Therio- Bovine- Estrous synchronization & Artificial Insemination

wilsbach's version from 2015-11-04 18:35


Question Answer
whats F-TAI?fixed-time AI
do PGF2α –based programmes affect the luteal or the follicular phases?LUTEAL bc prostaglandins rupture the CL (CL must be present for this to work, CL is in luteal phase)
do Progestagen-based programmes affect the luteal or the follicular phase?(artificial progesterone!) LUTEAL bc inhibits LH and GnRH to keep diestrus going on suppress estrus so that when removed, whole heard starts at same time
do GnRH-based programmes affect the luteal or the follicular phases?FOLLICULAR (stim follicles to develop)
how long is the bovine gestation period?about 280 days (9mo...cows are people)
how long is the voluntary waiting period usually, and what purpose does it serve?usually 45-70 days, allows the cow time to recover before becoming preg again
in beef systems, who breeds first- cow or heifer?heifer- first time, needs more time to conceive
when will PGF2α- based programmes not work?(these cause leuteolysis of the CL, so..) if in luteal phase, WONT work if there is no CL or the CL isn't ready (after ovulation it will respond), also wont work if she's in the follicular phase (pro/es)
If cow is responsive to the PGF2α- based program she’ll come into estrus in 2-5 days after injection…. Why?lysing CL signals end of diestrus, and destroying the thing that makes progesterone--> rapid decline in progesterone--> ceases inhibiting the GnRH/LH which allows the follicles which have matured during follicular waves to be stimulated by the LH and cause estrus/ovulation soon after--> NOTE: there is a range (2-5 days) because it depends on the follicular wave cycle if the follicle is immediately ready or needs a bit more time to mature
what are follicular waves? why do they occur?progesterone inhibits LH and GnRH, but does not inhibit SMALL amounts of FSH from coming and allowing follicles to mature to a certian point (and produce low levels of estrogen). So during diestrus follicles are still maturing but then regressing with no stimulation, waiting for leuteolysis so that they are not inhibited by the progesterone, so that they may get bigger and produce enough estrogen to trigger an LH surge
what percentage of cycling cows in a herd should respond to a single PGF2α injection?cycle is 21 days, and diestrus is about 12 days, so 12/21 days the cow will be responsive (since it works in diestrus), so 12/21= 0.57 aka 57% of herd is likely to be in diestrus.
what is the benefit of having a PGF2α program where there are TWO injections, 11-14 days apart? why that time gap?Then all cows that didn’t respond to the first injection will have a CL that’s between 6-17days old at the time of the second injection. And all cows that responded to the first injection will have a CL that’s about 11-12 days old. Then you give the second injection, and both groups get their CLs lysed, then going into heat all together around 48-72 hr
how would you go about AIing cows treated on a PGF2α- based program?Heat detection and AI using am-pm rule (F-TAI not recc)
(not sure if important) what is the natural PGF2A you can use to synch? how does the synth differ from it?Dinoprost (Lutalyse). Synths are more potent, so need to use less than the natural
(not sure if important) what are the synthetic PGF2A drugs?(more potent!) Cloprostenol (Estrumate®,Prostamate®) & Luprostenol (Prosolvin®)
what are the two different ways you can do the PGF2a program?(1) Option 1: After 1st injection, estrus detection & breeding. Any cows that are not bred, are given a 2nd injection 11-14 days later and bred (2) Option 2: Only do estrus detection & breed after 2nd injection
Progestagen-based programs--> how does this program work?Exogenous progestagen mimics the endogenous progesterone supplied by the CL (inhibits LH, which prevents the ovulation). Then, When exogenous source removed, cow ovulates and starts cycling again
how are progestagen based programs administered to the cows?can be (1) Orally: Melengesterol acetate (MGA) (2) Per vaginum: CIDR (3) Subcutaneously: Crestar
What is the optimal period to supplement exogenous progestagens?>14 days: get aged oocyte with decreasing fertility, but, < 14 days: may not get regression of the endogenous CL, therefore, use with PGF (day 14 is near the end of diestrus)
what is ONLY approved by FDA for estrus suppression in heifers?Melengesterol acetate (MGA)
explain how Melengesterol acetate (MGA) is used (what is it?)this is a exogenous progestagen (progesterone) which is supplemented orally, and can be given in a premix with food. used for estrus SUPPRESSION IT can also Can be used in combo with PGF2α to synchronize estrus
how does PGF2A affect estrus? how does Progestagen affect estrus?PGF2A is a prostaglandin and works by lysing the CL and starting the estrus cycle. Progestagen is an exogenous progesterone, meaning that it suppresses estrus by maintaining diestrus. This one works by when you stop giving it to all the cattle, they all have dec progesterone--> inc GnRH--> inc LH--> LH surge--> ovulation at the same time
what is CIDR? how does it work?(Controlled Internal Drug Release) is a progestagen which is inserted intravaginally, and is left in place for 7 days. Then, PGF2α given the day before implant removal. This assures that the cows are in diestrus, and then go into heat at the same time when the PGF2a is injected causes luteolysis (remove implant and watch for heat after injection)
what is Crestar? how does it work?(progestagen program) placed SQ behind the ear
how do GnRH-based programs work?GnRH causes release of LH from adenohyophysis--> Causes ovulation or luteinization of the most dominant follicle (even in the presence of high progesterone)--> Induces a new follicular wave--> Therefore, 7 days later, there is luteal tissue present to respond to PGF2α (as well as old CL if present) (~so basically, makes sure there is a CL no matter what which you can then lyse with PGF2A)--> THEN, 2nd GnRH injection causes ovulation of the dominant follicle--> Can use F-TAI 8-18h later
which program can you use with F-TAI with?GnRH based programs
what is ovsynch? how does it work?GnRH based program--> no estrus monitoring required so can use F-TAI (8-18h after 2nd GnRH). Start with 1 injection of GnRH to induce ovulation OR luteinization, as well as induce a new follicular wave. 7 days later, give a shot of PGF2a to cause leutolysis. then 2 days later, inject another GnRH, which induces ovulation. the next day you can go F-TAI
how does SelectSynch work?GnRH based program--> GnRH injection, 7 days later PGF injection-->Estrus detection starts 24-48h before PGF injection & continues for 5-7 days (go figure, "select" is less accurate with no F-TAI)
how does weaning affect the cattle's cycle?In beef cattle, temporarily removal of calves for 48h results in increased LH release and the cow comes into estrus within a few days


Question Answer
Bulls that are selected to be AI sires are kept where?"bull stations" (little individual cages)
what are some ways bull semen is collected?an artifical vagina (AV) with liner
what are some things needed for semen extender?Energy source (Glucose, lactose, fructose...), buffers aka TRIS, surfactants, abx (like Ticarcillin, tylosin, gentamicin), Cold shock protectants (like Lipoproteins, especially from egg yolk & skim milk), and Cryoprotectants for freezing (glycerol, DMSO)
after semen extender is added to the collected semen, what do you do with it?put it in "straws"(Generally 0.25ml or 0.5ml French straws) with a Cotton plug on one end, colored plug/heat sealed at the other end, and then freeze it
(not sure if important) how are the AI straws labeled?ID of bull, ID of AI center, CSS (Certified semen services), Breed registration #, Batch number, date
how many straws are needed for a cow?1 straw= 1 cow
how are the semen straws stored? Semen frozen & stored in liquid nitrogen!
Progeny Testing is what, and why do we do it?wait for calf from that bulls semen to grow up and see how it performs in areas like milk production, milk composition, calving difficulty, as well as Structural soundness & conformation (Udder conformation, Udder attachment, feet and legs)
what are some pathogens which can be transmitted in semen?Tritrichomona fetus, Campylobacter fetus subsp. Venerealis, BVDV, brucella, FMD, etc..
who uses AI more- beef or dairy cattle industry?dairy
Liquid nitrogen safetyALWAYS wear cryoprotectant gloves and eye goggles! Liquid nitrogen can cause severe burns and damage to the cornea. Always insert objects into liquid nitrogen SLOWLY to prevent boiling and splashing. Can cause asphyxiation, so never transport in a closed vehicle.
if you are looking to ID the straw in the nitrogen tank, where should you NOT move the straw?DO NOT lift the semen above the FROST LINE (..where the frost stops) (Any temperature fluctuation will result in thawing and then refreezing of semen, which will result in damage)
how do you thaw the straw if you wish to use it?Remove correct straw and thaw it in a water bath at 35-37°C (95-98.6°F) for 30 seconds (can be a bit longer)
BEFORE you use the straw for anything, once is has been thawed, what MUST you do?WIPE IT DRY FROM ITS BATH- water is spermicidal (dont wipe too much or youll warm it up too much though)
how much you cut the semen straw?1 cm above end of insemination pipette, and MUST be at a 90* angle or the semen will come out
why do we care about breeding sheaths? what can also help with the issue this addresses?dz control, you can also add a sanitary sleeve over the breeding sheath to help prevent contamination. (Insemination gun is pushed through sleeve when it reaches the cervix, therefore preventing uterine contamination)
how should you transport a loaded AI gun?keep safe and warm in your clothing
When’s the best time to inseminate?AM PM RULE If cow is seen standing in the morning, she is inseminated in the afternoon and vice versa
when does ovulation occur?12h after estrus
what conduct should you absolutely avoid with the semen?SEMEN IS SENSITIVE-- avoid temp fluctuation (like pulling above frost line and then dropping back down), or excessive rubbing which can warm the straw, or letting it cool in the gun before AI. thoroughly dry straw.DONT cut straw at an angle. dont let too much time pass between thawing and AI
WHERE/how do you gun the semen into the female?in the uterine BODY (not horns) and do so slowly!