Growth and humoral immune effects of dietary Original XPC™ in layer pullets challenged with Mycoplasma gallisepticum

Authors: ELLIOTT, K E - Mississippi State University; Branton, Scott; Evans, Jeffrey - Jeff; Leigh, Spencer; KIM, E - Dupont Nutrition & Health; Olanrewaju, Hammed; PHARR, G - Mississippi State University; PAVLIDIS, H - Diamond V Mills, Inc; GERARD, P - Clemson University; PEEBLES, E - Mississippi State University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2020
Publication Date: 6/15/2020
Citation: Elliott, K.C., Branton, S.L., Evans, J.D., Leigh, S.A., Kim, E.J., Olanrewaju, H.A., Pharr, G.T., Pavlidis, H.O., Gerard, P.D., Peebles, E.D. 2020. Growth and humoral immune effects of dietary Original XPC™ in layer pullets challenged with Mycoplasma gallisepticum. Poultry Science. 99(6):3030-3037.
DOI: https://doi.org/10.1016/j.psj.2020.01.016

Interpretive Summary: XPC™ (XPC; Diamond V Corp., Cedar Rapids, IA) is a fermentation product derived from the bacterium Saccharomyces cerevisiae which has been shown to positively affect commercial layer egg yolk yield and composition. To determine the effects of dietary XPC™ in commercial layer pullets challenged with the virulent, low passage R strain of Mycoplasma gallisepticum (Rlow MG), Hy-Line W-36 pullets sourced from Mycoplasma gallisepticum-clean breeders were fed a basal diet with or without (CON) XPC (1.25 kg/metric ton) from hatch until 12 wk of 32 age (woa). At 8 and 10 woa, half of the birds in each dietary treatment were challenged with Rlow MG. Body weight was recorded at 3, 8, and 12 woa and ovary, ceca, and bursa weights were recorded at 3 and 12 woa. Blood samples were taken immediately prior to the initial Rlow MG challenge at 8 woa and again at 12 woa to test for immunoglobulin (Ig) M and IgG antibody production against MG. All birds were evaluated for MG lesion scores at 12 woa. Results of the study show that regardless of challenge, inclusion of XPC in the diet did not significantly alter BW at 3 or 8 woa, or relative organ weights at 3 or 12 woa. However, at 12 woa, BW of XPC-fed birds, regardless of challenge, was significantly (P = 0.0038) heavier than CON by 25.7 g. All birds tested negative for MG antibodies prior to the 8 woa challenge. Respective percentage SPA and ELISA positive birds at 12 woa were 0% and 0% (CON, non-challenged, respectively), 1.4% and 0% (XPC, non-challenged), 100% and 47.2% (CON, challenged), and 100% and 50.0% (XPC, challenged). Diet did not significantly affect ELISA titers, but they were significantly (P < 0.0001) increased due to MG challenge. Furthermore, lesion scores were significantly higher for Rlow MG-challenged birds (P= 0.0012), and dietary treatment with XPC in challenged birds numerically reduced MG lesion scores from 0.278 to 0.194. In conclusion, although dietary XPC did not significantly alter the humoral immune response, antibody titer levels, or severity of MG lesions in layer pullets that were or were not challenged with Rlow MG, XPC led to an increase in rate of chicken growth through 12 woa.

Technical Abstract: Effects of dietary Original XPC™ (XPC) in commercial layer pullets challenged with the virulent, low passage R strain of Mycoplasma gallisepticum (Rlow MG) were investigated. Hy-Line W-36 pullets sourced from Mycoplasma gallisepticum-clean breeders were fed a basal diet with or without (CON) XPC (1.25 kg/metric ton) from hatch until 12 wk of age (woa). At 8 and 10 woa, half of the birds in each dietary treatment were challenged with Rlow MG. Body weight was recorded at 3, 8, and 12 woa and ovary, ceca, and bursa weights were recorded at 3 and 12 woa. Blood samples were taken immediately prior to the initial Rlow MG challenge at 8 woa and again at 12 woa to test for IgM and IgG antibody production against MG. All birds were evaluated for MG lesion scores at 12 woa. Regardless of challenge, inclusion of XPC in the diet did not significantly alter BW at 3 or 8 woa, or relative organ weights at 3 or 12 woa. However, at 12 woa, BW of XPC-fed birds, regardless of challenge, was significantly (P = 0.0038) heavier than CON by 25.7 g. All birds tested negative for MG antibodies prior to the 8 woa challenge. Respective percentage SPA and ELISA positive birds at 12 woa were 0% and 0% (CON, non-challenged), 1.4% and 0% (XPC, non-challenged), 100% and 47.2% (CON, challenged), and 100% and 50.0% (XPC, challenged). Diet did not significantly affect ELISA titers, but they were significantly (P < 0.0001) increased due to challenge. Furthermore, lesion scores were significantly higher for Rlow MG-challenged birds (P = 0.0012), and dietary treatment with XPC in challenged birds numerically reduced MG lesion scores from 0.278 to 0.194. In conclusion, although dietary XPC did not significantly alter the humoral immune response, antibody titer levels, or severity of MG lesions in layer pullets that were or were not challenged with Rlow MG, it led to an increase in their rate of growth through 12 woa.