Optimizing Winter Forages for Spring-Calving Cows Could There Be a Forgotten Player? By Kendall Whatley, M.S. Student, and Jennifer J. Tucker, Ph.D., Associate Professor and Extension Specialist, Department of Animal and Dairy Science, University of Georgia

Optimizing Winter Forages for Spring-Calving Cows: Could There Be a Forgotten Player?

By Kendall Whatley, M.S. Student, and Jennifer J. Tucker, Ph.D., Associate Professor and Extension Specialist Department of Animal and Dairy Science, University of Georgia Photo credit: Clover - Shauni Nichols; Cows - Kendall Whatley

In the Coastal Plains, the ability to extend the grazing season has allowed cattle producers more flexibility in choosing calving seasons, growing and stockering calves, and reducing the need for supplement. Cows require their highest nutrition from approximately 2-3 months prior to calving (late gestation) and until they are rebred after calving (approximately 3 months post-parturition). The effects of dam nutrition during late gestation, when 70-80 percent of fetal growth and development in utero occurs, have lasting consequences on postnatal growth and performance of subsequent progeny. Many cattle producers choose to calve in late winter or early spring, resulting in a higher nutritional requirement for the dam during this time period. Producers are constantly looking for alternative management strategies to help decrease costs and improve profitability, and winter feeding is one of the more costly components of management for cattle operations. Fortunately, many producers in Georgia have the possibility to achieve a nearly year-round grazing season through improved grazing management strategies.

It is well known that cool-season annual forages are higher in forage nutritive value, and warm-season forages are typically higher yielding. However, a year-round grazing season cannot be achieved on a monoculture forage base of either cool- or warm-season forages. Further, there are times (typically spring and fall) when perennial forage production lags as we transition from cool- to warm-season or from warm- to coolseason growth. During these transitional growth periods, it can be difficult to fill the forage gap to

provide the needed nutrients for gestating cows. Utilization of grass and legume mixtures has been well studied for serving the purpose of bridging the grazing-gap. Southeastern producers overseeding warm-season perennial sods with cool-season grass/legume mixtures have customarily utilized true annual clovers (i.e., Crimson or Arrowleaf) that have more of a bang-and-bust growth pattern. These clovers tend to provide their greatest contribution to the stand at one significant point in the growing season. These legumes are a great option for producers to consider, especially those overseeding hayfields with the goal of gaining the nitrogen benefit without fighting additional species during the warm season. However, what if we had a legume option that could provide a contribution even when our warm-season pastures wake up?

Recent research at the UGA Tifton Better Grazing Program has focused on the integration of short-term perennial legumes into warmseason grass bases and has identified red clover as a potential legume that can extend stand contribution beyond a single flowering event in the growth season, providing contributions well into the summer in some instances. Combining red clover with a high-quality winter grazing option, such as annual ryegrass, could prove to serve the needs of a cow herd through the transition from cooler into warmer months, especially if overseeded onto an existing bermudagrass stand.

Annual ryegrass accounts for 135,000 acres of pasture in Georgia and is a common cool-season annual in the Deep South, potentially providing grazing from approximately late January through May, depending on planting date and location. This availability matches the time frame when spring-calving cows would have their highest nutrient requirements. Likewise, bermudagrass accounts for approximately 3 million acres in Georgia but serves little purpose before green-up in late spring/early summer. Thus, there is still a need for additional grazing options to fill the gap between the decline of ryegrass and the surge of bermudagrass. Interseeding an annual ryegrass and red clover mixture into established bermudagrass could serve as an option to extend and transition the grazing season, provide additional necessary nutrients to dams, while increasing profitability by reducing associated costs with commercial feeding, additional supplementation, and nitrogen fertilizer. Nutrient needs for cows in early lactation are approximately 62-percent TDN and 11- to 12-percent CP. Looking at the proposed annual ryegrass and red clover system, annual ryegrass should contribute a TDN and CP of 60- to 65-percent and 12- to 16-percent CP, respectively, while the red clover offers approximately 20-percent CP and 60- to 65-percent TDN. With these nutrient characteristics combined with fertilizer cost savings from the nitrogen fixing properties of the legume component, this winter grazing mixture may be a value-added option for you and your operation next year!

As always, managed grazing will provide the greatest benefit of this system. It is well known that late-season annual ryegrass can have a delaying effect on bermudagrass green-up. Through timely forage removal under managed grazing, we should be able to effectively utilize this cool-season mixture of ryegrass and red clover and expect the red clover component to carry into bermudagrass green-up. Through this, we can develop a managed grazing system that transitions beautifully from our cool-season into our warm-season perennial pastures, helping better meet the nutritional needs of our lactating cows. Additionally, extending the grazing season allows us to be better stewards of the environment, reduce weather risk, increase animal performance through utilization of betterquality forages, decrease labor costs, and lower other feeding expenses.

*Research evaluations supported by the Georgia Beef Cattle Commodity Commission have been initiated in Tifton to further evaluate yield, quality, and rotation strategies of this mixture in the 2021 funded project: “Evaluating the potential of annual ryegrass and red clover overseeded onto bermudagrass sods to meet the nutritional needs of late-gestation and early-lactation cows during the spring transition.”