The present invention relates to the use of a combination of a protease and an inner salt of a quaternary amine carboxylic acid for the preparation of an agent for the treatment and/or prophylaxis of coccidiosis and bacterial infections such as necrotic enterities in animals. Preferred embodiments of the invention comprise the inclusion of a xylanase and/or an -amylase in the agent. A nutritional additive comprising a combination of an inner salt of a quaternary amine carboxylic acid protease and (optionally) a xylanase and an -amylase is also disclosed. It can be used for improving the rate of weight gain of animals.