Starch is the legend of modern dairy. The story begins with a cornfield where sunlight transforms water and carbon dioxide into sugar, which is stored in grains in the form of starch. Cows, as ruminants, have a unique ability to use cellulose (fiber) and starch (grain) as energy sources.
The challenge for dairy farmers is to maximize energy in their diets while minimizing the cost of starch or grain. In order to reduce the cost of starch, it is very important to improve the digestibility of starch.
Starch research in corn and cattle feed is not new, but the recently introduced "powdery" silage maize hybrid has caused market confusion. When someone claims that corn hybrids with "powdered" starch grains have higher starch digestibility, what right questions should be raised? In fact, is this trying to solve a problem that does not exist at all?
1. What's the difference between powdered corn and hard starch?
当种子公司谈论粉末状的淀粉杂交种(也被称为软杂交种)时，他们指的是在玉米粒中发现的白色淀粉颗粒的数量。玻璃状淀粉(又称硬淀粉)是一种存在于成熟玉米粒外缘的致密黄色淀粉粒。当玉米籽粒水分含量低于20% ~ 25%时(黑色层后)，玻璃状淀粉更加突出。
When seed companies talk about powdered starch hybrids (also known as soft hybrids), they refer to the number of white starch grains found in corn kernels. Glassy starch (also known as hard starch) is a kind of dense yellow starch grain existing in the outer edge of mature corn grain. When the moisture content of corn grain is lower than 20% - 25% (after the black layer), the glassy starch is more prominent.
In powdered and glassy corn grains, starch grains are surrounded by proteins (gliadin or zein). There are more zein in the glassy region, and through these zein, it shows stronger adhesion to starch. An example of a high glassy corn hybrid is popcorn. In addition, many northern European maize hybrids are hard type and contain more glass starch. Most Maize Hybrids in North America were bred with soft genotypes with high starch content.
2. Where is the starch digested?
Many claims about hybrids with high starch digestibility emphasize the importance of increasing the number of rumen microbes. This is important, but Rumen Digestibility is only part of it. Starch digestibility depends more on the answer to the following questions: how much starch is digested in the digestive tract (rumen + small intestine + large intestine), and how much is seed gene related to seed processing and storage management?
The content of starch in feces is easier to measure in the whole digestive tract. The results showed that when silage, high moisture corn or dry corn seeds were properly treated, the starch digestibility of the whole digestive tract of lactating dairy cows was over 95%.
Nutritionists measure less than 2% to 3% of starch in faeces from well managed herds. If 98% to 99% of the starch in corn silage and grains eaten by cattle is digested, then the question is: what are we going to solve?
Although the digestive capacity of the whole digestive tract is the most important, it also helps to understand the balance of digestive starch of the whole cow. The digestion of starch in rumen is conducive to the cultivation of more rumen microorganisms, so as to provide protein sources for dairy cows.
However, too much starch digestion in the rumen can lead to acidosis and reduce the food intake and milk composition of dairy cows. Rumen starch (absorbed by the gut in the form of glucose) produces 20% more energy than rumen digested starch.
3. Is there genetic difference in the digestibility of corn starch?
The results showed that when the moisture content of corn grain was more than 25% (typical moisture content of silage corn or high moisture corn), there was little difference in the starch content of hybrid.
In the harvest process, when the moisture content of corn grain is lower than 20% - 25%, there may be differences in the content of glassy starch among the hybrid varieties. Even these differences can be small and vary from year to year depending on the growing conditions.
4. What can improve the digestibility of starch?
The results showed that the main factors affecting the digestibility of corn silage, high moisture corn and dry corn starch were as follows:
Grain size of corn - mainly affected by corn processing or milling.
Fermentation time - the digestibility of starch in silo increased about 6 months before stabilization.
(3) harvest of corn grain maturity or moisture content (1 / 2 milk line and black layer) - influence the development of vitrified starch.
(4) corn planting environment, including weather related factors and nitrogen fertilizer.
The most important factor to manage the starch digestibility of maize is to constantly monitor the grain size of Maize during the field harvest. Although the market tends to be "powdery" starch maize hybrids, it is most advantageous to concentrate gene selection on Yield and agricultural economy.
The above is the relevant content introduced by corn starch granule manufacturers. To learn more, please visit the website: http://www.rsoau.com