Effects of standardized ileal digestible valine:lysine ratios, pharmacological levels of copper, and feed mitigants on swine growth

Abstract

This thesis contains three chapters that include: 1) evaluation of increasing standardized ileal digestible valine:lysine (SID Val:Lys) ratio on growth performance and plasma urea nitrogen of 21- to 116-kg pigs, 2) evaluation of copper (Cu) feeding strategies and sources on nursery and finishing pig performance, and 3) effects of a formaldehyde-based product or a blend of phytochemicals and carboxylic acids on growth performance, serum haptoglobin, serum cytokine levels, and intestinal morphology in enterotoxigenic Escherichia coli challenged nursery pigs. Chapter 1 utilized 998 pigs across three experiments to determine the optimal Val:Lys ratio within grow-finish pigs. A standardized ileal digestible valine:lysine ratio of at least 69% appeared to maximize gain or feed efficiency for 21-to 116- kg pigs. Chapter 2 included 2,204 nursery pigs to evaluate the effect of Cu feeding strategies and 2,160 grow-finish pigs to evaluate the effect of Cu source. In nursery pigs, when pharmacological levels of Zn were used, the addition of pharmacological levels of 150 mg/kg added Cu did not influence the overall average daily gain, average daily feed intake, gain: feed, removals, or mortality. In grow-finish diets, Cu source did not influence growth performance. However, feeding pharmacological levels of 150 mg/kg added Cu, regardless of source, improved growth performance. Chapter 3 utilized 84 nursery pigs to evaluate the effect two feed additives, a formaldehyde-based product and a second product containing a blend of phytochemicals and carboxylic acids, in enterotoxigenic Escherichia coli F18 challenged nursery pigs. Neither feed additive improved overall growth performance, fecal dry matter, intestinal morphology, or serum haptoglobin, with only marginal changes in serum cytokine concentrations when fed to enterotoxigenic Escherichia coli F18challenged nursery pigs. In summary, these experiments provide data on the optimal SID Val:Lys ratio for 21- to 116-kg pigs, the effect of tribasic copper chloride feeding strategies on nursery pigs, the impact of Cu source on grow-finish pigs, and the effects of formaldehyde-based product or a blend of phytochemicals and carboxylic acids on growth performance, serum haptoglobin, serum cytokine levels, and intestinal morphology in enterotoxigenic Escherichia coli challenged pigs.