Evaluation of innate immune responses between beef and beef × dairy cross steers under an immune challenge.

Authors: SMITHYMAN, M - New Mexico State University; Broadway, Paul; BARKER, SAMANTHA - Texas Tech University; LEGAKO, JERRAD - Texas Tech University; Sanchez, Nicole

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 2/11/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The increasing presence of dairy-beef crossbred cattle in feedlots emphasizes the need to better understand their immunological responses in order to optimize industry performance and health. The objective of this study was to evaluate the differences in innate immune responses between crossbreed beef steers and dairy-beef crossbred steers when exposed to endotoxin (lipopolysaccharide; LPS) to determine how breed differences influence immunity. Thirty steers (initial BW 194 ± 40 kg) were transported to the USDA-ARS Livestock Issues Research Unit, where they were housed in individual pens in a climate-controlled barn with ad libitum access to a receiving ration and water. Breeds evaluated were crossbred beef steers (BEEF; n=9), Charolais ' dairy crossbred steers (CHARX; n=10), and Angus ' dairy crossbred steers (ANGX; n=11). On d -1, steers were fitted with jugular catheters and indwelling rectal temperature loggers. On d 0, steers were challenged i.v. with LPS (0.15 µg/kg BW) and blood samples were collected at -2, 0, 1, 2, 4, 6, 8, 12, 24, 36, and 48h relative to LPS challenge. Data were analyzed using PROC MIXED in SAS. There was a breed × time interaction (P<0.01) for rectal temperature, where temperature increased for CHARX when compared to ANGX at 2 and 3h post-immune challenge. There were breed effects (P<0.01) for red blood cells, hemoglobin, and hematocrit where BEEF had decreased values compared to both ANGX and CHARX. There was a breed × time interaction (P<0.01) for white blood cells where concentrations were increased from -2, 0, and 24h for ANGX compared to both BEEF and CHARX. There was a breed × time interaction (P<0.01) for neutrophil:lymphocyte ratio where values were increased at -2h for ANGX compared to both BEEF and CHARX, however from 6 and 8h ANGX and BEEF had reduced values compared to CHARX. There was a breed × time interaction (P<0.01) for sickness behavior scores where ANGX and CHARX had elevated scores compared to BEEF at 2h and CHARX had elevated scores compared to BEEF at 4h following immune challenge. The results of this study suggests that breed-specific immune responses could influence the overall health and resilience of cattle in the feedlot, pointing to the importance of management practices and further research to maximize the health and performance of different breeds in commercial production systems.