Corn silage is a feedstuff commonly used as part of beef cattle diets, boasting an impressive dry matter (DM) yield and digestible fiber content.
However, some concerns exist regarding the use of corn silage for beef cattle. It is essential to be informed about all aspects of this feed before providing it to livestock.
Contents
Quality
Corn silage can be an excellent feed for dry cows and heifers due to its high energy content. However, the amount of corn silage fed should be limited or combined with lower energy forages.
Corn silage must be harvested when its dry matter content reaches near 65% and the milk line in the kernel has changed to plus or minus 50% (Figure 1), in order to guarantee maximum starch availability to rumen for digestion.
Corn silage’s quality is assessed based on its nutritional value, intake potential and protein/mineral content. Different methods exist to evaluate corn silage’s quality; chemical, biological or instrumental.
A low NDF concentration and high ADF value are ideal. A lower NDF content allows the addition of additional fiber sources in the diet, while a high ADF value suggests good nutrient value from corn silage. Furthermore, low lignin content should also be considered when selecting corn silage for consumption.
Moisture
Moisture content of corn silage plays an integral role in its quality and nutritional value. Bacteria responsible for fermenting or pickling the silage need moisture to thrive, so it’s essential that harvesters select corn plants with the ideal moisture concentration when picking.
For optimal moisture, the ideal range is 65-69% (34-6% Dry Matter). Deviations from this range may result in a product that does not meet the needs of livestock and promotes mold contamination.
It is also essential to be aware that certain molds, such as aflatoxin and deoxynivalenol (DON), can produce mycotoxins which may be hazardous for livestock. Mycotoxins tend to be linked with cool temperatures and diseases like ear or stalk rot in corn.
At the end of the day, it’s up to the farmer to determine what’s best for his crop and operation. Generally speaking, starting harvest should occur when plants have reached 68-70% moisture level and then aim for a total plant moisture/dry matter ratio of 65% (35% DM) when cutting.
Fermentation
Fermentation is an essential step in corn silage production for beef cattle. Bacteria living inside the rumen convert glucose and starch to lactic acid and protein, while producing ATP – essential for energy metabolism as well as cell repair.
In addition to lactic acid, the fermentation process produces high concentrations of NAD+ (nicotinamide adenine dinucleotide), an antioxidant essential for normal immune function and reproduction. Without NAD+, various metabolic issues may arise.
Corn hybrids produce both quantity and quality of forage depending on several factors, including indigestible neutral detergent fiber (NDF) content, starch content and growing environment.
The amount of NDF found in milk depends on several factors, including hybrid type and climate; nitrogen fertilization; and maturity at harvest. NDF content has an important role in dairy cow diets during early lactation to promote proper chewing and salivation. Nutritionists balance rations for high-producing dairy cows to achieve the optimum NDF concentration to maximize intake and body condition while minimizing fermentation acids or inadequate buffering.
Mycotoxin
This summer and autumn have created ideal conditions for mold growth on corn fields across America. The combination of hot, dry weather and wet, cool fall temperatures has created ideal growing conditions for these organisms to take hold.
According to South Dakota State University Extension Dairy Field Specialist Tracey Erickson, feeding corn silage to cows may not be a wise idea depending on the mycotoxins present. According to her, mycotoxins can interfere with milk production, weight gain and rumen function in ruminants; they also cause liver and spleen damage in animals as well as reproductive failure and death; they may even be carcinogenic.
At present, several mycotoxins are present in corn and corn silage, such as deoxynivalenol, fumonisins, T-2 family and Pencillium toxins. These mycotoxins pose a risk to dry matter intake, milk production, rumen function and immune response of dairy cattle when introduced into these environments.
