Effect of dietary sophorolipids on growth performance and gastrointestinal functionality of broiler chickens infected with Eimeria maxima

Abstract

Two experiments were conducted to evaluate the effects of dietary sophorolipids (SLs) supplementation as antibiotic alternatives on growth performance and gut health of chickens infected with Eimeria maxima. In experiment 1, 336 (zero-day-old) male broilers were used. The chickens were weighed and randomly allocated to the following 6 treatments groups with 7 chickens/cage and 8 cages/treatment: control group that received a basal diet (NC), positive control group that received a basal diet and was challenged with E. maxima (PC), PC+C18:1 lactonic diacetyled SL (SL1), PC+C18:1 deacetyled SL (SL2), PC+C18:1 monoacetyled SL (SL3), and PC+C18:1 diacetyled SL (SL4). Each SL (200 mg/kg feed) was added to the corresponding treatment group. In experiment 2, 588 (zero-day-old) male broilers were used. The chickens were randomly allocated to the following experimental groups with 10 or 11 chickens/cage and 8 cages/treatment: NC, PC, PC+ monensin at 90 mg/kg feed (MO), PC+SL1 at 200 mg/kg feed (SL1 200), PC+SL1 at 500 mg/kg feed (SL1 500), PC+SL4 at 200 mg/kg feed (SL4 200), and PC+SL4 at 500 mg/kg of feed (SL4 500). The chickens and feed were weighed at 0, 7, 14, 20, and 22 d to determine growth performance. In both experiments, all chickens except the NC group were orally infected with E. maxima (10,000 oocysts/chicken) at d 14. One chicken per cage was euthanized at d 20 to sample jejunal tissue to measure lesion scores, cytokines, and tight junction (TJ) proteins. Excreta samples were collected daily between d 20 and 22 to measure oocyst numbers. Data were analyzed using Mixed Model (PROC MIXED) in SAS. In experiment 1, SLs did not affect the growth of broiler chickens, but SL4 decreased (P < 0.05) the lesion score and oocyst number compared to PC chickens. In terms of cytokines and TJ protein gene expression, SLs increased (P < 0.05) IL-1β, IL-6, IL-17F, IL-4, IL-13, occludin, and ZO1 levels compared to PC chickens. In experiment 2, monensin increased (P < 0.05) body weight, and decreased (P < 0.05) the lesion score and oocyst number compared to the PC group. SL4 500 increased (P < 0.05) average daily gain and feed conversion ratio but decreased (P < 0.05) lesion score and fecal oocyst number. SL4 decreased (P < 0.05) IL-6, IL-17F, TNFSF-15, IL-2, and IL-10 levels but increased (P < 0.05) occludin and ZO-1 levels. Overall, dietary SL supplementation, especially SL4, improved growth and gastrointestinal functionality of young broiler chickens, demonstrating significant potential as an antibiotic alternative.

Keywords: antibiotic alternative; coccidiosi; gastrointestinal functionality; growth performance; sophorolipid.

Figure 1

Schematic outline of the experimental design in experiments 1 and 2.

Figure 2

Lesion score and oocyst shedding of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 1. All chickens except NC were infected by oral gavage at d 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.^a∼d Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The lesion score was collected from distal jejunal tissue at d 20 (6 days postinfection: dpi) and fecal sample was collected from 6 to 8 dpi to calculate the oocyst shedding. Abbreviations: NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL2, diet supplemented with C18:1 deacetyled sophorolipid; SL3, diet supplemented with C18:1 monoacetyled sophololipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid; the dose of SL in each treatment was 200 mg/kg feed.

Figure 3

Transcripts of proinflammatory cytokine in jejunum of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 1. All chickens except NC were infected by oral gavage at d 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.^a∼c Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The data were collected at d 20 (6 days postinfection). Transcript levels of the cytokines were measured using quantitative RT-PCR and normalized to GAPDH transcript levels. Abbreviations: NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL2, diet supplemented with C18:1 deacetyled sophorolipid; SL3, diet supplemented with C18:1 monoacetyled sophololipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid; the dose of SL in each treatment was 200 mg/kg feed.

Figure 4

Transcripts of Th1 and Th2 cytokines in jejunum of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 1. All chickens except NC were infected by oral gavage at d 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.^a∼c Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The data were collected at d 20 (6 days postinfection). Transcript levels of the cytokines were measured using quantitative RT-PCR and normalized to GAPDH transcript levels. Abbreviations: NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL2, diet supplemented with C18:1 deacetyled sophorolipid; SL3, diet supplemented with C18:1 monoacetyled sophololipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid; the dose of SL in each treatment was 200 mg/kg feed.

Figure 5

Transcripts of tight junction and mucin protein in jejunum of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 1. All chickens except NC were infected by oral gavage at day 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.^a∼c Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The data were collected at d 20 (6 days postinfection). Transcript levels of the tight junction proteins and mucin protein were measured using quantitative RT-PCR and normalized to GAPDH transcript levels. Abbreviations: NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL2, diet supplemented with C18:1 deacetyled sophorolipid; SL3, diet supplemented with C18:1 monoacetyled sophololipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid; the dose of SL in each treatment was 200 mg/kg feed.

Figure 6

Lesion score and oocyst shedding of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 2. ^a∼d Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The lesion score was collected from distal jejunal tissue at d 20 (6 days postinfection: dpi) and fecal sample was collected from 6 to 8 dpi to calculate the oocyst shedding. Abbreviations: MO, 90 mg monensin/kg feed; NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid; 200, 200 mg/kg feed; 500, 500 mg/kg feed. All chickens except NC were infected by oral gavage at d 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.

Figure 7

Transcripts of proinflammatory cytokine in jejunum of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 2. ^a∼d Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The data were collected at d 20 (6 days postinfection). Transcript levels of the cytokines were measured using quantitative RT-PCR and normalized to GAPDH transcript levels. Abbreviations: MO, 90 mg monensin/kg feed; NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid; 200, 200 mg/kg feed; 500, 500 mg/kg feed. All chickens except NC were infected by oral gavage at d 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.

Figure 8

Transcripts of Th1 and Th2 cytokines in jejunum of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 2. ^a∼b Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The data were collected at d 20 (6 days postinfection). Transcript levels of the cytokines were measured using quantitative RT-PCR and normalized to GAPDH transcript levels. Abbreviations: MO, 90 mg monensin/kg feed; NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid; 200, 200 mg/kg feed; 500, 500 mg/kg feed. All chickens except NC were infected by oral gavage at d 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.

Figure 9

Transcripts of tight junction and mucin protein in jejunum of chickens fed diet supplemented with various sophorolipid during infection with E. maxima in experiment 2. ^a∼d Bars with no common letter differ significantly (P < 0.05). Each bar represents the mean ± SEM (n = 8). The data were collected at d 20 (6 days postinfection). Transcript levels of the cytokines were measured using quantitative RT-PCR and normalized to GAPDH transcript levels. Abbreviations: MO, 90 mg monensin/kg feed; NC, basal diet; PC, basal diet for infected chickens; SL1, diet supplemented with C18:1 lactonic diacetyled sophorolipid; SL4, diet supplemented with C18:1 diacetyled sophorolipid, 200, 200 mg/kg feed; 500, 500 mg/kg feed. All chickens except NC were infected by oral gavage at d 14 with 1.0 × 10⁴ oocysts/chicken of E. maxima.