1. Types of feed sorghum

Sorghum used as feed can be divided into grain type sorghum and stem and leaf special type sorghum.

Sorghum grains are an excellent feed and have a long history [3]. In developed countries such as the United States, Canada, and Australia, sorghum grains are mainly used for compound feed, and 10% to 25% of sorghum grains are usually added to the feed as ingredients [4]; in France, 70% of sorghum grains are used as industrial fermented feeds [ 5]; while in my country, it mainly appears in the form of farmers directly feeding livestock. It is a primitive, unprocessed roughage with a dosage of less than 5%, and the proportion of sorghum in the formula feed is extremely small [6]. With the development of animal husbandry, sorghum will become one of the main raw materials of compound feed in my country.

Stem and leaf-specific sorghum includes two types, namely sweet sorghum and grass sorghum (sorghum-sudangrass hybrid).

Sweet sorghum is mainly used as silage in many countries such as my country and Australia. In addition to the general characteristics of grain sorghum, sweet sorghum has juicy stems, rich in sugar, tall plants, high biological yield, strong early resistance, good palatability, and strong regeneration ability, and can be used for green feeding and sun-made hay. Or silage, suitable for feeding various herbivores [7].

Grass sorghum has the characteristics of high yield, strong stress resistance, and high nutritional content. Its crude protein and crude fiber content are higher than other pastures such as Sudan grass, mignonette, and green cut corn. It is an excellent forage after alfalfa. Grass sorghum can be used for grazing, green forage, silage and hay storage.

2. Advantages of sorghum as feed

1) High yield, good quality and strong tillering ability

Generally, sweet sorghum plants used for forage are tall and strong, with juicy stems and lush stems and leaves. They can produce 6000~75 000 kg/hm2 of silage. The silage yield is higher than that of forage corn. At the same time, they can also receive 4500~7500kg/hm2. The nutritional content of grains is equivalent to or better than that of feed corn. Compared with corn, grass sorghum has stronger tillering ability and can be regenerated after being cut. It can be cut and utilized multiple times in one growing season. Corn has poor tillering ability and can only be cut once in one growing season.

2) Strong resistance to stress

Forage sorghum also has the advantages of ordinary sorghum, that is, it has strong stress resistance, is more resistant to drought, waterlogging, and salt and alkali than corn, and is more resistant to leaf diseases and smut. The amount of fibrous roots per unit area of forage sorghum is about twice that of corn, and the water absorption capacity of the root system is stronger than that of corn, but the leaf transpiration area is only half of that of corn, saving 1/3 of the water than growing corn. In the event of a severe drought, forage sorghum can enter a dormant state and will immediately resume growth once the drought is relieved, while corn will wither.

3) Wide adaptability

Because feed sorghum has the advantages of drought resistance, waterlogging resistance, and salt-alkali resistance, it can be planted in general cultivated land, wasteland, and saline-alkali land with a pH value between 5.0 and 8.5, and can make full use of more inferior land.

4) Wide range of uses and high nutritional value

Sorghum is a gramineous crop. Compared with other forage crops, sorghum loses less nutrients during forage processing and has a high utilization rate. It can not only be used for mowing, silage and making hay bales, but can also be made into grass meal compound feed. When feed sorghum is siled alone, its nutritional value is higher than that of corn or hay. When mixed with corn, it can make up for the lack of moisture and sugar in the silage corn. The silage is of good quality and rich in nutrients. Cows like to eat it and are easy to digest and absorb.