Effects of supplemental calcium butyrate on lamb growth, plasma metabolites, and hepatic gluconeogenic and inflammatory gene expression changes

Objective was to evaluate the effects of increasing supplemental calcium butyrate on intake, growth, plasma acute phase proteins and hepatic enzyme expression in lambs fed a concentrate-based diet. Twelve pens of crossbred Hampshire × Suffolk lambs (n = 2 lambs/pen) were assigned to 1 of 3 dietary treatments: (1) no butyrate (C), (2) 6.25 g calcium butyrate/kg of diet DM (B1), and (3) 12.5 g calcium butyrate/kg of diet DM (B2). All lambs were adapted to a basal concentrated-based diet for 2 weeks prior to the start of the experiment. Treatment diets were fed from d 0–56. Blood was collected on d 0, 28, and 55 for analysis of plasma β-hydroxybutyric acid (BHBA), total protein, glucose, ceruloplasmin (CP), and haptoglobin (HP). Intakes were recorded daily by pen and individual body weights were measured weekly. Liver tissue was collected via biopsy on d 56 to measure mRNA expression of gluconeogenic enzymes, acute phase proteins, and inflammatory transcription factors using NanoString. Orthogonal contrasts were used to determine the effects of increasing dietary inclusion of Ca butyrate on lamb growth performance. Interactions of treatment by day were examined for plasma concentrations collected over time. Lambs fed B1 had 67 % and 40 % greater average daily gain (ADG) (quadratic; P = 0.02) than the lambs fed C and B2, respectively. Similarly, lambs fed B1 had 13.4 % and 15.8 % greater DMI (quadratic; P = 0.02) than the lambs fed C and B2, respectively. Total protein, BHBA, glucose, and CP were not affected (P ≥ 0.12) by treatment. There was a treatment × day interaction (P = 0.01) on plasma HP. Plasma HP concentrations did not change in lambs fed B1. Plasma HP concentrations declined on d 55 compared to d 28 in lambs fed C; but, plasma HP concentrations increased on d 55 compared to d 28 in lambs fed B2. In the liver, mRNA expression of acute phase proteins and anti-inflammatory transcription factors were not affected (P ≥ 0.24) by calcium butyrate inclusion in the diet. Similar to DMI and ADG, gluconeogenic enzymes decreased (quadratic; P ≤ 0.08) in lambs fed B1 compared to the lambs fed C and B2. This decrease in mRNA expression of gluconeogenic enzymes may be associated with the feedback from increased DMI in lambs fed B1. Lambs fed B1 achieved greater DMI and ADG when compared to the lambs fed B2 and C and these performance results may be linked to key gluconeogenic pathways.