Effect of cutting age on forage yield and bromatological compositon of Brachiaria brizantha cv. Marandu

Abstract

Objective: To determine the influence of cutting age on forage yield and bromatological composition of Brachiaria brizantha cv. Marandu. Methodology: The study was conducted at the Río Suma Experimental Farm of Universidad Laica Eloy Alfaro de Manabí, located in El Carmen canton, Manabí province, Ecuador. Three cutting ages were evaluated: 20, 25, and 30 days. Treatments were arranged in a randomized complete block design with eight replications per treatment. Agronomic variables, green biomass production, dry matter, chemical composition, mineral composition, and fiber fractions were evaluated. Data were analyzed by analysis of variance, and mean comparisons were performed using Tukey's test at a 5% significance level. Results: Cutting age significantly influenced plant height, leaf/stem ratio, aboveground biomass/root biomass ratio, green biomass production, dry matter percentage, and dry matter yield. The 30-day cutting age showed higher plant height, green biomass, and dry matter yield, whereas the 20-day cutting age showed a higher leaf/stem ratio. In terms of chemical composition, crude protein did not show significant differences among cutting ages; however, ether extract and inorganic matter were affected. Differences were also observed in phosphorus, potassium, magnesium, and copper contents, as well as in neutral detergent fiber, acid detergent fiber, and lignin. Conclusion: Cutting age modified the agronomic performance, biomass production, and some bromatological components of Marandu grass. Cutting at 30 days favored forage yield, while cutting at 20 days showed a better leaf/stem ratio and higher concentrations of some minerals.