Compound enzyme preparation supplementation improves the production performance of goats by regulating rumen microbiota.

Enzyme preparation is one of the widely used additives in ruminant production. However, a suitable method of adding compound enzyme preparation (CEP) to the feeds is still lacking. This study investigated the effect of adding CEP on the diet of goats. Twenty 4-month-old Boer goats were randomly assigned to four groups. The dietary treatments contained different CEPs (Saccharomyces cerevisiae cells, cellulase, xylanase, β-glucanase amylase, and protease) at the concentrations of 0, 0.25, 0.50, and 0.75 g/kg of feed provided for a period of 56 days. Adding CEP in goat feed significantly increased average daily gain (ADG) during the entire test period. The oxidative indices, hormones, and immune cells did not differ significantly among the different groups. CEP significantly increased the content of total volatile fatty acids measured at the end of the experiment on day 56 of the final normal feeding phase. 16S rDNA sequencing revealed that CEP increased the abundance of Ruminococcaceae in the rumen and g__norank_f__Eubacterium_coprostanoligenes_group, Oscillibacter g__unclassified_f__Ruminococcaceae, and g__unclassified_o__Oscillospirales in fecal matter collected on day 56 of the final normal feeding phase. However, CEP decreased the abundance of unclassified_f__Lachnospiraceae, norank_f__UCG-010, Butyrivibrio, and Saccharofermentans in the rumen. The abundance of Ruminococcaceae in the rumen and propionic acid was positively correlated with ADG. Function prediction showed that carbon fixation, carbohydrate digestion and absorption pathways were significantly enriched in rumen microbiota in the treatment group. The findings indicated that supplementation with 0.5 g CEP/kg of feed for 56 days significantly improves the production performance of goats without adverse health effects. KEY POINTS: • Feeding with compound enzyme preparation for 56 days significantly improved the productive performance but did not affect the antioxidative capacity and immunity of goats. • Supplementing compound enzyme preparation in diet could increase the relative abundance of Ruminococcus to increase the levels of short-chain fatty acids produced. • The most appropriate supplemental amount of compound enzyme preparation per kilogram of the diet was 0.5 g.