Case Study: Effect of type of processor on corn silage processing score in samples of whole-plant corn silage

The objective of this study was to evaluate the effect of processor type on fermentation profile, corn silage processing score, and physically effective NDF of whole-plant corn silage samples. A data set composed of 3,900 whole-plant corn silage samples was obtained from Rock River Laboratory (Watertown, WI). All samples were collected from 2013 to 2016 by the Chr. Hansen team under specific protocols to label samples as shredlage (SHRD) only if confirmed by farmers or custom harvesters. A total of 309 and 3,591 samples were labeled as SHRD and nonshredlage (CONV), respectively. Samples had been previously analyzed for corn silage processing score, physically effective NDF, and predicted ruminal in vitro NDF digestibility at 30 h (using near-infrared spectroscopy). In addition, 2,394 samples (272 SHRD and 2,394 CONV) had previously been analyzed via wet chemistry for fermentation profile. Loss of DM during fermentation was calculated with a predictive equation. Data were analyzed using Proc Glimmix in SAS with type of processor (SHRD vs. CONV) as a fixed effect. Statistical significance and trends were declared at P ≤ 0.05 and 0.05 < P < 0.10, respectively. The pH was less (P = 0.01; 3.90 vs. 3.97) for SHRD than CONV, which was related to greater (P = 0.001; 4.89 vs. 4.34% of DM) lactic acid concentrations. Concentrations of acetate, propionate, butyrate, and ethanol did not differ (P > 0.10) and averaged 2.27, 0.35, 0.36, and 0.57%, respectively. Recovery of DM was improved (P = 0.05; 2.42 vs. 2.73%) for SHRD, but the difference is of minor importance. Corn silage processing score was 4.6 percentage units greater for SHRD than for CONV silages (P = 0.001; 68.1 vs. 63.53% starch passing through a 4.75-mm sieve). In contrast, physically effective NDF and predicted ruminal in vitro NDF digestibility were (P = 0.001) 1.8 and 1.6 percentage units greater for CONV. Our results suggest that harvesting whole-plant corn silage as SHRD improved kernel breakage while maintaining adequate fermentation patterns compared with CONV.