035 Omnigen-AF supplementation may attenuate liver damage during a high concentrate diet in finishing steers.

To determine the effect of OmniGen-AF (OG; a patented nutritional specialty product from Phibro Animal Health Corporation) supplementation on markers of metabolism and liver function in steers during backgrounding, transition, and finishing phases, 9 purebred Angus half-sibling steers were divided into 1 of 2 treatment groups: control (CNTL; n = 4) and OG (n = 5). Cattle were offered 0 (CNTL) or 56 g/animal per day of OG through a 28-d backgrounding period (limit fed a predominantly forage-based diet), a 14-d transition period, and finished on a high-concentrate diet for 56 d (104 d total). Serum was collected on d 0, 14, 21, 28, 35, 43, 56, 70, 84, 98, and 104 for haptoglobin, metabolites, and markers of liver function as measured by paraoxonase, albumin, aspartate aminotransferase (AST), and gamma-glutamyltransferase (GGT). Data were analyzed using repeated-measures-in-time analysis in PROC MIXED. Fixed effects of the statistical model were treatment (CNTL and OG), dietary phase, day (nested within phase), and their interactions. The values and variation of serum AST and GGT increased at the end of the finishing phase, resulting in a bimodal distribution prior to and at the end of finishing; therefore, we examined AST and GGT concentrations with a separate analysis on d 84, 98, and 104. A diet phase effect was present for metabolites and markers of liver function (P < 0.05); the interaction of diet phase and OG supplementation had no effect on metabolites, AST, paraoxonase, or albumin. Gamma-glutamyltransferase tended to increase in OG steers, whereas in CNTL steers, GGT decreased (P = 0.08) during the backgrounding phase. OmniGen-AF supplementation during the entire experiment (104 d) increased serum haptoglobin concentrations (P = 0.0002) and decreased serum NEFA concentrations (P = 0.002). OmniGen-AF supplementation also assuaged the decline in paraoxonase concentrations (P = 0.02) and tended to reduce the increase of a marker of liver cell necrosis (AST; P = 0.07) at the end of the finishing period (compared with control cattle on d 84, 98, and 104 of supplementation). Based on these data, we conclude that OG supplementation may attenuate liver damage during a high-concentrate diet in finishing steers.