While perennial forage species are the backbone of our livestock systems, this has not been a good year for making quality hay or haylage. Consequently, many farmers are seeking some crop they can still plant that will help fill the void in their forage supplies. For simplicity, I have grouped some of these crops based on the time of year they are planted in Summer or Fall.
Forage brassica crops such as turnip, swede, rape, and kale can be spring-seeded for grazing in August and September or they can be summer-seeded to extend the grazing season into November and December (Figure 1). Brassicas are highly productive and digestible but are utilized almost exclusive by grazing. In addition, crude protein levels are high, varying from 15 to 25 percent in the herbage and 8 to 15 percent in the roots depending on the level of nitrogen fertilization and weather conditions.
Figure 1. Planting and grazing sequence for forage brassicas.
Kale varieties differ markedly in rate of establishment, stem development, time required to reach maturity, and in winter hardiness. The stemless type kale has a faster rate of establishment than varieties which produce stems. Crop height of the stemless type is approximately 25 inches, whereas that of stem kale is 60 inches with primary stems often 2 inches in diameter. Stemless kale attains maturity in approximately 90 days, allowing two crops per year, whereas varieties that develop stems require 150 to 180 days to attain maximum production.
Rape is a multi-stemmed crop with fibrous roots. The stems vary in length, diameter, and in palatability. Forage yields of spring-planted rape increase until plants become physiologically mature. Growth slows or ceases at maturity and yields plateau until leaves senesce and die. Varieties differ in when this occurs. Generally, yields of rape varieties are maximized with two, 90-day growth periods. However, performance of some rape varieties is best with one 180-day growth period, and yields of rape hybrids were greatest with 60 days of growth before the first harvest and a 30-day growth period before the second harvest.
Turnip or Turnip Hybrids grow very fast, reaching near maximum production levels in 80 to 90 days. Studies in southwestern Pennsylvania showed that turnip can accumulate dry matter in October as fast as field corn does in August. Growing "out of season" (October/November) makes turnip a valuable crop for late fall grazing. The proportions of tops to roots in turnips varies markedly depending on variety, crop age, and planting date. Research by the USDA-ARS showed that turnip crops can vary from 90 percent tops and 10 percent roots to 15 percent tops and 85 percent roots. Some hybrids have fibrous roots which cannot be readily grazed by livestock. All varieties produce primarily tops during the first 45 days of growth. Sixty to 90 days after seeding, some turnip varieties continue to produce a high proportion of tops while other varieties have nearly equal top and root production. The significance in the proportion of tops and roots is that the crude protein concentration of roots is approximately one-half of that in turnip tops. Therefore, greater root production tends to reduce the crude protein yield of the total crop. On the other hand, stockpiled tops appear to be more vulnerable to weather and pest damage than roots. Varieties differ in resistance to diseases, but this often is not evident until the crop is more than 80 days of age and the plants are reaching full production.
Cows grazing turnips in November.
Swedes, like turnip, produce a large edible root. Yields are higher than those of turnip, but they grow slower and require 150 to 180 days to reach maximum production. Swedes usually produce a short stem but can have stems 2 1/2 feet long when grown with tall crops which shade the swede. Unfortunately, stem elongation is at the expense of root development. In general, all swede varieties are recommended for late fall grazing.
Brassica Grazing Management
Grazing management is important to optimize the true potential of brassica crops. Strip grazing small areas of brassica at a time provides the most efficient utilization. Grazing a large area increases trampling and waste of the available forage. Rape is more easily managed for multiple grazings than are the other brassica species. Approximately 6 to 10 inches of stubble should remain after grazing rape to promote rapid regrowth. Regrowth may be grazed in as few as 4 weeks after the first grazing. Graze rape close to ground level during the final grazing.
When turnips are grazed more than once, only the tops should be grazed until the final grazing when the whole plant can be consumed. Like rape, regrowth of turnips can be sufficient to graze within 4 weeks of the first grazing.
Winter cereal crops such as wheat, barley, rye or triticale can provide grazing, silage and/or grain options. If these crops are used for fall and spring grazing, certain management practices need to be modified from what is normally done for grain production. Plant three to four weeks earlier than for grain production alone (mid-August to early September). Increase the seeding rate to 3 bu/acre and apply 40 lbs N per acre at planting.
With adequate fall moisture, forage should be available from October through December and then again in late winter. One acre of properly fertilized and managed small grain should support one animal unit (feeding value of a 1000 lb. dry cow) on a limited grazing basis. Small grain pasture is lush, high in protein, and low in fiber during most of its grazing period. Crude protein levels normally range from 15% to 34% of dry matter, making this forage an excellent protein supplement for many classes of livestock.
Stocking rate and time of grazing will be somewhat determined by the intended use of the crop. If you are planning to take a silage or grain harvest, grazing should only be moderate. Heavy grazing can reduce grain yields. Moderate grazing in the fall should not result in significant silage or grain losses provided that moisture and soil fertility are adequate. In fact, fall pasturing can be beneficial where the small grain was seeded early and has made excessive growth.
Spring grazing may be started when growth resumes. If a grain or silage crop is to be harvested, grazing should be discontinued when the plants start to grow erect just previous to jointing (nodes begin forming on stems). Plants will be injured by grazing at any time after their growing points are above the ground.
The use of temporary electric fencing should provide a practical way to manage these pastures. Small grains can be continuously grazed but rotational or strip grazing can allow for a higher carrying capacity because of reduced wastage and trampling.
Table 1. Average spring forage yield and quality of small grains when planted in September of the previous year in central Pennsylvania