Dr. Nicky Oosthuizen’s interest in beef reproduction physiology brought her from her home country of South Africa to study in the U.S., leading to her working for ABS Global as the reproduction specialist on the beef team. She also serves as the district sales manager for North Dakota and South Dakota.
Nicky came to the U.S. to study at the University of Florida under Dr. Cliff Lamb, whose work primarily focuses on beef cattle reproduction. She obtained her master’s degree in animal science at a research station in Florida, and then once Lamb transitioned to Texas A&M University, Nicky chose to accompany him to obtain her Ph.D. in the physiology of reproduction. Her Ph.D. work specialized in estrus synchronization strategies and the fertility of beef females and sexed semen.
Nicky graduated during the peak of the COVID-19 pandemic and stayed on to do postdoctoral research with Lamb, before moving to Sioux Falls, SD, to work for ABS Global.
Nicky spoke with WLJ on estrus synchronization strategies, including differences between heat detection and timed AI, and fixed-time AI protocols.
“We definitely have a lot of options for people of all different skill levels when it comes to protocols,” Nicky told WLJ. “There’s simpler protocols for people to use and some that are a little bit more complicated, and some that are more time-consuming versus some of our shorter protocols.”
Protocol sheets are released every year by the Beef Reproduction Task Force. These sheets help producers make decisions and adopt reproductive technologies, and they can be found at beefrepro.org.
Joe Jones, ABS Global district manager for the western region, told WLJ the value of synchronization is extremely high. “Synchronization alone will make you money by front-loading your calving season. Age matters; cattle have a daily rate of gain and older calves are heavy calves,” he said. “The genetic merit of sire selection then becomes the icing on the cake as it relates to profitability.”
Protocol options
There are several protocol options for cow heat detection and timed AI, including the use of CIDR inserts or not.
“I know a lot of people this year are concerned about CIDR prices and they keep increasing every year,” Nicky said. “I do have a lot of people that have asked me about protocols without CIDRs, and one of the really good protocols is the Select Synch and timed AI, which is a heat detection and timed-AI protocol, but it does not involve a CIDR.”
A producer needs to be able to do heat detection before giving a shot of prostaglandin and must heat detect until they perform timed AI. The benefit of the protocol is there is no need to purchase a CIDR, but there is a lot more labor involved due to the heat detection aspect.
Another protocol is the PG 6-Day CIDR timed AI, which is actually referred to as pre-synchronization because an extra shot of prostaglandin is given three days before the CIDR is put in. Nicky said she feels this protocol is underutilized, and research shows it receives good pregnancy rates. It does involve a CIDR insert, and the CIDR is in for only six days. Heat detection and AI takes place before the CIDR is inserted, as well as when the CIDR is removed.
“We’re able to really maximize our pregnancy rate when we’re able to do both heat detection and AI because we’re able to catch those females that come in heat early before everyone gets mass-bred,” Nicky said. “So it’s definitely a great way if you’re able to put in that extra labor to do that heat detection and timed AI.”
There are similar protocols on the heifer side, but there is also the ability to feed melengestrol acetate (MGA) in heifers, which is a cost-reducing factor if you have the facilities to do so. MGA suppresses estrus and must be consumed consistently every day over a 14-day period to be effective.
When it comes to fixed-time AI protocols, all of the females are able to be bred at the same time point on the same day. If utilizing an AI technician, they only need to come out once, and you get 50% or so of your herd bred on the first day, Nicky said. Labor can also be minimized for heat detection.
“But I would definitely say if you’re able to do that heat detection, your pregnancy rates are going to be a little bit higher,” Nicky said.
She noted that the 7-Day CO-Synch + CIDR protocol is the most widely used protocol for both beef cows and heifers, which is largely due to the fact that females are run through the chute only three times and the whole protocol takes place over 10 days. This protocol requires less forward planning compared to some of the longer heifer protocols, which could span 33-36 days.
There is a new protocol on the protocol sheet this year that is approved for both cows and heifers, Nicky said. The 7 & 7 Synch takes place over about 17 days and a CIDR is in place for about 14 of those days. A shot of GnRH must be given in the middle of the CIDR insert in order to ensure the females have a fresh follicle and fresh egg at the time of AI, Nicky said.
“I did some of the research on this protocol in beef heifers and we definitely noticed a huge increase in estrus expression,” Nicky said. “We always saw a huge increase in estrus expression. A lot of the time we did see increases in pregnancy rates, but not all of the time.”
She added, “We’re still not sure why it works so well in some locations and not as well in others.” There is still research going into the 7 & 7 Synch protocol for both heifers and cows, but so far it seems quite successful, she said.
In terms of what the best protocol to use is, Nicky said there isn’t one single best protocol and it depends on the producer’s goals and capabilities.
“I think the 7-Day CO-Synch + CIDR is a gold standard just because we are only running them through the chute three times,” she said. “So for somebody that’s looking to minimize handling, the 7-Day CO-Synch would be probably one of the ones to consider.”
For producers trying to maximize their estrus response, the 7 & 7 Synch protocol may be the best fit. If a producer isn’t necessarily planning on AI’ing but plans to do a fixed-time embryo transfer, the 7 & 7 Synch protocol would be the way to go because such a high heat response is received off the protocol, she said. Nicky added that if money is not a factor and if a producer is just looking for higher pregnancy rates without having to do heat detection, the 7 & 7 Synch protocol is something to consider for both cows and heifers.
If money is the biggest factor when determining which protocol to use, Nicky recommended the use of the MGA-PG timed-AI protocol for heifers, because MGA is more affordable than a CIDR insert. For cows, using the Select Synch and timed-AI protocol may be more affordable because it doesn’t require the cost of a CIDR.
“It just depends on what a producer is trying to do, what they are trying to achieve and what they are trying to maximize and minimize in their operation,” Nicky summarized. “One thing I would say—just because there’s so many different factors that go into your overall pregnancy rate—I would try to be as careful with every aspect as possible and try to do everything as best as possible so that it all adds up to a greater pregnancy rate.” — Anna Miller, WLJ managing editor
