**1. Introduction**

Durian, a seasonal fruit, is grown widely in tropical countries, where Malaysia and Thailand are the main producers [1]. Approximately 20 to 30% of durian is appropriate for human consumption, and 80 to 70% accounts for the durian peel, which is discarded as waste [2]. Discarded durian peel (DP) contains 10.30% crude protein (CP), 3.24% fat, 22.33% crude fiber (CF), 50.51% nitrogen-free extract (NFE), 9.50% cellulose, and 10.32% acid detergent lignin (ADL) [3]. Due to a high NFE content, DP spoils shortly after discarding. Ensiling is a well-known technique and is used to preserve high-fermentable-containing feed resources using lactic acid bacteria (LAB), converting sugar into lactic acid, resulting in low pH [4]. Ensiling additives including *Lactobacillus* strains, cellulase, and molasses are usually added to improve fermentation quality [5–8]. *Lactobacillus casei* TH14 (*L. casei* TH14), LAB strain, is a local strain isolated from sweet corn silage, which has high lactic acid production with a low pH range [9]. Cellulase is a popular fibrolytic enzyme added to break down cellulose, releasing soluble carbohydrate for LAB growth [10,11], while

**Citation:** Panyawoot, N.; So, S.; Cherdthong, A.; Chanjula, P. Effect of Feeding Discarded Durian Peel Ensiled with *Lactobacillus casei TH14* and Additives in Total Mixed Rations on Digestibility, Ruminal Fermentation, Methane Mitigation, and Nitrogen Balance of Thai Native–Anglo-Nubian Goats. *Fermentation* **2022**, *8*, 43. https://doi.org/10.3390/ fermentation8020043

Academic Editor: Christian Kennes

Received: 26 December 2021 Accepted: 18 January 2022 Published: 21 January 2022

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**Copyright:** © 2022 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/).

molasses is added as a carbon source for LAB to ensure adequate lactic acid production if ensiling materials contain low water-soluble carbohydrate numbers [5]. Using *L. casei* TH14, cellulase and molasses have been reported to improve quality of sorghum [4], rice straw [12], and sugarcane bagasse [5]. In addition to fermentation quality improvement, *L. casei* TH14, cellulase, and molasses addition also improves feed utilization, propionate production, and methane mitigation [7,8,13]. However, the effect of *L. casei* TH14, cellulase, and molasses on DP quality and using fermented DP as roughage source in goat rations have never been evaluated. This study hypothesized that *L. casei* TH14 combined with molasses could improve DP quality, nutrient digestibility, propionate production, and methane mitigation. The objective of this study was to evaluate the effect of fermented discarded durian peel with *Lactobacillus casei* TH14, cellulase, and molasses separately or in combination in total mixed rations on feed utilization, digestibility, ruminal fermentation, and nitrogen utilization in growing crossbreed Thai Native–Anglo-Nubian goats.
