Dry matter yield and digestibility of Lolium perenne L. cultivars under three grazing pressures

An experiment was conducted to evaluate dry matter yield (DMY) from three ryegrass cultivars (Lolium perenne L.) (Barlatra, Talbot and Cropper) under three grazing pressures: 3 (high), 6 (medium) and 9 (low) kg DM/100 kg body weight (BWW)/day, and four periods of one month each using Holstein heifers (150 to 180 kg, initial BW). Dry matter yield was lower for high pressure. Barlatra had the highest average DMY, followed by Cropper and Talbot. In vitro and in situ dry matter digestibility (DMD) were evaluated at 0,2,4,6,12,24,48 and 72 h of incubation for the three ryegrass cultivars, plus Moapa alfalfa as control group, where samples from the third grazing period and medium pressure were used. Talbot and Cropper ryegrass had higher in vitro and in situ DMS as compared to Barlatra. Significant correalations (95%) was found between both techniques of DM digestibility evaluation in Lolium perenne Se evaluo el rendimiento de materia seca (RMS) de tres variedades (Barlatra, Talbot y Cropper) de ballico perenne (Lolium perenne L.) sometidas a tres presiones de pastoreo: 3.0 (alta), 6.0 (media) y 9.0 (baja) kg MS/100 kg peso vivo (PV)/dia, en 4 periodos de un mes cada uno, con vaquillas Holstein de 150 a 180 kg PV inicial. El RMS fue menor con la presion alta. Barlatra con el mayor promedio seguido por Cropper y Talbot. Se evaluo digestibilidad de materia seca (DMS) a 0,2,4,6,12,24,48 y 72 h de incubacion in vitro e in situ de ballicos y alfalfa Moapa como testigo en muestras provneientes del tercer periodo de pastoreo a presion media. Talbot y Cropper tuvieron los valores mayores de DMS a 72 h de incubacion. Hubo un valor alto (95%) de correlacion entre ambas tecnicas de evaluacion de la digestibilidad