What is the right particle size is a tricky question. Forage particle size affects rumen function and dry matter intake (DMI). A dairy farmer's highest priority is milk production and DMI is crucial for achieving high milk production.
How Rumen Works?
Maximum DMI can only be reached by having optimal rumen fermentation through proper diet, mixing and feeding.
Rumen acts as a fermentation vat.
The rumen microbial population is responsible for fermentation and is sensitive to changes in rumen pH.
Proper pH needs to be achieved in order to increase number of microbes for better digestibility.
Rumination or "cud" chewing produces saliva which helps to maintain a proper pH.
Importance of Particle Size
Consuming too finely processed forages decreases rumination.
Diets with too many small particle will cause feed to spend less time in rumen, hence, less microbial digestion.
This will reduce digestibility and cause digestive upsets.
The particle size also affects rumen mat which is formed by small particles adhering to longer-stem forages that float in the rumen.
The attachment enables the smaller particles to float in the rumen to be properly fermented.
Without sufficient fiber, particles may sink into less desirable part of the rumen where it cannot be digested easily.
Forages with small particle size may also decreases butterfat.
It can also cause metabolic disorders such as ruminal acidosis.
Length of chop is also important as it affects fermentation in the storage structure.
It is recommended that drier corn silage be cut shorter to facilitate packing.
Particle size is important regardless of which forage you feed. However, it is even more important with highly digestible forage like BMR corn silage.
Due to lower lignin and higher digestibility of BMR, it is crucial to manage the rate of passage through the rumen by maintaining enough effective fiber.
Chopping at a longer particle size will help slow digestion and prevents upset.
Another important consideration in corn silage particle size is mechanical processing.
Silage processing can help to improve the ensiling characteristics and starch digestion by exposing corn kernel to rumen bacteria.
Although processing helps with nutrient utilisation, it can also reduce particle size.
BMR hybrids have moderately textured kernels. Hence, less aggressive processing is recommended to maintain particle size in BMR corn silage.
So What Is the Ideal Particle Size?
Truth is, there is no one size fit all answer.
It is crucial to find out what works for your dairy to optimise health and milk production.
Discuss and plan with your time for peak performance.