Productive response of grazing dairy cows to fresh chopped maize supplementation under a small farming system in the Mexican Highlands.

The aim of this study was to evaluate the animal performance of late lactating grazing dairy cows in response to fresh chopped maize (FCM) supplementation under a small farming system. Twenty-four multiparous Holstein dairy cows were used in a rotational grazing on a mixed alfalfa-orchard grass sward. Three treatments were evaluated: 0, 4, and 8 kg dry matter (DM) of FCM cow(-1) day(-1). The experimental design was a crossover, with three periods lasting 19 days each. There were no differences on individual milk production nor on milk composition. Herbage DM intake decreased (P < 0.0001) from 8.4 to 5.2 and 3.1 kg DM when increasing FCM from 0 to 4 and 8 kg DM, respectively. Total DM intake increased (P < 0.0001) with 8 kg DM of FCM, averaging 14.8 kg. Substitution rate was 0.75 and 0.67 kg of pasture per kilogram of FCM with 4 and 8 kg DM of FCM, respectively. Consequently, stocking rate (STR) increased (P < 0.0001) from 3.8 to 6.2 and 8.8 cows ha(-1), and milk production per hectare increased (P < 0.0001) from 39.3 to 64.5 and 95.5 kg of milk, with 0, 4, and 8 kg DM of FCM, respectively. This means that STR increases 0.63 cows ha(-1), and 0.75 kg of milk ha(-1) when FCM is increased in 1 kg of DM. In conclusion, offering FCM as supplement to grazing dairy cows in their final lactation stage had no benefits in individual milk production or milk composition, but had benefits on milk production per hectare.