Expeller-Pressed Canola (Brassica napus) Meal Modulates the Structure and Function of the Cecal Microbiota, and Alters the Metabolome of the Pancreas, Liver, and Breast Muscle of Broiler Chickens

Abstract

The inoculation of one-day-old broiler chicks with the cecal contents from a mature broiler breeder resulted in a highly diverse and uniform cecal bacterial community. CM did not affect feed consumption, weight gain, nor the richness, evenness, or diversity of the cecal bacterial community. However, the structure of the bacterial community was altered in birds fed the CM diet. Although the CM diet was formulated to contain equivalent metabolizable energy to the control diet, it contained more dietary fiber. The abundance of bacterial families, including those that are known to contain species able to metabolize fiber was altered (e.g., bacteria within the families, Methanobacteriaceae, Atopobiaceae, Prevotellaceae, Clostridiales Family XIII, Peptostreptococcaceae, and Succinivibrionaceae), and concentrations of SCFAs were higher in the ceca of birds fed the CM diet. Moreover, concentrations of isoleucine, isobutyrate, glutamate, and 2-oxoglutarate were higher, whereas concentrations of phenyllactic acid, indole, glucose, 3-phenylpropionate, and 2-oxobutyrate were lower in the digesta of chickens that were fed CM. The metabolic profiles of pancreas, liver, and breast muscle tissues of birds fed the CM diet differed from control birds. Metabolites that were associated with energy production, protection against oxidative stress, and pathways of amino acid and glycerophospholipid metabolism had altered concentrations in these tissues. Some of the observed changes in metabolite levels may indicate an increased disease risk in birds fed the CM diet (e.g., pancreatitis), and others suggested that birds mounted metabolic response to offset the adverse impacts of CM (e.g., oxidative stress in the liver).

Keywords: breast muscle; broiler chickens; canola meal; cecum; liver; metabolome; microbiota; pancreas.

Figure 1

(A) Temporal feed consumption (g/bird/d) of broilers fed a diet supplemented with canola meal (20%) relative to a control diet. Feed consumption increased (p < 0.001) over time, but there was no difference (p = 0.514) between the diet treatments. (B) Temporal change in body weights (g) of female and male broilers fed a diet with canola meal (20%) relative to a control diet. Increases in the body weights of female and male birds differed over time (p < 0.001), and male birds were heavier (p ≤ 0.008) than female birds at day 21. There was no effect (p = 0.118) of the diet treatment on body weights.

Figure 2

The relative abundance of archaea and bacterial phyla (A) and families (B) observed in the cecal digesta of 35-day-old female and male broilers fed a diet supplemented with canola meal (20%) or a control diet with ≥22,000 reads (n = 43). Data were averaged for female and male birds by diet treatment.

Figure 3

Principle coordinate analysis (unweighted UniFrac) of bacterial communities in the cecal digesta of female and male 35-day-old broilers fed a diet supplemented with canola meal (20%) or a control diet. Ellipsoids highlight the differences in community structure between communities in the digesta of birds fed the canola meal and control diets. The cecal communities differed between the two diets as determined by Jaccard (p = 0.001), Bray Curtis (p = 0.001), and unweighted (p = 0.001) and weighted (p = 0.016) UniFrac analyses.

Figure 4

The relative abundance of select archaea and bacterial families (phylum-family names presented) in the cecal digesta of 35-day-old female and male broilers fed a diet supplemented with canola meal (20%) or a control diet. (A) Archaea-Methanobacteriaceae. (B) Archaea-Methanocorpusculaceae. (C) Actinobacteria-Atopobiaceae. (D) Bacteroidetes-Prevotellaceae. (E) Bacteroidetes-Bacteroidales D4 uncultured. (F) Firmicutes-Christensenellaceae. (G) Firmicutes-Clostridiales vadin BB60 group. (H) Firmicutes-Clostridiales D4 Family XIII. (I) Firmicutes-Peptostreptococcaceae. (J) Proteobacteria-Desulfovibrionaceae. (K) Proteobacteria-Succinivibrionaceae. The first name is the phylum and second name the family. Vertical lines that are associated with histogram bars are standard error of the means, and histogram bars indicated with a black asterisk indicate that abundances differed (p ≤ 0.047) between the two diet treatments. Bars marked with white asterisks indicate that abundances differed (p ≤ 0.050) between male and female broilers.

Figure 5

Short-chain fatty acid (SCFA) concentrations in the cecal digesta of 35-day-old broilers fed a diet supplemented with canola meal (20%) relative to a control diet as measured by gas chromatography. (A) Acetate. (B) Proprionate. (C) Butyrate. (D) Valerate. (E) Total SCFAs. (F) Ratio of two carbon to three carbon SCFAs. There was no difference (p ≥ 0.549) between females and males, and in both sexes higher (p ≤ 0.025) concentrations of SCFAs were observed in the cecal digesta of birds fed the diet with canola meal (indicated by asterisks).

Figure 6

(A,B) Principle Component Analysis (PCA) showing unsupervised multivariate analysis of the cecal digesta metabolome among female (left) and male (right) from birds fed a diet supplemented with canola meal (20%) or a control diet. (C–H). Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) showing supervised separation (p ≤ 0.014) for female (left) and male (right) birds fed the two diets. (C,D) Pancreas. (E,F) Liver. (G,H) Breast muscle. Each triangle or square represents one individual bird, and ellipsoids represent significant clustering by diet treatment at 95% confidence interval. For Figures A,B, the x-axis represents principle component 1, and the y-axis represents principle component 2. For Figures C–H, the x-axis represents the between-group variance (T-score), and the y-axis represents within-group variance (orthogonal T-score). Percent values in parenthesis show variances.

Figure 7

Average percent differences of individual metabolite quantities associated with female and male birds fed a diet supplemented with canola meal (20%) or a control diet as identified by a Mann-Whitney U test. All metabolites shown were significantly altered based on a p-value less than 0.05. (A) Cecal digesta. (B) Pancreas from female birds. (C) Pancreas from male birds (D) Liver. (E) Breast muscle. Negative values are less abundant, and positive values are more abundant in birds fed the canola meal diet.