Conversations: Ask your nutritionist about feeding drought-stressed corn silages
The hot and dry weather this year affected the dairy industry in a variety of ways. In addition, feed costs continue upwards, along with high fuel and health costs, shrunk credit lines and tight environmental regulations. As producers and their advisors meet in the months ahead, making best use of drought-stressed corn silage (DSCS) will likely be a common topic of conversation.
By Renato Schmidt, PhD
& Bob Charley, PhD, PMSB, CBiol
Drought-stressed corn typically has decreased field yield and lower grain concentration. Although ensiling drought-stressed corn results in a different type of silage; as long as the whole ensiling process is closely monitored and well-managed, the result should still be a reasonably good feedstuff.
1) How is silage made with drought-stressed forage different from the typical silage?
To begin with, drought-stressed silages can have a wide range of moisture contents. DSCS may be harvested immature, because of the dried appearance, although the stalks hold a lot of moisture. Data from Dairyland labs showed that the corn silages analyzed in July (1,386 samples) averaged only 25.2% DM. Also, within a crop you can also see high variability in the moisture content due to inconsistent dry-down/ overall maturity at the time of harvest.
Discuss with your nutritionist when and how often to test the moisture content of your silages. Inquire about the tests available and about adjusting the feeding rates of the other ingredients in the ration to minimize inconsistency.
2) What other nutrients may vary significantly in DSCS?
Levels of starch and sugars are affected, due either to harvesting the corn plant too early and/ or poor ear fill and grain yield. Note that the high moisture content associated with high level of soluble sugars will have an impact on the fermentation and feed-out stability of the silages.
Ask your nutritionist about analyzing the silage for starch and digestibility and possible need to adjust levels of concentrate/ grain in the diet accordingly.
3) What about nitrates?
DSCS may accumulate nitrates, which, in the animal, may be converted to nitrites, which can interfere with blood hemoglobin, preventing normal oxygen uptake. Corn that is rained on after a drought should not been harvested for 4-5 days. However, the best method to re
duce nitrates is ensiling, which can lower their levels to approximately 50%.
Test the silage for nitrates before feed-out and also check the water nitrate levels. Ask your nutritionist to help interpret the lab results: they may be expressed in ppm or %DM, and as nitrate or nitrate-N.
4) Is there any hazard working with drought-stressed corn silage?
High concentrations of nitrates may increase the production of the gas nitrogen dioxide(NO2). NO2 is heavier than air and accumulates in low spots. It smells like bleach, has a yellow-orange color and inhalation can cause lung damage or even immediate death.
Make sure you run a blower before entering an upright silo, wear a mask/respirator and be careful around vents in silo bags. If you see yellow/ orange gas, allow it to dissipate before going near the area.
5) There have been reports of corn fields infested with ear rot. Are there any major issues that can be associated with that?
This disease is caused by two Aspergillus molds that may produce aflatoxins, an extremely toxic compound, or other mycotoxins. The dry, hot conditions during grain fill can increase the risk of toxin production. However, these molds need ears and/or kernels on the ears to develop and potentially produce aflatoxin; thus salvage corn without ears or kernels, should be at lower risk.
Work with your nutritionist to properly collect silage samples for mycotoxins analysis. If aflatoxins are present, consider use of clay-based absorbents. If there are other mycotoxins, e.g. T-2, vomitoxin (DON), zearalenone, consider using yeast cell wall extracts (MOS products).
- Renato Schmidt, PhD (left) is Technical Services – Forage for Lallemand Animal Nutrition. Contact him via phone 414-578-3443 or e-mail firstname.lastname@example.org.
- Bob Charley, PhD (right) is Forage Products Manager and Technical Services Manager for Lallemand Animal Nutrition. Contact him via phone 414-336-9549 or e-mail email@example.com.