Dietary autolysed yeast modulates blood profiles, small intestinal morphology and caecal microbiota of weaning pigs

Yeast products are potential feed additives due to their beneficial effects on gut health. Thus, we verified the potential impacts of autolysed yeast (AY) on growth performance, blood profiles, gut morphology and microbiota in weaning pigs. In total, 72 castrated, commercial, crossbred, weaning pigs were divided into three groups, with each group consisting of eight replicates with three piglets each. The experimental diets were as follows: 1) control diet (0% AY); 2) diet with 1.0% AY; 3) diet with 3.0% AY. For the overall period, using 1.0% AY in the diet seemed to improve the feed conversion ratio (P = 0.09); whereas, other productive performance parameters were not significantly affected by the supplementations. Using 1.0% AY in the diet significantly decreased the blood urea nitrogen and neutrophil/lymphocyte ratio (N/L ratio) but increased the eosinophil count (P < 0.05). Adding AY to the diet did not influence caecal microbial diversity; using 1.0% AY in the diet decreased the abundances of the phylum Actinobacteria, the class Coriobacteriia and the family Coriobacteriaceae (P < 0.05). At the genus level, an AY inclusion level of 1.0% reduced the abundances of Collinsella, Clostridium and Catenibacterium and increased that of Marvinbryantia (P < 0.05). Furthermore, the abundance of butyrate-producing bacteria seemed to be increased by AY supplementation (P = 0.06). Pearson’s correlation coefficient (r) analysis revealed that AY intake was negatively associated with the abundance of pathogens of the genera Dorea (r = −0.84; P = 0.03) and Catenibacterium (r = −0.80; P = 0.04). This indicates that AY intake potentially reduces the population of some pathogenic bacteria at family level. Thus, using an appropriate AY inclusion level (1.0%) seemed to improve the feed use of postweaning pigs and clearly improved their small intestinal morphology, blood profiles and caecal microbiota.