ChileanJAR

The influence of four leveis of fertilization (I: N_OP_OK_O; II: N_OP₅₀K_O; III: N₂₅P₁₀₀K₂₅ and IV: N₅₀P₂₀₀K₅₀) on the availability of forage; protein percentage; in vitro digestibility; digestible energy; and calcium and phosphorus content was studied at the Remehue Experiment Station (Osorno), during a five years period. An area of 3 hectares was used for each treatment; with and average stocking rate of 2 cows/ha for and II, and 2.17, for III and IV. Al) treatmentswere grazed during the whole year; a hay supplement, whjch carne trom the correspondent treatment, was supp)ied to the animais in situ, in late winter. Forage availabitiy was critical between the months of June and August, being more serious in treatments I and II, which presented larger periods with availabilities below 1,000 kg of DM/ha. Total protein did not reach critical levels for dairy cows on any treatment, occurring favorable differences in direct relation with the levels of fertilization. Summer was the season with the lowest protein percentage. In vítro digestibility improved with increasing levels of fertilization, reaching values near 8O% dry matter digestibility. The highest level of digestibility in ah the treatments was found during the spring season. Digestible energy level, determined in vitro, was higher in the fertilized treatments, reaching during spring values of 3.15 Mcal/kg. The lowest values were found at the end of the winter season. Calciurn content, in alI the treatments, was higher than the minirnum required for cows with production below 30 lt/day. The lowest values were observed during winter. Phosphorus content was only acceptable in treatrnent IV. The other treatments had values that were lower than normal (0.33%) during sumrner; treatment I had also lower than normal values at the end of spring. The consequ