65-75%
frozen: 40-50%
