TALL FESCUE AND RYEGRASS PASTURES FOR GRAZING DAIRY COWS IN SMALL-SCALE DAIRY SYSTEMS IN THE HIGHLANDS OF CENTRAL MEXICO

Background. Grazing pastures in small-scale dairy systems reduces feeding costs in these farms in the highlands of central Mexico. Tall fescue (Lolium arundinaceum) is a temperate climate grass resistant to hydric deficit, extreme temperatures, and high stocking rates, which make it attractive for these systems. However, many varieties are susceptible to endophyte infection that may cause toxicosis in cattle, which has not been studied in Mexico. Objective. To evaluate grazing of tall fescue pastures of K31 variety susceptible to endophytes, compared to perennial ryegrass (Lolium perenne) cv. Bargala pastures, both associated with white clover (Trifolium repens cv. Ladino). Methodology. An on-farm experiment was undertaken with a participant farmer with six Holstein cows with similar number of calvings, stage of lactation, and milk yields (kg/day). Treatments were BGL: grazing for 8 h/day on a perennial ryegrass cv. Bargala pasture and K31: grazing for 8 h/day of a tall fescue cv. K31 pasture. Cows were also supplemented with 4.6 kg dry matter of a commercial concentrate (18% crude protein) and 5 kg fresh basis of chopped green maize forage. A double cross-over design was applied, with three 14 day each experimental periods. Results. There were no significant differences (P>0.05) between treatments in chemical composition of pastures or supplementary feeds, nor between animal production variables. Implications. The comparison of tall fescue vs ryegrass pastures as alternative temperate pasture to reduce production costs in small-scale milk production systems. Conclusions. It is concluded that both grasses have similar performance in these systems.