Felina Tan | ALES Graduate Seminar

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES PhD Final Exam Seminar by Felina Tan. This seminar is open to the general public to attend.

Zoom Link: https://ualbertaca.zoom.us/j/91725321914?pwd=tcjvTzdObGRP1kVFarGYHn2d5EgBjv.1

PhD with Dr. Ruurd Zijlstra

Thesis Topic: Effects of resistant starch on gut health and growth in pigs

Abstract:

Starch from cereal grains, pulse grains, and tubers is a major energy substrate in swine rations constituting up to 55% of the diet. Starch types that are high in amylose content constitute a source of resistant starch (RS). The current state of knowledge indicates that RS as a prebiotic can enhance gut health of weaned pigs; however, the potential mechanisms still require further investigation. The overall objective of the thesis was to discover the interaction between resistant starch and the digestion kinetics along the gastrointestinal tract, which may induce alteration to the metabolites, butyrate production pathway genes, gut immunity specifically mucosal barrier function and immunomodulation, and energy metabolism in pigs.

In study 1, seven ileal-cannulated barrows (initial BW 30 kg) were fed 6 diets containing 96% of test ingredient (faba bean, field pea, chick pea, barley, wheat, or corn) or a N-free diet in a 7 ´ 7 Latin square at 2.8 ´ maintenance DE to collect feces and digesta. The apparent ileal digestibility (AID) of starch was lowest in faba bean followed by field pea, chick pea, and cereals. Apparent hindgut fermentability (Apparent total tract digestibility, ATTD – AID) of starch was greatest for faba bean and field pea. The ATTD – AID of total dietary fiber (TDF) was greatest for faba bean and lowest for wheat. The ATTD-AID of energy was greater in pulses than cereals. The greater fermentation of pulses contributed to their energy value but, the variation observed in the digestibility of energy and AA likely suggest possible interactions with other starch-associated compounds such as protein, and fiber.

In study 2, a total of 32 weaned pigs were randomly allocated to 1 of 4 diets containing purified starch containing 0, 20, 35, and 70% amylose for 21 d. Increasing dietary amylose quadratically decreased ileal digestibility of starch and quadratically increased hindgut fermentation of starch, and cecal and colonic digesta SCFA. Increasing dietary amylose upregulated expression of SCFA transporters in the mid colon but downregulated GPR109A in the proximal colon. The 35% amylose diet upregulated mucosal expressions of tight junction proteins in ileum and proximal colon. Increasing dietary amylose quadratically increased butyrate production pathway genes. Total SCFA was negatively correlated with pro inflammatory cytokines. Butyrate was positively related with MUC2. Increasing dietary amylose enhanced hindgut starch fermentation and total SCFA levels in weaned pigs. These changes are associated with increased butyrate production enzymes and improved gut health mechanisms including maintenance of gut barrier function and reduced proinflammatory cytokine.

This thesis demonstrates that starch from different botanical sources affects starch digestion and hindgut fermentation in pigs. While RS fermentation offers potential benefits, the reduced energetic efficiency of SCFA compared to glucose may hinder growth. To balance prebiotic benefits with sustained growth, the optimal dietary inclusion, source, and duration of RS supplementation must be determined.