Penn State Particle Size Separator (PSPS)

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- [Instructor] The Penn State Particle Size Separator or PSPS is an effective tool that can be used to evaluate feed particle size, sorting activity, length of harvested forages, and feeding or total mixed ration mixing protocols.

Dr. Jud Heinrichs, retired professor of dairy nutrition at Penn State University, co-developed this valuable tool with Dr. Dennis Buckmaster of the ag and bioengineering department of Penn State in 1994.

Since then, Dr. Heinrichs has overseen continued improvements to the PSPS separator as the understanding has changed how particle size influences the health and production of dairy cows.

The PSPS separator consists of screens containing holes that measure 19 millimeters, eight millimeters, four millimeters, and a solid bottom pan for collecting fine particle sizes.

There is an optional 1.18 millimeter screen that is available with the PSPS separator.

While it is generally not used for forage analysis, it is a valuable tool to measure grain particle size.

One of the primary goals of analyzing the particle size of a TMR is measuring the distribution of feed and forage particles the cow actually consumes.

Adequate forage particle length is necessary for proper rumen function.

Since particle length of forages is first determined in the field, the PSPS separator is also used to measure particle size of forages at harvest.

This can alert producers of potential problems with harvesting equipment and make the appropriate corrections.

The PSPS separator is a valuable asset to utilize during harvest.

Take time to measure particle length of forages as they're harvested.

Particle length is essential to obtain a successful pack, ensure proper fermentation and for the cows to efficiently utilize the nutrients available to them.

If particle length of forages is too long, cows will do more sorting of feeds, take more time to eat, and ultimately eat less pounds of total feed.

The PSPS separator can also be used to check the efficiency of TMR mixers.

Under or over mixing can affect particle length and create inconsistency from one end of the feed bunk to the other.

Feed samples need to be analyzed as soon as fresh feed is delivered.

For a more complete analysis, refusal samples can also be analyzed to determine exactly what the cows are consuming.

With so many valuable uses, it is important to understand how to properly use this device to analyze a feed or forage sample.

For proper analysis, collect a fresh sample that cows have not had the chance to eat or sort through.

Using a scale, collect a minimum of 500 grams of feed.

Individual forages such as corn silage and haylage can also be analyzed with a PSPS separator.

To begin the process, stack the four plastic separator boxes on top of each other in the following order: the sieve with the largest holes on top, the medium-sized holes next, then the smallest holes, and the solid pan on the bottom.

Place the collected sample of TMR or forage on the upper screen.

On a flat surface, rapidly move the sieves back and forth five times, then rotate the separator box clockwise one-quarter turn.

Repeat this process three more times, then begin turning the boxes counterclockwise for four more sets, rotating the separator after each set of five movements.

In total, you will have moved the boxes eight sets or 40 rapid movements.

It is important to remember to move the boxes with enough force so that the feed or TMR is able to pass back and forth over the holes allowing the pieces to pass down through all three screens.

Once the sample is separated, the feed remaining on each sieve is collected and weighed individually.

To determine what percentage of the sample stays on each sieve, you will want to divide each captured set of particles by the total weight of the sample.

For example, with 525 grams of TMR to begin with, we measured 30 grams left in the uppermost sieve, meaning 5.7% of the sample.

The 19 millimeter sieve captures particles that form the forage mat.

This fraction represents feed that stimulates chewing, which produces saliva and helps maintain proper rumen pH.

This screen also represents feed that is often found in refusals.

Feed that is long in length will easily be sorted and also will slow intake amounts.

The eight millimeter sieve collects particles that will be part of the rumen forage mat, but will be broken down faster than particles on the top sieve.

Compared to are the longest particles, this fraction requires less cud chewing and hydrates more quickly in the rumen which allows microbes to break it down faster.

Feed particles found on the four millimeter sieve will primarily be small forage pieces that are often but not necessarily high fiber in nature.

Initially, these particles will likely be trapped in the forage mat of the rumen, but they can be broken down easily with minimal rumination or by rapid microbial action.

These feed particles will have a small, yet significant impact on buffering the rumen.

The percentage of feed collected on the solid bottom pan represents the portion of the sample that is not considered effective fiber for the cow.

If they are starch or digestible fiber, they will be quickly digested in the rumen supplying immediate nutrients to the cow for milk production.

This chart represents the correct percentages that should be found on each sieve of the separator for different types of samples.

A desired TMR sample should have 2-8% of the sample remain on the top screen, 30-50% on the second screen, 10-20% on the third screen and 30-40% of the sample falling all the way through to the solid bottom pan.

Some forage labs may use slightly different distributions than the chart shown here.

With its numerous diagnostic abilities, the Penn State Particle Size Separator is an effective and convenient on-farm tool that can benefit your dairy in many ways.

To learn more about the physical effects of particle size and the proper distribution of various forages, please visit the following Penn State website extension.psu.edu/penn-state-particle-separator.