Effects of rhamnolipids on growth performance and intestinal health parameters in Linnan yellow broilers

Abstract

This study determined the effects of dietary supplementation of rhamnolipids (RLS) on the growth performance, gut morphology, immune function, intestinal volatile fatty acid, and microflora community in Linnan yellow broilers. A total of 480 1-day-old broiler chicks were randomly assigned to groups for supplementation with one of the following for 56 d: no supplement (control), 30 mg/kg bacitracin (ANT), 500 mg/kg RLS, or 1,000 mg/kg RLS (RLS2). The RLS2 diet was found to improve the final BW and ADG on day 56. The RLS diet reduced jejunal crypt depth, increased jejunal villus length, and increased serum IgA, IgM, IgY, IL-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) levels. The RLS broilers had higher cecum concentrations of acetic acid, propionic acid, butyrate, isobutyric acid, valerate, and isovalerate. High-throughput sequencing indicated that RLS affected microbial quantity and diversity in the cecum. Bacterial richness was higher in the RLS broilers than the ANT broilers. The RLS broilers had higher relative abundances of Megasphaera hypermegale and Lachnospiraceae bacterium 19gly4 on day 28 and Clostridium spiroforme and Alistipes obesi on day 56. These results suggest that RLS supplementation improves growth performance, benefits the intestinal villus morphology, regulates host immune function, and raises intestinal volatile fatty acid content and the relative abundance of the gut microbiota in broiler chickens.

Keywords: broiler; growth performance; intestinal health parameter; rhamnolipid.

Figure 1

Effect of the RLS on jejunum villus of broilers. A represents the villus length in the jejunum. B represents the crypt depth in the jejunum. C represents the ratio of the villus length and crypt depth. NCO represents the control broilers; ANT represents the broilers supplemented with 30 mg/kg bacitracin; RLS1 represents the broilers supplemented with 500 mg/kg RLS; RLS2 represents the broilers supplemented with 1,000 mg/kg RLS. Different lowercase letters indicate a significant difference (P < 0.05). Values means n = 8 for the analysis of the jejunum form. Data are means ± SD. Abbrevaition: RLS, rhamnolipid.

Figure 2

Effect of RLS on the serum IL-1β, IL-6 and TNF-αin broilers. NCO represents the control broilers on day 28 and 56, respectively; ANT represents the broilers supplemented with 30 mg/kg bacitracin on day 28 and 56, respectively; RLS1 represents the broilers supplemented with 500 mg/kg RLS on day 28 and 56, respectively; RLS2 represents the broilers supplemented with 1,000 mg/kg RLS on day 28 and 56, respectively. Diverse lowercase letters show significant differences between treatments (P < 0.05). Values means n = 8 for the analysis of serum inflammatory. Data are means ± SD. Abbrevaition: RLS, rhamnolipid.

Figure 3

Effect of the RLS on the VFA in cecal content of broilers. NCO represents the control broilers; ANT represents the broilers supplemented with 30 mg/kg bacitracin; RLS1 represents the broilers supplemented with 500 mg/kg RLS; RLS2 represents the broilers supplemented with 1,000 mg/kg RLS. Diverse lowercase letters show significant differences between treatments (P < 0.05). Values means n = 6 for the analysis of VFA. Data are means ± SD. Abbrevaitions: RLS, rhamnolipid; VFA, volatile fatty acid.

Figure 4

Summary of microbial community in cecal contents of broilers on day 28. (A) Venn diagram. (B) UPGMA cluster tree. (C) Principle component analysis. (D) Shannon index. (E–G) The top 10 taxa by relative abundance (E: phylum; F: genus; G: species). (H–J) Species with significant inter-group differences (H: phylum; I: genus; J: species). Broiler basal diet supplementation: NCO, none; ANT, 30 mg/kg bacitracin; RLS1, 500 mg/kg rhamnolipids; and RLS2, 1,000 mg/kg rhamnolipids. OTU, operational taxonomic unit. Broilers were regarded as the experimental units, n = 6 per treatment. Significant differences: ∗ at P < 0.05, ∗∗ at P < 0.01. Abbreviation: UPGMA, unweighted pair group method with arithmetic mean.

Figure 5

Summary of microbial community in cecal contents of broilers on day 56. (A) Venn diagram (B) UPGMA cluster tree. (C) Principal component analysis. (D) Shannon index. (E–G) The top 10 taxa by relative abundance (E: phylum; F: genus; G: species). (H–L) Species with significant inter-group differences (H: phylum; I: genus; J, K, L: species). Broiler basal diet supplementation: NCO, none; ANT, 30 mg/kg bacitracin; RLS1, 500 mg/kg rhamnolipids; and RLS2, 1,000 mg/kg rhamnolipids. OTU, operational taxonomic unit. Broilers were regarded as the experimental units, n = 6 per treatment. Significant differences: ∗ at P < 0.05, ∗∗ at P < 0.01. Abbreviation: UPGMA, unweighted pair group method with arithmetic mean