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LA DX & TX II > Exam 3 - Manipulation of Estrus > Flashcards

Exam 3 - Manipulation of Estrus Flashcards

1
Q

should you breed heifers earlier than cows?

A

yup

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2
Q

what is the point of synchronizing animals’ estrous cycles?

A

creates a tighter estrus period to breed a group of animals providing an economic benefit - estrus detection time is reduced providing a larger group of animals in estrus

can breed animals earlier in the breeding season

calves are larger at weaning

replacement heifers are older at the time of breeding

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3
Q

why synchronize horse estrous cycles?

A

need to for embryo transfer

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4
Q

what is the benefit of using an artificial photoperiod to synchronize estrous cycles?

A

influence GnRH secretion

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5
Q

what is the benefit of using prostaglandins to synchronize estrous cycles?

A

induce luteolysis

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6
Q

what is the benefit of using progestins to synchronize estrous cycles?

A

prolong the luteal phase - benefit for artificial breeding, inhibit behavioral estrus, & inhibit LH surge so that when it is withdrawn, an LH surge is induced

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7
Q

what is the benefit of using GnRH administration to synchronize estrous cycles?

A

you stimulate FSH & LH release

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8
Q

what is the benefit of using gonadotropins to synchronize estrous cycles?

A

ovarian stimulation

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9
Q

what animals do we use the introduction of males for synchronizing estrous cycles?

A

small ruminants & pigs

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10
Q

how does removing offspring help with synchronizing estrous cycles?

A

increases LH release

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11
Q

what is the goal of estrous synchronization in cows?

A

precise control of estrus & ovulation requires manipulation of both follicular waves & luteal lifespan to accommodate timed breeding without estrus detection

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12
Q

what days can you use prostaglandin for estrous synchronization in cows? why?

A

days 5 - 15 after ovulation

the CL must be mature to respond!!! have to wait for a few days for it to grow, but if you wait too long, the body has already released endogenous PGF2a, so it’s pointless to wait

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13
Q

how is prostaglandin used for estrous synchronization in cows with the double injection scheme?

A

two injections done 11 days apart

give cows an injection during diestrus to get them all to come into estrus at the same time to get them on the same follicular growth cycle & then give them another injection for timed AI

animal will go into estrus about 3 days after the 2nd injection

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14
Q

why is there such a variation in response to prostaglandin in cattle?

A

the response is dependent on the stage of the cycle

if given after day 10, more cows will respond & there will be less synchronization of estrus

if given between days 5 & 10, fewer cows will respond (max response is 7-9 days) & the interval to estrus will be shorter & you will get more synchronization

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15
Q

why would a cow fail to respond to prostaglandins for estrous synchronization?

A

if you give it to acyclic cows - they are in anestrus

cows must be reproductively normal & having regular cycles & in more sensitive luteal phase

need to make sure they are not pregnant - can cause them to abort

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16
Q

how does CIDR work for estrous synchronization in cattle?

A

inhibits LH release, mimics progesterone, & artificially prolongs the luteal phase - inserted into the vagina

when removed, it mimics progesterone withdrawal allowing cows to come into estrus (control-internal-drug-release-device)

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17
Q

what breed factors affect efficacy of CIDR in cattle?

A

works well in dairy cows & bos taurus beef cows

less effective in bos indicus influenced breeds

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18
Q

how does maturity/parity affect efficacy of CIDR in cattle?

A

less effective in heifers of all breeds - because they may not be cyclic

heifers come into estrus sooner than cows, so the protocol may be less effective

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19
Q

how does days postpartum affect efficacy of CIDR in cattle?

A

most effective if more than 50 days post-partum especially in dairy cows

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20
Q

how does nutritional plane affect efficacy of CIDR in cattle?

A

most effective if they are in a good body condition & positive energy balance

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21
Q

how does a 48 hour calf removal affect efficacy of CIDR in cattle?

A

enhances effectiveness for most protocols but labor intensive

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22
Q

how is manipulating follicular waves used for synchronizing estrous cycles in cows?

A

ovsynch initial protocol

use of PGF2a & GnRH injections to control the onset of follicular waves & control the lifespan of the spontaneous & induced CL

also control the time of ovulation by inducing LH surge prior to the endogenous LH surge

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23
Q

what are some reasons there is failure of the ovsynch protocol for estrous synchronization of cattle?

A

lack of response to 1st GnRH injection

atresia of the dominant follicle before PGF2a

spontaneous luteolysis after GnRH & before PGF2a

heifers respond POORLY

does not improve the competency of the dominant follicle

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24
Q

what is an example of the ovsynch protocol used for estrous synchronization in cattle?

A

group of 21 cows are all at a different point of the 21 day cycle - they all get an injection of GnRH, so, the follicles that are big enough to ovulate will (or won’t), so all of the cows that can will go into diestrus

on day 7 - need them to be responsive to PGF2a, so you give them PGF2a to get rid of the CL

on day 9 - another injection of GnRH is given which will cause the animals that can to ovulate because they will have another follicle ready to ovulate from the 2nd FSH wave

you then AI them 1 day later

more labor intensive & no estrus detection used in this protocol

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25
Q

how is manipulating the photoperiod used for estrous synchronization in mares?

A

you are manipulating anestrus & transitional period

the normal photoperiod has the breeding season starting at feb 15th because they are long day breeders

so you shorten their anestrus period & get them to enter the transition earlier

26
Q

how exactly is photoperiod manipulated for mares to synchronize estrous cycles?

A

expose mares to 14.5-16 hours of light per day - lengthening in the evening is most important

27
Q

how long does photoperiod need to be manipulated for mares for normal cyclicity? when do you start?

A

more than 60 days - start december first

want them to foal the next year in january

28
Q

how is regumate (progestin) used for synchronizing estrous cycles in mares?

A

manipulates the transition - inhibits LH release from the adenohypophysis

so they will go into estrus 2-5 days after withdrawal - causing a sufficient LH surge & shortens the transition with affects on follicles > 20-25mm (mid-late transition)

29
Q

what is the dose dependent response of injectable progesterone in horses?

A

50 mg/day prevents estrus but not ovulation

100mg/day prevents both estrus & ovulation

30
Q

what drug is most commonly used for lactation in mares? how does it work?

A

domperidone - stimulate prolactin release/induction of lactation

late transitional mares ovulate 12-22 days after treatment is started & deep anestrus mares take longer to ovulate (50-60 days) with ambient temperatures being important (<50° F inhibits the mare’s response)

31
Q

with horses, what are we synchronizing in regards to reproduction?

A

synchronizing WHEN we BREED them & WHEN they OVULATE

32
Q

with scheduled breeding, what factors play into natural cover, cool shipped semen, & frozen-thawed semen?

A

natural cover - stallion availability

cool shipped semen - stallion availability & decreased sperm quality

frozen thawed semen - more so decreased sperm quality

33
Q

how is hCG used for ovulation synchronization in mares?

A

mimics LH - only works on follicles > 35mm

ovulation occurs in 36-48 hours (80% with > 35mm follicles will ovulate within 48 hours)

34
Q

how is deslorelin used for ovulation induction in mares?

A

GnRH analogue - causes LH increase

works on follicles > 30mm, so probably more reliable than hCG

35
Q

what is an example of how GnRH may be used on a horse that you are breeding with cool shipped semen with a 35mm follicle seen on the ovary & edema in the uterus?

A

you need to administer hCG or deslorelin today - she will ovulate 36-40 hours later

breed her the next day

36
Q

what is the benefit of using estrumate over lutalyse?

A

estrumate has less side effects

37
Q

what side effects are associated with lutalyse administration?

A

sweating/colic

38
Q

is estrumate approved for horses?

A

nope

39
Q

what must a horse have for estrumate to work?

A

must have a mature CL to respond!!

40
Q

how much do follicles of a mare grow in a day?

A

about 3-5 mm

41
Q

how would you manage these two examples with prostaglandins?

mare 1 - mature CL & the largest follicle was 10mm

mare 2 - mature CL & the largest follicle was 25mm

A

mare 1 - going to be awhile until the follicle will be big enough to respond to this protocol

mare 2 - maybe 2 days to get up to 30mm to work, then you could give lutalyse or estrumate

42
Q

what is the protocol that gives the tightest synchronization of estrus with better intervals in mares?

A

progesterone + estradiol + 17B + PGF2a

progesterone (150mg) + estradiol-17B (10mg) in oil - IM injection for 10 days

on day 10, PGF2a injection is given - animal will go into estrus in 5-7 days

hCG/deslorelin given - for follicles > 35mm

43
Q

what are some reasons for estrus suppression in mares?

A

obviate signs of estrus - performance mares (racing or show)

reduce objectionable behavior - associated with estrus

44
Q

what are some long term effects associated with GnRH vaccines given to horses to suppress estrus?

A

decreased libido in stallions

keeps mares out of heat - may have long term problems

45
Q

what are some indications for estrous synchronization in sheep & goats?

A

seasonally polyestrous - breeding season in late august-october, so you can induce estrus during the winter (when they are usually in anestrus)

induce cyclicity during the transitional period - advance breeding season into the summer with a winter-spring transitional period

manipulate estrus during the luteal phase (either extend or shorten) - synchronize during the fall breeding season

46
Q

what is the benefit of estrous synchronization in sheep & goats for out of season breeding?

A

you get to market kids when prices are high

year round milk production

increase # of kids/does

47
Q

what is the procedure of manipulating the photoperiod of sheep & goats which are short day breeders?

A

exposure of 16 hours of light in late winter & then stop light exposure with a minimum of 30 days required to work

this mimics the long days of summers then shorter as natural day length still less than the lighted period

exposure of 16 hours of darkness for 60 days - mimics the short days of autumn

48
Q

how is melatonin used to alter the photoperiod of sheep & goats?

A

hormone that is normally released with increased darkness - so mimics more darkness to stimulate the early onset of breeding season

49
Q

how are rams/bucks used for estrous synchronization in sheep & goats?

A

you introduce a ram/buck during late summer to induce a surge of LH

animals will ovulate in 3-6 days - usually a silent estrus (ovulation without estrus, CL fails prematurely & another silent estrus) with CL develops of normal duration on the 2nd ovulation of the season

normal subsequent estrus 14-24 days later depending on species

50
Q

what are your options for progestins in sheep & goats for synchronizing estrous? which is better?

A

flurogestone acetate - impregnated sponge placed into vagina for 14-16 days but vaginitis if not handled properly & bigger loss rate from vagina

CIDR - fewer losses, less vaginal irritation, better choice

after removal, animals will enter estrus 24-36 hours after removal

51
Q

what is the difference in how prostaglandins work in sheep & goats when compared to cattle? why? how does it work?

A

they are effective at an earlier time than in cattle

they will have a mature CL 4-5 days post-ovulation (earlier than cow/mare)

induces luteolysis in cyclic animals - will destroy the CL & the animal will come into estrus in 2-4 days

52
Q

what are the indications of estrous synchronization for swine?

A

increase the efficacy of management - facilities & labor

artificial insemination, pregnancy diagnosis, & parturition induction

initiate follicular maturation, control CL lifespan, & synchronize ovulation

53
Q

what is the big difference in PGF2a response between sows & gilts? when can PGF2a be used? why?

A

sows are more responsive to it than gilts

only used on day 16, they are unresponsive prior to day 12!

54
Q

how is boar exposure used for estrous synchronization in sows?

A

150-170 days of age - hastens the onset of the 1st ovulation in peripubertal gilts

55
Q

how is relocation/transportation used for estrous synchronization in sows?

A

enhances effects of the boar for follicular growth & synchronous estrus in 3-5 days

moving gilts into the breeding pen & mixing animals from different groups

56
Q

how is group weaning used for estrous synchronization in sows?

A

sows have a true lactational anestrus so they won’t cycle when lactating

follicular growth is initiated at weaning of piglets (days 16-22) for synchronous estrus 4-9 days after weaning

57
Q

what is the main disadvantage of group weaning as a means of estrous synchronization in sows?

A

poor piglet survival if weaned too early

need to be > 2 weeks old at age of weaning

58
Q

what is the 2/3s rule for pigs in estrus?

A

natural ovulation occurs during the first 2/3 of estrus regardless of the length of estrus

59
Q

how is prostaglandin used for sows in estrous synchronization?

A

sow CL is unresponsive to PGF2a until day 12 of the cycle

short cycling is ineffective but can shorten the luteal phase a couple days - breed & abort

60
Q

what is altrenogest?

A

prostaglandin feed additive thing fed to gilts at 15-20 mg/day for 14-18 days which gives a synchronous estrus in ~5 days (65-80% within 2 days)

61
Q

what maintains the CL in pigs?

A

hCG & estrogen

62
Q

what is in p. g. 600 for pigs? why is it used?

A

serum gonadotropin and chorionic gonadotropin for injection

induces fertile estrus in pre-pubertal (non-cyclic) gilts

induction of estrus in healthy, weaned sows experiencing a delayed return to estrus (delayed return most prevalent after 1st litter)

GnRH is ineffective alone - short 1/2 life

LA DX & TX II (44 decks)

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