Compound preparation containing mutant enzyme and application of compound preparation in preparation of feed additive for promoting growth of livestock

The invention discloses a compound preparation containing mutant enzyme and application of the compound preparation in preparation of a feed additive for promoting livestock growth. The compound preparation is prepared from phytosterol and a cellulase-xylanase bifunctional enzyme solution according to a volume ratio of 1: (1-3), wherein the cellulase-xylanase bifunctional enzyme solution is prepared from a cellulase-xylanase bifunctional enzyme mutant CelXyn2-S343 with an amino acid sequence as shown in SEQ ID No.2 (Sequence Identifier Number 2). The compound preparation is simple in preparation process, and experiments prove that the compound preparation has an obvious effect of promoting the growth of bred pigs, particularly, the daily average weight gain and daily feed intake of fattening pigs, nursery pigs and growing pigs are obviously improved, the feed-gain ratio is reduced, and the compound preparation is suitable for various livestock and is beneficial to the breeding development of the livestock. 本发