The potential of bioactive compounds in maternal and post-weaning pig diets

The principal objective of this thesis was to investigate the potential of bioactive compounds, namely casein hydrolysates, beta-glucans, and mushroom powders, in maternal and post-weaning pig diets in order to enhance gastrointestinal (GIT) health, growth performance, antioxidant capacity and meat quality. Chapter 2 investigated the effects of maternal supplementation of a casein hydrolysate and yeast ß-glucan (CH-YBG) from day 83 of gestation until weaning (day 28) on sow faecal microbial populations and measures of piglet gastrointestinal health parameters at weaning. Maternal supplementation positively affected small intestinal morphology, increased the gene expression of nutrient transporters, mucins and tight junction protein genes, decreased the gene expression of proinflammatory markers (IL6/TNF/TGFB) and enhanced the caecal and colonic microbiota of weaned pigs. Chapter 3 investigated the molecular, physiological, and microbial effects of mushroom powder (MP), vitamin D2-enriched mushroom powder (MPD2) and zinc oxide (ZnO) in pigs post-weaning. While supplementation with MPD2 enhanced small intestinal morphology, upregulated the expression of the anti-inflammatory gene IL10, nutrient transporter genes, increased total volatile fatty acid concentrations and reduced the expression of pro-inflammatory gene IL6, it adversely affected average daily feed intake (ADFI) and average daily gain (ADG). Mushroom powder supplementation reduced ADFI, improved small intestinal morphology, upregulated the expression of nutrient transporters and tight junction protein genes, but had no effect on the expression of inflammatory markers. Chapter 4 investigated the effects of MP and MPD2 in finisher pig diets on growth performance, carcass traits and meat quality parameters such as colour, drip loss, cooking loss, lipid peroxidation and antioxidant status. Dietary supplementation with MP and MPD2 decreased feed intake, improved gain to feed ratio (G:F) and improved the colour stability and water-holding capacity of the Longissimus Thoracis (LT) samples, however it had no effect on the antioxidant status or lipid peroxidation of pork LT samples. Chapter 5 investigated the effects of mushroom powder supplemented with inorganic selenium (inSeMP) and mushroom powder enriched with organic selenium (orgSeMP) on pig growth performance during the first 21 days post-weaning and investigated the molecular and microbial effects of inSeMP and orgSeMP supplementation in these pigs on day 39 post-weaning. Supplementation with orgSeMP reduced ADFI, improved faecal scores and increased the caecal abundance of bacterial members of the Firmicutes and Bacteroidetes phylum, including Lactobacillus, Agathobacter, Roseburia and Prevotella. Supplementation with inSeMP reduced villus height, modulated the expression of genes associated with inflammation and increased the caecal abundance of Prevotella. It can be concluded that mushroom powder supplementation is most effective in pig diets when enriched with selenium or vitamin D. Overall, these studies demonstrate innovative ways of incorporating bioactive compounds into the diet of pigs to enhance aspects of intestinal health, growth performance and meat quality.