Chinese Herbal Extracts Mitigate Ammonia Generation in the Cecum of Laying Hens: An In Vitro Study

Abstract

The objectives of the study were to screen one or several Chinese herbal extracts with good ammonia emission reduction effects using an in vitro gas production study. The study consisted of a control (without Chinese herbal extract), and 11 experimental groups with added cinnamon extract (CE), Osmanthus extract (OE), tangerine peel extract (TPE), dandelion extract (DE), Coptis chinensis extract (CCE), honeysuckle extract (HE), Pulsatilla root extract (PRE), yucca extract (YE), licorice extract (LE), Ginkgo biloba extract (GBE), or astragalus extract (AE). The results showed that HE, PRE, YE, LE, GBE, and AE significantly reduced ammonia production (p ≤ 0.05). The most significant ammonia inhibition was achieved via AE, resulting in a 26.76% reduction. In all treatments, Chinese herbal extracts had no significant effect on pH, conductivity, or uric acid, urea, and nitrate-nitrogen concentrations (p > 0.05). However, AE significantly reduced urease activity and the relative activity of uricase (p ≤ 0.05). AE significantly increased the relative abundance of Bacteroides and decreased the relative abundance of Clostridium, Desulfovibrio, and Prevotell (p ≤ 0.05). Astragalus extract inhibited ammonia emission from laying hens by changing the gut microbial community structure, reducing the relative abundance of ammonia-producing bacteria, and reducing microorganisms' uricase and urease activities.

Keywords: Chinese herbal extract; ammonia; astragalus extract; gut microbiota; laying hen.

Figure 1

(a) Effect of different types of Chinese herbal extracts on the in vitro production of total gas. (b) Effect of different types of Chinese herbal extracts on the in vitro production of ammonia. CK—control group, CE—cinnamon extract, OE—Osmanthus extract, TPE—tangerine peel extract, DE—dandelion extract, CCE—Coptis chinensis extract, HE—honeysuckle extract, PRE—Pulsatilla root extract, YE—yucca extract, LE—licorice extract, GBE—Ginkgo biloba extract, AE—astragalus extract. Error bars indicate standard errors (n = 6). Different letters above the bars indicate statistically significant differences between the samples (ANOVA followed by Duncan’s test, p ≤  0.05).

Figure 2

(a) Effect of different types of Chinese herbal extracts on the in vitro ammonium-nitrogen content. (b) Effect of different types of Chinese herbal extracts on the in vitro nitrate-nitrogen content. CK—control group, CE—cinnamon extract, OE—Osmanthus extract, TPE—tangerine peel extract, DE—dandelion extract, CCE—Coptis chinensis extract, HE—honeysuckle extract, PRE—Pulsatilla root extract, YE—yucca extract, LE—licorice extract, GBE—Ginkgo biloba extract, AE—astragalus extract. Error bars indicate standard errors (n = 6). Different letters above the bars indicate statistically significant differences between the samples (ANOVA followed by Duncan’s test, p ≤  0.05).

Figure 3

(a) Effect of different types of Chinese herbal extracts on the in vitro urea acid content. (b) Effect of different types of Chinese herbal extracts on the in vitro urea content. CK—control group, CE—cinnamon extract, OE—Osmanthus extract, TPE—tangerine peel extract, DE—dandelion extract, CCE—Coptis chinensis extract, HE—honeysuckle extract, PRE—Pulsatilla root extract, YE—yucca extract, LE—licorice extract, GBE—Ginkgo biloba extract, AE—astragalus extract. Error bars indicate standard errors (n = 6). Different letters above the bars indicate statistically significant differences between the samples (ANOVA followed by Duncan’s test, p ≤  0.05).

Figure 4

(a) Effect of different types of Chinese herbal extracts on the in vitro relative activity of uricase. (b) Effect of different types of Chinese herbal extracts on in vitro urease activity. CK—control group, CE—cinnamon extract, OE—Osmanthus extract, TPE—tangerine peel extract, DE—dandelion extract, CCE—Coptis chinensis extract, HE—honeysuckle extract, PRE—Pulsatilla root extract, YE—yucca extract, LE—licorice extract, GBE—Ginkgo biloba extract, AE—astragalus extract. Error bars indicate standard errors (n = 6). Different letters above the bars indicate statistically significant differences between the samples (ANOVA followed by Duncan’s test, p ≤  0.05).

Figure 5

(a) Effect of different types of Chinese herbal extracts on the in vitro pH. (b) Effect of different types of Chinese herbal extracts on in vitro electrical conductivity. CK—control group, CE—cinnamon extract, OE—Osmanthus extract, TPE—tangerine peel extract, DE—dandelion extract, CCE—Coptis chinensis extract, HE—honeysuckle extract, PRE—Pulsatilla root extract, YE—yucca extract, LE—licorice extract, GBE—Ginkgo biloba extract, AE—astragalus extract. Error bars indicate standard errors (n = 6). Different letters above the bars indicate statistically significant differences between the samples (ANOVA followed by Duncan’s test, p ≤  0.05).

Figure 6

(a) Effect of different types of Chinese herbal extracts on Chao 1 index of fermentation bacteria. (b) Principal coordinate analyses based on unweighted Unifrac distances. (c) Effect of different types of Chinese herbal extracts on the phyla of the microbial community. (d) Effect of different types of Chinese herbal extracts on the genera of the microbial community. CK—control group, CE—cinnamon extract, OE—Osmanthus extract, TPE—tangerine peel extract, DE—dandelion extract, CCE—Coptis chinensis extract, HE—honeysuckle extract, PRE—Pulsatilla root extract, YE—yucca extract, LE—licorice extract, GBE—Ginkgo biloba extract, AE—astragalus extract.

Figure 6

(a) Effect of different types of Chinese herbal extracts on Chao 1 index of fermentation bacteria. (b) Principal coordinate analyses based on unweighted Unifrac distances. (c) Effect of different types of Chinese herbal extracts on the phyla of the microbial community. (d) Effect of different types of Chinese herbal extracts on the genera of the microbial community. CK—control group, CE—cinnamon extract, OE—Osmanthus extract, TPE—tangerine peel extract, DE—dandelion extract, CCE—Coptis chinensis extract, HE—honeysuckle extract, PRE—Pulsatilla root extract, YE—yucca extract, LE—licorice extract, GBE—Ginkgo biloba extract, AE—astragalus extract.

Figure 7

(a) Microbial function prediction analysis between CK and GEB. (b) Microbial function prediction analysis between CK and AE. CK—control group, AE—astragalus extract, GBE–Ginkgo biloba extract.