Evaluation of novel Rhizopus microsporus fungal biomass and its impact on growth performance, and nutrient digestibility in the diet of nursery pigs

Feed is a major variable cost that impacts efficient and economical pork production. Recent expansion of the ethanol industry has created competition for corn used as livestock feed. This expansion has increased water and energy usage, creating a need for greater efficiency in production. As a result, fungal cultivation of thin stillage leftover from ethanol production represents an opportunity for reducing water and energy usage and adding value to the nutrient profile of ethanol by-products. The ensuing fungal biomass (FB) is more nutrient rich in amino acids and lipids than corn or dried distillers grains with solubles (DDGS), and is seen as a potential feedstuff for animal agriculture. Therefore, the overall objective of this thesis was to evaluate a novel FB (Rhizopus microsporus var. oligosporus grown on thin stillage) in the diet of nursery pigs, and determine its lysine bioavailability, nutrient digestibility, and its effects on growth performance and tissue accretion. To accomplish these objectives, a series of experiments were conducted and are outlined in two research chapters (Chapter 2 and 3). In Chapter 2, two experiments were conducted using crossbred nursery pigs. The first experiment assessed growth performance parameters and apparent total tract digestibility (ATTD) of the FB incorporated into diets at three concentrations. The second experiment further examined apparent ileal digestibility (AID), lysine bioavailability using slope-ratio assays, tissue accretion rates and intestinal health. The last chapter (chapter 3) was conducted to assess if probiotic (Pr) supplementation would increase nutrient digestibility of the FB and improve growth performance, and tissue accretion of nursery pigs. Piglets for all experiments were randomly assigned and housed in individual metabolism pens with free access to water. Pigs were fed ad libitum for the first and third experiments, and restricted for the second to ensure appropriate lysine uptake. Pigs were fed a nursery diet consisting of corn, soybean meal (SBM), and whey protein and substituted with or without FB. All feed contained an exogenous digestibility marker, titanium dioxide, for ATTD and AID of the diets. Feces were collected from all three experiments to determine total tract nutrient digestibility and ileal digesta from the second and third for ileal nutrient digestibility. In the second and third experiments, serial slaughter methods were used that contained initial (ISG) and final (FSG) slaughter group animals for whole body composition and tissue accretion rates. Intestinal health was assessed ex vivo using pig ileum and cecum mounted into modified Ussing chambers. Results from the first chapter (Experiment 1) indicated that 10 and 20% FB inclusion had no negative effects on growth performance parameters of ADG, ADFI and gain:feed. ATTD coefficients for energy, nitrogen, fat, and phosphorus were all reduced in the 20% FB diet compared to the control (P \u3c 0.05). However, compared to the control treatment pigs, digestible energy (DE; 4.01 Mcal/kg) values were significantly improved when feeding 10% FB (4.16 Mcal/kg), but not with 20% FB (3.81 Mcal/kg). The value of FB as a swine feed stuff is largely dependent on the bioavailability of its lysine to support growth. The lysine bioavailability was assessed in Experiment 2 using slope-ratio assay methods. These results showed that compared to Reference (Ref) diets containing increasing amounts of crystalline lysine that is freely available to support pig growth, when FB had to supply lysine as the first limiting amino acid, pigs had reduced growth performance (P \u3c 0.05). Increasing lysine concentration in the diet did increase lean muscle deposition, but with 100% of the lysine coming from FB, lean and protein accretion rates were lower than the Ref diets (P \u3c 0.05). Lipid accretion was also diminished in FB fed pigs compared to Ref counterparts (P \u3c 0.01). Using these slope-ratio assays, we determined that lysine bioavailability for ADG, G:F, and lean gain to be 54, 61, and 70%, respectively. This is similar to that of DDGS (53-69% available lysine), but lower than corn (74% available lysine). Apparent ileal digestibility and ATTD data followed a similar trend to Experiment 1. No differences were observed between pigs at the 85% lysine requirement, however, there was a 10-20% drop in AID for FB fed pigs compared to the Ref at the 100% lysine requirement (P \u3c 0.05). No differences were observed for lysine, glutamine, and glucose nutrient transport, and ex vivo measures of intestinal health. Using the data from the previous two experiments, we hypothesized that reduction in lysine bioavailability and digestibility of nutrients in FB diets was due to the high amount of complex polysaccharides such as chitin and chitosan. Therefore, our objective in Chapter 3 (Experiment 3) was to test whether the addition of a Pr would increase the digestibility of FB and improve growth performance of nursery pigs. Results from this experiment showed no significant FB Ã? Pr interaction in any parameters assessed. However, Pr increased ADG (0.47 vs. 0.45 kg/d) and G:F (0.61 vs. 0.57), compared to the no Pr treatments (P \u3c 0.05). Additionally, Pr supplementation increased AID of energy (59 vs. 53%, P \u3c 0.10) and nitrogen (71 vs. 55%, P \u3c 0.01). However, compared to non-FB diets, FB treatments decreased AID of nitrogen (57 vs. 69%, P \u3c 0.01) and ATTD of energy (79 vs. 86%), nitrogen (74 vs. 84%) and DM (82 vs. 88%) (P \u3c 0.01) respectively. Inclusion of Pr to either 0% or 20%FB diets had no effect on ATTD of nutrients and energy. In conclusion, the FB feedstuff composition is high in fat and energy, protein and essential amino acids such as lysine, representing an attractive option for monogastric nutrition. Further, we have determined its lysine bioavailability to be 54% for ADG, which is similar or lower to reported values for DDGS but decreased compared to corn. We have demonstrated that FB can be used as suitable replacement for corn or SBM at low inclusion levels (\u3c 10%) without influencing nursery pig performance. However, the reduced nutrient digestibility and lysine bioavailability at higher inclusion levels (\u3e 20%) would reduce overall efficiency. The reduced nutrient availability also decreases overall growth and tissue accretion, although no changes to intestinal health were observed. Further investigation is needed to evaluate other methods for increasing digestibility, such as different bacterial species or exogenous enzyme supplementation. Additionally, FB may be suited for formulation in diets of species with greater native chitinase production e.g., poultry. Lastly, given the anti-obesity benefit of chito-oligosaccharides, adaptation of FB for human consumption is an avenue that warrants research

Assessing the Effects of Genetic Selection for Porcine Circovirus Type 2 Resistance or Feed Additives on Nursery and Grow-Finish Pig Performance

The swine industry is ever evolving as it strives to produce healthy, wholesome pork for consumers. As such, the industry is constantly looking for ways to improve production and reduce costs. This includes using novel feed ingredients to reduce cost and improve animal health, genetic selection for increased performance, and vaccines to attenuate or prevent illness. Research plays a significant role in assessing the effectiveness of these strategies. Overall, the objective of this thesis was to assess how genetic selection, vaccines, and feed additives may impact growth performance, health, nutrient digestibility, and the microbiome. In Chapter 2, pigs were either infected with or vaccinated for PCV2. Fecal samples taken from these pigs were used to assess changes in the microbiome. Overall, the microbiome did not differ at the phylum level, although some organisms were shown to be positively and negatively associated with growth and IgG production. In Chapter 3, experiments were performed to assess the impact of genetic selection for PCV2 resistance on nursery and long-term performance of pigs. Pigs resistant to PCV2 infection had reduced viremia and IgG production. Despite no overall effect on growth performance, the resistant genotypes were found to have lower production costs, especially when infected with PCV2. In Chapter 4, pigs were supplemented with tryptophan to improve postweaning response. Tryptophan improved feed efficiency in experiment 1 and reduced production costs. Tryptophan did not provide the same benefit in experiment 2. Supplementation of tryptophan numerically increased Lactobacillus abundance in experiment 1, but not in experiment 2. In Chapter 5, a series of cell culture experiments were performed to assess the effects of rhamnolipids on IPEC-J2 cells and jejunal explants. Rhamnolipid concentrations exceeding 0.01% were found to be cytotoxic. Lower concentrations were found to be less cytotoxic, but reduced transepithelial resistance in a dose dependent fashion. Secretion of interleukin-8, a marker of inflammation, was observed to be similar to control and LPS samples. Jejunum explants treated with 0.5% rhamnolipid had an IL-8 response higher than controls

Assessing the Effects of Genetic Selection for Porcine Circovirus Type 2 Resistance or Feed Additives on Nursery and Grow-Finish Pig Performance

The swine industry is ever evolving as it strives to produce healthy, wholesome pork for consumers. As such, the industry is constantly looking for ways to improve production and reduce costs. This includes using novel feed ingredients to reduce cost and improve animal health, genetic selection for increased performance, and vaccines to attenuate or prevent illness. Research plays a significant role in assessing the effectiveness of these strategies. Overall, the objective of this thesis was to assess how genetic selection, vaccines, and feed additives may impact growth performance, health, nutrient digestibility, and the microbiome. In Chapter 2, pigs were either infected with or vaccinated for PCV2. Fecal samples taken from these pigs were used to assess changes in the microbiome. Overall, the microbiome did not differ at the phylum level, although some organisms were shown to be positively and negatively associated with growth and IgG production. In Chapter 3, experiments were performed to assess the impact of genetic selection for PCV2 resistance on nursery and long-term performance of pigs. Pigs resistant to PCV2 infection had reduced viremia and IgG production. Despite no overall effect on growth performance, the resistant genotypes were found to have lower production costs, especially when infected with PCV2. In Chapter 4, pigs were supplemented with tryptophan to improve postweaning response. Tryptophan improved feed efficiency in experiment 1 and reduced production costs. Tryptophan did not provide the same benefit in experiment 2. Supplementation of tryptophan numerically increased Lactobacillus abundance in experiment 1, but not in experiment 2. In Chapter 5, a series of cell culture experiments were performed to assess the effects of rhamnolipids on IPEC-J2 cells and jejunal explants. Rhamnolipid concentrations exceeding 0.01% were found to be cytotoxic. Lower concentrations were found to be less cytotoxic, but reduced transepithelial resistance in a dose dependent fashion. Secretion of interleukin-8, a marker of inflammation, was observed to be similar to control and LPS samples. Jejunum explants treated with 0.5% rhamnolipid had an IL-8 response higher than controls

Meta-Analysis of Genome-Wide Association Studies for Abdominal Aortic Aneurysm Identifies Four New Disease-Specific Risk Loci

RATIONALE: Abdominal aortic aneurysm (AAA) is a complex disease with both genetic and environmental risk factors. Together, 6 previously identified risk loci only explain a small proportion of the heritability of AAA. OBJECTIVE: To identify additional AAA risk loci using data from all available genome-wide association studies. METHODS AND RESULTS: Through a meta-analysis of 6 genome-wide association study data sets and a validation study totaling 10 204 cases and 107 766 controls, we identified 4 new AAA risk loci: 1q32.3 (SMYD2), 13q12.11 (LINC00540), 20q13.12 (near PCIF1/MMP9/ZNF335), and 21q22.2 (ERG). In various database searches, we observed no new associations between the lead AAA single nucleotide polymorphisms and coronary artery disease, blood pressure, lipids, or diabetes mellitus. Network analyses identified ERG, IL6R, and LDLR as modifiers of MMP9, with a direct interaction between ERG and MMP9. CONCLUSIONS: The 4 new risk loci for AAA seem to be specific for AAA compared with other cardiovascular diseases and related traits suggesting that traditional cardiovascular risk factor management may only have limited value in preventing the progression of aneurysmal disease