Effects of dietary Original XPC™ on selected blood variables in layer pullets challenged 3 with Mycoplasma gallisepticum

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

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2020
Publication Date: 9/21/2020
Citation: Peebles, E.D., Elliott, K., Branton, S.L., Evans, J.D., Leigh, S.A., Kim, E.J., Olanrewaju, H.A., Pharr, G.T., Pavlidis, H.O., Gerard, P.D. 2020. Effects of dietary Original XPC™ on selected blood variables in layer pullets challenged 3 with Mycoplasma gallisepticum. Poultry Science. 99:4373-4383. https://doi.org/10.1016/j.psj.2020.06.005.
DOI: https://doi.org/10.1016/j.psj.2020.06.005

Interpretive Summary: Effects of the proprietary dietary component Original XPC™ (XPC) which is technically considered as an immunomodulator has been reported to reduce gut pathogen colonization and to improve intestinal development and growth in chickens. XPC was investigated with respect to selected blood variables in commercial layer pullets challenged with the virulent, low passage R strain of Mycoplasma gallisepticum (RlowMG). Specifically, MG-clean Hy-Line W-36 pullets were fed a basal diet with or without (CON) XPC (1.25 33 kg/metric ton) from hatch until 12 wk of age (woa). At 8 and 10 woa, half of the birds in each treatment were challenged with RlowMG with blood samples were taken immediately prior to the initial RlowMG challenge at the respective ages. At 8 woa, blood pH was lower and glucose concentration was higher in the pre-assigned challenge treatment groups while at 12 woa, the concentration of oxygen dissolved in the blood (sO2)was significantly lower in the RlowMG -challenged birds as compared to the unchallenged group of birds regardless of dietary treatment. The RlowMG challenge significantly increased blood carbon dioxide partial pressure (pCO2), calcium, sodium, anion gap, osmolality, glucose, and corticosterone levels, but significantly decreased blood oxygen partial pressure, oxyhemoglobin concentration, sO2, chloride, and pH levels. Because blood pH and glucose concentration at 43 woa were examined prior to challenge, their baseline values were biased with respect to challenge treatment before treatment was applied. However, the lack of a significant main effect due to diet at 8 woa for blood pH and glucose concentration, along with the other 15 blood variables, indicates that the baseline data with respect to dietary treatment was unbiased, allowing for real dietary effects to be accurately assessed. In conclusion, layer pullets challenged with RlowMG undergo a stress response associated with changes in various physiological blood variables, and a decrease in pH in addition to an increase in pCO2, in association with a lack of change in bicarbonate, thereby indicating that the stress response caused by the RlowMG challenge was associated with respiratory acidosis. Nevertheless, feeding XPC did not influence the effects of challenge treatment on these post-challenge physiological blood values.

Technical Abstract: Effects of dietary Original XPC™ (XPC) on 17 selected blood variables in commercial layer pullets challenged with the virulent, low passage R strain of Mycoplasma gallisepticum (RlowMG) were investigated. Hy-Line W-36 pullets sourced from Mycoplasma gallisepticum-clean layer breeders were fed a basal diet with or without (CON) XPC (1.25 33 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 RlowMG. Blood samples were taken immediately prior to the initial RlowMG challenge at 8 woa and again at 12 woa (4 wk post-challenge). At 8 woa, blood pH was lower and glucose concentration was higher in the pre-assigned challenge treatment groups. At 12 woa, the concentration of oxygen dissolved in the blood (sO2)was significantly lower in the RlowMG -challenged compared to the unchallenged group of birds regardless of dietary treatment. The RlowMG challenge significantly increased blood carbon dioxide partial pressure (pCO2), calcium, sodium, anion gap, osmolality, glucose, and corticosterone levels, but significantly decreased blood oxygen partial pressure, oxyhemoglobin concentration, sO2, chloride, and pH levels. Because blood pH and glucose concentration at 8 woa were examined prior to challenge, their baseline values were biased with respect to challenge treatment before treatment was applied. However, the lack of a significant main effect due to diet at 8 woa for blood pH and glucose concentration, along with the other 15 blood variables, indicate that the baseline data with respect to dietary treatment was unbiased, allowing for real dietary effects to be accurately assessed. In conclusion, layer pullets challenged with RlowMG undergo a stress response associated with changes in various physiological blood variables, and a decrease in pH and increase in pCO2, in association with a lack of change in bicarbonate, indicates that the stress response caused by the RlowMG challenge was associated with respiratory acidosis. Nevertheless, feeding XPC did not influence the effects of challenge treatment on these post-challenge physiological blood values.