Cattle grazing on rich green pasture is a typical scene in the British
countryside. The grasses that the cows eat fresh during the summer
months can also be harvested and preserved for winter use as hay
or silage. Farmers often also feed their animals with starchy energy-rich
cereal grains.
Pastures old and new
Unlike many plants, grasses can survive regular cutting or grazing.
With shoot buds that stay close to the ground and leaves that elongate
from the base of the blade, grasses continue to grow even if their
leaf tips are regularly chewed off. Most old grasslands are a mixture
of grasses and other plants. Their composition depends on the climate
and soil conditions: in damp meadows, rough-stalked meadow grass
(Poa trivialis) predominates while on exposed mountain sides,
sheepÍs fescue (Festuca ovina) is common. However, many
of these species-rich old grasslands have been replaced by short-term
pasture, usually sown with a carefully controlled mixture of grasses
including either perennial or Italian ryegrass (Lolium perenne
or Lolium multiflorum). These pastures are extremely productive
in terms of animal fodder, if less biodiverse and beautiful than
the original flower-filled meadows.
Kentucky blue grass (Poa pratensis), a common pasture grass
in the eastern states of the USA, was taken there by European settlers.
In the UK, it is known as smooth-stalked meadow grass.
Making hay
Farmers traditionally make hay by cutting mature grass and allowing
it to dry in the field to a moisture content of less than 15%. It
can then be stored as haystacks or in barns until needed. Hay meadows
are often rich in grasses such as meadow foxtail (Alopecurus
pratensis) which cannot survive in spring-grazed pasture.
Another method of preserving grass is in the form of silage. The
grass is cut before it is fully mature so the feed is more nutritious
for livestock. Once it has been wilted and chopped, it is loaded
into a huge air-tight container where it is effectively pickled
by the action of various acid-producing bacteria. A suitable mixture
of grasses for silage would be ryegrass (Lolium species),
timothy (Phleum pratense) and meadow fescue (Festuca
pratensis). Silage can also be produced from whole crop cereals
including maize and sorghum.
Many cereals are grown specially as animal fodder. Barley, maize
and sorghum grains are energy-rich foods. |
