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Ask the Vet Column: 2023 was a bad year for forages, what should I be looking out for when feeding stored feeds?

By Dayna Locitzer, DVM

Dayna Locitzer, DVM

Last year’s forage year in the Northeast brought many challenges. You might have been able to hit a sweet spot if you completed first cut in late May, but for many that was not possible and you were then stuck with two months of wet weather. This led to a few common problems when making baleage: Baleage that was wrapped too wet, first cut hay that was cut too late, and baleage made from grass covered in silt from the flooding. Now, I am not a nutritionist but I do know that I have seen serious health issues caused by the above mentioned problem bales.

Wet baleage is like a wet blanket at a party, no fun. It is heavy to lift, messy, and most importantly detrimental to rumen function and animal health. This is because the increased moisture promotes the development of butyric acid during the fermentation process or clostridial fermentation. High butyric acid feed has been known to cause ketosis as well as poor rumen function. To encourage proper fermentation, it is best to aim for 50-60% dry matter.

Improper fermentation also promotes the overgrowth of bad bacteria. These bacteria can be damaging to the normal flora of the cow’s rumen and can even be deadly. The most concerning of these bacteria is called Listeria monocytogenes and causes what’s known as Listeria or “Circling Disease”. Listeria is a bacteria that infects the central nervous system of a cow and progresses quickly. The only known effective treatment is antibiotics and even animals treated rarely recover. Listeria can also be shed to the milk and poses a serious food safety risk to humans. Be very careful of any mold on your bales, you can manually remove the spots you see but really moldy bales were not properly fermented and should not be fed to any animals. Keep in mind, there could be smaller spores throughout the bale that can be harder to see.

Improper fermentation can also occur when there are not enough sugars to support the fermentation process. We see this scenario with late first cut bales that ensiled mature grasses with minimal starches. This might have happened last summer if you were not able to get to your fields until late July or August. This situation could lead to an overgrowth of yeast as well as molds. These yeasts negatively impact the rumen, creating a severe indigestion health crisis. This indigestion can be so severe that it shuts down rumen function resulting in death. A good way to know how many yeasts and mold causing bacteria you have is by doing a mold and yeast count on your feed. The lab will provide parameters when you receive results.

This year we experienced record flooding all over New England. Most immediately, it resulted in animals stranded and unable to get back to the barn, farms were unable to graze for weeks due to water logged pastures, and forage was unable to be harvested in a timely manner. If your hay field was under water from a flooded waterway, it likely has areas covered in silt. If harvested, this led to excess debris collected in your forages and likely resulted in improper fermentation. This silt provides a medium for bad bacteria and yeasts to overgrow, leading to hay that is not actually preserved, but spoiled. This scenario would be reflected in the ash content of your forage analysis and be interpreted with the other fermentation parameters.

All of these risk factors are important to keep in mind when considering making baleage and the quality of your stored fermented feeds, but the only way to know is by getting it tested. Not only is it important to do a basic feed analysis but it is critical to also get a fermentation analysis and mold and yeast count. I’ll go through some fermentation parameters to keep in mind when looking at your forage analysis. Ideally, you want the pH to be below about 5.0, indicating there is an acidic environment representative of lactic acid fermentation. To make sure lactic acid fermentation occurred, ideally the lactic acid should be greater than 3% and the butyric acid should be 0. As for the ash content, that represents the internal sources (macrominerals in your plants) as well as external sources (soil, silt, sand, clay)--you want to minimize the amount in that latter category. The target value for ash is below 10%. And like I mentioned above, mold and yeast counts will show you if your bales are safe to feed in the realm of microorganisms.

Knowledge is power in this situation. If you know you have better quality bales than others, you can alternate what bales get fed. You can reserve your highest quality bales for your lactating herd. Or, you could consider purchasing feed. While you can get away with feeding small quantities of poor quality hay, you are only hurting your bottom line and the wellbeing of your cows if you feed a lot of it.