Effects of Italian ryegrass with multi-enzymes supplementation on growth performance, gut microbial, and manure odor emission in finisher pig

Abstract

This study investigated the effects of addition of Italian ryegrass with multi-enzyme on growth performance, fecal odor, and microbiome. The experiment had a two-factor factorial design, using three levels of Italian ryegrass (0%, 2.5%, and 5%) and two levels of multi-enzymes (no enzyme and commercially recommended level) to formulate experimental diets. In total, 60 crossbred Landrace × Yorkshire × Duroc (LYD) pigs (88.35 ± 2.57 kg) were allocated into six dietary treatments with five replicates. After four weeks, fecal samples were collected via rectal massage for microbiome and odorous compound analysis. Results showed no significant difference (p > 0.05) in growth performance, except for feed intake (p < 0.05), which was higher in enzyme-added diets. Fecal microbiome exhibited no differences (p > 0.05) between treatments, with Firmicutes and Bacteroidetes being the major phyla, similar to the general pig population. Alpha and beta diversity analyses showed no significant differences (p > 0.05). Odorous compounds displayed no significant differences (p > 0.05), except for indoles (p < 0.05) influenced by the enzyme. In conclusion, 5% Italian ryegrass with multi-enzymes can be used as an alternative feed ingredient, having no negative effects on the growth performance, microbiome, and odorous compounds of growing pigs.

Keywords: Growth performance; Italian ryegrass; Manure odor; Microbiome; Non-starch polysaccharide (NSP) enzyme.

Fig. 1.. Fecal microbiome classification at the phylum level.

Fig. 2.. Alpha diversity analysis with ASVs, Chao1, Shannon, and Gini-Simpson method.

(A) AVSs, (B) Chao1, (C) Shannon, (D) Gini-Simpson. ASVs, amplicon sequence variants; C, control diet; IRG2.5, 2.5% IRG added diet; IRG5, 5% IRG added diet.

Fig. 3.. Beta diversity analysis using Bray–Curtis distance method.

(A) between all treatment, (B) IRG effect, (C) enzyme effect. C, control diet; IRG2.5, 2.5% IRG added diet; IRG5, 5% IRG added diet; +, commercially recommended level of enzyme added in diet; −, no enzyme added in diet.