Browsing by Author "Risley, Chad Richard"

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    Effect of feeding fumaric or citric acid on weanling pig performance and selected intestinal digesta measurements at varying times postweaning
    Risley, Chad Richard (Virginia Tech, 1990)
    Five studies were conducted to elucidate a possible mode of action of dietary organic acids in weanling pigs (n=536). The effect of feeding 1.5% fumaric or citric acid on growth performance, intestinal digesta pH, chloride ion concentration (Cl-), VFA profile and microflora populations was studied. In study 1, feeding citric acid improved ADG and feed conversion (F:G), whereas fumaric acid only numerically improved ADG and F:G. No significant dietary effect on intestinal pH, Cl- or VFA profile was observed. In study 2, feeding organic acids with and without a microbial supplement (Lactobacillus acidophilus) resulted in no interactive effects, but fumaric acid and the microbial supplement each improved ADG and F:G. In study 3, pigs fed organic acids were killed at -2, 0, 3, 7, 14 and 21 d postweaning. Organic acids had no significant effect on intestinal pH, Cl-, VFA profile or microflora populations. Postweaning age affected intestinal digesta measurements in these ways: pH decreased; VFA concentrations increased; lactobacillus decreased to d 3 postweaning; E. coli increased to d 7 postweaning; and clostridia decreased to d 21 postweaning. In study 4, pigs were fed organic acids and orally challenged with 10¹⁰ enterotoxigenic E. coli (0157:K88) (ETEC) at d 3, 7 and 14 postweaning. Organic acids had no measurable effect on intestinal pH, Cl- or VFA profile. ETEC challenge increased jejunum lactic acid concentration, lower colon VFA concentration and severity of scouring. Postweaning age affected these intestinal digesta measurements: cecum pH decreased; jejunum Cl- increased; jejunum lactobacillus count decreased; lower colon lactobacillus count increased; and E. coli count decreased in all intestinal sections. In study 5, pigs were fed organic acids and challenge with ETEC on d 3 postweaning. Organic acids had no significant effect on severity of scouring or protection against reduced growth performance from the ETEC challenge. The ETEC challenge resulted in an increased severity of scouring and a reduction in ADG of 20% and F:G of 19%. In summary, feeding organic acids generally improved weanling pig growth performance and had little effect on intestinal digesta measurements. Postweaning age did have an effect on intestinal digesta measurements. The primary mechanism of action of dietary organic acids does not seem to be the lowering of intestinal pH or modifications to the intestinal microflora, but may act as an additional energy source.
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    Response of early weaned pigs to an escherichia coli challege and their absorption to ovalbumin or xylose as influenced by creep feeding
    Risley, Chad Richard (Virginia Tech, 1987-06-05)
    The effect of exposure to creep feed at 10 d of age vs no exposure to creep feed or sow's feed on the ability of pigs weaned at 21 d of age to respond to an oral challenge of E. coll or to absorb ovalbumin or xylose was investigated. Eighty pigs (45 exposed, 35 control) were orally challenged 24 h after weaning with 3x1011 organisms of E. coli (0157 H88AC:H43); control pigs tended (P<.10) to scour more than the exposed pigs (46% vs 27%). Ovalbumin absorption was similar for both exposed and control pigs (P>.10), but absorption for both treatments increased (P<.001) from d 1 to d 4 and decreased to d 13 (P<.001). Xylose absorption was less (P<.02) at d 1 for exposed pigs compared with control pigs (0.781 vs .825 mmol) with no differences (P>.20) occurring thereafter. Lowest xylose absorption for both treatments occurred on d 7. Creep feeding conferred some protection to the E. coll challenge, but had little effect on intestinal absorption of ovalbumin and xylose.