Refusals read the peNDF story

Achieving the right physically effective fiber on paper only matters if that structure survives the bunk. Forage particles need enough length to support rumination and salivary buffering, yet the mix must stay uniform enough that cows cannot strip out the highly fermentable fraction. The on-farm tool that makes that visible is a particle separator used on both fresh TMR and refusals.

A Penn State–style shakeout on the delivered TMR shows what left the wagon. Targets for upper, middle, and lower sieves are diagnostic baselines — they shift with herd stage, forage dry matter, mixer type, and ingredients — not universal law. What they do give you is a repeatable picture of the physical profile you intended to feed.

Shake the weighback the same way, same day. When the refusal holds clearly more long material than the as-fed mix, cows have been sorting toward fines and concentrates. That consumed ration is finer and more fermentable than the ticket — peNDF theft measured instead of guessed. Large as-fed vs refusal gaps raise SARA and milk-fat risk for the group.

Sample fresh TMR at delivery and refusals before the next feeding for several days. Compare upper-sieve shares side by side. If refusals run heavier in long particles while cows look full, fix delivery and push-up uniformity before you rewrite peNDF targets.