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Doctor of Philosophy / Department of Animal Sciences and Industry / Joel M. DeRouchey / A total of 7,061 finishing pigs were used in 7 experiments. Experiment 1 investigated the effects of withdrawing high-fiber ingredients prior to marketing to optimize growth performance, carcass yield, and carcass fat quality. Switching pigs from a high-fiber to a low-fiber corn-soy diet approximately 15 to 19 d before slaughter restored carcass yield and partially decreased carcass fat IV compared to pigs fed the high-fiber diet until slaughter. Experiment 2 studied 30% distillers dried grains with solubles (DDGS) and 5% added fat prior to slaughter on growth performance and carcass characteristics. Adding 5% fat to finishing pig diets containing 30% DDGS approximately 20 d before slaughter improved ADG and G:F but did not overcome the reduction in carcass yield from feeding DDGS. Experiment 3 investigated the Cu source on growth performance and carcass characteristics. Increasing dietary Cu in high byproduct diets improved growth and feed intake, resulting in increased final BW and HCW for pigs fed both Cu sources. Experiment 4 examined added Cu and standardized ileal digestible (SID) lysine (Lys) level on growth performance, carcass characteristics, and carcass fat quality. Feeding 150 mg/kg Cu to pigs in the 100% SID Lys requirement diet had improved growth but in the 85 or 92.5% SID Lys requirement diet no response to added Cu was found. Furthermore, increasing SID Lys increased ADG and HCW, but added Cu did not influence growth when feeding low SID Lys. Experiment 5 investigated diet ingredient type and added Cu on growth performance, carcass characteristics, gross energy digestibility, and small intestine histology and gene expression. When comparing diet type and added Cu, pigs fed a byproduct diet with DDGS and bakery meal tended to have lower G:F and reduced HCW compared to pigs fed a corn-soy diet. Adding Cu did not influence growth or carcass characteristics. However, adding Cu to the byproduct diet improved gross energy digestibility and decreased the crypt depth in the distal small intestine. Finally, a linear programming model was developed as a decision tool for commercial swine producers to help guide pig flow decisions to maximize the return to the operation.

Doctor of Philosophy / Department of Animal Sciences and Industry / Duane L. Davis / Jim L. Nelssen / A total of 188 sows and their litters were used in 2 experiments to evaluate methods to induce estrus and ovulation in lactating sows and effects on pig growth. In Exp. 1, an altered suckling method (ALT) was designed to combine split-weaning and intermittent suckling as a means to reduce the suckling stimulus in primi- and multiparous sows during the last week of lactation (d 18 to 25). The ALT sows were also removed for daily boar exposure. The ALT treatment produced lactational estrus in 75% and 95% of primiparous and multiparous sows, respectively. The ALT sows were in estrus earlier (P < 0.01) than controls post-farrowing, with no effect on subsequent reproductive performance. From d 18 to 32, the ALT treatment benefited (P < 0.01) growth of lightweight pigs but decreased (P < 0.01) BW gain of heavyweight pigs, resulting in overall similar growth. However, variation in BW was reduced (P < 0.01) by 50% for ALT litters. In Exp. 2, varying suckling reduction strategies were applied to boar-exposed lactating sows. Overall, 76% of sows in suckling reduction treatments expressed estrus in lactation. Split-weaned and ALT sows performed reproductively similar to controls, whereas sows with daily litter separation or a single 24 h litter removal tended (P < 0.10) to have reduced conception rates versus controls or split-weaned sows. Reduced suckling treatments differed in their ability to induce lactational estrus and impact on pig BW gain immediately post-weaning. However, no evidence was found of benefit for pig growth to market weight or litter BW variation. Four additional experiments using 902 nursery pigs were conducted to test the efficacy of potential detoxifying agents against deoxynivalenol (DON) in swine diets. The effects of DON were not offset by adding an algae-modified montmorillonite clay nor by a proprietary blend of preservatives and clays. However, hydrothermally treating DON-contaminated diets with sodium metabisulfite modified the structure of DON to a non-toxic DON-sulfonate adduct and restored nursery pig growth via improved (P < 0.05) ADG, ADFI and G:F.

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

published_or_final_version / Biochemistry / Master / Master of Philosophy

Master of Science / Department of Animal Sciences and Industry / Joel DeRouchey / Jason Woodworth / Two experiments using a total of 646 nursery pigs were used to determine the effects of increasing phytase on nursery pig growth performance and bone ash characteristics. Two experiments using a total of 821 sows were used to determine the impact of increasing standardized ileal digestible (SID) lysine (Lys) in lactating sows. Experiment 1 determined the available phosphorus (aP) release of Natuphos E 5,000 G phytase in nursery pigs. Increasing phytase from 0 to 1,000 FTU/kg in phosphorus deficient diets improved nursery pig performance and bone ash characteristics. Using percentage bone ash and formulated phytase concentrations, an equation was developed to predict aP release up to 1,000 FTU/kg of Natuphos E phytase. Experiment 2 was conducted to determine the effect of Superdosing Natuphos E 5,000 G phytase on nursery pig performance and bone ash characteristics. Increasing phytase in diets marginal in P improved pig performance and bone ash values. Increasing phytase in P sufficient diets improved bone ash percent and tended to improve feed efficiency. Experiments 3 and 4 determined the impacts of increasing SID Lys in primiparous and multiparous lactating sows and their litters. In Exp. 3, increasing SID Lys above 0.80% in primiparous sows decreased backfat loss, but had no effect on sow BW loss, ADFI or litter gain. Conception rate at d 30 and percentage born alive tended to improve at 0.95% SID Lys. In Exp. 4 with mixed parity sows, increasing SID Lys to 1.05% increased sow weaning BW, litter gain, and reduced weight loss in lactation. Sow backfat loss increased as SID Lys increased from 0.75 to 1.20%, however loin eye depth loss was reduced as SID Lys increased. Percentage of females bred by d 7 after weaning was improved in primiparous females with increasing SID Lys, however no difference was observed in multiparous sows.

Fiber-rich (HF) diets are typically supplemented with enzymes to improve their nutritive value and to offset their negative effects on pig growth. However, studies on enzyme effect in pigs have yielded inconsistent results on nutrient digestibility and growth. Although the inconsistencies observed could be explained by differences in substrate and experimental conditions and enzyme characteristics among studies, how enzymes influence metabolic and physiological responses in pigs is still not clear. Therefore, three experiments were conducted, using 3 dietary treatments (control, HF and HF diet supplemented with enzymes), to elucidate the effects of supplementing an HF diet with enzymes in growing pigs. Experiment one investigated HF and enzyme supplementation on energy and nutrient digestibility, digesta volatile fatty acid (VFA) concentrations, and gut microbial profile in pigs. Compared with the HF diet, enzymes improved dry matter, starch, energy and some amino acid (AA), but not nitrogen digestibility. Further, the enzymes stimulated the growth of gut bacterial groups, which have xylanolytic and cellulolytic properties in the HF-fed pigs, but enzymes did not influence digesta VFA concentration or fiber fermentation. Experiment 2 evaluated the effects of enzyme supplementation on growth performance, glucose uptake in jejunum tissue samples mounted in Ussing chambers, and intestinal nutrient transporter mRNA levels in pigs. Diet had no effect on feed intake and jejunal glucose uptake. The enzymes influenced nutrient transporter mRNA levels but did not improve pig growth rate and feed efficiency relative to the HF diet. The third experiment investigated the effect of supplementing the HF diet with enzymes on postprandial portal vein-drained viscera (PDV) nutrient fluxes and energy expenditure (measured as O2 consumption) by the PDV and whole-animal in pigs. Diet had no effect on energy expenditure. The HF diet reduced portal glucose, VFA and essential AA absorption and insulin production. Enzyme supplementation improved portal glucose and VFA absorption, but not essential AA absorption and insulin production. Overall, improvements in nutrient utilization due to enzyme supplementation did not improve the growth rate of pigs, which appears to be due to the lack of enzyme effect on essential AA and energy use by the PDV and insulin production / October 2016

Master of Science / Department of Animal Sciences and Industry / Joel DeRouchey / Michael Tokach / Six experiments using a total of 2,974 nursery pigs were used to determine the effects of monosodium glutamate (MSG) and amino acids (AA) on nursery pig growth performance. Experiments 1 and 2 evaluated increasing dietary MSG for nursery pigs. Increasing dietary MSG up to 2% without balancing for sodium and chloride content decreased nursery pig performance, and feeding sodium levels equivalent to 1% MSG also decreased performance. When sodium and chloride were balanced, there were marginal effects of increasing dietary MSG on pig performance. Experiment 3 was conducted to determine the standardized ileal digestible (SID) lysine (Lys) requirement for pigs weighing 7- to 11- kg. The SID Lys requirement was estimated to be 1.45% and greater than 1.60% depending on the statistical model applied for both ADG and G:F. This experiment served to validate the SID Lys requirement for use in formulating diets for the subsequent experiments. Experiment 4 evaluated increasing SID valine (Val) to Lys ratio for nursery pigs weighing 7- to 10- kg. A SID Val:Lys ratio of 62.9% optimized ADG. Maximum feed efficiency (G:F) was captured using 71.7% SID Val:Lys ratio, however, 99% of maximum was achieved with SID Val at 64.4% of Lys. For ADFI, maximum performance was at 74% SID Val:Lys ratio, with 99% of maximum intake achieved at 68%. Experiments 5 and 6 investigated increasing SID isoleucine (Ile) to Lys ratio for 6- to 11- kg pigs. When ADG and ADFI were modeled, broken-line models reported maxima of 52.0% Ile:Lys ratio while quadratic models were as high as 64% of Lys.

Master of Science / Department of Food Science / Elizabeth Boyle / Salmonellosis is one of the most important bacterial foodborne infections in the United States resulting in over 1 million illnesses and 375 deaths annually. Salmonella serotypes cause several types of disease in humans: gastroenteritis, enteric fever, septicemia, focal infections, and an asymptomatic carrier state. Salmonella-shedding pigs are known to constitute a risk factor for contamination of carcasses during the slaughter process. Vaccination has generally not been effective in the prevention of Salmonella, partially because of the rapid mutation rate. Previous research has indicated that >70% of farms tested in Iowa were positive for Salmonella during 2006-2009. Salmonella-colonized pigs are usually asymptomatic carriers of the bacterium and can shed upon exposure to stress causing contamination of pen-mates, trailers used for shipping, and lairage areas at processing facilities. Emergence and dissemination of antimicrobial-resistant pathogens, which antibiotics are commonly used in pig production, have become a public health concern worldwide. For this reason, alternative interventions need to be evaluated for effectiveness. The objective of this report was to determine if there is a genetic basis for host resistance or susceptibility to Salmonella through quantitative and/or molecular selection. Genetic improvement of disease resistance and/or tolerance in animals is a potentially effective intervention for addressing pre-harvest food safety issues. Previous research has demonstrated genetic control of the immune response to pathogens. Developing a strong innate response to infection, so the animal does not become ill or become a carrier, is the basis for a genetic intervention for Salmonella. Quantitative trait loci for humoral and innate immune response have been detected for E. coli through leucocyte counts, cytokine concentration, mitogen-induced proliferation, and levels of pre-infection antibody titers. Single nucleotide polymorphisms have been found and can be exploited for genetic improvement of the innate immune response in pigs when infected with Salmonella. Pigs that differentially express polymorphisms and persistently shed the bacteria versus pigs that do not shed or shed little can be used as criteria for selection when developing the intervention.