PSII-1 An Evaluation of a Nutrient Drench Administered to Calves at Arrival into the Feedlot on Subsequent Health Status and Assessment of Immune Status with a Rapid Immunity Test

Abstract

Abstract A functionally effective immune system is required to maintain health and resist disease challenges for cattle received into the feedlot. Transport is a primary stressor that can decrease trace mineral status and impair immune function. The objectives of this study were to 1) evaluate a trace mineral drench providing key supplemental trace minerals (Cu, Mn, Se and Zn) administered to cattle at arrival into the feedlot on subsequent health and morbidity and 2) application of a novel technology for assessing immune status in stressed calves at risk for respiratory disease (BRD). From October through December 2021, 20 loads of Angus x Holstein heifers (n=1,988; 218± 2.7 kg) were transported from a calf rearing facility in northwest OH to a commercial feedlot in southwest NE. At initial processing, calves were individually identified and weighed and were administered a common processing protocol. Based on individual ear tag number heifers were either provided no drench (even-numbered tags; CONTROL) or 45 mL of a supplemental nutrient drench (odd-numbered tags; Profusion™, Zinpro Corporation, Eden Prairie, MN). Across 10 loads blood samples were collected from approximately 300 animals for subsequent measurement of humoral immunity status (D2Dx™; Nano Discovery Inc., Orlando, FL). Subsequent morbidity was monitored throughout the weeks following arrival. Data were analyzed using Proc Mixed and Proc Glimmix with fixed effects of treatment and load with heifer as experimental unit. Morbidity status of each heifer was classified based on whether the animal was subsequently pulled and treated for a diagnosed disease. Initial BW did not differ between treatments (P ≥ 0.67); however, BW varied among loads (P ≤ 0.01) and was lower (P ≤ 0.01) in calves subsequently pulled and treated for BRD. Reported mortality from all causes was minimal and not analyzed. Respiratory disease was the primary cause of disease; however, incidence was not affected (P ≥ 0.55) by treatment (21.1% vs. 23.5% for CONTROL and PROFUSION, respectively). Time from arrival to first recorded treatment varied among loads (range: 4 – 35 d) with a mean and median value of 26 and 21 d respectively with no treatment effects. Measured D2Dx scores at initial processing did not differ (P ≥ 0.43) between heifers assigned to CONTROL or PROFUSION treatments; however, scores were different among loads (P ≤ 0.01). In heifers subsequently treated for BRD, initial D2Dx scores were approximately 23% lower (P ≤ 0.07; D2Dx score =0.0138) compared to non-BRD treated animals (D2Dx score = 0.0180). These results suggest that administration of PROFUSION at arrival may not have been optimum based on subsequent observed morbidity patterns and calves with lower D2Dx score at arrival may have a lower humoral immunity especially a lower Th-1 immunity and thereby be more susceptible for clinical BRD.