Abstract
Two experiments were conducted to compare the effects of feeding organic acids and antibiotic growth promoters in weaned pigs. In Exp. 1, 96 nursery pigs (Large WhitexLandrace; initial weight 7.80±0.07 kg) were randomly allotted into one of four dietary treatments. Pigs in treatment 1 were fed a complex starter diet. Treatments 2 to 4 were the same as treatment 1 but supplemented with antibiotics (200 ppm chlortetracycline plus 60 ppm Lincospectin), 0.5% potassium diformate or 0.5% dry organic acid blend ACTIVATE Starter DA (ASD). During the 4-week post-weaning period, pigs fed ASD or antibiotics had better gain (p = 0.03) and feed efficiency (p = 0.04) than pigs fed the control diet. On d 14 post-weaning, pigs fed the control diet had the lowest fecal lactobacilli count among all dietary treatments (p = 0.02), whereas pigs fed ASD or antibiotics had a trend for lower fecal E. coli count compared to the control pigs (p = 0.08). Serum insulin-like growth factor-1 (IGF-1) of pigs fed ASD did not differ from pigs fed the control diet (p>0.05) at d 14 after weaning. In Exp. 2, 24 weaned pigs (Large WhitexLong White; initial weight 5.94±0.33 kg) were allotted into four groups and housed individually. Pigs were fed a control diet or diets supplemented with antibiotics (100 ppm colistin sulfate, 50 ppm Kitasamycin plus 60 ppm Olaquindox), 0.5% or 1% ASD. All pigs were orally challenged with E. coli K88 + on d 5. During d 5 to 14 after challenge, pigs fed antibiotics, 0.5% or 1% ASD had better gain (p = 0.01) and feed efficiency (p = 0.03) than pigs fed the control diet. On d 14, compared to the control pigs, pigs fed 0.5% ASD had higher lactobacilli in the duodenum and pigs fed 1% ASD and antibiotics had a trend for higher lactobacilli in the ileum (p = 0.08). Pigs fed antibiotics, 0.5% or 1% ASD diets tended to have decreased ileal E. coli count compared to those fed the control diet (p = 0.08). Serum interleukin-6 and cortisol and digesta pH values were not affected by treatment or time. These results indicate that feeding ASD can improve the growth performance of weaning pigs, mainly via modulating intestinal microflora populations without affecting gastrointestinal pH or immune indices.
Highlights
After weaning, young pigs are submitted to a variety of nutritional, environmental and social stressors, which often lead to growth depression and post-weaning diarrheic syndrome (Ravindran and Kornegay, 1993)
All bacteria were counted and plus 60 ppm Lincospectin), 0.5% potassium diformate, or expressed as total cfu/ml digesta, and the numbers of 0.5% ACTIVATE Starter DA (ASD)
On d 14 post-weaning, pigs fed the control diet had the lowest fecal lactobacilli count among all dietary treatments (p = 0.02), whereas pigs fed antibiotics or 0.5% ASD had a trend for lower fecal E. coli count compared to the control pigs
Summary
Young pigs are submitted to a variety of nutritional, environmental and social stressors, which often lead to growth depression and post-weaning diarrheic syndrome (Ravindran and Kornegay, 1993). In some research publications, there was no effect of feeding organic acids on growth performance (Omogbenigun et al, 2003; Sacakli et al, 2006) and microbial populations (Risley et al, 1992) Both potassium diformate (Partanen and Morz, 1999) and dry organic acid blend ACTIVATE Starter DA (ASD) (a product of Novus International Inc., St. Louis, MO, USA) (Yi et al, 2006) were found to enhance the growth performance of weaning pigs and modulate the intestinal microbial population and pH of early-weaned pigs, but the studies on the somatotrophic axis and immune response were very limited. Two experiments were conducted to evaluate the impact of feeding organic acids or antibiotics on growth performance, digesta pH values and microbial population of GIT, and serum indexes including cortisol, interleukin-6, urea nitrogen, and insulin-like growth factor-1 (IGF-1) of weaned pigs with or without enterotoxigenic E. coli K88+ challenge
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