Time for a checkup: Corn silage quality may be highly variable this year

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corn silage

Many health insurance providers request that you obtain a biometric health screening, get an annual physical exam by your primary care physician and possibly complete a series of questions relating to your physical and emotion health, referred to be some as your personal health assessment.

For some health insurance providers, now is the time of the year they want you to complete these items (I started to say ‘exercises’, but this is probably not the best word to use in this context). In addition, it’s the time of the year to get the flu vaccination.

Farm checkup

So for the feeding program on the farm, it’s the time of the year when we need to do a checkup on the corn silage. It has likely been in storage long enough now that some of you are feeding the 2015 crop of corn silage, possibly out of necessity, or it has been in storage long enough (four to eight weeks preferred) to be stable from the fermentation. Each year, we need to be checking the quality of the corn silage so rations can be reformulated based on the current crop.

Lots of variation

Due to the excessive rainfall early in the growing season, there has been considerable variation in corn development — and that means there is certainly variability in quality of the crop, based on geographical area relative to rainfall received. However, there is considerable variation this year from farm to farm in the sample geographical area and from field to field within a farm due to slope of the field and suitability of the soil drainage. Thus, yield and quality of corn silage within a farm may be highly variable this year.

Energy and fiber

The primary nutrient that is provided by corn silage is carbohydrates (about 75% of DM) for energy and fiber. Of course, it provides other nutrients, such as protein, but of lesser total contribution to diets for dairy cattle. As noted in Table 1 below, DM of the corn silage can be very variable and to the extent that this relates to maturity at harvest, it certainly affects quality of the corn silage. Areas of the field this year with short stalks and poor ear development will likely result in corn silage with lower starch and higher NDF concentrations. If the stalks were just short but ear development was good, then concentrations of starch may be higher and NDF lower than for typical corn silage.

An increase in NDF and decrease in starch will lower the energy concentration in the forage, or vice versa. However, the growing conditions also may negatively affect the digestibility of the NDF. The fiber in the corn silage is very important for keeping the rumen healthy, but the digestibility of the NDF is very important for providing energy to the animal.

Sample it now

Work with your nutritionist on obtaining proper samples and interpreting the results from the laboratory. It’s time to do this now rather than waiting to see how the cows do on the new corn silage when considerable milk yield could already be lost. With current low milk prices, you need to sell all the milk you can rather than experiencing lost opportunity from unbalanced rations. And by the way, go ahead and schedule your annual physical exam and flu shot.

Table 1. Typical composition of corn silage based on samples submitted from May 1, 2000, to April 30, 2015, to the Dairy One Forage Lab in Ithaca, N.Y. (dairyone.com)

ItemAverageSDCV%Typical Range
DM, %36.614.740.221.8-51.3
CP, % of DM7.861.2415.86.61-9.10
Starch, % of DM33.07.823.625.2-40.8
ADF, % of DM24.44.317.620.1-28.7
NDF, % of DM42.56.314.836.2-48.8
NDFD 30 hr, % of NDF52.16.312.145.8-58.4

DM = dry matter, CP = crude protein, ADF = acid detergent fiber, NDF = neutral detergent fiber, NDFD = NDF digestibility, SD = standard deviation, and CV = coefficient of variation ((SD/average) * 100).

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