For farmers that faced with decreasing supplies of forage due to delayed planting or harvest, it may be encouraged to increase the level of corn silage fed to the cows.
Feeding high forage diets can be an economical way to feed dairy cows and this can be accomplished using corn silage exclusively as forage source. Here are some of the concerns farmers should be aware of when feeding high corn silage:
1. Evaluate silage kernel processing
Starch in corn silage is a valuable but the kernels have to be sufficiently damaged to allow complete starch digestion.
It is encouraged to send samples of kernels to get a better understanding of how well the starch will be digested in the rumen and small intestine.
2. Don't overfeed starch
Starch in corn silage is often the culprit when cows fed high levels of silage experience low butterfat or inconsistency in manure scores.
It is important to test he corn silage to allow nutritionists to factor in the effect time in fermented storage has on increasing ruminal starch availability.
From the point of ensiling until 6 months later, starch digestibility in corn silage can increase by as much as 20%.
Careful not to use too much high-moisture corn in the diet as they will also have elevated ruminal digestion rates late into the storage season.
3. Take note on effective fiber
If the chop length of the corn silage is short, it may be necessary to find an effective fiber source such as a lower quality hay or straw to create a rumen mat matrix to help stimulate cud-chewing and production of saliva to buffer rumen acid production.
It is important to evaluate the freshly delivered TMR and the refusals after 3 - 4 hours in the feedbunk with a Penn State Particle Separator in order to determine if sufficient effective fiber is present and if any sorting has occured.
4. Do not overfeed supplemental fat
Having tallow supplementation (2% of ration) in rations with high corn silage will reduce intake and lower fat test although the cause and effect is not fully understood.
It is recommended instead to feed rumen bypass fats which will help provide sufficient energy to the cows to improve milk production.
Understanding the types of fat is equally important as not all types of fat sources are created equally.
5. Rumen bacteria will provide a lot of protein
High energy corn silage will grow lots of rumen bacteria, which the cow will digest as a high quality protein source.
In a field trial, success have been achieved in rations containing up to 25 pounds of dry matter from high starch corn silage by targeting around 16 - 17.5% crude protein levels with conservative levels of ruminally degraded protein to fuel bacterial needs and attention dietary lysine and methionine levels.
6. Avoid feeding rations high in corn silage to dry cows or heifers
It is not encouraged to feed exclusive corn silage rations to dry cows or heifers as these energy rich diets will result in fat heifers and cause problems for dry cows.