Dietary Requirements of
Different Species of Smallstock

The different species of livestock have different nutrient and feed type requirements. This is largely based on their different types of digestive systems, but also on body size, and to some extent the shape of jaw and teeth, bite rates and selectivity of feeding. Ruminants (cattle, sheep, goats and buffalo) have 4 compartments to their stomachs. The rumen is the largest compartment. Because fermentation by bacteria in the rumen, they are able to utilize high fibre feeds, such as grass. Pigs, poultry and horses have a digestive system which is more like that found in humans, with a single compartment to the stomach. These digestive systems can not digest high-fibre feeds to the same extent, and these species require more easily digested feeds to grow and produce efficiently.

Ruminants The Rumen    Sheep    Goats   Non-Ruminants    Poultry References and Further Reading For more details on the different digestive systems of sheep and goats, poultry and pigs, go to Digestion of Feeds

Ruminants evolved to consume and subsist on roughage, grasses and shrubs made up largely of cellulose. An understanding of the ruminant digestive system is useful in order to appreciate the dietary requirements of ruminants.

Ruminants have a stomach with four compartments. When a sheep, goat or other ruminant eats, the food initially goes into the first stomach, called the rumen. From there, it moves gradually into the reticulum where it is broken down by bacteria and acid to form cud. Muscles in the reticulum push the cud back into the animals's mouth for a second chewing to help break down the food material even further (rumination). Once the sheep swallows the cud it then enters the omasum for further digestion before it enters the abomasum.

From the abomasum the food material then enters the small intestine. The abomasum is the ruminant's true, or glandular stomach, and it is very similar to the stomach of non-ruminants, or monogastrics. Combined, these organs occupy almost three quarters of the abdominal cavity, filling most of the left side and extending significantly into the right hand side (Animals with rumen problems often look swollen on the left side due to bloating of the rumen).

When ruminants are born, the rumen is not developed. New-born ruminants only use the abomasum to digest milk, and they are unable to digest plant fibres. As the animals get older and start to eat fibrous foods, the rumen grows and the animals start to ruminate.

Feed, water and saliva are delivered to the rumen and reticulum (reticulorumen) through the oesophagus. Heavier components in the feed (including foreign objects such as nails and stones) tend to enter the reticulum straight away. Otherwise, the material enters the rumen. The rumen then contains the older fluid-saturated roughage, e.g. from the previous day, towards the bottom, and the newer and lighter feed above this. Fermentation produces a lot of gas and this rises to the top before being belched out through the mouth.

Secretion of fluid into the gastrointestinal tract is of particular importance to herbivorous animals that rely on microbial fermentation for their digestion. A stable environment is important to maintaining a healthy microbial population, and fluid secreted into the gastrointestinal tract, particularly that produced by the salivary gland, is an important contributor to that stability. The saliva provides:

• Fluid for the fermentation vat
• Alkaline buffering. Saliva is rich in bicarbonate, and this buffers the large quantity of acid produced in the rumen and is critical for maintenance of rumen pH.

 

Below are guidelines for the energy and protein requirements for small livestock in different stages of production. It is unlikely that you will know the actual composition of the diet, especially if there is any element of grazing/browsing/scavenging activity. However, combined with the information in the sections on the nutritive values of different feeds, you may be able to estimate which if any nutrient is limiting in any given situation, and then select the best available feeds for supplying that nutrient.

 

Required concentrations of nutrients (on a dry matter basis)
in the diets of sheep in different states or stages of growth .

Table sourced from: Carles, A.B. (1983). Sheep production in the tropics. Oxford University Press, Oxford, UK. pp110-111.

¹DM: dry matter;
²Dig. prot.: digestible protein;
³ADG: average daily gain.

Recommended mineral concentrations in the sheep’s diet (on a dry matter basis)

Table sourced from Carles, A.B. (1983). Sheep production in the tropics. Oxford University Press, Oxford, UK. p.112.

Total energy requirements (MJ ME/day) for goats

Data from Peacock, C. (1996). Improving goat production in the tropics. Oxfam/FARM-Africa, Oxford, UK. p.86.

Digestible crude protein (DCP) requirements (g/d) for maintenance and growth of goats

Data from Peacock, C. (1996). Improving goat production in the tropics. Oxfam/FARM-Africa, Oxford, UK. p.86.

Simplified nutrient requirements for a laying hen (concentrations in diet on air dry basis)

Table sourced from Smith, A.J. (1990). Poultry. In: Coste, R. (Series editor) The tropical agriculturalist. Macmillan Publishers, London, UK. p.83

Summary of nutrient requirements of chicks, broilers and ducklings (air dry material)

Table sourced from Smith, A.J. (1990). Poultry. In: Coste, R. (Series editor) The tropical agriculturalist. Macmillan Publishers, London, UK. p90.

Nutrient requirements of laying fowls and laying ducks (air dry material)

Table sourced from Smith, A.J. (1990). Poultry. In: Coste, R. (Series editor) The tropical agriculturalist. Macmillan Publishers, London, UK. p91.

Free ranging chickens forage for
natural sources of nutrients