The author is an assistant professor and ruminant nutrition extension specialist at the University of Wisconsin-Madison.

Forages are a key part of dairy diets with implications for dairy farm productivity and sustainability. The objective of this article is to describe and discuss some of the forage research presented at the American Dairy Science Association (ADSA) annual meeting held in West Palm Beach, Fla., earlier this year. These studies were hand-picked to represent different areas within forage research; however, they represent a small portion of the many research trials presented.

Chop length has implications on cattle and storage: Forage particle size is one of the many factors that can be controlled during harvest and will have a significant impact on silage quality, diet formulation, and animal performance. Forage with long, coarse particles makes packing more difficult, requiring longer packing times and leaving more oxygen left in the silo after sealing. On the other hand, finer particles are less effective in stimulating rumination and maintaining rumen health than coarser particles.

A study from Texas evaluated the effect of chop length on effluent production of male-sterile sorghum silage. In this study, sorghum silage had about 23% dry matter at harvest and was processed with a chop length of 6 or 20 millimeters. Fine chopping enhanced effluent production, which not only weakened the nutritive value of the sorghum silage but is also a contaminant of groundwater and surface water.

What do cows think about forage particle size? We conducted a meta-analysis to evaluate how the proportion of different size particles in lactating cow diets affected animal performance and feeding behavior. Feeding diets with a high proportion of coarse particles (those above the top screen of the Penn State Particle Separator) was associated with reduced feed intake and milk production. Cows also spent more time at the feedbunk, extending eating time, yet had a slower eating rate. Although not enough data was available to evaluate the cause of this, cows were probably spending more time sorting feed and masticating instead of eating. This extra time spent eating usually comes at the expense of resting time and may impair milk production.

So, what is the ideal chop length? There is not a one-size-fits-all recommendation. The same chop length setting will likely yield different results depending on the uniqueness of each dairy. Different chop length settings are warranted for different dry matter contents and kernel processor types and settings to achieve the desired particle size and physically effective fiber. As a rule of thumb, aim for finer chop length when harvesting drier material and coarser chop length when the crop is wet. Evaluate particle size during harvest and at feedout to make any necessary mechanical or feeding adjustments.

Starch digestibility gets better with microbial inoculation: Silage fermentation is well-known to improve starch availability of corn silage and high-moisture corn. Therefore, keeping silage in the silo longer has become a common practice for dairy herds feeding corn silage, high-moisture corn, and earlage when land availability is not an issue. This is because of the breakdown of the starch-protein matrix during silage fermentation.

The starch-protein matrix is the cross-linking between zein proteins and starch. Zein proteins surround starch granules and limit the access of rumen bacteria and intestinal enzymes to starch, reducing its digestion. The breakdown of these proteins during silage fermentation is caused primarily by bacterial proteases. Two studies presented at the ADSA annual meeting reported that microbial inoculation improved the starch availability of corn silage or high-moisture corn thanks to the breakdown of the starch-protein matrix.

Researchers from Delaware evaluated an inoculant containing L. buchneri, L. hilgardii, and P. pentosaceus. Silage was ensiled from 30 to 180 days and the microbial inoculation improved starch digestibility after 120 and 180 days of the study. Reduced zein protein and greater amounts of ammonia nitrogen and soluble protein concentrations were also reported, suggesting the inoculation facilitated better access to starch by breaking down the zein protein.

The second study was conducted in Brazil and aimed to determine if microbial inoculants can alter the starch-protein matrix of high-moisture corn. Inoculating high-moisture corn with L. buchneri, L. hilgardii, and P. pentosaceus, individually or mixed together, bolstered starch availability through the breakdown of the starch-protein matrix. Inoculation was efficient in modulating silage fermentation as well as improving aerobic stability.

The question that remains is if these inoculants have proteolytic activities or if this effect is driven by a more extensive silage fermentation achieved with the use of a microbial inoculant. Regardless of the mechanism, improving starch availability while protecting the shelf life of your corn silage is beneficial.

The ruminal degradability of plastic bale wrap: Another study from Pennsylvania evaluated the in situ degradability of two biodegradable plastic bale wraps. Don’t worry — their goal was not to evaluate if we can feed plastic to cows. These biodegradable wraps were developed with the intention of mitigating the chances for the accumulation of foreign material within the rumen and any related health issues caused by the involuntary ingestion of plastic wraps by ruminants.

Researchers cut the plastic wraps in pieces and allocated them in nylon bags before incubating them in the rumen of dairy cows for up to 36 hours. This approach is similar to the in situ assay typically used to evaluate nutrient degradability of forages. Both plastic wraps were more than 95% degraded after 36 hours in the rumen and show promise as tools to minimize health issues when ruminants involuntarily consume plastic.