title: Response to an Escherichia coli K88 oral challenge and productivity of weanling pigs receiving a dietary nucleotides supplement.
abstract: BACKGROUND
  Dietary nucleotides, considered as antibiotics alternative, were shown to have positive effects on intestinal hyperaemia, systemic immunity, small-intestinal growth, and hepatic composition in pigs. However, there is no previous research on nucleotide supplementation in weanling pigs under an oral challenged E. coli K88. Therefore, 2 experiments were conducted to investigate the effects of dietary nucleotides on weanling pig growth performance, nutrient digestibility, fecal score, and blood profile after being orally challenged with E. coli K88.
  
  
  METHODS
  In Exp. 1, a total of 140 weanling pigs [8.33 ± 0.33 kg of body weight (BW), 28-d old] were used in this 42-d feeding trial. Pigs were distributed into 1 of 4 treatments, 5 pigs/pen (3 barrows and 2 gilts) and 7 pens/treatment. Treatments were a control basal diet (CON) or the CON supplemented with 150 (R150), 220 (R220), or 275 (R275) mg/kg to give the three treatment diets. In Exp. 2, 28 weanling pigs (BW = 8.40 ± 0.22 kg, 28-d old) were distributed into 1 of 4 treatments to give 1 pig/pen and 7 pens/treatment in a 42-d feeding and challenge trial. Dietary treatments were the same as in Exp. 1. On d 14, all those pigs (BW = 13.3 ± 0.15 kg, 42-d old) were orally dosed with 1.5 mL suspension containing 10(10) cfu/mL of E. coli K88. Twenty four hours after challenge, blood and excreta samples were collected from each pigs for analysis. Fecal scores were measured on d 7, 14, 21, and 28 of the study.
  
  
  RESULTS
  In Exp. 1, overall BW, average daily gain (ADG), gain/feed (G/F) ratio, and nutrient digestibilities were lower (P < 0.05) in CON group compared with the nucleotides fed pigs. In Exp. 2, after challenge, IgA, IgM, and IGF-I were higher (P < 0.05) in the nucleotide groups compared with CON. However, the nucleotide groups had lower (P < 0.05) cortisol and TNF-α compared with CON. Fecal E. coli counts and fecal score for the nucleotide groups were lower (P < 0.05) than for CON.
  
  
  CONCLUSIONS
  In conclusion, dietary nucleotides supplementation could improve growth performance, nutrient digestibility, immune status, microbial balance, reduce diarrhea, and provide protection against enterotoxigenic E. coli K88 infection in weanling pigs.
authors.affiliation: Department of Animal Resource & Science, Dankook University, No. 29 Anseodong, Cheonan, Choongnam, 330-714 South Korea.
authors.forename: Hanlin
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Animal Resource & Science, Dankook University, No. 29 Anseodong, Cheonan, Choongnam, 330-714 South Korea.
authors.forename: Pinyao
authors.initials: P
authors.lastname: Zhao
authors.affiliation: Department of Animal Resource & Science, Dankook University, No. 29 Anseodong, Cheonan, Choongnam, 330-714 South Korea.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lei
authors.affiliation: Department of Animal Resource & Science, Dankook University, No. 29 Anseodong, Cheonan, Choongnam, 330-714 South Korea.
authors.forename: Tianshui
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Animal Resource & Science, Dankook University, No. 29 Anseodong, Cheonan, Choongnam, 330-714 South Korea.
authors.forename: InHo
authors.initials: I
authors.lastname: Kim
keywords: Dietary nucleotides; Escherichia coli K88 challenge; Growth performance; Immunity; Nutrient digestibility; Weanling pigs