Jae Cheol Kim

Different cereal types, in combination with different protein sources, are fed to pigs after weaning, but their interactions and possible implications are not well researched. In this study, 84 male weaned piglets were used in a 21-day feeding trial to investigate the effects of feeding either medium-grain or long-grain extruded rice or wheat, in a factorial combination with protein sources of either vegetable or animal origin, on postweaning performance, shedding of β–haemolytic Escherichia coli, and the coefficient of total tract apparent digestibility (CTTAD). Pigs fed either rice type performed the same (p > 0.05) as wheat-fed pigs after weaning. The use of vegetable protein sources reduced growth rate (p < 0.001) and feed intake (p = 0.007) and deteriorated the feed conversion ratio (p = 0.028) in weeks two and three compared to pigs fed animal protein sources. The number of antibiotic treatments given for clinical diarrhoea was similar (p > 0.05). However, the faecal E. coli score showed a trend for the main effect of protein source, with pigs fed animal proteins showing a higher E. coli score than pigs fed vegetable proteins (0.63 vs. 0.43, p = 0.057). There was also a tendency for an interaction (p = 0.069) between cereal type and protein source (p = 0.069), with this difference being associated with a greater faecal score in pigs fed diets with long-grain rice plus animal proteins and wheat plus animal proteins. Significant interactions occurred for the CTTAD when assessed in week three. In general, pigs fed diets with medium-grain rice or long-grain rice with animal proteins had a higher (p < 0.001) CTTAD for dietary components than pigs fed all other diets, and vegetable proteins depressed (p < 0.001) CTTAD compared to animal proteins (main effect of protein: p < 0.001). In summary, pigs tolerated the extruded rice-based diets well and performed equivalently to pigs fed wheat as the sole cereal, and the use of vegetable proteins decreased the E. coli score.

This study investigated whether the inclusion of a stimbiotic (STB) can improve performance, influence intestinal microbiota and fermentation activity, and reduce pro-inflammatory cytokines in piglets fed a low zinc oxide diet without antimicrobial growth promotors compared to fructo-oligosaccharide (FOS) and mannan-oligosaccharide (MOS) when housed either in good sanitary (GS) or poor sanitary (PS) environments. One hundred forty-four male pigs (28-day-old) were sorted by initial body weight (BW) and allocated to one of six experimental treatments: 1) GS environment without any additive (GS-CTR); 2) GS environment with 0.01% stimbiotic (GS-STB); 3) PS environment (without cleaning and disinfection of a previously populated room) without any additive (PS-CTR); 4) PS environment with 0.01% STB (PS-STB); 5) PS environment with 0.1% MOS (PS-MOS); and 6) PS environment with 0.2% FOS (PS-FOS). Each treatment had six replicates, with four animals each. Three feeding phases, based on corn, wheat, and soybean meal were available ad libitum for the 42-days of the study. Housing piglets under PS conditions negatively influenced performance, increased plasma tumor necrosis factor alpha (TNF-α), affected the fecal microbial populations and increased concentrations of branched-chain fatty acids (BCFA) compared to GS. Stimbiotic improved 42-d-BW under PS conditions (P < 0.05) whereas MOS or FOS had no effect. On d35, plasma TNF-α was reduced with STB in PS (P < 0.05). The ratio between VFA:BCFA increased (P < 0.05) with STB, MOS or FOS in PS, and under GS condition, STB also increased the ratio. Stimbiotic increased the proportion of Clostridiales Family XIII Incertae Sedis and Clostridiaceae, while MOS and FOS increased Selenomonadaceae, Catabacteriaceae and Fibrobacteraceae. These results indicate that STB shifted the intestinal microbiome to favor fiber fermentation which likely contributed to reduced inflammatory response and improved performance, particularly in piglets reared in PS conditions.

Dietary tryptophan (Trp) is a precursor for serotonin, a neuromediator involved in stress responses. Tryptophan competes with other large neutral amino acids (LNAA: tyrosine, isoleucine, leucine, valine, and phenylalanine) to cross the blood–brain barrier; therefore, the regulation of circulating LNAA can influence Trp availability in the cortex and serotonin biosynthesis. The hypothesis examined in this study was that increased supplementation of dietary Trp and a reduction in LNAA for weaned pigs experimentally infected with enterotoxigenic Escherichia coli (ETEC; F4) will increase Trp availability in plasma and reduce indices of the stress response, which will translate to reduced production losses. At 21 ± 3 d of age (mean ± SEM), 96 male pigs (Large White × Landrace) weighing 6.3 ± 0.98 kg (mean ± SEM) were individually penned and allocated to a 4 × 2 factorial arrangement of treatments, with respective factors being 1) four dietary standardized ileal digestible (SID) Trp and LNAA contents, being H_TrpHLNAA (Low Trp-High LNAA; 0.24% SID Trp: 5.4% SID LNAA), H_TrpHLNAA (Low Trp-Low LNAA; 0.24% SID Trp: 4.6% SID LNAA), H_TrpHLNAA (High Trp-High LNAA; 0.34% SID Trp: 5.4% SID LNAA), and H_TrpHLNAA (High Trp-Low LNAA; 0.34% SID Trp: 4.6% SID LNAA), and 2) without/with ETEC infection. Pigs were orally infected with 0.8 mL (3.6 × 10⁹ CFU/mL) ETEC at days 7 and 8 after weaning. Pigs fed diets high in Trp irrespective of the level of LNAA (H_TrpH_LNAA and H_TrpL_LNAA) had higher plasma Trp concentrations (P < 0.001) and a Trp:LNAA ratio (P < 0.001) before infection and 6 d after infection. Following infection, noninfected pigs had higher plasma Trp (P = 0.03) and a Trp:LNAA ratio (P = 0.004) compared with pigs infected with ETEC. Plasma cortisol levels after infection were higher in ETEC-infected pigs (P = 0.05) and altering dietary Trp and LNAA concentrations did not influence (P > 0.05) plasma cortisol. Pigs fed diet H_TrpL_LNAA had higher serum serotonin levels 24 h after infection (P = 0.02) compared with pigs fed diets L_TrpL_LNAA and H_TrpH_LNAA. Similarly, pigs fed diet H_TrpL_LNAA had a higher (P = 0.02) average daily gain during the 3-wk study. Overall, average daily feed intake tended to be higher in pigs fed an H_TrpL_LNAA diet compared with the other diets (P = 0.08). These results suggest that the increased supplementation of dietary Trp with reduced LNAA increased circulating Trp levels that, in turn, likely caused higher serum serotonin levels, irrespective of infection with ETEC, and improved aspects of post-weaning performance.

An infection model with enterotoxigenic Escherichia coli (ETEC) harbouring the F4 fimbriae can be used to assess the impacts that various challenges associated with weaning (e.g., dietary, psychological, environmental) have on the expression of post-weaning diarrhea. The objective of this study was to develop a novel inoculation method for administering an ETEC culture that would induce a higher proportion of ETEC-F4 diarrhea, in pigs that genetically showed ETEC-F4 susceptibility or resistance. The study was designed as a factorial arrangement of treatments with the factors being (a) partially susceptible or resistant to ETEC-F4 based on genetic testing, and (b) four challenge treatments, being (i) a conventional liquid broth method using a drenching gun (Positive control (PC)) (ii) a Syringe method, (iii) a Capsule method, and (iv) Negative control (pigs not challenged (NC)). At 21 ± 3 days of age (mean ± SEM), 48 male castrate pigs (Large White x Landrace) weighing approximately 7.0 ± 1.18 kg were allocated to four treatment groups in two replicate pens (6 pigs/pen). Initial ETEC-F4 susceptibility was based on a DNA marker test and each treatment group had nine partially susceptible and three resistant pigs. On d 7 and 8 after weaning, pigs were challenged with ETEC (serotype O149:K88/F4; toxins LT1, ST1, ST2 and EAST). On each inoculation day the PC pigs were orally dosed with 9 mL 7.12 x 10⁹ colony-forming unit (CFU), the Syringe pigs with 0.8 mL 6.72 x 10⁹ CFU, the Capsule pigs were orally administered two capsules containing 0.8 mL 3.28 x 10⁹ CFU, and the NC pigs 1 mL of phosphate buffered saline (PBS) solution. Approximately 72 hrs after infection, 44%, 22%, 78% and 0% of partially susceptible pigs in the PC, the Syringe, the Capsule, and the NC group had developed ETEC-F4 diarrhea (P = 0.007). Partially susceptible pigs had a higher diarrhea index (DI) compared to resistant pigs (31.5 vs 4.8, P < 0.001). The NC group had a lower DI compared to the PC and Capsule pigs (3.9, 38.1 and 40.3 respectively, P < 0.005). Following infection, genetically resistant pigs in the Capsule group had a DI of zero and the partially susceptible pigs had a DI of 55.6 (P = 0.014). This study showed that genetically screening pigs and using a Capsule to deliver ETEC-F4 can increase cases of diarrhea and the efficiency of the challenge model. Taken together, these methods have the potential to reduce the number of pigs needed in future experimental infection studies.