ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

CROP RESIDUES

• Crop Residues are the left over portion of the crop after the main crop is harvested for human consumption.
• Crop residues may be grouped under the following headings

Straws	Stover	Aerial portion of other crops	Others
Wheat Paddy Oats Barley Millets	Maize Sorghum	Sugarcane tops Groundnut haulms Soyabean haulms	Corn cobs Bagasse Peanut hull Rice hull

Nutritional quality of crop residues

• Crop residues are generally low in crude protein, energy and micronutrients.
• They are usually high in cell wall constituents like lignin and silica.
• Hence their palatability is low leading to low voluntary intake.
• Their digestibility is also low and bulky in nature.

Straws

• Straws are produced from most cereal crops and from some legumes.
• They consist of the stem and leaves of plants after the removal of the ripe seeds by threshing.
• They are fibrous, rich in lignin and of extremely low nutritive value.
• Straw feeding is not recommended for pig and poultry.

Paddy straw

• The Paddy straw consist of lignin, about 6-7% dry matter is however lower than that of other cereals straw.
• But it has an exceptionally high ash content (17% of dry matter) having high silica level.
• In contrast to other straws, the stems are more digestible than the leaves.
• The poor nutritive values of straws may be attributed to the following facts.
  • Straw digestion is limited due to the formattion of strong physical and/or chemical bonds between lignin and the structural polysaccharides (Cellulose and Hemicellulose).
    • Although cellulose by itself has a highly ordered crystalline structure, it has a very strong association with lignin, which even the most potent cellulosic enzymes cannot have access to the cellulose unless the bondage between lignin and cellulose is broken.
  • Crystalline structure of cellulose is also responsible for low digestibility of cellulose.
  • Highly deficient in other nutrients like minerals, vitamins, fatty acids and in proteins. 
  • High silica content of straw is known to depress organic matter digestibility.
• It is economical to increase the nutritive values of all types of poor quality roughages by physical, chemical or biological treatment.

Legume straws

• The husks of the pods with leaves and tender stems are remain as byproducts after harvesting the seeds of pulses.
• These products can be utilised as nutritious cattle feeds.
• Most common pulse are
  • Urad (Phaseolus mungo),
  • Moong (Phaseolus radiatus),
  • Moth (P.aconiti folius),
  • Cow peas (Vigna catiang ) etc.
• The energy value of these straws is comparable with those of cereal straws but they are a fairly good source of digestible protein.
• Supplementation with energy-rich feeds like cereal grains will, however will be necessary in the case of high milk producing cattle.

Other straws (Cereals) that are commonly fed to animals are

• Wheat straw, Rye straw and Oat straw.

Stover

• Consists of the leaves and stalks of corn (maize), sorghum or soybean plants that are left in a field after harvest.
• It can be directly grazed by cattle or dried for use as fodder (forage).
• Its nutritive value is similar to straw.

Sugarcane tops

• It is the top portion that has been removed from the highest fully formed node in sugarcane.
• It includes the green leaves, bundle leaf sheath and variable amounts of immature cane.
• At the time of sugarcane harvest, abundant quantities of sugarcane tops are available.
• Though sugarcane tops serve as green fodder, it has low nutritive value (4 % crude protein and 48 per cent TDN), dries up quickly and hence wasted.
• To preseve sugarcane tops in succulent form, ensiling with one percent urea, molasses and salt is beneficial. 

Haulms

• The stems of peas, beans etc., are called as haulms.
• The aerial portion of groundnut plant (groundnut haulms) and Soybean plant (Soybean haulms) can serve as a potential source of fodder for livestock.
• Haulms contain about 15 percent crude protein and 30 % crude fibre and have better nutritive value than stovers.

Others

• A corncob is the left over protion after removal of maize grain.
• Corncobs can be used as fibre souce in ruminant feeding.
• Bagasse is the fibrous residue remaining after sugarcane is crushed to extract their juice. It has very low palatability.
• Hulls are outer shell of pods and are fibrous in nature with low nutritive value.