PSVI-12 - Comparison of a visual health scoring system with vaginal temperatures of newly received feedlot heifers

Abstract: Newly received feedlot cattle frequently succumb to bovine respiratory disease (BRD), which can be visually diagnosed and medically treated by employing a 4-point scoring system based on depression, appetite, respiration, and temperature (DART). Using this system, cattle are treated with antimicrobial medications for BRD if they have a rectal temperature (RT) ≥ 40°C and a DART score of 2 (scale = 1 to 4), or if they have a DART score of 3 or 4 regardless of the 40°C RT threshold. However, cattle often exhibit several visible clinical symptoms of BRD but do not have a RT above the 40°C threshold to warrant medical treatment. The objective of this study was to evaluate if DART scoring could be used to identify cattle with elevated vaginal temperatures (VT) throughout a 28-day receiving period. Upon feedlot arrival, 198 crossbred heifers (primarily Angus influence; initial BW = 219 ± 63 kg) were initially processed, weighed, and allocated to one of 10 soil-surfaced pens (12 ´ 35 m; 20 heifers per pen). A blank Controlled Intravaginal Drug Release (CIDR) device attached with an indwelling temperature probe (iButton DS1925L) was inserted vaginally into each heifer to collect and store VT every 10 minutes for 28-days. All heifers were evaluated daily (0700 h) for signs of morbidity by three individuals (blinded from each other) implementing the DART scoring system. Individual DART evaluations were then pooled prior to determination of heifers needing further evaluation for medical treatment. Results confirmed that DART score increases as VT increases (P < 0.001). Similarly, mean time DART ≥ 2 (TDART≥2) increased as mean time VT ≥ 40°C (TVT≥40) increased (P < 0.001). Accuracy of DART ≥ 2 to VT ≥ 40°C analogous by day is denoted as (MATCH). Simple regression analysis of MATCH and TVT≥40 for determining accuracy of visually diagnosing clinical BRD, was MATCH = 0.89 – 0.71 × TVT≥40 (r² = 0.70; P < 0.001). The accuracy to visually diagnose BRD decreases as the number of days spent with a VT ≥ 40°C increases. Average daily gain decreased (P < 0.001) as TDART≥2 and TVT≥40 increased. The BRD symptoms indicating high VT and DART score (P ≤ 0.01) were nasal discharge, anorexia, abnormal respiration, and teeth grinding. Additionally, weakness, cough, lowered head, and ocular discharge indicate greater DART score (P ≤ 0.01). Basophils and hemoglobin decreased with elevated VT and DART score (P ≤ 0.02). Monocytes increased with elevated DART score (P ≤ 0.04). In conclusion, data from this evaluation employing VT sensors and the DART scoring method provided an overview of how effective clinical BRD can be visually diagnosed, therefore contributing to the improvement and development of more effective strategies for identifying respiratory diseases in feedlot cattle.