<span name="style_bold">Agronomic and nutritional evaluation of perennial tetraploid ryegrass-based pastures (<span name="style_italic">Lolium perenne</span>) in dairy farms on the highlands of Costa Rica. II. Nutritional Value.</span> The nutritional value of perennial tetraploid ryegrass (<span name="style_italic">Lolium perenne</span>) in dairy farms on the highlands of Costa Rica. II. Nutritional Value.<span name="style_italic">Lolium perenne</span>)-based pastures was evaluated in four commercial dairy farms in the district of Chicuá, Oreamuno, Cartago (latitude 09°59’, longitude 83°52’, 3090 m of altitude). Samples were taken every 2 months during a one year period in the paddocks ready to be grazed, simulating DM consumption by lactating cows. Average nutritional value was 25.21% CP, 46.26% NDF, 25.57% ADF, 3.29% lignin, 15.40% NFC, 77.95% IVDMD on dry matter basis. Estimated energy content, expressed as TDN, DE, ME, NE<span name="style_sub">L</span> (3X) and NE<span name="style_sub">G</span>, was 61.95%, 2.92, 2.45, 1.53 y 0.92 Mcal.kg<span name="style_sup">-1</span> of DM, respectively. Nutritional value of perennial ryegrass pastures is affected by season and pasture management, specially as regards the regrowth period of the paddocks. These pastures have a high CP and NFC content, which allows microbial protein production, but also requires supplements rich in NFC to maximize utilization of these nutrients. In general, nutritional value of this pasture grown at altitudes higher than 2500 m in Costa Rica is similar to the same grass species grown in temperate climate regions, where it is native. of DM, respectively. Nutritional value of perennial ryegrass pastures is affected by season and pasture management, specially as regards the regrowth period of the paddocks. These pastures have a high CP and NFC content, which allows microbial protein production, but also requires supplements rich in NFC to maximize utilization of these nutrients. In general, nutritional value of this pasture grown at altitudes higher than 2500 m in Costa Rica is similar to the same grass species grown in temperate climate regions, where it is native.

Temperate climate grasses; Lolium perenne; nutritional value; energy content