After a busy season of breeding, pulling bulls, pregnancy diagnosis and weaning, we’d like to hope cows can turn on autopilot for a few months during the winter. However, that’s not the case; cows are always working for us, whether that means lactating, raising a calf, preparing to become pregnant or gestating next year’s calf. It’s our responsibility to make sure they are in the proper body condition to do so.
Body condition is an estimate of the fat cover (energy reserves) that a cow carries and is scored on a 9-point scale in beef cattle (1 = emaciated, 9 = obese) to evaluate nutritional status. Being able to visually evaluate the body condition of cattle is an extremely helpful management tool for cattle producers. In a perfect world, our cows would maintain a moderate body condition (i.e., a body condition score, or BCS, of 5) in all seasons; however, we know that is not the case. There are instances where cows may lose considerable condition, such as after calving due to the demands of lactation, distance to travel on summer pasture and low forage quality or availability. Regardless of the reason, there are always a few cows that end up walking out of the weaning pen in poorer condition than we would ideally like to see going into winter. It’s important for cows to regain lost body condition, as body condition has clear implications to other areas of production, such as reproductive efficiency and profitability. Remember, a cow will devote energy and nutrients to her own maintenance before she invests in lactation, breeding or fetal growth. Thus, cows that are chronically thin may experience embryonic loss or dystocia, produce unthrifty calves next year and will likely be difficult to rebreed after calving if they do not regain body condition.
Calving season score
To avoid the consequences of poor body condition on production efficiency, it has long been proposed for cows to enter the calving season at a target BCS of 5. Not only do thin cows have lower pregnancy rates compared to moderately conditioned cows, but years of research have shown that cows in thinner body condition at calving (a BCS of less than 5) are more likely to have a postpartum interval longer than 80 days. It’s no secret that cows need to become pregnant within 80 to 85 days of calving to maintain a yearly calving interval. Thin cows with a BCS of less than 5 are far more likely to extend their calving interval, push back their calving date and wean a lighter calf of lower value next year. On the other hand, cows in optimum condition (a BCS of 5 or higher) at calving start cycling within 60 days after calving, on average. These cows have the opportunity to get pregnant and calve earlier compared to thinner cows, which can contribute to additional pounds of weaning weight and greater profit margins for properly conditioned cows.
Fall tends to align with the second trimester of pregnancy in the majority of spring-calving cows. As producers, this is a tremendous opportunity to focus on economically adding condition to thinner cows to ensure appropriate body condition at calving. In the fall, producers have likely weaned calves, so cows are no longer lactating, yet cows have not yet reached the last two months of pregnancy when 75% of fetal growth occurs. Therefore, the energy requirements of cows are lower during midgestation compared to other seasons, and body condition can be added to thinner cows cost-effectively. Furthermore, due to increasing calf size, feed intake generally decreases as gestation continues, making improving body condition during late gestation challenging.
Feed availability
Logistically, accomplishing the task of adding body condition to cows can be difficult depending on feed availability during the fall and winter months. As a first step, thin cows should ideally be sorted from cows in moderate body condition to avoid supplementing cows that will not benefit from the added condition, saving feed resources and expense. Additionally, the number of pounds needed to gain a single body condition from thin (a BCS of 4) to moderate (a BCS of 5) is dependent on mature cow weight. For example, a 1,200-pound cow at a BCS of 4 would need to gain 84 pounds to reach a moderate BCS of 5; whereas a 1,400-pound cow would need to gain 98 pounds for the same increase in condition. Thus, knowing the size and frame of your cattle is key when adding body condition.
Time frame
A final consideration is the time frame that you have to increase body condition before calving. As a cow progresses in gestation, more energy is required for fetal growth. Thus, it can be very expensive to add body condition in the last two months of pregnancy. You are better off supplementing thinner cows to reach a moderate body condition during midgestation and then supporting maintenance during late gestation up to calving; however, that requires both time and planning. If only a short time frame is available to add the desired body condition, utilizing feeds with a higher energy density (such as corn, sorghum, barley, etc.) may be necessary, whereas having a more flexible timeframe of 90 or 100 days allows additional feedstuffs and forages to be utilized despite being less energy dense. For example, a 1,200-pound cow requires a set amount of energy to gain the weight required to raise her body condition by a single score, regardless of how long you give her to accomplish that task. In a 100-day period, it may be very feasible to offer quality alfalfa hay to existing grass hay at a rate of 5 to 10 pounds per cow per day to achieve the change in body condition. When your window of opportunity for weight gain decreases to 30 days, supplementing alfalfa hay may not provide enough excess energy to meet a cow’s requirement for weight gain. Therefore, it is best to plan ahead, periodically assess body condition in your herd and test forage quality so that body condition can be added in a way that supports profitability.
