– John F. Grimes, OSU Extension Beef Coordinator
This is truly exciting time for cow-calf producers across the state. Winter finally appears to be in the rear view mirror and the signs of spring are all around us. Temperatures are rising and pastures and hay fields are starting to grow. More importantly, spring calving herds have been busy delivering the 2016 calf crop.
This exciting time for cattlemen is also an extremely critical time for the future profitability of their operations. It is important to recognize that the transition from late winter to early spring is the most challenging time of the year for the nutrition of the spring-calving beef cows. As pastures begin to green and grow, beef cattle quickly begin to show their preference for lush, green grasses as opposed to dried, cured forages. While we may welcome the idea of not having to feed hay after months of winter drudgery, the cow’s preference for green grass may not be in her best interest.
It has been well-documented that body condition at the time of calving is an important factor that can impact rebreeding performance of beef cows. Body condition scores (BCS) are an important indicator of potential reproductive efficiency. Body condition score ranges from 1-9 where 1 is emaciated while 9 is extremely obese. Numerous research studies have shown that BCS scores of 5-6 at calving and through the breeding season give females the greatest opportunity for reproductive success. A change in a single BCS (i.e. 4-5) is usually associated with about a 75 pound change in body weight. Evaluation of BCS prior to calving and from calving to breeding is important to ensure reproductive success.
Body condition changes from the time the cow calves until she begins the breeding season can play a significant role in the rebreeding success story. This appears to be most important to those cows that calve in the marginal body condition score range of “4” or “5”. If nutritional needs are not met from calving to breeding, this can result in reduced BCS which can yield disastrous rebreeding performance. Research from Oklahoma State (Wettemann, et al. , 1987 Journal of Animal Sci., Suppl. 1:63) demonstrated that cows that lost almost one full condition score from calving to breeding season had dramatically lower rebreeding rates (73% vs 94%) compared to cows fed adequately to maintain the body condition that they had prior to calving.
Maintenance requirements for energy and protein can increase by 25% or more for most beef cows after calving. Cows currently grazing high moisture, low energy density grasses, instead of more energy dense hays can quickly lose body condition. First-calf heifers are at particularly high risk of losing body condition. It would be a sound management decision to provide extra feed such as moderate to good quality grass hay free choice and/or high energy feed grains to provide both the energy and protein that the lactating cows need. Given the beef animal’s current preference for lush grass over dried hay, offering grain over hay will probably be the more effective choice to supplement females. Yes, the feed will increase costs. However, the cost of losing 21% of next year’s calf crop is even greater!
The clock is ticking on the time you have to impact the number of calves that your herd may produce in 2017. Devote some time to evaluate the body condition of your cow herd. Take the proper steps to keep these females in the proper condition to achieve satisfactory reproductive rates.