Digestibilidad y consumo voluntario del pasto kikuyo (Pennisetum clandestinum Hochst) en ovinos bajo fertilización nitrogenada

Abstract

En el Centro Nacional de Investigaciones Agropecuarias del Instituto Colombiano Agropecuario (ICA) situado en la Sabana de Bogotá, se efectuó un experimento para determinar la producción de materia seca y el valor nutritivo del pasto kikuyo (Pennisetum clandestinum Hochst) cosechado a los 39, 50 y 78 días de rebrote y fertilizado con 0, 50 y 100 kg/Ha de N. La producción de forraje a los 39, 50 y 78 días de rebrote fue 1,27; 1,75 y 3,25 t/Ha de materia seca, respectivamente. La respuesta de kikuyo a la aplicación de 0, 50 y 100 kg/Ha de N, fue de 1,43; 1,99 y 2,86 t/Ha de materia seca por corte respectivamente. Las diferencias observadas en los diversos estados de desarrollo fueron altamente significativas. Similar observación se aplica a los niveles de N utilizados. El consumo voluntario (g/kg W 75/día) se incrementó por efecto del avance en madurez y no por el efecto de la aplicación de N. Se encontró relación negativa del consumo voluntario (g/kg W 7 ) y digestibilidad de la materia seca con los contenidos de FDA, lignina y sflice (P (0,01) y Ia relación positiva con la proporción hoja: (P ( 0,05).

At the Tibaitata Experimental Center of the Instituto Colombiano Agropecuario (ICA) located in the savannah of Bogota, an experiment was conducted to determine the dry matter yield and the nutritive value of kikuyu grass. The crop was cut at 39, 50 and 78 days of growth and fertilized with 0, 50 and 100 kg N/I-la. Forage yields at 39, 50 and 78 days of growth were 1.27; 1.75 and 3.25 t/Ha of dry matter (D.M.). The N fertilization of 0, 50 and 100 kg N/Ha increased the DM production of kikuyu grass in 1.43; 1.99 and 2.86 t/Ha, respectively (P (0,01). Voluntary intake (g/kg W 75 /day) increased as the herbage matured. The highest voluntary intake (V.1.) 66.86 and 70.64 g/kg W 5 /day were observed at 50 and 78 days of growth respectively. There were not significant differences between the two treatments but it was with the 57.86 g/kg W 75/day V.I. determined at 39 days of growth. Voluntary intake (g/kg W' 5 / day) of kikuyu grass was increased 6 units approximately by the application of 50 and 100 kg N/i-Ia. Voluntary intake of drymatter (g/kg W 75/day) was increased more effectively by stage of growth of kikuyu grass than by N application. This was atributed to the fact that the digestibility of dry-matter, neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose and cellulose was influenced more positively by the advance in maturity than by N application. Similar tendences were observed in leaf to steam ratio and digestible energy contents. The explanation for the observed results is the negative correlation between V.I. (g/kg W'75 /day) and DM digestibility with ADF, lignin, and silice contents and positive correlation with leaf to stem ratio. 8