Fractionation of carbohydrates and nitrogenous constituents of late-crop 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 ( ? = 1.718 + 0.0041?SM; P = 0.009; R2 = 39.2), soluble sugars ( ? = 0.9502 - 0.003445?SM; P < 0.001; R2 = 59.9), and soluble fiber ( ? = -0.4731 + 0.01158?SM; P = 0.025; R2 = 31.2). In addition, SM also affected carbohydrate fraction B1 in a linear manner ( ? = 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 ( ? = 2.003 - 0.01065?SM + 0.000036?SM2; P = 0.041; R2 = 38.8), non-protein N ( ? = 1.436 - 0.01103?SM + 0.000036?SM2; P = 0.060; R2 = 35.1), soluble N ( ? = 1.715 - 0.01450?SM + 0.00005?SM2; P = 0.024; R2 = 43.8), or neutral detergent insoluble N ( ? = 0.4979 - 0.001057?SM; P < 0.001; R2 = 70.6). The results also contributed to the differences in fractions A ( ? = 66.47- 0.5291?SM + 0.00174?SM2; P = 0.095; R2 = 30.4), B2 ( ? = 6.78 + 0.05857?SM; P = 0.076; R2 = 20.8), and B3 (? = 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.

Keywords

• Açúcares
• Amido
• Fibra
• Lignina
• Nitrogênio
• Zea mays.