|BUNTYN, JOE - University Of Nebraska|
|Carroll, Jeffery - Jeff Carroll|
|SMITH, T - Mississippi State University|
|RIVERA, J - Mississippi Agricultural And Forestry Experiment Station (MAFES)|
|SCHMIDT, TY - University Of Nebraska|
Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2016
Publication Date: 6/20/2016
Citation: Buntyn, J.O., Carroll, J.A., Smith, T., Rivera, J.D., Sanchez, N.C., Broadway, P.R., Falkenberg, S.M., Schmidt, T.B. 2016. Evaluation of the innate immune response of Angus heifers with genetic marker variation for intramuscular fat deposition following a lipopolysaccharide challenge. Livestock Science. 188:103-110.
Interpretive Summary: Intramuscular adipose tissue is directly related to beef quality (USDA quality grades), enhanced flavor, and an overall improvement in consumer satisfaction of beef. With the mapping of the bovine genome, numerous quantitative trait loci for important production traits of cattle have been identified and as such, commercially available DNA marker assisted tests are available for cattle producers. A primary DNA marker assisted test available is the GeneSTAR® Molecular Value Predictions (GS-MVP; Zoetis, NJ) which is a 56-marker panel utilized to evaluate three core management traits of beef cattle; feed efficiency, marbling, and tenderness. Due to the important role of intramuscular adipose tissue, both within the living animal and the final product, the selection of sire and dam combinations for marbling QTL’s may provide a dual benefit. However to date, there has been no evaluation of the possible benefits for selection of marbling QTL’s on the immune response of cattle. Therefore, the objective of this study was to evaluate the innate immune response of cattle genetically selected to possess either one or more copies of the two QTL’s associated with marbling deposition (QG1 and/or QG2). Overall, the results of this study indicate that there is a very distinct difference between the immune response of heifers within the at least one Molecular Value Predictor QTL group when compared to the heifers in the No Molecular Value Predictor group. Heifers possessing one or more GeneStar® Molecular Value Prediction QTL’s, when challenged with LPS had an increase in vaginal temperature, increased IFN-' concentrations, and decreased haptoglobin production compared to the No-MVP heifers. These distinct differences in the immune response may be related to an increase in available energy. These data will be of interest to scientists in the field of immunology and physiology, as well as cattle producers.
Technical Abstract: This study evaluated the effect of genetic selection for markers related to marbling deposition in Angus heifers on the immune response following a lipopolysaccharide (LPS) challenge. Fall-born heifers (n = 19; ~7 months of age, 274 +/- 24 kg) with genetic variation for marbling were utilized including 10 heifers with no genetic markers (No-MVP) and 9 heifers with >1 markers (1+MVP). Genotypic variation for quantitative trait loci QG1 and QG2 heifers was determined. Twenty-four hours prior to the LPS challenge, heifers were fitted with jugular catheters and vaginal temperature (VT) monitoring devices. Temperature monitoring devises were programed to record VT in 1 min intervals. On day 0, 2 hours prior to LPS challenge and 8 hours post challenge, serum was collected in 0.5 hour intervals (0800 – 1800 h). Serum was also collected at 12, 16, 20, and 24 hours post LPS challenge. The LPS challenge was administered to the heifers at 1000 hours via intravenous bolus (0.5 microgram/kg body weight). Serum was analyzed for cortisol, TNF-alpha, IL-6, IFN-gamma, and haptoglobin (HAPT). A treatment x time interaction existed (P = 0.001) for VT; prior the LPS challenge, VT was similar. Vaginal temperature was elevated from 6 to 21 hours post-LPS in 1+MVP compared to No-MVP. A treatment x time interaction (P = 0.02) was observed for IFN-gamma. Prior to the LPS challenge, IFN-gamma concentrations were similar between the two groups. However, 3.5 to 7 hours post-LPS concentrations of IFN-gamma were greater (P = 0.05) for 1+MVP compared to No-MVP. There was no treatment effect (P = 0.17) for cortisol, TNF-alpha or IL-6. A treatment effect (P = 0.02) was observed for HAPT; 1+MVP had decreased HAPT compared to No-MVP. Overall, results suggest that heifers selected based upon genetic markers for marbling may have an altered immune in response when challenged with LPS.