THE INTERACTION OF ACID-PRESERVATION OF WHEAT OR BARLEY, WITH OR WITHOUT ENZYMES, AND PARTICLE SIZE ON WEANLING PIG PERFORMANCE AND GUT HEALTH
Sotto, Danilo J Marcos 1977-
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Low-quality high-moisture grains may be preserved by acidification as an alternative to artificial drying. Because weanling pig diets are commonly acidified to help the weaning transition, these series of experiments were conducted to determine whether the benefits of acidification are maintained when acid-preserved high moisture grains are fed. The interaction with particle size and enzyme activity was also investigated because acidification and particle size both influence gastric pH and thus enzyme activity. In Chapter 2, bench-scale trials were conducted to determine the effect of acid preservation of high moisture wheat or barley (20% moisture) using propionic acid (Prop) or a phosphoric-acid-based organic-inorganic acid blend (OIB) at low or high concentrations, with or without enzymes (phytase, carbohydrases and protease) on grain quality and estimates of phosphorus and nitrogen availability. The absence of visible mould growth in any of the treatments throughout the 153-day trial indicates that OIB is as effective as Prop in preserving high moisture wheat or barley. A pH of below 5 was maintained in wheat and barley using high concentration of Prop (7.5 g kg-1) up to 153 d, and high concentration of OIB (7 g kg-1) up to 14 d. Acid binding capacity of the high moisture wheat or barley preserved using OIB were lower compared to Prop. Protein dispersibility index, an estimate of N availability, was improved with the addition of enzyme in Prop-preserved wheat and barley. Available P was improved in grains preserved with Prop. In Chapter 3, a nursery and a metabolism trial were conducted to determine the efficacy of feeding acid-preserved high moisture wheat (APW), with or without enzymes, and the interaction with particle size (Fine or Coarse) on weanling pig (21 d) performance and gut health. Average daily gain (ADG), daily feed intake (ADFI), and feed efficiency (G:F) of pigs fed diets with acid preserved wheat (APW) were comparable (P > 0.10) to pigs fed acidified diets (AD). Acidification, enzyme supplementation or fine grinding improved (P < 0.05) ADG and G:F with no evidence of interaction with mode of acidification. Phosphorus digestibility was improved with either OIB or enzyme supplementation. Energy digestibility was comparable in pigs fed Fine or Coarse APW but decreased in Coarse compared to Fine when fed AD. Treatment had no effect on markers of gut health (P > 0.10). Because of the differences in chemical composition of wheat and barley, the same study was conducted using barley in Chapter 4. In the barley study, treatment had no effect on ADG, ADFI or G:F during phase 1 (P < 0.05). During phase 2, ADG was higher in pigs fed diets with acid-preserved barley (APB) than those fed AD. Feed intake and G:F were comparable in pigs fed diets with APB or AD. Enzyme supplementation increased (P < 0.05) ash (mineral) digestibility while dry matter and energy digestibility were increased (P < 0.01) in pigs fed Coarse compared to Fine when fed as APW but not AD. Similar to the wheat trial, treatment had no effect on markers of gut health (P > 0.10). Overall, these observations indicate that feeding acid preserved high moisture grains may be an alternative to direct diet acidification for weanling pigs. The comparable nutrient digestibility of Fine and Coarse when fed as APW but not AD suggests improvement in digestibility in APW. Conversely, nutrient digestibility was improved when APB was fed Coarse compared to Fine. These improvements suggest that fine grinding may not be required when acid preserved grains are used. Economic analysis shows that feeding acid-preserved high-moisture grains may improve income by $1.73 (wheat-based diet) to $2.38 (barley-based diet) per market pig considering costs of acidification, grinding, and savings accruing from avoiding the cost of grain drying.
DegreeDoctor of Philosophy (Ph.D.)
DepartmentAnimal and Poultry Science
CommitteeMutsvangwa, Timoty; Brooke, Ryan; Newkirk, Rex; Tabil, Lope; Yu, Peiqiang
Copyright DateJune 2019