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Evolution of Inoculants as a Forage Management Tool

 

Evolution of Inoculants as a Forage Management Tool

by Bill Mahanna

Dairy producers and their nutritionists are constantly looking for ways to improve forage yield and nutritional quality. This includes areas such as:

  • Hybrid or variety selection
  • Use of crop consultants to help manage agronomic issues
  • Harvesting at optimal crop maturity
  • Wide-swathing alfalfa or high-chopping corn silage
  • Ensuring proper chop length (and kernel processing in corn silage), proper moisture, silage compaction and use of oxygen-barrier film and plastic to protect against surface spoilage
  • Silage inoculation
  • Proper face management to reduce nutrient loss and improve palatability
  • Increased understanding of how length of time in fermented storage changes feed digestibility

When one thinks back on the technological advances that have directly impacted forage, the inoculant industry may be among the most innovative. Granted, there have been improvements in forage genetics, and the equipment industry has delivered significant gains in harvest efficiency and implements, such as mergers or bunker facers. However, when you think of the scientific advances in microbiology that makes improving fermented feeds possible, the inoculant industry has delivered significant technologies over the past few decades which help:

  • Reduce silage pH and conserve sugars
  • Reduce heating on increasingly large silage faces
  • Reduce dry matter loss (shrink) whose energy value must be replaced with very expensive grain sources
  • Improve consistency and palatability of ensiled feeds
  • Produce fiber-degrading esterase enzymes that grow in silage when treated with inoculants which contain a Lactobacillus buchneri strain

Improving fiber digestibility has long been the ultimate goal for companies selling inoculants. Research clearly shows that adding certain enzymes to the TMR can improve fiber digestibility. The problem is that growing enzyme-producing bacteria in commercial fermentation tanks, purifying and stabilizing the enzymes and selling through distribution channels makes their use economically unviable for the silage market. Products that contain traditional fermentation bacterial strains along with enzymes have never been shown to improve digestibility beyond those containing bacteria alone. This is likely due to the high cost of purified enzymes prohibiting adequate inclusion rates. Our research microbiologists have isolated a bacterial strain that is resistant to low pH and still capable of producing an esterase enzyme that allow rumen bacteria to access the fiber portion of the cell wall with less interference from the surrounding lignin.

Research at our Livestock Nutrition Center as well as dozens of field studies have shown that the carbohydrate pools (B1, B2 and B3) as defined in the Cornell Model, have an increased rate of digestion in silages inoculated with an esterase-producing bacterial strain. Changing these digestion rates in ration-balancing software (like the CNCPS model) shows that the inoculated silage produces more metabolizable energy (ME) and metabolizable protein (MP) predicted milk while also yielding more microbial protein production (from rumen bacteria being able to more easily access the digestible portion of the cell wall).

As a practical example, the ration that comes pre-loaded with CNCPS V6.1.32 is balanced for 90 pounds of milk, 55 pounds of dry matter intake and includes 62 pounds of as-fed corn silage. Increasing the digestion rates on the carbohydrate pools with the use of an esterase-producing corn silage inoculant, caused the program to predict 2.1 pounds more ME milk, 5.26 pounds more MP milk and 96 grams more microbial protein yield.

Some nutritionists are finding success with removing grain and protein from rations containing silages treated with the Lactobacillus buchneri strain that produces fiber-degrading esterase enzymes, allowing for increased forage inclusion rates and typically less expensive rations. In the example above, the model shows it is possible to remove 1.6 pounds of corn grain and 1.0 pound of 44 percent soybean meal while increasing corn silage inclusion by 6 pounds, and after paying for the inoculant, a producer would still save nearly 15 cents per cow per day at current Midwest feed prices ($6.00 per bu corn and $250 per ton soybean meal). Further, this does not include the value that inoculation can deliver in reducing shrink within the bunker.

Photo

Cutting-edge inoculant products should probably be viewed as more of a management tool to improve nutritive value rather than as an insurance policy to reduce potential losses. Photo by Progressive Dairyman staff.

As inoculants become more sophisticated in their ability to manipulate fermentation and digestibility, it will be possible to make forages higher in nutritional value than the day they were harvested; much like kernel processing improves corn silage nutritional value. Cutting-edge inoculant products should probably be viewed as more of a management tool to improve nutritive value rather than as an insurance policy to reduce potential losses.

As the inoculant industry evolves, it will be important for nutritionists to fully understand the mode of action of products, because ration formulation may need to be altered to fully capture the value delivered by these products.


Originally published in the July 2011 Progressive Dairyman issue. Reproduced with permission.

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