The invention relates to low-protein biological feeds, which comprise the following components in parts by weight: 72 to 85 parts of corns, 6 to 18 parts of soybean meal, 3 to 6 parts of wheat bran, 0 to 1.5 parts of soybean oil, 0.4 to 0.8 part of limestone, 0.5 to 1.5 parts of calcium hydrogen phosphate, 0.3 to 0.6 part of table salt, 0.6 part of premix, 1 part of compound microecological preparation, 0.2 to 0.6 part of L-lysine, 0.05 to 0.12 part of DL-methionine, 0.03 to 0.08 part of L-tryptophan and 0.08 to 0.13 part of L-threonine, wherein the compound microecological preparation comprises butyric acid bacteria, fermentative lactobacillus and bacillus subtilis. According to the low-protein biological feeds, the utilization rate of a nitrogen source in animal feeds can be remarkably increased, the emission of the nitrogen source is reduced, the growth performance of animals can be improved, and remarkable technical effects are achieved.