Fractionation of carbohydrates and nitrogenous constituents of latecrop corn silages ensiled with different specific masses

Abstract

The present study aimed to evaluate the chemical composition of carbohydrates and nitrogenous fractions of late-crop corn silages with different specific masses (SM; 90, 134, 172, and 214 kg dry matter m-3. The silage was held in 20-L mini-silos, and the experimental design was completely randomized, with four replications (mini-silos) per treatment. Fractionation was performed according to The Cornell Net Carbohydrate and Protein System (CNCPSv5.0). The SM of the silage significantly affected the contents of ether extract (γ = 1.718 + 0.0041.SM; P = 0.009; R2 = 39.2), soluble sugars (γ = 0.9502 - 0.003445.SM; P < 0.001; R2 = 59.9), and soluble fiber (γ = -0.4731 + 0.01158.SM; P = 0.025; R2 = 31.2). In addition, SM also affected carbohydrate fraction B1 in a linear manner (γ = 14.88 + 0.2566.SM; P = 0.043; R2 = 38.4), whereas the remaining fractions were unaffected. Furthermore, no change was observed in total N (γ = 2.003 - 0.01065.SM + 0.000036.SM2; P = 0.041; R2 = 38.8), non-protein N (γ = 1.436 - 0.01103.SM + 0.000036.SM2; P = 0.060; R2 = 35.1), soluble N (γ = 1.715 - 0.01450.SM + 0.00005.SM2; P = 0.024; R2 = 43.8), or neutral detergent insoluble N (γ = 0.4979 - 0.001057.SM; P < 0.001; R2 = 70.6). The results also contributed to the differences in fractions A (γ = 66.47- 0.5291.SM + 0.00174.SM2; P = 0.095; R2 = 30.4), B2 (γ = 6.78 + 0.05857.SM; P = 0.076; R2 = 20.8), and B3 (γ = 19.03 - 0.05565.SM; P = 0.018, R2 = 34,1) of the Cornell model. In the present study, differences in the compression (i.e., SM) of corn silages caused changes in the contents of soluble sugar and nitrogenous constituents; however, SM alone did not explain the entire preservation of the ensiled material.