This post will wrap up the 3 part series of the Beef Cattle Synchronization Q & A with Cliff Lamb, Ph. D., and will focus on cow specific questions. Catch up on the series by viewing part 1 and part 2- heifers. If you still have questions you want to ask Dr. Lamb please still use the comments section to post those and we will answer them.
ABS has also received numerous requests regarding the setting up and scheduling of the protocols. ABS encourages you to visit with your experienced and Professional ABS Representative to set up an effective synchronization and AI protocol, especially if synchronization and AI is new to your operation. Iowa State University has a free estrus synchronization planner, found here http://www.iowabeefcenter.org/estrus_synch.html, provided by the Beef Reproduction Task Force. By registering, you can download and utilize the planner worksheet and calendar features to effective map out the critical timings to the synchronization protocol you select.
Q 1.) What protocol is best for someone new to synchronization and AI?
A.) For producers new to estrus synchronization the 7-day CO-Synch + CIDR protocol would be the best system to start. It only requires three animal handlings and is a TAI system, so producers can schedule and expert to do all of the AI without being concerned with heat detection.
Q 2.) Which protocol has the best results for fixed TAI? Heat detect and TAI?
A.) Either the 7-day CO-Synch + CIDR or 5-day CO-Synch + CIDR protocol would be effective systems for TAI. The two most effective systems for heat detection and TAI would be the Select Synch + CIDR and TAI or the PG 6-day CIDR and TAI. Producers should refer to the protocol sheets with recommendations from the Beef Reproduction Task Force. These sheets provide the most recent and effective systems for synchronization of beef cows.
Q 3.) What, if any, is the benefit(s) of the 5 Day CO-Synch over the 7-Day CO-Synch?
A.) On the average there is little benefit of the 5-day over the 7-day protocols. In general there appears to be about a 3 to 5 % improvement in fertility. The group of cows that this advantage appears to be associated with is the young cows (2 and 3 year old cows). There appears to be little benefit in mature cows.
Q 4.) On the 5-Day CO-Synch protocol is it necessary to give the second shot of PGF2a?
A.) The Beef Reproduction Task Force recommends two injections of PGF (the 1st at CIDR removal and the 2nd 8 hrs later). A single shot is not advisable, and a double dose at CIDR removal is less advisable because it less consistently provides the best opportunity for pregnancy success.
Q 5.) If cows are ¼ or less Brahman influence, should I follow the newly released Bos indicus protocol? Even if I heat detect vs. fixed TAI?
A.) Yes, regardless of Brahman influence you should consider the PG 5-day CO-Synch+CIDR protocol. This should be considered even in cows that will be heat detected.
Q 6.) If I still use the single shot of PGF (Lutalyse®) as the only synchronization aid to breed off standing heat, and don’t observe standing heat within 4 days of the Lutalyse® shot, how many days do I have to wait before giving another shot?
A.) The interval should be 11 to 14 days between the two injections of PGF.
Q 7.) Can PGF stimulate an anestrus cow to cycle again post calving before starting a synchronization protocol? If not, should I go ahead and synchronize all postpartum cows at the same time even if some cows are still anestrus?
A.) Conventional wisdom is that PGF does not stimulate non-cycling cows to start cycling. When using PGF alone then all cows should be cycling to ensure a good response. In cases where there may be anestrus cows, a system that includes a CIDR will be most effective to stimulate non-cycling cows to cycling. Any cow that is at least 21 days postpartum (after calving) may receive a CIDR. Cows between 21 and 50 days postpartum likely will not have similar pregnancy rates to those more than 50 days postpartum, but the estrous synchronization system may initiate cyclicity in the non-cycling cows and they will become pregnant sooner in the breeding season.
Q 8.) If GnRH is given at time breeding, how long/quick is the effect? If I notice a cow I bred this afternoon in standing heat tomorrow morning and/or tomorrow night, what are the chances she settled to AI? Should I re-breed her with another straw of semen with the AM/PM rule of seeing her in standing heat?
A.) Within minutes of administration GnRH initiates its action to induce an LH surge, which occurs about 1 to 2 hours after receiving GnRH. Within about 12 hours after administering GnRH heat activity will be shut down. Therefore, you will see very little activity 12 to 24 hours after administering GnRH. Cows that do display heat 24 or more hours after GnRH may be rebred because it is unlikely that they will become pregnant to the initial AI.
Q 9.) If I notice a cow in standing heat within 5 days of breeding her, I know something in the synchronization didn’t work. How long do I have to wait after observing heat to restart synchronization?
A.) If a cow comes into heat within 5 days after breeding her, it does not necessarily indicate that she did not respond to estrous synchronization. She may not have been cycling when estrous synchronization start and the system induced her to start cycling. If you cannot AI her 12 to 16 hours after seeing her in heat then re-synchronization is an option. Depending on the system will be an indicator of when to start this system; however, a good rule of thumb would be to start a new system at about 6 to 8 days after she was in heat.
Q 10.) How long after breeding should I wait before turning a bull out?
A.) This is not a straight forward question. If it is most important to determine whether the calf is pregnant to AI (such as purebred operations) then it would be advisable to wait at least 10 days after AI; however, in most commercial operations a live calf is just as important and it would be wise to turn a clean-up bull in with the herd 24 hours after AI. In this case there may be a small percentage (< 2%) of calves that could be sired by the clean-up bull that may appear to be sired by AI.
Q 11.) I’m noticing a high percentage of my females that miss on the first round of AI are not settling until the 3rd cycle. Is there a correlation to them missing on the 2nd cycle because of Synchronization?
A.) Actually, this is not likely associated with the synchronization or estrous synchronization products. However, there are multiple reasons why producers may see a decrease in cows becoming pregnant during the second cycle than the third cycle. Two primary reasons are: 1) since we now do an excellent job of synchronizing cows, most of the non-pregnant cows will come into heat from 15 to 24 days after AI. Therefore, you need to have the necessary bull power to cover the cows during this period of time to ensure that all the cows that come into heat have a chance to become pregnant, but just as importantly, the bulls need to be capable of breeding the cows and should all go through a breeding soundness exam; 2) a small percentage of cows undergo embryonic loss. These cows may have become pregnant to the AI, but lose the pregnancy sometime between 25 and 40 days after AI. After losing the pregnancy they come back into heat and then settle to the clean-up bull, thus appearing to have not come into heat during the second cycle.
Q 12.) Is there any benefit to holding calves off cows for a 12-24 hour window immediately before breeding?
A.) If holding off calves to enhance fertility is considered then it should be for at least 48 hours. This has improved fertility from between 3 and 10%. In the newer systems that include a CIDR the magnitude of improvement is not as great as other non-CIDR based systems. However, the drawback of this temporary removal also affects subsequent calf performance. To reduce or eliminate these negative effects of calf removal on calf performance then calves should be creep fed for at least 30 days prior to AI and calves should receive clean water and feed during the 48 hour calf removal interval.
Q 13.) Are there any associated stress factors of weaning calves from inseminated cows that can decrease conception rates or cause them to abort depending on length of time from insemination to weaning?
A.) Stress has negative effects on fertility and may play a role in increasing embryonic mortality. Exactly when the negative effects occur are not exactly known; however, if stress is exposed to cows the most desirable periods of time would be within the first 7 days of pregnancy and after 40 days of pregnancy. There is little data indicating the effects of weaning on fertility, however weaning calves at least 30 days after the end of the breeding season will likely not affect pregnancy maintenance noticeably.
Q 14.) If a drought forces early weaning, will the weaning time have any affect on pregnancy rates? What is the earliest, post insemination one should wean calves?
A.) This answer is unknown, but a good practice would be to reduce stress (including weaning) until at least 40 days after establishment of pregnancy.
Q 15.) If I only place steers into slaughter programs and want my cattle to go into NHTC and drug free programs (maintaining or selling all heifer mates to not enter the program) but synchronize their mothers while calves are still nursing, will this disqualify the bulls calves too?
A.) Each program is different and producers should look at the guidelines for each program. In most cases, estrous synchronization of the dam will not disqualify the offspring.
Q 16.) What is the best protocol if you need to abort a cow?
A.) This all depends on the stage of pregnancy. It is always advisable to contact a veterinarian first when considering terminating a pregnancy in cows. Cows pregnant for less than 150 days will likely respond to an injection of prostaglandin F2α (PGF). Cows pregnant more than 150 days may or may not respond to PGF. Other alternatives after 150 days are available, but producers should contact a veterinarian for options.
Dr. Lamb’s response to questions submitted from previous posts:
Q.) Referring to question number 8 (part 1), if you put the CIDR back into the cows you AI’d, 12 days after, and removed 19 days later, you could then catch 70-80 % of cows that did not breed with the first AI?
A.) Yes, the answer is that you would detect 70 to 80% of the cows that do not become pregnant to the initial AI in heat in about 3 days.
Q.) 12 hrs after AI on an observed Standing heat if blood is present, indicating ovulation, what are the percentages of a heifer becoming pregnant from the AI?
A.) One thing that most are not aware of is that ovulation usually only occurs about 24 to 31 hours after AI or GnRH injection. Therefore, in this case if a female received GnRH at AI, but is still in heat 12 hours later, there is still a good chance that she will become pregnant. It is tough to know the exact fertility, but it is likely not much less than cows that were in heat at the time of AI.
Q.) I recently took a controlled group of 80 head of heifers and split the herd into two groups of 40. I applied the 7 day Co-synch – CIDR to both groups to see how each pen would respond to the protocol. Both groups were given a ration of free choice blue stem hay as well as protein tubs and daily regulated oat hay. GnRH was administered at day 0, on day 3, six heifers in pen 1 came into standing heat and 7 head in pen 2 exhibited the same. All where AI’d and separated from the herds. On day 7 the remaining cattle were given PGF. 48 hrs later 30 head in pen 1 came into standing heat and two more exhibited standing heat at 72 hrs and the remaining 2 head were AI’d and given GnRH that did not exhibit heat. In pen 2, 28 head came into standing heat with in 48 hrs and 4 head followed at 72 hrs. The remaining heifer was bred and given GnRH to finish the protocol. The heifers were ultrasound at 44 days and 66 head were confirmed pregnant giving us an 82% conception. All heats that presented on day 3 became pregnant. All fixed TAI that presented no signs of heat on day 7 did not become pregnant. If I was to apply the CIDR to the group would my conception been greater?
A.) (Dr. Lamb’s answer is based off the assumption that the 7-day CO-Synch + CIDR protocol mentioned was altered to not include the CIDR – which is not an actual protocol per the Beef Reproduction Task Force)
It is hard to know if addition of the CIDR would have enhanced pregnancy rates to AI in the non-responding heifers. Generally these are the heifers that are non-cycling and usually have the poorest pregnancy rates. One thing is sure, is that addition of a CIDR would help the non-responding heifers become pregnant sooner after AI than if they had not received a CIDR. Therefore, addition of a CIDR would have a benefit.
The pregnancy rates are excellent and it is amazing that these rates were that high without a CIDR. This is something I would not expect every time.
Thanks to Dr. Lamb for continuing his work with us and providing this Q & A session!
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Cliff Lamb, Ph. D , is currently the Assistant Director and Professor at the University of Florida North Florida Research and Education Center in Marianna, Florida. He graduated with a B.S. in Animal Science at Middle Tennessee State University. He received his M.S in 1996 and Ph. D. in 1998 at Kansas State University. As Assistant Director of the North Florida Research and Education Center he oversees one of the largest beef cattle feed efficiency facilities in the world. Dr. Lamb oversees a research program that focuses on applied reproductive physiology in beef cattle emphasizing efficient management systems for replacement heifers and postpartum cows. A primary research focus has been on the development of practical and economical estrous synchronization protocols for beef cows and heifers. He has also published numerous research articles on the use of ultrasound technology for reproductive management of beef cattle, and has a strong research background in embryo transfer technologies. He is author of more than 60 refereed journal articles, 3 chapters in texts, and more than 200 presentations and articles in other scientific and popular press.
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