A dairy system based on forages and grazing in temperate Mexico

Mexican dairy farmers will face in the near future the challenge of increased competition and the strategy to survive this at farm level will have to be based on competitive free trade world prices. This thesis describes the design of a dairy system based on forages and grazing to reduce production costs in temperate Mexico. This dairy system is based on a sequential cropping system of permanent pastures of alfalfa and orchard grass, winter annual pastures of oats and annual ryegrass and silage maize. Between May and October the cows graze on permanent pastures and between November and April they graze both types of pastures. Between October and April the cows also receive supplementary feeding with maize silage. The cows are supplementarily fed with moderate amounts of concentrates during the lactation. The responses of stocking rate and milk production per hectare to increasing levels supplementary feeding with maize silage and concentrates were studied in two experiments. In both experiments a high and uniform pasture utilisation was targeted irrespective of the level of supplementary feeding. Milk production per hectare was more closely affected by changes in stocking rate than by changes in production per cow. Supplementary feeding with maize silage up to 4.8 kg DM of silage cow -1day -1and 4 kg of concentrate cow -1day -1appeared to be economically feasible. The right economic decision could not have been based on the response in milk production per cow to supplementary feeding. The allowance - intake relationship for dairy cows grazing oats and annual ryegrass pastures is reported. The responses of herbage intake and composition of the ingested herbage to different levels of herbage allowance were used to identify the levels of stocking rate and height of residual herbage that maximised production per unit of area. The number of bites taken per unit of area appeared to be an adequate variable to interpret the responses to herbage allowance. The effects of nitrogen fertilisation and irrigation on herbage and nitrogen yield of oats and ryegrass pastures were evaluated in a cutting trial. Nitrogen fertilisation between 50 and 100 kg N ha -1harvest -1increased herbage production, reduced the cost of produced herbage and improved the efficiency of utilisation of irrigation water. Using a high level of irrigation reduced the efficiency of utilisation of irrigation water and the recovery of fertilizer-N. However, increasing the frequency of irrigation increased the efficiency of use of absorbed N. The results of two years of operation (1998 and 1999) of the Farmlet for Dairy Production Under Grazing of Chapingo University are reported. The average stocking rate was 2.6 cows ha -1, the average production per cow was 6200 kg milk per lactation and the average productivity was 16 Mg milk ha -1year -1. Feeding costs in this dairy system were 43% lower than the average feeding costs in prevailing dairy systems. The net revenues (1273 US $ ha -1year -1) indicate that this dairy system is a feasible option. Based on these results, an improved pasture-crop rotation is proposed with a targeted productivity of 29 Mg milk ha -1year -1.