PSVII-20 Supplementing pHix-Up® to feedlot cattle consuming a corn-based finishing diet

Abstract

Abstract This experiment evaluated the inclusion of a rumen-buffering agent on performance and carcass traits of feedlot cattle. Angus-influenced steers and heifers (n = 64 animals/sex) were ranked by sex and body weight (BW) into 1 or 16 drylot pens. Pens were randomly assigned to receive a corn-based diet without (CON = 8 pens) or with the inclusion (SUPP = 8 pens) of pHix-Up® (magnesium-based product; Timab, Dinard, France) at 0.50% of diet dry matter. Both dietary treatments contained monensin Na (360 mg animal/daily) but did not contain tylosin. Two animals per pen were equipped with an intraruminal bolus (smaXtec Premium Bolus, smaXtec Animal Care GmbH, Graz, Austria) that recorded pH every 15 min. Cattle received treatments for 128 d until slaughter. No differences (P ≥ 0.22) between SUPP and CON cattle were noted for BW gain (0.93 vs. 0.97 kg/d, respectively), feed intake (7.51 vs. 7.78 kg/animal daily, respectively), or feed efficiency (0.121 vs. 0.125 kg/kg, respectively). Rumen pH was greater in SUPP vs. CON cattle during 33% of the time (e.g. 6 h of the day; mean pH of 5.87 vs. 5.80, respectively). No treatment differences were noted (P ≥ 0.12) for carcass merit. Incidence of cattle with liver abscess upon slaughter was greater in CON vs. SUPP (16.4 vs. 4.7%, respectively), including incidence of severe liver abscess (A+; 8.2 vs. 0.0%, respectively). These results indicate that pHix-Up® inclusion into a corn-based finishing diet improved rumen pH without benefiting cattle productive responses. It should be noted that average temperature-humidity index during this experiment was 78, which hindered feed intake and potential benefits of pHix-Up® to rumen pH and cattle performance. Nonetheless, pHix-Up® inclusion substantially reduced the incidence of liver abscess, resulting no severe diagnoses. Hence, additional research is warranted to further explore the benefits of pHix-Up® to feedlot cattle.