Health Benefits of Supplementing Nursery Pig Diets with Microalgae or Fish Oil

Abstract

Weaning stress can negatively impact a pig's performance; dietary supplementation with omega-3 polyunsaturated fatty acids (n-3 PUFA) reduces inflammatory stress and promotes nursery pig's health and growth. Fish oil (FO) is a major source of n-3 PUFA; however, microalgae (AL) may provide an alternative source of n-3 PUFA. The aim of this study was to assess the health benefits of supplementing a plant protein-based nursery diet with 3.12% AL or 1.25% FO providing equal total n-3 PUFA compared to a control (CON) diet. Seventy-two pigs were fed experimental diets for three weeks (phases 1 and 2), followed by a common standard diet for three weeks (phase 3). Following phase 2, 8 pigs per treatment underwent a lipopolysaccharide (LPS) immune stress challenge to assess the acute-phase response and 8 pigs per treatment were vaccinated with novel antigens to assess acquired immunity. No significant differences in piglets' growth were observed, despite decreased feed intake in FO piglets compared to AL piglets in phase 3. AL supplementation tended to reduce, and FO supplementation significantly reduced the LPS-induced fever response. The AL pigs had significantly reduced cortisol responses, increased cytokine concentrations, and increased chromogranin A concentrations compared to FO and CON pigs following LPS challenge. Results suggest that AL or FO supplementation in nursery diets differentially modulate the acute-phase response, possibly due to different n-3 PUFA profiles between the two ingredients.

Keywords: acute-phase response; fish oil; immune response; lipopolysaccharide; microalgae; swine nutrition.

Figure 1

Schematic timeline of trial events. OVA, ovalbumin; CAA, Candia albicans antigen; LPS, lipopolysaccharide; IgG, immunoglobulin G; DHR, dermal hypersensitivity response.

Figure 2

(A) Fever response and (B) serum cortisol response following piglet LPS immune challenge in pigs fed diets supplemented with microalgae (AL, n = 8), fish oil (FO, n = 8) or a corn oil control diet (CON, n = 6). Results presented as LSM ± SEM. * Significant differences (p < 0.05) compared to CON treatment; ** trends (p < 0.1).

Figure 3

Plasma chromogranin A levels over time following an LPS immune challenge in piglets fed with diets containing microalgae (AL, n = 8), fish oil (FO, n = 8), or fed a corn oil control diet (CON, n = 6). Results are presented as LSM ± SEM. * Significant differences (p < 0.05).

Figure 4

Expression of serum (A) IL-1β (B) IL-6, (C) IL-10 and (D) TNF-α, over time in piglets fed with diets supplemented with microalgae (AL, n = 8), fish oil (FO, n = 8), or corn oil control (CON, n = 6). Results are presented as LSM ± SEM. *Significant differences (p < 0.05) between treatments at a time point are denoted with a single asterisk. ** Trends (p < 0.1) are denoted with a double asterisk.

Figure 5

(A) OVA-specific IgG1 serum antibody levels and (B) CAA-specific serum IgG2 antibody levels on trial days 7, 21, and 35 in pigs fed diets supplemented with microalgae (AL, n = 8), fish oil (FO, n = 8), or corn oil control (CON, n = 8). Results are presented as LSM ± SEM.

Figure 6

Change in skin-fold thickness in response to (A) OVA antigen and (B) CAA antigen at 6, 24, and 48 h post-injection in pigs fed with diets supplemented with microalgae (AL, n = 8), fish oil (FO, n = 8), or corn oil control (CON, n = 8). Results are presented as LSM ± SEM.