|Carroll, Jeffery - Jeff Carroll|
|Hulbert, Lindsey - Former ARS Employee|
|Ballou, Michael - Texas Tech University|
|Dailey, Jeffery - Jeff|
|Caldwell, Lisa - Texas Agrilife Research|
|Vann, Rhonda - Mississippi State University|
|Welsh Jr, Thomas - Texas Agrilife Research|
|Randel, Ronald - Texas Agrilife Research|
Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2015
Publication Date: 6/23/2015
Citation: Carroll, J.A., Sanchez, N.C., Hulbert, L.E., Ballou, M.A., Dailey, J.W., Caldwell, L.C., Vann, R.C., Welsh Jr, T.H., Randel, R.D. 2015. Sexually dimorphic stress and innate immunological responses of pre-pubertal Brahman cattle following an intravenous endotoxin challenge. Veterinary Immunology and Immunopathology. 166(3-4):108-115. doi:10.1016/j.vetimm.2015.06.009.
Interpretive Summary: This research represents a collaborative effort between scientists from Texas AgriLife Research, the Livestock Issues Research Unit, Mississippi State University, and Texas Tech University to determine if sexually dimorphic innate immune responses exist in cattle. Studies in animal models and humans have demonstrated that there are sexually dimorphic innate and adaptive immune responses, and that these responses may play a role in the succeptibility to disease, as well as mortality. Therefore, we utilized purebred Brahman heifers and bulls from the Texas AgriLife Research Center in Overton, Texas, to determine if sexually dimorphic innate immune responses to a lipopolysaccharide challenge exist in cattle. Data from this study suggest there are differences in the physiological and innate immune responses between pre-pubertal bulla and heifer calves. Specifically, heifer calves maintained greater rectal temperature compared to bull calves throughout the study and produced a greater peak in the pro-inflammatory cytokine tumor necrosis factor-alpha. However, bulls displayed greater sickness behaviors than heifers. In contrast, cortisol concentrations following lipopolysaccharide administration did not differ between heifers and bulls. These data demonstrate the existance of sexual dimorphic physiological and innate immune responses in Brahman calves. Additionally, these data suggest that heifers may have a more robust acute innate immune response to lipopolysaccharide challenge, which may be beneficial during different managerial practicies. This data will be of interest to scientists in the fields of stress physiology and immunology, as well as cattle producers, and can be used to adjust management practices in order to enhance performance of heifer and bull calves.
Technical Abstract: This study was designed to characterize potential sexually dimorphic immunological responses following endotoxin challenge. Six female (heifers) and five male (bulls) Brahman calves (267 ± 11.5 days of age) were challenged with 0.25 microgram of LPS/kg body weight. Following administration of endotoxin, all cattle displayed sickness behavior between 0.5 to 12 hours, with heifers displaying less sickness behavior than bulls from 6.5 to 12 hours. A febrile response was observed in all animals from 4 to 5.5 hours, with greater rectal temperatures in heifers. All animals displayed elevated concentrations of cortisol from 0.5 to 8 hours,tumor necrosis factor-alpha from 1 to 2 hours, interleukin-6 from 2 to 8 hours, and interferon-gamma from 2.5 to 7 hours. Additionally, serum concentrations of tumor necrosis factor-alpha were also greater in heifers than bulls from 2 to 2.5 hours after the endotoxin challenge. Leukopenia occurred from 1 to 8 hours, with a decreased neutrophil to lymphocyte ratio for the first 6 hours among all animals. These data demonstrate the existence of a sexually dimorphic innate immune response in Brahman cattle. Specifically, heifers may have a more robust acute innate immune response to endotoxin challenge, even though bulls display more sickness.