Location: Livestock Issues Research
Project Number: 3096-32000-008-029-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Feb 1, 2021
End Date: Feb 29, 2024
To determine if feeding a rumen protected amino acid, methionine (MetaSmart), to newly received beef calves will alter their innate immune response to an endotoxin challenge.
Weaned beef steers (n = 40; 500 to 600 lb) will be sourced from a commercial ranch, and transported to the West Texas A&M University Research Feedlot where they will be fed a control ration (Control, n = 20 hd) or the control ration supplemented with MetaSmart (n = 20 hd; Adisseo). Steers will be allowed ad libitum access to the assigned treatment diets and water, and clinical health will be assessed daily by trained evaluators. Following 28 days of supplementation, 32 calves (n = 16/treatment) will be selected based upon uniform body weight, temperament, treatment history, and health status, and transported to the Livestock Issues Research Unit’s Bovine Immunology Research and Development Complex in Lubbock, TX (day -2). Upon arrival, calves will be placed in outdoor, covered holding pens with access to water and their respective treatment rations overnight. The following day (day -1), calves will be weighed, and restrained via halter in a squeeze chute to allow the neck, caudal to the jaw, to be shaved, cleaned, and disinfected. Calves will then be fitted with indwelling jugular catheters and rectal or vaginal temperature recording devices that will measure body temperature continuously at 5-min intervals. Following these procedures, calves will be placed in individual bleeding stalls for the duration of the challenge with access to water and their treatment ration. On day 0, all calves will be challenged intravenously with lipopolysaccharide (LPS; 0.25 µg/kg body weight (dose may vary due to condition of the calves)). Three blood samples will be collected at -2, 0, 2, 4, 6, 8, 10, 12, 18, 24, 36 and 48 hours relative to the LPS challenge at time 0. One whole blood sample will be utilized for measuring hematology parameters, one blood sample will be processed to harvest serum for analyzing cortisol and acute phase proteins, and the remaining blood sample will be processed to harvest plasma for a blood chemistry analysis and indicators of oxidative stress.