Developing silage strategies
Silage technology can help you improve herd health and productivity; however, it’s wise to plan well in advance of harvest, according to Michelle Chang-Der Bedrosian, Ph.D.
Chang-Der Bedrosian directs research and development at Animix LLC and presented “Beyond the Basics: Cutting-Edge Silage Strategies that Will Change Your Season” at the recent Herd Health & Nutrition Conference hosted by Cornell PRO-DAIRY and Northeast Agribusiness & Feed Alliance.
Chang-Der Bedrosian believes that recent advances in silage science can matter a lot if farmers implement changes before silage season starts.
“Our conversations need to change,” she said. “We used to talk about dry matter at harvest, chop length, packing density and lactic acid-producing inoculants.”
But she thinks those conversations need to change as emerging research looks more closely at microbial ecology, fermentation pathways, nutrient preservation, aerobic stability, feed out management and length of storage.
Silage is more than fermented feed; it’s a microbial ecosystem. About 60% to 70% of farms, especially larger farms, use inoculant. But Chang-Der Bedrosian wants more farmers to ask, “What fermentation pathway are we trying to push and why?” and “What risk organisms are likely on this crop and how can we combat those?”
Recent work focuses on the microbial ecology of silage, such as microbial communities driving fermentation trajectory and looking at the wide population of native silage. Elements affecting silage include crop species and maturity, fertilization, location, weather and the previous crop. The fermentation outcomes depend upon microbial competitions of temperature, oxygen and microbial ecology.
“Microbial communities inherent on the plant drive fermentation trajectory,” Chang-Der Bedrosian said.
Leveraging microbial ecosystems can help maximize nutrient preservation.
“Dry matter losses are not uniform,” she said. “Dry matter losses lead to less silage. There’s poorer quality silage. Spoilage yeasts and aerobic bacteria target the highly digestible portion of the crop.”
New research focuses on energy losses during fermentation, not only dry matter losses. “Historically, you’ll have 8% to 10% loss of silage,” Chang-Der Bedrosian said. That figure implies that it’s over the whole crop, but she clarified that the loss is primarily the best of the silage.
“When someone robs your house, they don’t steal the garbage,” she said. She wants more farmers to pay attention to the “gems and jewels” of highly digestible silage robbed by dry matter loss.
Poorly sealed silage causes poor dry matter recovery, less sugars for fermentation, less total acids produced, higher pH and more Clostridia.
“We used to think we have to get alfalfa pH below 4.5,” Chang-Der Bedrosian said. “Now we know in wet crops you need to work harder to get pH even lower.” (Silages that are delayed in sealing have a higher overall pH.)
“Inoculants are not all the same,” she said. “I encourage you to ask for research. There are also good low-cost inoculants. [But] inoculants don’t replace good management.”
Fermentation happens faster than was previously thought. “It used to be 21 to 31 days,” Chang-Der Bedrosian said. “Now we know the dominant microbial community stabilizes very quickly. The war is a short one. The first 72 hours are disproportionately important. The reality is, it’s when people are tied.”
Sugar availability, microbial populations, packing density and oxygen exclusion have not decreased in importance. But there are more methods for achieving these goals.
“Microbiome sequencing helps to understand microbial shifts during fermentation and how we can manipulate these to our benefit,” Chang-Der Bedrosian said. “Enzyme and microbial combinations are advancing quickly to improve digestibility and fermentation. We used to think bacteria act alone. Now we know each bacterium is part of a larger microbial ecosystem with metabolic cooperation between them all.”
Novel stability additives – including possibly essential oils – can provide new ways to combat spoilage, although more research is needed.
Inoculants are facing more challenges with extreme heat and extreme cold, as climate variability is changing silage risk. This can cause unstable fermentations, unusual fermentation proles and higher spoilage risk.
More yeasts are surviving than previously realized.
“Yeasts remain dormant during fermentation; they do not die as much as we thought they do,” Chang-Der Bedrosian said. “They use lactic acid as the main fuel for spoilage when exposed to oxygen. If you pick up the silage and it’s warm, that’s bad ‘bunk life.’”
Oxygen is the most expensive issue with silage, as it’s used up within hours of sealing and oxygen infiltration can extend 1.5 to five feet into the face of the bunk silo.
“A large volume of your silage can be slowly deteriorating before visible heating occurs,” Chang-Der Bedrosian warned.
Major drivers include packing density, particle size, silo structure, feed out face management and silo plastic integrity and management.
She advised filling silos quickly, packing tightly, using six-inch layers, minimizing mud from tires, using heavy tractors, keeping the tractor on the pile and staying attentive for good silo density.
After packing, seal the silage in with an oxygen barrier lm, seal the edges and use uniform surface weight to help prevent undue spoilage. Since most silage loss happens near the surface and sides – not the core – farmers need to protect these areas better with tight seals.
“I’ve seen a lot of people using spray glue to seal the seams and I like that a lot,” Chang-Der Bedrosian said.
To decrease ash in the silage, she encouraged farmers to drive slower.
“The minimum time to store silage before feeding is three months for corn, three weeks for alfalfa,” Chang-Der Bedrosian said. “Where will you put your carryover silage to make sure we’re meeting that minimum?”
She wants farmers to consider before silage season which fermentation pathway they want to favor and why; what microbial risks exist in the crop; the aerobic stability risk during feed out; if the packing strategy is adequate for oxygen control; and how the farm can leverage time to get the most nutrients out of the fields and into their animals.
