**Growth Performance, Meat Quality, and Fecal Microbial Population in Limousin Bulls Supplemented with Hydrolyzable Tannins**

**Andrej Mergeduš 1, Marjan Janžekoviˇc 1, Dejan Škorjanc 2, Tadeja Kraner Šumenjak 3 and Maksimiljan Brus 1,\***


**Abstract:** The objective of this study was to investigate the effects of supplementation of hydrolyzable tannins (HT) from sweet chestnut wood extract (*Castanea sativa* Mill.) to the diet of Limousin bulls on growth rate, carcass and meat quality traits, and fecal *Clostridia* strain levels in a 7-month feeding trial. Thirty-two bulls were randomly assigned to four treatment groups (CON (without addition of HT); TAN 1 (1 g HT kg−<sup>1</sup> DM); TAN 2 (1.5 g HT kg−<sup>1</sup> DM); and TAN 3 (1.5 g HT kg−<sup>1</sup> DM with a nominally lower dose of concentrate). Compared with the CON group, supplementation with HT significantly (*p* < 0.050) increased bull growth rate during 4–7 months, whereas carcass and meat quality traits were unaffected during the last three months of fattening. Supplementation of HT significantly reduced meat drip loss (*p* = 0.000) compared with the CON group. No effects were observed on the total number of fecal *Clostridia* strains; however, the concentration of *Clostridium perfringens* was significantly lower (*p* = 0.004) in TAN 1 than that in the CON group. The results obtained in fattening bulls indicate that the addition of HT is justified in practice to improve growth performance and feed efficiency without adverse effects on the carcass and meat quality.

**Keywords:** carcass characteristic; chestnut tannins; fecal *Clostridia*; growth performance; Limousin bulls; meat quality
