ChileanJAR

During the consecutive periods (1975-79), the effects of 4 levels of fertilization on milk production and reproductive parameters were evaluated. A quadratic function was fitted(y = 10.39 + 0.03 F-0.000056 F²; r² 0.99; P 0.05) for the increase in pasture dry matter production, in relation with the levels of fertilization (I = N₀P₀K₀, II = N₀P₅₀K₀; III = N₂₅P₁₀₀K₂₅; and tV = N₅₀P₂₀₀K₅₀). The milk production function, in relation with the same leveis of fertilization, was y = 54.42 + 19.96 F - 0.050 F² (r² 0.87; P = 0.05). There were no significant differences among treatments (P 0.05) for post-birth weights; weights of the cows at the end of lactation; gains of weight;butterfat percentages ;days of lactation; pregnancy percentages; and days from parturition to pregnancy. There were significant differences among treatments (P 0.05) in milk production (4% B.F.) per cow and per hectare. Productions/cow were 2,798, 2,948; 3,208; and 3,213; and productions/ha were 5,596; 5,896; 6,957; and 6,972 kg of mil k (4% B.F.), for the pasture fertilization levels I,II, III, and IV, respectively.