To provide an animal productivity improver consisting of a lactic acid condensate mixture or a neutralized salt thereof capable of improving the productivity of animals such as livestock by feeding them thereto, and to provide a feed containing the mixture.

This animal productivity improver consists of a lactic acid condensate mixture obtained by heat condensation of lactic acid. The improver has the following characteristics: when the improver is subjected to high- performance liquid chromatography under the conditioned described below, the peak area for lactic acid is ≤20% and the peak area for a fraction appearing 3-20 min after beginning an elution is ≥30%; the conditions: [column] ODS column with an inner diameter of 4.6 mm and a length of 15 cm; [eluent] A-liquid is a 0.002 wt.% aqueous trifluoroacetic acid solution, and B-liquid is acetonitrile, flow rate is 1.0 mL/min, mixing ratio is 75 vol.%/25 vol.% (A/B) from beginning the elution to 5 min thereafter, a linear gradient 5-35 min after beginning the elution, and 0 vol.%/100 vol.% (A/B) 35-40 min after beginning the elution; and [detection wavelength] at 210 nm.