Concentrates are the main cash expenditure in smallholder campesino dairying in the highlands of Central Mexico. Improved, low-cost, appropriate feeding strategies have been therefore identified by campesinos as a priority. An on-farm trial was undertaken in 1998 to evaluate the response to supplementation with concentrates by dairy cows in early lactation during the rainy season with restricted access to grazing of ryegrass/white clover pastures. A base of 3·0 kg commercial concentrate/cow/day (S3) was compared against the higher rate used by farmers of 5·0 kg/cow/day (S5). Three farmers with one, and one farmer with two pairs of freshly calved upgraded Holstein cows participated in the trial (24±10·7 days into lactation). Data were analysed by a random block split-plot design where supplementation treatments were main plots and measurement periods were split-plots. Milk yield was recorded once per week for 9 weeks, and live weight and condition score for four 28 day periods. Milk yields were 21·8 for S3 and 21·9 for S5 (±0·714) kg milk/day/cow (P > 0·05); live weight S3 = 444·0 and S5 = 496·0 (±12·663) kg/cow (P > 0·05), and condition score S3 = 1·9, and S5 = 1·8 (±1·127) (P >0·05). There were no significant (P> 0·05) effects of measurement periods, and there was no significant (P > 0·05) interaction. The lack of response in milk yield, live weight or condition score to increased concentrate supplementation demonstrates that at these levels of production and management, the access to grazing of improved pastures, plus limited concentrate, enables cows in campesino systems to meet their nutrient requirements, and the feasibility of efficient milk production from grazed pastures as an appropriate technology. It is also concluded that it is an appropriate technology and that the results have implications for research and extension workers in rural development who have promoted large amounts of concentrate to dairy cows as the only way towards high yields and efficient milk production.