Some cattle are excelling at rapidly producing a high-quality end product; however, they are usually not the low maintenance females that producers want to have in their cow herd. Similarly, the ideal bull for producing replacement females may not produce high-value feeder or carcass cattle. Rather than focusing our breeding goals on being heavily terminal or primarily maternal, sexed semen allows commercial herds of all sizes to “take both roads.” Intentionally making quality replacement females while maximizing terminal value from non-replacement animals. Kenny Wells from ABS Global detailed innovations in this space during the Advancements in Producer Education breakout session. The session part of the Beef Improvement Federation (BIF) Symposium June 11, 2024, in Knoxville, Tennessee.
Wells emphasized that competing industries have already capitalized on creating breeding programs which allow them to achieve maximum profitability. Pork producers leverage optimized genetic lines along with maternal and terminal heterosis to increase in product value of offspring. Dairy farmers have refined their maternal unit for milk production with female sexed semen while also making use their former byproduct, dairy steers, by utilizing terminal beef genetics.
Sexed semen is not just a tool for dairy producers, beef operations can use it to meet maternal and terminal goals within the same calf crop. During his presentation, Wells discussed ways that ABS has deployed sexed semen in beef settings. One example is the 60/40 Sync Program, which builds on the idea of segmenting your cow herd so that your most fertile cows are bred to produce your replacement heifers, while the rest will produce a more terminal animal.
The 60/40 Sync Program works by synchronizing and fitting all females with an estrus detection aid, just as recommended for fixed-time AI protocols. Females that display estrus with fully activated patches, usually around 60%, are then time AI bred with female sexed semen from maternally designed bulls. The remaining females that have not displayed estrus, around 40%, are time AI bred with conventional semen from terminally focused bulls and all cows are exposed to a terminally oriented sire for clean-up. This program aims for the resulting calf crop to be made up of 35% maternally designed heifer calves to retain in the herd and 65% terminally focused animals, the majority of which are steers, to market.
Wells discussed how the strategic use of sexed semen could allow even very small producers to implement a structured crossbreeding program by using different breeds of bull as maternal and terminal sires. Programs like the 60/40 also have long-term reproduction benefits within herds. It allows the most fertile cows to have heifer calves born early in a calving season. This “head start” results in older replacement females that conceive earlier and have heavier calves throughout their productive lives. Wells was clear that even though this program may not maximize pregnancy rate to AI, it does create the opportunity to generate the “right” calf from every mating.
Wells’ presentation discussed a multi-year demonstration of the 60/40 program between ABS and the Bair Ranch in central Montana. The study assigned 250 cows to either a control group, which followed a fixed-time AI protocol using conventional semen, or a test group, which implemented the 60/40 Program. Over four years of data collection, the Bair Ranch averaged 25-30% of the calf crop being maternally designed heifers resulting from sexed semen — exceeding the ranch’s target of 23-24% to keep as replacements every year. Key takeaways included that female sexed semen resulted in an average of 91% heifer calves and that female sexed and overall pregnancy rates in the 60/40 test group were lower than those of conventional semen. Their work also indicated that the 60/40 program reduced the relative proportion of calves being born in the first interval when compared to the control. However, more 60/40 calves were born in the second calving interval, suggesting that 60/40 sync likely doesn’t significantly impact the length of the calving season.
Wells was clear: For the 60/40 program to work, producers must choose the right genetic inputs for their respective programs. With sexed semen, producers can adjust areas of their herd that previously they could not: more selection pressure can be applied to terminal traits without throwing maternal quality out of balance, and maternal traits can be selected for without reducing terminal profitability. The implementation of crossbreeding also allows for significant increases in efficiency through heterosis, particularly for lowly heritable maternal traits such as fertility and health.
Taken together, 60/40 Sync Program provides a framework for a more efficient, sustainable, and resilient breeding system. The concept laid out by Wells represents a flexible and adaptable strategy for producers to focus on making fertile, feed efficient, and moderate replacement females while enhancing growth and carcass quality on their terminal calves.
— by Garrett Ulmer, University of Tennessee beef cattle genomics graduate student