Grains & Concentrates
Imported grain and concentrate supplements play an important role in feeding cows so they maintain health and productivity. This is because the quantity and quality of home-grown feed is rarely enough to fill feed gaps or fully meet animal nutrient requirements as they emerge.
Cereal grain supplements
Starch-based concentrates, such as wheat and barley are very common on most dairy farms in Australia. They are high in metabolisable energy (12.5 to 13.5 MJ ME per kilogram of dry matter) and provide a good supply of fermentable carbohydrates to the rumen. These feeds are complementary to grazed pasture as they are lower in crude protein than pasture but provide more fermentable energy. Usually, the rumen uses this energy to take advantage of the excess rumen degradable protein that is often present in high-quality pasture and use it to produce more milk.
However, there are limits to the amount of starch-based concentrates that can be safely supplemented to dairy cows. The starch in wheat and barley is quickly degradable in the rumen, which can cause rumen pH to drop quickly if too much is fed to cows, leading to acidosis.
It is generally recommended that roller or disc mills be used to process wheat, barley and triticale. Many farmers feed pellets instead of crushed grain. While generally more expensive pellets do have several advantages, the biggest being there is no time or equipment required to process pellets. In addition, pellets may be safer for rumen health at high levels of feeding, compared to crushed wheat or barley. This is due to the heat treatment received while being processed into pellets, potentially slowing down the rate of starch degradation in the rumen.
Maize grain is high in energy density and starch content. The starch in maize grain has a slower rate of rumen degradation than wheat, barley or triticale, making it slightly safer to feed to cows than other grain supplements.
Maize grain may be useful as a complementary grain to wheat when grain is fed at high levels per cow per day, cows are freshly calved, cows are at increased risk of ruminal acidosis or there is hot weather. To optimise milk responses from maize grain, processing prior to feeding needs to carefully control particle size. Hammer milling is more suitable for harder grains such a maize grain and sorghum grain.
Canola meal can be a useful supplement for dairy farmers looking to make the most of available pasture and has become a primary protein supplement for dairy cattle in Australia.
There are two types of canola meal – solvent extracted and expeller extracted. Solvent extracted canola meal stimulates dry matter intake and milk responses in grazing milking cows. If using expeller canola meal, ensure the diet does not exceed the recommended maximum of 5 per cent total fat.
Best milk responses occur when canola meal replaces part of barley or wheat supplement at moderate to high levels of intake. At least 1.7 kilograms of canola meal per cow per day is normally required for a substantial milk response. Feeding canola meal may also be a useful grazing tool to maintain quality of spring pasture and canola meal is also an effective supplement for calves, heifers and springers.
Lupins have a hard outer shell and must be cracked in order to be efficiently digested. Heat treatment of protein grains during processing can increase the amount of bypass protein – the protein digested beyond the rumen – which, in some instances, can result in improved milk yield responses.