*Review* **Exogenous Enzymes as Zootechnical Additives in Animal Feed: A Review**

**Brianda Susana Velázquez-De Lucio <sup>1</sup> , Edna María Hernández-Domínguez <sup>1</sup> , Matilde Villa-García 1 , Gerardo Díaz-Godínez <sup>2</sup> , Virginia Mandujano-Gonzalez <sup>3</sup> , Bethsua Mendoza-Mendoza <sup>4</sup> and Jorge Álvarez-Cervantes 1,\***


**Citation:** Velázquez-De Lucio, B.S.; Hernández-Domínguez, E.M.; Villa-García, M.; Díaz-Godínez, G.; Mandujano-Gonzalez, V.; Mendoza-Mendoza, B.; Álvarez-Cervantes, J. Exogenous Enzymes as Zootechnical Additives in Animal Feed: A Review. *Catalysts* **2021**, *11*, 851. https://doi.org/ 10.3390/catal11070851

Academic Editors: Chia-Hung Kuo, Chun-Yung Huang, Chwen-Jen Shieh and Cheng-Di Dong

Received: 19 June 2021 Accepted: 13 July 2021 Published: 15 July 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Abstract:** Enzymes are widely used in the food industry. Their use as a supplement to the raw material for animal feed is a current research topic. Although there are several studies on the application of enzyme additives in the animal feed industry, it is necessary to search for new enzymes, as well as to utilize bioinformatics tools for the design of specific enzymes that work in certain environmental conditions and substrates. This will allow the improvement of the productive parameters in animals, reducing costs and making the processes more efficient. Technological needs have considered these catalysts as essential in many industrial sectors and research is constantly being carried out to optimize their use in those processes. This review describes the enzymes used in animal nutrition, their mode of action, their production and new sources of production as well as studies on different animal models to evaluate their effect on the productive performance intended for the production of animal feed.

**Keywords:** animal nutrition; enzyme; animal feed; zootechnical additive; digestibility; antinutritional factors
