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Rosemary Extract Reduces Odor in Cats Through Nitrogen and Sulfur Metabolism by Gut Microbiota–Host Co-Modulation
by
,
Ziming Huang
1,
Miao Li
1,
Zhiqin He
1,
Xiliang Yan
1,2,3,
Yinbao Wu
1,2,3,
Peiqiang Mu
4,
Jun Jiang
4,
Xu Wang
5 and
Yan Wang
1,2,3,* 1
State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
2
Guangdong Provincial Key Lab of Agro-Animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou 510642, China
3
National Engineering Research Center for Breeding Swine Industry, South China Agricultural University, Guangzhou 510642, China
4
College of Life Science, South China Agricultural University, Guangzhou 510642, China
5
Institute of Quality Standard and Monitoring Technology for Agro-Products of Guangdong Academy of Agricultural Sciences, Guangzhou 510642, China
*
Author to whom correspondence should be addressed.
Animals 2025, 15(14), 2101; https://doi.org/10.3390/ani15142101
Submission received: 28 May 2025
/
Revised: 11 July 2025
/
Accepted: 14 July 2025
/
Published: 16 July 2025
(This article belongs to the Section Companion Animals)
Simple Summary
Odorous emissions from pet cats are an important contributor to the quality of life of cat owners. Plant extracts rich in bioactive compounds offer a potentially effective solution to this problem. This study evaluated twelve plant extracts via in vitro fermentation, identifying rosemary and licorice as the most effective. Further analysis revealed that rosemary fractions below 100 Da (Dalton) had the best deodorizing effect. Building on these findings, feeding trials were conducted to evaluate the practical effectiveness of rosemary extract in reducing odor emissions and to explore its underlying mechanisms. In feeding trials with British Shorthair cats, rosemary extract, particularly its fractions below 100 Da, significantly reduced ammonia and hydrogen sulfide emissions. It reduced odor emissions by decreasing urease and uricase activity, inhibiting sulfur-containing protein degradation and sulfate reduction, while increasing the relative abundance of the intestinal probiotic (Bifidobacterium) and enhancing immune function. These results suggest that rosemary extract, particularly its fractions below 100 Da, is a promising natural pet deodorizer.
Abstract
Odors from pet cats can negatively affect the quality of life of cat owners. The diverse bioactive compounds in plant extracts make them a promising candidate for effective odor reduction. This study evaluated twelve plant extracts for deodorizing efficacy via in vitro fermentation tests. Rosemary extract and licorice extract exhibited better deodorizing effects, with fractions of rosemary extract below 100 Da demonstrating the most effective deodorizing performance. Based on these findings, subsequent feeding trials were conducted using rosemary extract and its fractions below 100 Da. In the feeding trial, adult British Shorthair cats were divided into three groups (Control Check, RE, and RE100) and housed in a controlled-environment respiration chamber for 30 days. Measurements included odor emissions, fecal and blood physicochemical parameters, immune parameters, microbiota composition based on 16S rRNA sequencing, and metabolome analysis. The results of the feeding trial indicated that rosemary extract significantly reduced ammonia and hydrogen sulfide emissions (46.84%, 41.64%), while fractions below 100 Da of rosemary extract achieved even greater reductions (55.62%, 53.87%). Rosemary extract regulated the intestinal microbial community, significantly increasing the relative abundance of the intestinal probiotic Bifidobacterium (p < 0.05) and reducing the population of sulfate-reducing bacteria (p < 0.05). It also significantly reduced urease and uricase activities (p < 0.05) to reduce ammonia production and inhibited the degradation of sulfur-containing proteins and sulfate reduction to reduce hydrogen sulfide emissions. Furthermore, rosemary extract significantly enhanced the immune function of British Shorthair cats (p < 0.05). This study suggests that rosemary extract, particularly its fractions below 100 Da, is a highly promising pet deodorizer.
