Brought to you by Limagrain
Rumen energy from maize is good for cows and the climate
The share of maize in dairy rations is under pressure. That is a shame, because silage maize is valuable in the diet of dairy cows, says researcher Wilfried van Straalen. Energy from maize is crucial for the efficient production of milk protein from nitrogen. In addition, feeding corn helps to reduce emissions of the greenhouse gas methane.
Cows need energy for milk production, says Wilfried van Straalen, cattle nutrition consultant at the Schothorst Feed Research animal nutrition institute. "If you can feed little or no maize, you have to go to alternative energy sources, such as starchy concentrates, maize flour or crushed grains. From the point of view of feed costs, it is interesting to be able to save on concentrates with good maize in the ration."
Rumen available or gut available
The energy of maize comes largely from starch. For the feed of ruminants, a distinction is made between unstable and resistant starch. The first variant is digested in the rumen and provides rumen-available energy in the form of volatile fatty acids (including propionic acid). The second form passes through the rumen intact and is largely broken down in the small intestine, where it provides intestinal available energy in the form of glucose.
Both energy sources are good, the optimal starch composition of the maize is related to the rest of the ration. Grass-fed rations can use a lot of energy available in the rumen to utilize the nitrogen. As the proportion of grass or non-resistant protein in the livestock's diet decreases, so does the need for non-resistant starch. Too much energy at rumen level causes rumen acidosis. As the proportion of maize increases, the starch may be more resistant.
But excess hurts. "If the small intestine cannot process the amount of resistant starch, part of it enters the large intestine undigested. Then colon acidification can occur. The animals become thin on the manure and production declines. The optimal amount of resistant starch is between 45 and 75 g/kg.
Digestibility cell walls
In addition to the amount of starch, the digestibility is interesting. Almost half of the energy in maize comes from starch. A quarter to a third comes from the cell walls. A cow can use the starch almost completely. The digestion coefficient is 95 percent or even higher. For cell walls, the digestion coefficient is 45 to 60 percent. The number can vary greatly per breed. Digestibility becomes more important for rations with a lot of maize, says Van Straalen. Because in that case it is not the starch content but the feed intake that is the limiting factor. The better the digestibility, the better the use of energy. With a small proportion of maize in the ration (less than 30 percent on a dry matter basis), the more starch the better.
What is the best breed?
What does all this mean for the grower's choice of varieties? Which breed is best? Van Straalen: "Livestock farmers tend to pay attention to yield and VEM. But you also have to look at the figures behind it. How much starch does the maize contain and the VEM comes mainly from the starch or also from a good digestibility of the cell walls?"
STARPLUS varieties for an extra large amount of unstable starch
When choosing the silage maize variety, a farmer has to consider various considerations. The desired properties of the maize in the ration are important in this regard. To make the choice easier, Limagrain is introducing a new label within the LG Animal Nutrition range. The maize varieties with a very high proportion of non-resistant starch get it STARPLUS label† These varieties are ideal for low maize rations:
