Changes in the chernical cornposition and digestibility of sorne roughages during their utilization period in two dairies of the Metropolitan Region

Ignacio Ruiz N.1, Gabriela Chahin A.1 y Carlos Pedraza G.1

During a period of two years, starting in abril 1990, a study was conducted at La Platina Research Station (INlA), in order to evaluate the variations in nutritive value (chemical composition and in vitro digestibility) of the roughages used in two dairies of the Metropolitan Region. In both dairies, abrupt and noticeable changesamong dates were detected in all roughages, for the majority of the components measured. The highest variability was found in protein and fiber content, meanwhile energy showed the lowest fluctuation. The results suggest that important errors may occurwhen formulating rations if-as it usually happens-the chemical composition of fodder is considered rather constant through the season of utilization.

Keywords: roughages, chemical composition.
1 Estación Experimental La Platina (INIA), Casilla 439, Correo 3, Santiago, Chile.