The objective of this study was to study the effects of feeding spray-dried plasma (SDP) or glutamine (GLN) on performance, intestinal morphology, immunological, and somatotropic responses in weaned pigs challenged with enterotoxigenic E. coli strain K88+ (ETEC K88+).
Forty weaned barrows (17+/- 2 d of age, 5.3+/- 0.3 kg), obtained from a commercial pig farm in Missouri were used in this study. The piglets were from sows that did not receive ETEC vaccination. Piglets were assigned to one of four experimental treatments according to a randomized complete block design. The experimental treatments were 1) non-challenged control (NONC, pigs fed control diet, no ETEC K88+ challenge), 2) challenged control (CHAC; pigs fed control diet and challenged with ETEC K88+), 3) spray-dried plasma (SDP, pigs fed control diet supplemented with 7% SDP and challenged with ETEC K88+), and 4) GLN (pigs fed control diet supplemented with 2% GLN and challenged with ETEC K88+). Pigs were housed in individual pens in the nursery with ad libitum access to food and water. Pigs were fed respective experimental diets for 11 days post-weaning and then were fitted with indwelling jugular catheters. On day 12 of the experiment, blood samples were obtained for determination of baseline levels of ACTH, GH, IGF-1, and IL-6. Pigs were then challenged orally with 5mL of skim milk containing 5.5 x 108 CFU of ETEC K88+. The ETEC K88+ was isolated by Rollins Animal Disease Diagnostic Laboratory and PCR was used to confirm genes necessary for enterotoxin expression (LT+/STb+). Blood samples were collected from all pigs at 6, 12, 24, 36, and 48 hours after ETEC K88+ inoculation. At the end of the experiment (14 days post-weaning) pigs were euthanized and intestinal segments were harvested and processed for histological evaluation.
In the first 48 hours following ETEC inoculation, the CHAC group exhibited lower average daily gain (ADG) (P=0.08) and gain: feed (P=0.07) compared with NONC pigs. Feeding pigs diets containing 7% SDP did not prevent decreases in performance in response to ETEC K88+ challenge but had similar gain: feed compared with NONC. Pigs fed diets supplemented with 2% GLN did not exhibit statistically significant reductions in growth rates or gain: feed in response to ETEC K88+ challenge when compared to NONC (ADG = 424g and 319g for NONC and GLN groups, respectively). Daily feed intake did not differ between experimental treatments. Histological evaluation of intestinal segments revealed significant villus atrophy in the jejunum and ileum of CHAC pigs compared with NONC pigs. Feeding pigs 2% GLN or SDP appeared to prevent ETEC K88+ -induced villus atrophy in the proximal and mid-jejunum, and ileum. Serum IL-6 and ACTH were not affected by treatment after challenge (P=0.11). Serum IGF-1 levels were lower in CHAC and SDP groups compared with initial baseline values (P=0.06) whereas NONC and GLN groups maintained serum IGF-1 levels.
Overall, data from this study indicate that feeding 2% GLN in nursery diets minimized growth-depressing effects of experimental ETEC K88+ infection. Furthermore, feeding GLN appeared to prevent villus atrophy and reductions in serum IGF-1 in response to ETEC K88+ challenge.
Reference:
Yi GF, Carroll JA, Allee GL, Gaines AM, Kendall DC, Usry JL, Toride Y, Izuru S.Effect of glutamine and spray-dried plasma on growth performance, small intestinal morphology, and immune responses of Escherichia coli K88+-challenged weaned pigs. J Anim Sci. 83:634-643, 2005.