CHANGES IN THE YIELD AND CHEMICAL COMPOSITION OF MARALFALFA GRASS (Cenchrus sp) AT DIFFERENT AGE

Maralfalfa grass is an excellent option for the Mexican tropics; however, it is necessary to know its yield and chemical composition changes during its development to determine the optimal harvest age. The objective of this experiment was to determine the optimal harvest time of Maralfalfa grass (Cenchrus sp) evaluating the effect of maturity on yield and chemical composition. The percentage content of crude protein (PC), crude fiber (FC), acid detergent fiber (FDA), neutral detergent fiber (FDA) and in vitro digestibility of dry matter (DIVMS) were determined. The experiment was established in plots of the INIFAP Experimental Site Papaloapan. The chemical analysis was carried out in the Animal Nutrition laboratory of Departamento de Zootecnia of the Universidad Autonoma Chapingo. Treatments were evaluated at intervals of 15 days, in a period of 180 days. The data were analyzed using the GLM procedure of SAS, in a randomized block experimental design, with 3 replicates in time. Significant differences (P < 0.01) were observed in plant morphology during the different physiological states. The maximum production of aerial biomass was reached on day 151 after sowing with 37,297 kg MS ha-1. The nutritional value was inverse to the age of the forage, affecting its chemical composition (P < 0.05). The contents of FDN, FDA and FC increased by advancing the cut-off age by 12 %, 8.9 % and 12.4 %, respectively, and the concentration of PC decreased by 5.6%. The in vitro digestibility of the dry matter was reduced at a rate of 0.60 percentage units per day, from 83.25 % on day 33 to 49.78 % on day 167. Then, it is concluded that nutritional quality of Maralfalfa significantly decreased by the age of the forage, and in order to maintain protein concentration in forage, cutting is recommended after 61 days.