February 2025 NEBRASKA CATTLEMAN 31 Herd Pregnancy Rates 10 bulls, drop feed/supplement in 10 different locations in the pasture. Work with your nutritionist or Extension educator to determine the amounts needed. Always have mineral and salt available. Bull-to-cow ratios can vary based on age of bull and terrain. The bull-to-cow ratio is less for young bulls compared to mature bulls (have experienced at least one breeding season). Your experience will help guide your bull-to-cow ratio. For bulls that are 15 to 20 months of age and in their first breeding season, pencil them in at servicing 15 to 20 females. Mature bulls may service 30 to 50 cows, depending on terrain. If possible, avoid single-sire pastures. If the bull goes bad, there is no back up. When managing single-sire pastures, observe breeding activity at least three times per week. For multiple-sire breeding pastures, observe breeding activity two to three times per week. Record cows that are observed being bred and make sure they are not coming back in heat during a later visit. Don’t neglect the bulls. Bull management strategies are not hard to implement and are an important piece of the puzzle to manage against open cows. Managing Nutrition The heritability of reproduction in beef females is low, meaning genetic factors play a small role in reproduction compared to environmental factors like management practices. Data says – under the same environmental factors, same mature weight and same milk output – reproductively, crossbred females outperform straightbred females. To accomplish your goals for the cow-calf enterprise, it may mean straightbred females. If not, consider a crossbred female. Have some heterosis in commercial beef females. Data indicates most cows that don’t wean a calf don’t get pregnant during the breeding season. Nutrition has the greatest impact on reproductive performance. Mistakes in your nutrition program before and/or after calving impact body condition and equates to more open females. Manage the nutrition program so mature cows calve with a BCS of 5 and first-calf-female are a BCS 6 at calving. Score females a couple of times before calving to make sure they are on track to calve in the desired body condition. The last time to change condition economically is 90 days prior to calving. Trying to change body condition after calving is nearly impossible. After calving, extra energy above what is required to meet energy needs goes into milk production and not putting on condition. After calving, don’t let spring-calving females slide in condition. Good quality feeds are needed to meet requirements. Again, feed first calvers to calve at a BCS 6. First calvers need extra energy (TDN) to meet requirements because they are lactating, repairing their reproductive tract to get ready to conceive for the second time and are still growing. It is hard for them to compete for feed when fed with the mature cows. Most females open at fall preg check are young females and are open as a result of the nutrition program. For young females, avoid low body condition, make sure rations are balanced and have enough energy, take calving difficulty out of the equation, feed them separate from the cow herd and breed them to start calving ahead of the mature cows. Finally, if year after year, there are thin cows and open cows, so take a deeper dive. Look at mature weight and milk production or a combination of both. Have these traits increased over time? Both factors impact quality and quantity of feed needed. ~NC~ EXTENSION SPECIALIST, UNIVERSITY OF NEBRASKA-LINCOLN
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