Effects of kernel processing during harvest with pull-type forage harvesters on corn silage and dairy cow performance

Whether kernel processing during harvest is more effective than post-ensiling ground corn supplementation in dairy systems using pull-type forage harvesters remains unclear. This study evaluated the effects of kernel processing during harvest on silage physical characteristics, fermentation profile, and the productive and economic responses of dairy cows. Corn was harvested using pull-type forage harvesters with or without a kernel processor, respectively Menta ATM 1.3 and Menta ATM 1.1-AR. Harvesters were adjusted to a theoretical length of cut of 10 mm, silages were stored for 140 d. Twenty-one lactating Holstein cows were assigned to a replicated 3 × 3 Latin square design and fed diets containing processed corn silage (PCS), unprocessed corn silage (UCS), or UCS supplemented with ground corn (UCS+GC). Kernel processing increased grain fragmentation, as indicated by a higher kernel processing score (KPS; 48.3 vs. 37.2%) and a greater proportion of particles smaller than 4.75 mm (69.9 vs. 61.6%). Processed silage also showed higher non-fiber carbohydrate (NFC) concentration and changes in fermentation end-products, without affecting preservation characteristics. Milk yield tended to be greater for PCS than UCS (26.9 vs. 25.9 kg/d), whereas animal performance was similar between PCS and UCS+GC. Milk production was similar between PCS and UCS+GC, whereas the UCS+GC strategy had a higher estimated feeding cost and a lower relative net margin than PCS under the evaluated prices. These findings indicate that kernel processing increased grain fragmentation and tended to increase raw milk yield relative to unprocessed silage. Under the evaluated prices, PCS also had a greater estimated net margin than UCS+GC.