Grazing in Late Fall and Early Winter

Extending the grazing season into the winter is key to profitable livestock production.

Preserved forages are the most prominent cost of livestock production, often accounting for as much as 60–70% of the total production costs. In addition, handling manure in the feedlot requires labor, equipment, and fuel. Therefore, extending the grazing season is key to improving the profitability of livestock production. We can extend the grazing season in late fall and early winter in Pennsylvania with pre-planned diverse forage resources.

Grazing 4–6 weeks prior to the average first killing frost

The growing period prior to the first killing frost (24°F) is a critical time in perennial forage management, particularly for perennial legumes. To replenish their organic food reserves and N-containing compounds in their storage organs and develop their winter hardiness, perennial legumes should not be grazed 4–6 weeks prior to the first-killing frost. Perennial cool-season grasses, which dominate most Pennsylvania pastures and haylands, are less sensitive to fall grazing than perennial legumes. Further, annual forages that do not need to overwinter can be grazed in this period. Due to their high regrowth potential, annual cool-season grasses such as annual ryegrass and Italian ryegrass seeded either in the spring or previous fall can be harvested as haylage in spring and summer and after the second cut is a good forage resource for grazing prior to the first killing frost.

Similarly, we can graze the regrowth of annual warm-season grasses teff, pearl millet, and sudangrass or sorghum-Sudan hybrids seeded in late spring after the first cut as preserved forages. A good soil fertility program, especially N, is needed after each cut of these annual species for a high regrowth yield. Weather conditions also control the regrowth yield, varying from 1000–2000 lbs. dry matter per acre. In order to use these annual forage species to extend the grazing season, a plan much ahead of the current fall grazing season is needed. What if I missed these annual forage species?

Sacrifice pasture dominated by perennial cool-season grasses can be an option to extend grazing season 4–6 weeks prior to the first killing frost. A pasture designed as a sacrifice pasture is due to variable reasons, such as proximity to the facilities and infrastructures and planned renovation area for next spring. The perennial cool-season grasses have two growth peaks, one in the spring and another in the fall. The fall regrowth of perennial cool-season grasses is nutritious due to lower temperature and shorter photoperiod-induced morphological and physiological changes, such as long and wide leaves, prostrate growing habit, and high nonstructural carbohydrate concentrations. With a mild winter and good management next spring, the sacrifice pasture can be recovered for another year of decent production. Low grass tiller density with an open canopy can result from grazing in this critical period of perennial cool-season grasses. Therefore, a follow-up plan with the sacrifice pasture should be developed that fits the whole farm/ranch management goals.

Grazing after the first killing frost

Crop residues, especially corn stover, which consists of stalks, leaves, and husks, can be used to extend the grazing season. A general rule is about 30 cow days per 100 bushels of corn produced. Grazing corn stover can be a win-win for both crop and livestock producers. Cover crops seeded in late August or early September in Pennsylvania can also be grazed after the first killing frost. Spring cereals (e.g., oats), annual legumes (such as crimson clover), and brassicas are the prevalent species in this category. With more than two months of growth, the forage yield of these cover crops can reach 2,000–4,000 lbs. per acre under variable weather conditions. Brassicas are cold-tolerant. Kale can survive temperatures as low as 20°F. A balanced mixture of cover crop species will be superior for grazing. Otherwise, the high moisture and very digestible brassicas need to be supplemented with low-quality and high-fiber roughage. The forage yield of winter cereals is limited in the fall and early winter due to their vegetative-only growth without a proper vernalization process so they should be reserved for grazing later.

Stockpiling is a popular method to graze after the first killing frost. Stockpiling involves saving standing perennial forage in late summer/early fall for winter grazing after start of dormancy. Stockpiling is different from sacrifice pastures because stockpiling requires concerted planning and effort to make it successful. Late July to early August is the time to begin the stockpiling process for winter grazing. Getting started in this timeframe provides more time for maximizing yield. Ideally, 60–75 days ahead of the first killing frost. The field intended for stockpiling should be grazed or cut down to 3–4 inches. Nitrogen should be applied to stands that are mainly grass. Anywhere from 50 to 100 lbs N/A is recommended and can be manure or nitrogen fertilizer. Fields intended for stockpiled pasture with a heavy legume content (30%+) do not need additional nitrogen. However, they should be utilized earlier or given very light grazing to allow livestock consumption of the legume before its quality deteriorates due to leaf drop. Otherwise, the field should be allowed to grow all fall ungrazed. Most cool-season perennials, such as tall fescue and orchardgrass, can be stockpiled. However, tall fescue tends to have better growth in cooler conditions than the other cool-season perennial grasses. Furthermore, the heavy waxy coating on the leaves of tall fescue allows it to withstand winter weather and retain more of its nutritional content for a longer period when compared to other grasses. Species other than tall fescue that are stockpiled should be used on the earlier side of the stockpile grazing timeframe due to their tendency to deteriorate more rapidly.

Grazing management and precautions

Besides sacrifice pasture and crop residue grazing, other late fall and early winter forage is best utilized through strip-grazing. Breaking out enough forage for 1–3 days of grazing is ideal. Long occupation periods, and especially continuous grazing, are strongly discouraged. Research has shown that relatively short grazing periods result in much more efficient utilization of the accumulated forage. Longer periods allow more trampling and fouling with manure and urine. Annual forages without significant anti-quality constituents, such as annual ryegrass, teff, and pearl millet, can be grazed short, allowing longer grazing time or more grazing animals. In comparison, grazing of perennial grasses should leave at least 3–4 inch stubble to guarantee hardiness and stand longevity. Grazing cereals and sorghum-Sudan hybrids less intensive will avoid nitrate and prussic acid poisoning.

Nitrate concentrations in barley, oats, sudangrass, sorghum-Sudan hybrids, and brassicas can reach toxic levels (>4,500 ppm) under heavy N fertilization rates or adverse growing conditions such as drought and early frost. To mitigate potential nitrate poisoning, livestock producers can mix these with other forage species, supplement with high-energy feed such as corn, leave a high stubble for grazing, and avoid grazing right after drought or frost. The prussic acid concentration in sorghum-Sudan hybrids and sudangrass can be high right after frost or drought and cause livestock prussic acid poisoning. Delaying grazing 1–2 weeks after frost will mitigate the potential of prussic poisoning. Due to the antiquality constituents glucosinolates and S-methyl cysteine sulfoxide (SMCO), livestock grazing brassicas can develop goiter and suffer from acute anemia. Iodine supplementation and limiting brassica forage intake on a daily basis in grazing animals can mitigate these negative impacts on livestock production and health.

Soil management considerations

Grazing is a natural way to feed herbivores and can help improve soil if done properly. The manure and urine improve the soil naturally. Underneath and in the manure pies, one always finds a lot of beneficial organisms such as earthworms and dung beetles and extensive fungal growth. Soil fertility will be improved where the manure and urine are deposited. To improve manure distribution, it is beneficial to rotate the animals through small paddocks and rest the pasture until the next grazing rotation. The grass will notably be greener where the manure piles were, reflecting the improved soil. Strong pasture roots stimulate soil health. The practices described previously, leaving sufficient residual height, benefit strong roots.

The greatest threats to soil are erosion and compaction from grazing animals. To avoid soil erosion, the soil should be covered at all times or only left bare for very short periods. Therefore, the pasture should not be grazed down to the soil level. Having mobile water sources is beneficial because it is often around the water where the field is degraded. Renovating pastures and establishing annuals using no-till practices allows for preserving residue cover and protecting the soil from erosion. Long-term no-till soil is also more resistant to soil compaction—there will be less pugging of the animal hoofs. Further, it will be important to monitor soil moisture conditions when grazing. Backfencing is a way to avoid repeat hoof traffic.

Also, some pastures are more susceptible to compaction than others. From most to least compactable: annual broadleaves> annual grasses > broadleaf perennials > perennial grasses > tall fescue. Moving animals more frequently when soils are wet is another strategy to avoid detrimental soil compaction. Finally, if conditions are excessively wet, move the animals into a sacrifice lot or enclosure until soil conditions improve.

Conclusion

Grazing season extension should be a management goal for every livestock producer. Extending grazing season in late fall and early winter can be achieved with well-planned selection and raising diverse annual and perennial forage species.