Jeff Carroll

Dr. Jeff Carroll completed his B.S. in Animal Science at Texas A&M University in 1991, followed by his M.S. in 1993, and his Ph.D. in 1996, both from Texas A&M University as well. Upon completing his Ph.D., he joined the USDA-Agricultural Research Service’s Animal Physiology Research Unit located in Columbia, Missouri where he served as a Research Physiologist for 8 years. In 2004, he moved to Lubbock, TX where he serves as the Research Leader for ARS’ Livestock Issues Research Unit. As a Research Physiologist, he focuses on improving livestock performance and well-being through elucidating the interactions associated with growth, stress, nutrition, and immune regulation. He has served on 47 MS/Ph.D. graduate committees and has authored/co-authored 625 publications consisting of 168 scientific journal articles, 7 book chapters, 360 abstracts, and 90 proceedings/technical articles. He has also received over 120 invitations to present his research including 20 international presentations.

To further elucidate a possible “immunological priming” effect of yeast-based products, two studies were conducted to investigate the effects of feeding Saccharomyces cerevisiae boulardii (Scb; CNCM I-1079) to weanling pigs prior to an immune challenge. The first study evaluated the physiological and immunological responses of weaned pigs supplemented with Scb prior to an E. coli-derived lipopolysaccharide (LPS) challenge. Castrated male pigs were assigned to 1 of 2 treatment groups; with (Scb; n = 15) and without (Control; n = 15) the in-feed inclusion of Scb (200 g/ton) for 16 d. On d 16, all pigs were dosed via indwelling jugular catheters with LPS (25 ug/kg BW) at time 0. In Scb-treated pigs, ADG was increased (P < 0.05) by 39.9% and LPS-induced pig mortality was reduced by 20% as compared to Control pigs. White blood cells, lymphocytes, and neutrophils were increased (P < 0.05) in Scb-treated pigs prior to LPS dosing compared to Controls. Peak production (P < 0.05) of IL-1 beta and IL-6 was decreased in Scb-treated pigs after LPS administration when compared to Controls. Peak TNF-alpha production in Scb-treated pigs was accelerated by 0.5 h and was greater (P < 0.05) than peak production in Controls. The peak production of IFN-gamma was greater and had increased (P < 0.05) amplitude persistent for 3 h in Scb-treated pigs when compared to Controls. The second study evaluated the effect of supplementing the diets of weanling pigs (26 ± 0.2 d) with Scb on performance and tissue content of Salmonella following a dual challenge with LPS and Salmonella. Castrated male pigs were assigned to 1 of 2 treatments (n=10 per treatment): 1) Control, fed a non-medicated commercial starter diet or 2) Scb, fed the non-medicated commercial diet supplemented with Scb (200 g/ton). On d 20, pigs were administered LPS (25 ug/kg BW) i.v. at 0 hr. At 3 h, pigs were orally dosed with Salmonella typhimurium (10⁶ CFU/pig). On d 24, pigs were euthanized, and intestinal and lymph tissue contents were collected. Both pre- and post-challenge intraperitoneal temperatures were lower in Scb pigs compared to Control pigs. Additionally, tissue content of Salmonella was reduced in the rectal (P < 0.005) and lymph (P < 0.06) tissues from Scb pigs compared to Control pigs. Collectively, these studies demonstrate that supplementation with Scb can potentially “prime” the immune system of newly weaned pigs, thus improving the immune response to a pathogenic challenge.