61
Cold Winter Climates
3. Beef Cattle Nutrition
BEEF CATTLE NEED AN ADEQUATE SUPPLY of good quality feed if they are to grow, reproduce, and maintain
health. Developing balanced, high performing rations for cattle is complicated by the diferent dry matter
content of each feed, the variance in energy, protein, ibre and mineral content of each feedstuf, and the
cost of each. In addition, each type of animal to be fed has a diferent
nutrient requirement, whether they be young, growing animals with high energy and protein needs, mature
animals with moderate energy and protein needs, or lactating animals with high energy and moderate protein
needs. The cost of feed used in both the breeding herd and the feedlot is a major expense for the business.
The basic sources of feed for beef cattle are native herbage and pastures, crop residues, sown forages, and
grains. The most economical sources of feed in most areas are when grasses and legumes are grazed.
3.1. Ruminant Digestive System
Cattle belong to the group of animals known as ruminants, which also includes sheep, goats and deer.
Ruminants difer from other animals in having four compartments before the small intestine - the reticulum,
the rumen, the omasum and the abomasum, each with a special function Fig. 3.1. Other animals monogastric
have a single stomach before the small intestine.
Ruminants take fairly large bites when consuming forages, swallowing the herbage with a minimum of chewing.
After eating, ruminants stand or lie down to ruminate or “chew the cud”, where boluses of coarse feed are
regurgitated, re-chewed and swallowed. This reduces the size of the forage particles and greatly increases the
surface area available for microbial digestion. The reticulum is where all eaten material collects. It
interacts with the rumen to push regurgitate food back up into the mouth to be chewed again - a process
called rumination. Rumination is stimulated by long ibres in roughage; chewing grinds down the ibres and
promotes the production of saliva.
The rumen, the largest of the four compartments, contains a concentrated and diverse range of bacteria,
fungi and protozoa that are responsible for much of the initial digestion of feed. The capacity of a well-
developed adult cattle rumen can be as much as 200L. The presence of a rumen allows ruminants to utilise
roughages as a major source of nutrients. Movement of masticated feed and the overall eiciency of breakdown
in the rumen are assisted by contractions of the ruminal wall that keep rumen contents moving.
The main purpose of the omasum, with its much folded surface, is absorption of water from the rumen luid, but
some other nutrients are also absorbed. Decreasing the water content of the rumen luid increases the
efectiveness of digestion in the abomasum.
The abomasum or ‘true stomach’ secretes digestive acids and bile. The microbes are digested, and their
protein is used by the animal; fats and remaining starch are also digested at this stage.
Small intestine and large intestine - The intestinal system in a ruminant is somewhat similar to that of
a monogastric animal. The small intestine absorbs minerals and proteins while the large intestine absorbs
more water along with some energy components, proteins and minerals.
62
Beef Breeder MANUAL
Figure 3.1. The ruminant digestive tract.
3.2. Concepts of Nutrition and Feeding
