Today’s forage sorghum market offers a huge range of varieties and it can often be a maze
to navigate which variety is best for your circumstance.
Forage sorghums are bred from multiple crosses and combinations and hybrids of Sudan grasses, sorghums, and sweet sorghums. With good nutrition and adequate moisture, forage sorghums can be multiple grazed or cut for hay or silage. Sorghums are quick to establish, they use water efficiently and produce good amounts of dry matter.
All forage sorghums need to be managed to obtain their best quality. Ideally they should be grazed between 650 and 1200mm height. If sorghums are left to grow beyond these heights they produce a lot of bulk but the quality dramatically declines.
Periods of plant stress due to cold or dry conditions increase the potential incidence of prussic acid poisoning. This can be a serious issue for animal health. To help minimise prussic acid poisoning risk and digestibility issues, graze or cut the forage at the heights mentioned above. The inclusion of a Sulphur lick block in the pasture can also be helpful.
Sudan crosses often have finer leaves and recover quicker after grazing or cutting for hay or silage. Sudan grass types still have the potential for prussic acid issues but are a lower risk than other forms.
FeedEx forage sorghum is a fine leaved hybrid forage Sudan x sorghum cross. Its fine stem lends
itself to grazing, hay and silage production. It has very good leaf to stem ratio with the
ability to recover quickly after cutting or grazing.
BMR Fuel® forage sorghum is a new variety in our range. It also has fine stems with very quick regrowth potential with its Sudan x sorghum cross. What is special about Fuel is it is a BMR, Brown Mid-Rib, variety. The inclusion of this gene can produce quality feed with lower levels of lignin (Indigestible fibre) compared to conventional types.
Nudan Sudan grass is also a fine stem quality forage at the top end of the market. It has established a strong reputation for quality hay production and grazing. Its finer stems allow a quicker dry down and has a lower prussic acid risk.
Millets can be a safer option than forage sorghum as they don’t have any issues with prussic acid. However millets will not produce the same volume of dry matter as forage sorghums as the potential for millets to recover from grazing or cutting for hay is generally low.
Millets can be useful to fill feed gaps through early spring and autumn. The dual purpose types Japanese and Shirohie will germinate in cooler soil temperatures (14 – 16 degrees) than other millets and forage sorghums. Both these varieties have rapid early growth and can be grazed in four to six weeks at 250-400 mm of growth. Both varieties are quick to mature and should be grazed early to maximise quality.
The variety Siberian is not as cold tolerant as Japanese and Shirohie. It performs best with soil temperatures similar to forage sorghums at 18 degrees. Its early growth is not as quick as Japanese and Shirohie but it has a longer growing season which really peaks in the warmer conditions. Due to its longer production window it also produces more dry matter. It has a prostrate growth habit with a higher tillering capability and has the ability to recover from grazing well, maintaining good palatability and quality.
Pearl millet types require soil temperatures of 18 degrees and rising. These types will produce higher levels of dry matter and are suited to grazing and hay production.
Other varieties of millet can be very quick maturing and don’t produce large volumes of dry matter.
White French, for example, is not very palatable and can cause photosensitivity issues for stock.
Nutritional inputs of millets are lower than forage sorghums with Nitrogen preplant levels of 30 – 50 kg/ha being required for most reasonable dryland crop production.
For best results legume crop seed should be inoculated. As they are legumes nitrogen fertiliser
is usually not needed. However other elements such as phosphorous are important. Nitrogen
fixation is an important by product of growing legumes along with the improved protein content
and forage quality.
The table below shows some indications of feed quality of these legumes in general terms by NSW DPI:
ME (MJ/ kg DM)
There are a range of suitable summer forage grass and legume crops that can be grown for grazing and hay or silage production. The choice of crop/s depends on the livestock enterprise and the end use required. In the current conditions where many areas are in severe drought the primary need will be for quick feed where pasture and fodder supplies have been exhausted. The forage sorghums, sudan grasses and millets have usually been the crops of first choice. Seed shortages of these will mean producers may need to look at other options such as the legumes cowpeas, lab lab and soybean if they are in suitable environments for these crops.
Animal health risks such as prussic acid poisoning and nitrate poisoning can be worse in drought conditions. Careful management of summer crops will be required to minimize these risks.
NSW Department of Primary Industries: Summer legume forage crops: cowpeas, lab lab, soybeans