Growing Beef Newsletter
December 2024, Volume 15, Issue 6
Can the Commercial Cow Herd Benefit from Reproductive Strategies?
Denise Schwab, ISU extension beef specialist
When we think about reproductive strategies to improve the beef cow herd, we usually think about AI, synchronization, sexed semen, ET, and IVF. These technologies may seem to lend themselves to the seedstock industry more than commercial herds, but what is the value of those technologies to the commercial cattleman?
Maybe one of the biggest benefits is the genetic improvement potential from using artificial insemination. AI allows for the use of the top proven bulls in an effective crossbreeding rotation or pure bred system regardless of operation size, at a fraction of the cost of purchasing and maintaining a bull year-round. The commercial herd may use AI to produce top-quality crossbred replacement females while purchasing natural service bulls focused on producing high growth, carcass merit calves for the feedyard. However, utilizing AI successfully requires good estrus detection, manpower to implement the process, and good working facilities.
Estrus synchronization is typically paired with AI, however it doesn’t have to be. The initial benefit of synchronization is in shifting the calving distribution to earlier in the season, resulting in more older and therefore heavier calves at weaning time. What is this worth? Assuming nursing calves are gaining about 2 pounds per day, a calf that is 21-days older than herdmates results in an additional 42 pounds of weaning weight. At a value of $3 per pound, these older calves could result in an additional $126 per calf. These early-born steer calves also produce heavier carcasses with greater marbling scores, and the heifer calves breed earlier in their first breeding season (Funston et al., 2012).
Research by Day (2024) showed a wide range of cows (17-67%) were not cycling at the start of the breeding season, thereby preventing them from calving at the start of the next calving season. Estrus synchronization protocols using progesterone have the ability to induce cycling in these cows setting them up to breed sooner and calve earlier. To demonstrate this, Rogers et al. (2012) exposed one group of cows to a natural service breeding season and another group received the 7-day CO-Synch + CIDR synchronization, and AI followed by natural service. The group synchronized and AI resulted in 44% of the cows calving in the first 21 days, compared to 25% of the natural service cows, plus the synchronized cows weaned an addition 38 pounds per cow exposed. A secondary impact is that heifers that calve in the first cycle as a heifer will continue to calve early throughout their lifetime, further increasing lifetime weaning weights.
Estrus synchronization is not without costs – product, labor, trips through the chute, semen, and possibly more bull power. Protocols vary greatly and can be very simplistic or quite elaborate. Typically, the more elaborate the protocol, the more trips through the chute and more product used. Probably the biggest factor in success of synchronization is implementing the protocol accurately and precisely. For instance, if a protocol says to remove a CIDR 7 days after insertion and breed 60-66 hours later, you need to follow that exactly. The Estrus Synchronization Planner can assist in calculating timing of trips through the chute for various protocols. So what is the cost vs return? Again, it depends on the protocol, but for example the Select Synch with timed AI requires an injection of GnRH, followed by an injection of PGF2a 7 days later, then heat detect and AI cows who come into heat, 72-84 hours post PGF2a shot, AI remaining cows and inject GnRH on any cows who failed to express estrus. The cost of one PGF2a and two GnRH injections is roughly $12, semen cost of approximately $30, plus the time and labor of three trips through the chute along with heat detection.
A more simplified synchronization protocol may actually work better for commercial producers who still want to bull breed but move more cows to calving earlier in the calving season. In this case bulls are turned out with cows for 5 days, and anything that conceives then will not be affected by the protocol. On day 5, cows are gathered and given one injection of PGF2a which will shorten the cows estrous cycle and cause any cows not bred by the bull in the first 5 days to go into heat a few days after receiving the shot of PGF2a. Bull power needs to be adequate (1:25 for mature bulls, 1:15 for yearling bulls) and bulls must have been breeding soundness evaluated prior to turnout. Fort Keogh Research Center at Miles City, Montana, implemented this protocol for three years resulting in a pregnancy rate of 85% in a 32-day breeding season.
Embryo transfer may not have as much of a direct impact for commercial herds, however several producers have been able to capitalize on ET by producing quality recipient cows for ET programs. Cows that aren’t producing the quality of calves that fit your own market, may perform well as a recipient provided they maintain their weight well and milk adequately.
One reproductive technology we seldom discuss but is fundamental for all herds is a bull Breeding Soundness Exam (BSE). The BSE includes a semen evaluation including both morphology (structure or defects) and motility (movement) of the sperm. But it also needs to include observations of feet, legs, eyes and an exam of the scrotum and penis to ensure there are no defects or signs of disease that would inhibit breeding.
Finally, these reproductive technologies are effective tools to assist both the commercial and seedstock herd to improve reproduction and therefore profits. A sound foundation of nutrition, health, and management are critical for the success of any of these technologies. Adequate forage and feeds to support a body condition score of 5 to 6, a healthy immune system backed with a good vaccination protocol, low stress handling practices, and protection from weather challenges are all required to optimize reproduction efficiency. No technology can override management mistakes.
For more information and assistance with optimizing reproductive efficiencies contact one of our Iowa Beef Center team members. And for assistance with developing a synchronization protocol calendar download the Estrus Synchronization Planner. To learn more about reproductive technologies and how to implement them into your herd, you won’t want to miss the Iowa Beef Center’s 2nd Annual Genetic Symposium focusing on reproduction on December 16th and 17th in Ames, Iowa. For more information and registration, please visit the website.
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