Endophyte-free tall fescue pastures for small-scale dairy systems in the highlands of central Mexico

The objective was to assess dairy cows in small-scale dairy systems grazing pastures of endophyte-free tall fescue (Lolium arundinaceum cv. Cajun II), or perennial ryegrass (Lolium perenne cv. Tetragrain), both associated with white clover (Trifolium repens). An on-farm double cross-over experiment was undertaken with 10 Holstein cows, continuously grazing 10 h/day of Cajun II or Tetragrain pastures, plus 4.6 kg DM of a concentrate/cow/day. Animal variables were milk yield, milk fat and protein content, live-weight, body condition score, and milk urea nitrogen. The analyses of pasture variables was with a split-plot experimental design. Pasture variables were sward height, net herbage accumulation, and chemical composition of herbage for CP, NDF, ADF, in vitro digestibility of organic matter, and estimated herbage intake from utilised metabolizable energy. There were significant differences between treatments for OM, ADF, IVDOM, and eME, with tall fescue showing higher IVDOM which resulted in a slightly higher eME value. An economic analysis compared incomes and feeding costs. There were no statistical differences in animal or pasture variables. Cajun II endophyte-free tall fescue pasture performed similarly to Tetragrain perennial ryegrass in animal, pasture, and economic variables.