Replacing dietary antibiotics with 0.20% L-glutamine and synbiotics following weaning and transport in pigs

Authors: MCCONN, BETTY - Orise Fellow; DUTTLINGER, ALAN - Purdue University; KPODO, KOUASSI - Purdue University; Eicher, Susan; RICHERT, BRIAN - Purdue University; Johnson, Jay

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2020
Publication Date: 8/25/2020
Citation: Mcconn, B.R., Duttlinger, A.W., Kpodo, K.R., Eicher, S.D., Richert, B.T., Johnson, J.S. 2020. Replacing dietary antibiotics with 0.20% L-glutamine and synbiotics following weaning and transport in pigs. Journal of Animal Science. https://doi.org/10.1093/jas/skaa272.
DOI: https://doi.org/10.1093/jas/skaa272

Interpretive Summary: Immediately following weaning, pigs must adapt to multiple stressors such as transportation, handling, litter mixing, crowding, and delayed access to feed and water. Antibiotics have traditionally been used to help combat the negative impacts of weaning and transport in pigs. However, their use has been limited in the United States swine industry due to consumer pressures and concerns regarding antibiotic resistance. Therefore, nutraceutical supplements such as L-glutamine and synbiotics may be beneficial alternatives to improve piglet health and welfare following weaning and transport stress. The results from this study suggest that the provision of dietary antibiotics and 0.20% L-glutamine may improve some biological markers of immune function (e.g., haptoglobin). In addition, adding synbiotics (probiotic and prebiotic mix) may be of benefit to intestinal health through an increase in goblet cells that produce mucin to protect the intestine from pathogenic bacteria. Moreover, withholding dietary antibiotics resulted in an increase in gene expression for pro-inflammatory cytokines in the intestine. Despite the improvements in some metrics of intestinal health for pigs provided either nutraceuticals or antibiotics, an increase in growth performance was not detected, but this may be due to the lack of stress in the research setting relative to previous experiments. Taken together, results from this experiment demonstrate that both nutraceuticals and antibiotics can improve biomarkers of immune function and intestinal health, but growth performance improvements may not be apparent when pigs are transported and housed under non-stressful conditions.

Technical Abstract: Dietary antibiotic use has been limited in United States swine production due to concerns regarding antibiotic resistance. However, this may negatively impact the health, productivity and welfare of pigs. Therefore, the study objective was to determine if combining dietary synbiotics and 0.20% L-glutamine would improve pig growth performance and intestinal health following weaning and transport when compared to traditionally used dietary antibiotics. Because previous research indicates that L-glutamine improves swine growth performance and synbiotics reduce enterogenic bacteria, it was hypothesized that supplementing diets with 0.20% L-glutamine (GLN) and synbiotics [SYN; 3 strains of Lactobacillus (1.2 x 10^9 cfu/g of strain/pig/day) + ß-glucan (0.01 g/pig/day) + fructooligosaccharide (0.01 g/pig/day)] would have an additive effect and improve pig performance and intestinal health over that of dietary antibiotics. Mixed sex pigs (N = 226; 5.86 ± 0.11 kg BW) were weaned (19.4 ± 0.2 d of age) and transported for 12 h in central Indiana. Pigs were blocked by BW and allotted to 1 of 5 dietary treatments (5 to 6 pigs/pen): antibiotics (A; chlortetracycline [441 ppm] + tiamulin [38.5 ppm]), no antibiotics (NA), GLN, SYN, or the NA diet with both the GLN and SYN additives (GLN+SYN) fed for 14 d. From d 14 post-weaning to the end of the grow-finish period, all pigs were provided common antibiotic-free diets. Data were analyzed using PROC MIXED in SAS 9.4. Overall, haptoglobin was greater (P = 0.03; 216%) in NA pigs compared to A pigs. On d 13, GLN and A pigs tended to have reduced (P = 0.07; 75.2 and 67.3%, respectively) haptoglobin compared to NA pigs. On d 34, the jejunal goblet cell count per villi and per mm tended to be greater (P < 0.08; 71.4 and 62.9%, respectively) in SYN pigs compared to all other dietary treatments. Overall, jejunal mucosa TNFa gene expression tended to be greater (P = 0.09; 40.0%) in NA pigs compared to A pigs on d 34. In addition, jejunal mucosa TNFa gene expression tended to be greater (P = 0.09; 33.3, 41.2, and 60.0%, respectively) in GLN pigs compared to SYN, GLN+SYN, and A pigs on d 34. Although it was determined that some metrics of pig health were improved by the addition of GLN and SYN (i.e., haptoglobin and goblet cell count), overall there were very few differences detected between dietary treatments and this may be related to the stress-load incurred by the pigs.