Influence of Chlorella vulgaris on growth, digestibility and gut morphology and microbiota of weaned piglet

Abstract

The purpose of this study was to evaluate the impact of Chlorella vulgaris (5% in the diet), supplemented or not with two exogenous carbohydrase mixtures on piglets' performance, nutrient digestibility and gut morphology, fermentation products and microbiota. Forty-four male piglets weaned at 28 days of age, with 11.2 ± 0.46 kg of live weight, were used and assigned to 1 of 4 dietary treatments: cereal and soybean meal based-diet (control, n = 11), control diet with 5% of C. vulgaris (CH, n = 10), CH diet supplemented with 0.005% of Rovabio^® Excel AP (CH + R, n = 10) and CH diet supplemented with 0.01% of a recombinant 4-carbohydrase mixture (CH + M, n = 11). Growth performance was not changed by the of C. vulgaris inclusion during 21 days of trial. However, total tract apparent digestibility of nutritional fractions was negatively impacted by the inclusion. In addition, the viscosity of duodenum plus jejunum contents slightly increased in all groups fed with the microalga. In contrast, dietary microalga increased duodenum villus height and promoted a healthier gut microbiota, with higher abundance of some specific bacterial taxa (Colidextribacter, Oscillospira and Lactobacillus). This study indicates that the dietary inclusion of 5% C. vulgaris improves piglets' gut health without impairing performance. Data also indicate that C. vulgaris reduces nutrient digestibility but promotes compensatory developments of gut mucosa and prebiotic effects. Dietary supplementation with exogenous carbohydrases does not seem to be necessary for this inclusion level. Therefore, the incorporation of CH as a sustainable feed ingredient in piglets' nutrition is a viable alternative approach.

Figure 1

(A) Boxplots showing alpha diversity for Chao1, Shannon, InvSimpson indices. (B) PCoA plot using a Euclidian distance matrix. Dietary treatments: Control = control diet; CH = Chlorella vulgaris diet; CH + R = C. vulgaris diet supplemented with Rovabio® Excel AP; CH + M = C. vulgaris diet supplemented with a pre-selected enzymatic mixture.

Figure 2

Barplot of Linear discriminant analysis (LDA) effect size (LEfSe). Horizontal bars represent the effect size for each taxon. The length of the bar represents the LDA score. LDA threshold score for discriminative features was set to 3.0. Dietary treatments: Control = control diet; CH = Chlorella vulgaris diet; CH + R = C. vulgaris diet supplemented with Rovabio® Excel AP; CH + M = C. vulgaris diet supplemented with a pre-selected enzymatic mixture.