PSI-13 Effect of Targeted Metaphylaxis Using Blood Leukocyte Status on Health, Performance, and Economic Outcomes of Auction-Derived Feedlot Heifers

Abstract The study objective was to evaluate health, performance, and antimicrobial costs of heifers where targeted metaphylaxis guided by a commercial blood leukocyte analyzer compared traditional regimen. Using randomized complete block design, (n=1,271; initial body weight (BW) = 233.3±1.08 kg) were randomly allocated treatment pens (n=20; 10 blocks). Treatments were: 1) cattle administered metaphylactic with gamithromycin at arrival (META), 2) according the outcome (TARGETED). indicated immune status individual animals number proportion different leukocytes in blood; red signified “abnormal” green “normal” status. Only TARGETED treatment. Of all enrolled study, 73% deemed normal 27% abnormal chute side analyzer. Treatment groups had an equal distribution (META 74%) 28% 26%) study. Cattle fed common starter ration for duration 62-d Pen riders blinded pen Data analyzed using PROC MIXED GLIMMIX SAS. Final BW, ADG, feed conversion less (P≤0.02). However, processing cost 11.77 $3.27/heifer) total 17.77 $9.12/heifer) reduced (P< 0.01) TARGETED. savings $8.50/heifer overall drug input $8.65/heifer. BRD morbidity rate 18.85% more than (26.49%; P< 0.01). Normal mortality 3.17 vs. 5.80% (P=0.03). In conclusion, but performance also less.