Characterization of the nutritional quality of corn silage from the cool humid region of southern Chile using the Cornell Net Carbohydrate and Protein System model

The objective was to characterize the quality of dent corn silages (CS) produced on southern Chile (cool humid region) using a data set from a commercial laboratory. Corn silage samples submitted for routine nutritional analysis (n = 690) from 68 dairies in 2021 were analyzed by NIRS. Regression models between nutritional variables to determine potential associations were carried out. Data set was arranged by DM content and divided in half using the median value of the distribution (low and high DM). Then, nutritional values for each subsample were input in a ration formulation software that use the CNCPS model. There was a positive curvilinear association between DM and starch, but no association with its digestibility. There was a moderate positive curvilinear association between DM and ND; but no association with NDF digestibility at 240 h. There was a linear negative association between DM and VFA concentration in silage; but a slight positive association with pH. Maximum milk yields were obtained with DM between 32.5% and 37%. Crude protein, ADF, aNDFom, lignin, soluble fiber and soluble carbohydrates were statistically higher in low DM CS than high DM CS (P ≤ 0.05); however, starch was statistically greater in high DM CS than low DM CS (P ≤ 0.05). Digestibility of NDF was similar between silages. Milk yield responses predicted by the CNCPS model in the ration formulation software were higher in high DM CS than low DM CS. Methane production (L/d) was lower for high DM CS than low DM CS. Metabolizable protein produced from rumen bacteria was higher in high DM CS than low DM CS and the opposite occurred with the nitrogen excess produced by the cow. In conclusion, the nutritional composition of CS produced in the cold and humid weather of southern Chile is within the normal values reported by the scientific literature. Data suggest that corn for silage should be harvested with DM between 32 and 38% to maximize starch content and milk yield, with no losses in digestibility. This led to a predicted greater production of rumen microbial protein, milk yield and lower methane.