Fresh grass, feed crop, and other hay and silage made by these kinds of raw materials are generally of well palatability, high nutritive value, they can be fed to the livestock directly. Coarse feed with low quality such as straw, grain husk, pod shell, bamboo shoot shell and etc. have bad palatability, low digestibility and nutritive value. If these kinds of feed are fed to cud chewer directly, it can’t reach the feeding result they should be. In order to obtain a better feeding result, the low quality coarse feed should be processed properly in production practice. The processing method can be divided into physical processing, chemical processing, biological processing and recombination processing.

I. Feeding Directly

Feeding directly is the original method of coarse feed using. Coarse feed with high quality such as gramineous hay, leguminosae hay, mulberry leaves, brewer’s grain, aginomoto residue and sugar beet pulp etc. can be directly fed to cud chewer, because their high nutritive value and utilizability, they can obtain a good feeding effect even without any processing. Therefore, these kinds of feed are generally fed directly or mixed with other materials without processing.    

II. Feeding after Processing

Broadly saying, formulation of hay and silage belongs to feed processing, the aim is feed storing, not improving the nutritive value. The processing methods we introduced are mainly technologies of increasing the feed nutrition and improving the feed nutritive value.

1. Physical Processing

Physical Processing is the method of change the shape of coarse feed, but keep the chemical property. Main methods including the following:

(1) Machine processing, such as cutting, crushing and grinding, are the most convenient and general method of coarse feed processing. Coarse feed being processing by these ways can be easy for animals to chew, reducing the energy consumption and increasing the food consumption, reducing the waste of straw. Machine processing has no obviously effect of increasing the digestibility, if the feed are crushed too fineness, it would reduce the digestibility. Experiment indicate that cutting and crushing of the feed can enhance the food consumption, but shorten the period of feed stayed in the rumen, this would result in the digestibility of fibrous matters decrease, producing speed of volatile fatty acids in the rumen and propionic acid ratio increase, ruminate reduce and pH value of rumen decrease.

(2) Hot processing, such as cooking and extruding. Cooking can soften the coarse feed, increasing palatability and food consumption. Extruding is using the high pressure vapor to process the feed and depressurization suddenly to destroy the fiber structure, effective to straw and even wood. According to the research, extruding has the effective of both physical and chemical. Extruding can low molecularization the lignin and resolve the structural carbohydrate, to increase the solubility elements. In this way, being extruded under the proper condition can sharply improve the digestibility of straw. However, this processing technology takes especially equipment cost, large energy consumption and high treatment cost, it is hard to popularization and application in the production now.

(3) Salinzation, mix the salt water of 1% with the grinded straw at the same weight, put the fee  into the container or on the concrete floor, cover by plastic film, standing for 12-24 hours, feed would soften naturally, and improve the palatability and food consumption obviously. This method is widely used in the northeast area and its effective.

2. Chemical Processing

Effect of chemical processing is generally better than the simple physical processing, and the equipment cost is less than physical processing. Most common and effective method of chemical processing are alkalization processing, ammoniation processing, ammonia/alkali recombination processing and acid processing, These method can effectively enhance the food consumption and digestibility of straw feed.

(1) Alkalization Processing

Straw feed protein content is low, when meet with ammonia, the organic matter come up ammonolysis reaction with ammonia, destroy the fat key combination between lignin and polysaccharide (cellulose, hemicellulose) chain, and become ammonium salt, which is the nitrogen source of microbial in the rumen of cows and sheep. At the same time, ammonia dissolves in water to form ammonium hydroxide, which can alkalize the coarse feed. For this reason, ammoniation is the processing method to ammoniate and alkalize the straw to improve its nutritive value. Being ammoniated processing, coarse protein of straw can increase 100-150%, cellulose decrease 10%, digestibility of organic matter increased to more than 20%, becoming the good coarse feed for cows and sheep.

(2)Alkalization Processing

Alkaline matters can weaken the hydrogen bond combination in the feed fiber, cellulose molecules puffing has less combination with the cellulose and lignin in cytoderm. Dissolution hemicellulose is better for cud chewers to digest the coarse feed. At present, there are mainly two kinds of treatment, sodium hydroxide processing and lime processing. Sodium hydroxide processing has a better effect but higher cost, and larger environment pollution; lime processing costs less but the effect is not so good as sodium hydroxide processing.

(3)Ammonia and alkali recombination processing

In order to improve the nutritive value of straw feed and enhance the digestibility at the same time, we can combine the advantages of ammoniation and alkalization. That is to alkalization the straw feed after ammoniating. If the digestibility of straw after ammoniating is 55%, it would rise to 71.2% after the recombination. The processing of recombination costs a lot but it can give full play to the economic benefit and potential productivity of straw feed.

(4)Acid Processing

Using vitriol, hydrochloric, phosphoric and formic acid to processing the straw feed, the principle is same as the alkalization processing. Acid would destroy the cellulose structure of the feed to improve the digestibility. But cost of acid processing is too high, it uses less in production.

3. Biology Processing

Biology processing take advantages of microorganism and enzyme, degraded the fiber of coarse feed, and produce sugar and mycoprotein to improve the palatability, digestibility and nutritive value. In production, there are usually three ways: ensiling, enzymolysis and fermentation. This method have few effect on coarse fiber dissimilation, but mainly water leaching and soften the feed, and produce sugar, organic acid, which improve the palatability. However, heat producing while fermentation would cause feed energy loss. 

(1)Ensiling is a kind of green feed store method which take advantage of the acidic condition by lactobacillus fementation, inhibit or kill the harmful microbe. Green feed and corn stalk with higher sugar content is easy to be ensiled, but straw, wheat straw are not easily to be ensiled.   

(2)Enzymolysis is to solve the cellulose, hemicellulose clastic enzyme in water, and spray on the straw to improve its digestibility, but the processing cost is high, difficult to carry out in practice.

(3) Microbe processing improve the digestibility by the fermentation of beneficial microorganism to reduce the wood fiber in the low quality coarse feed, soften the straw. Straw micro fermentation is one of the microbiological processing.

4. Recombination Processing

Singleness processing can not always can not reach to the ideal effect, especially the industrialization large-scale processing. Therefore, different processing technology should be reasonably assembled and matched, to make up mew type modulation processing. At present, most of the processing is to combine the chemical processing with machinery shaping, that is to cut or grind the raw material firstly, then alkalized or ammoniate the grinded material, adding necessary nutritious supplementary, and then further pelleting the straw feed or grass. This kind of recombination can satisfy the ammoniation and alkalization processing of feed, and also improve the physical behavior and palatability of straw feed, enhance the density of straw feed, which is convenient to transport, store and application. Recombination processing is high-efficient for factory, it’s the important method for the feed utilization in future.  

Selection of processing method should be decided according to the composite factor such as local production condition, coarse feed feature, economic input, feed nutritive value increasing range and economic benefit of livestock feeding. Feed processing of large scale enterprise should developed to intensification and factory-like. The vast rural areas should chose easy and proper methods and develop to professional processing and service system in order to promote the animal husbandry develop at high speed.