Effects of three distinct two-week long diet strategies after transport on weaned pigs’ short and long-term welfare markers, behaviors and microbiota.

Authors: PAROIS, SEVERINE - French National Institute For Agricultural Research; DUTTLINGER, ALAN - Purdue University; RICHERT, BRIAN - Purdue University; LINDEMANN, STEPHEN - Purdue University; Johnson, Jay; Marchant, Jeremy

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2020
Publication Date: 3/17/2020
Citation: Parois, S.P., Duttlinger, A.W., Richert, B.T., Lindemann, S.R., Johnson, J.S., Marchant Forde, J.N. 2020. Effects of three distinct two-week long diet strategies after transport on weaned pigs’ short and long-term welfare markers, behaviors and microbiota.. Journal of Animal Science. https://doi.org/10.3389/fvets.2020.00140.
DOI: https://doi.org/10.3389/fvets.2020.00140

Interpretive Summary: There is growing widespread concern about antimicrobial resistance and the use of antibiotics in livestock production, which is driving research into alternatives that will safeguard the health and welfare of animals during times of stress. For pigs, one of the most stressful events is weaning, during which the piglet has sudden change in diet from milk to solid food, is separated from the sow and mixed with unfamiliar piglets, and may be transported to a different farm. Often piglets at this time develop post-weaning diarrhea which is treated or prevented by use of antibiotics delivered in the diet. Rather than delivering antibiotics unnecessarily, the livestock industry is investigating alternative compounds that produce similar beneficial effects. Our study examined an experimental diet containing the amino-acid L-glutamine, comparing it with diet containing antibiotics and a control diet containing neither. We found that piglets fed the glutamine diet showed similar responses to stressors as the piglets fed the antibiotic diet. They showed less aggression, had smaller tear stain areas (a stress indicator) and were more interactive with novel objects placed in the pen, than piglets on the control diet. The gut microbiota of glutamine-fed pigs was more diverse and some of the microbial populations were associated with some of the behaviors measured. Overall, glutamine appeared to confer similar benefits to antibiotics and could be a viable alternative for piglets at weaning.

Technical Abstract: Alternative feed supplements have shown promising effects in terms of performance, but their effects on welfare have had little evaluation. A total of 240 piglets were weaned and loaded into a trailer for a 12h-transport. After transport, they were assigned to one of 3 diets fed for a 14-day period: A – an antibiotic diet including a common commercial prophylactic antibiotic combination (441 ppm of chlortetracycline + 38.6 ppm tiamulin), NA – a control diet without any prophylactic antibiotic or feed supplement, GLN – a diet including L-glutamine (0.20% L-glutamine as-fed). After the 14-day period, all piglets were fed the same diet. Tear staining was measured 11 times post-weaning (from d0 to 147). Skin lesions were counted before and after weaning (d-2, 2 and 36). Novel object tests (NOT) were done in groups in the pigs’ home pen 4 times post-weaning (d17, 47, 85, 111). Samples for 16S microbial DNA composition were collected following the 14-day diet treatment period and at the conclusion of the nursery phase (d14 and 34). The NA pigs tended to have larger tear stains than A pigs on d84 (P = 0.070) and 110 (P = 0.080), and larger tear stains than GLN pigs on d84 (P = 0.022) and 110 (P = 0.003). On d2, NA pigs had more lesions than A (P = 0.005) and GLN pigs (P < 0.001). During the NOT on d17, NA pigs avoided the object less than A pigs (P = 0.033) and tended to avoid it less than GLN pigs (P = 0.058). On d85, NA pigs spent less time exploring the object than the two other groups (A: P = 0.008, GLN: P = 0.025), and on d111, NA pigs took longer to interact with the object than A pigs (P = 0.037) and GLN pigs (P = 0.002). In terms of microbiota composition, GLN had higher '-diversity (both richness and evenness components) than A and NA (P < 0.001). Differences between dietary treatments were all only demonstrated at d14 and disappeared at d34. Pearson correlations between aggression, stress and anxiety indicators and bacterial populations were medium to high from 0.31 to 0.69. The results demonstrate that short-term feeding strategy can have both short- and long-term effects on behavior and welfare, that may partly be explained by changes in gut microbiota composition. NA pigs appeared less interested by novel objects and more sensitive to environment and management than pigs on the other two treatment groups. Supplementation with GLN appears to confer similar benefits to, and thus could be a viable alternative to dietary antibiotics.