Glycerine kinase gene expression, nutrient digestibility and gut microbiota composition in post-weaned pigs fed diets with increasing crude glycerine levels

The effects of substituting maize with crude glycerine (CG) as an energy source, on nutrient digestibility, liver glycerine kinase (GK) gene expression, and gut microbiota composition were investigated in 18 weaned pigs [30 days old, 7.8 kg initial body weight (BW)]. Pigs were fed one of three diets containing 0, 75 and 150 g CG/kg, formulated on equal digestible energy (DE) basis, with similar crude protein (210 g CP/kg dry matter; DM) and amino acid (12.9 g lysine and 8.2 g methionine+cystine/kg DM) content. The GK relative mRNA expression in liver and microbiota composition in ileal and caecal samples were assessed at 72 days of age. The digestibility of GE decreased (P<0.05) at 37 days, but increased linearly (P<0.05) at 65 days of age with CG increment, due to CG level by age (P<0.01) interactions. Caecal Clostridium spp. and Lactobacillus spp. were linearly reduced (P<0.05) by CG inclusion level. The GK relative mRNA expression in liver increased linearly (P<0.001) with increasing CG. In conclusion, post-weaned pigs after an adaptation to increasing levels of CG may efficiently absorb and activate prior to metabolism, up to 150 g CG/kg diet as dietary energy source.