Feed Lot Magazine Online, Alternative Feeds Can Be Used to Extend the Grazing Season

Volume VII Number 5

September/October 1999

Alternative Feeds Can Be Used to Extend the Grazing Season

Extending the grazing season can be accomplished by growing and feeding plants from the brassica family. This family of plants includes turnips, rape, kale, and swedes.

They are very fast growing, highly nutritious, and can be grazed 70 to 90 days after seeding, according to Penn State University (PSU), the University of Wisconsin Extension Service and the Ag Connection newsletter, which is published by the Missouri Agricultural Extension Serivce. Protein values of the plants range from 14 to 24 percent and can have digestibility values from 85 to 95 percent. Weight gains for stocker cattle grazing these forages have been reported at one and a half to two pounds-per-day.

The different varieties of kale differ markedly from one another in rate of establishment, time required to reach maturity and in winter hardiness, according to a report from PSU. Depending on the variety of plant, it takes 90 to 180 days to attain maximum production and have the possibility of overwintering in some climates.

Rape is a multistemmed crop with a fibrous root system and can be harvested more than once in a single season, according to the PSU report.

Swedes, like turnips, produce a large edible root. They yield better than turnips, but they grow slower. The PSU study recommends all swede varieties for late fall grazing.

Turnip or turnip hybrids are fast-growing crops that reach maturity in 80 to 90 days, according to PSU. Studies conducted in Pennsylvania showed that turnips can accumulate dry matter in October as fast as field corn does in August.

The drawbacks to feeding these are the low fiber content and the need to feed hay or other pasture forages. The low fiber content can cause a fast rate of passage through the rumen, which causes incomplete digestion, the report stated. Because of this brassicas should comprise no more than two-thirds of the forage portion of the diet.

They can also interfere with the uptake of iodine because they contain glucosinolates. The magnesium availability can also be adversely affected due to a higher than desired calcium to phosphorous ratio along with high levels of potassium. They can also accumulate nitrates when fertilized with high levels of nitrogen. Proper mineral supplementation and controlling the intake of brassicas can solve these problems.

A report from the University of Wisconsin suggests two management practices to keep problems from occurring while feeding brassicas.

Introduce animals to brassica pastures slowly, over three to four days, and avoid abrupt changes from dry summer pastures to lush brassica pastures. Do not turn hungry animals that are not adapted to brassicas into a pasture containing them.

Either supplement with dry hay if continually grazing brassicas or allow the animals access to grass pastures during the time on brassicas.

The forage quality of brassica is high enough to be considered similar to concentrate feeds, therefore precautions should be taken accordingly.

These crops have been used for years in Europe and other parts of the world very successfully for livestock feed. They can survive light freezes, making them ideal to extend the fall and winter grazing seasons.

Greatest utilization will come from a controlled gazing program to reduce trampling of the forage, which will allow re-growth and an extension of the grazing season. These plants have the potential to complement several grazing systems and can work well with stockpiled tall fescue for fall grazing.

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