PSVII-40 Late-Breaking Abstract: Ultrasonography and bacterial community of naturally occurring liver abscesses and non-abscessed livers in finishing Holstein steers

<jats:title>Abstract</jats:title> <jats:p>Liver abscesses persist in feedlot cattle representing a financial burden to both pre- and post-mortem sectors of the beef industry. Pre- and Post-mortem strategies are needed to understand onset, duration, and resolution of abscesses, etiology, and fully quantify their impact on performance. Holstein steers (n = 56; Initial BW=384±13.5 kg) consuming a finishing diet (90% concentrate) for 188 d (Final BW=660±42 kg) were used for live ultrasonography of the liver. Feed intake was recorded daily and BW and liver ultrasound images recorded every 28 d. At harvest, livers were graded and imaged to compare with ultrasound images. Tissue was sampled from both abscessed and non-abscessed livers and 16s rDNA sequencing performed. Steers ranked within feedlot performance variables for 188 days on feed (DOF) and the final 48 DOF were compared with post-mortem liver score using the FREQ procedure of SAS. A contingency table for abscess dete