313 Effects of Bismuth Subsalicylate on Ruminal Fermentation of Cattle Consuming a Feedlot Diet

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Abstract A replicated 3 × 3 Latin square was used to determine the effects of bismuth subsalicylate on ruminal fermentation parameters of beef cattle consuming a feedlot diet. Six ruminally-cannulated Angus-crossbred steers (n = 3; 573 ± 105 kg BW) and heifers (n = 3; 553 ± 77 kg BW) were assigned 1 of 3 treatments: 1) low sulfur (S = 0.27% diet DM; LSUL); 2) high sulfur (S = 0.38% diet DM; HSUL); and 3) HSUL + 0.33% bismuth subsalicylate in diet DM; (BSS). Cattle were adapted to treatments for 14 d followed by 7 d of collections. Ruminal gas cap samples were collected at 0, 4, 8, and 12 h post-feeding on d 14, and ruminal fluid samples were collected on d 15 every 3 h post-feeding for 24 h. Data were analyzed using the MIXED procedure of SAS. Treatment tended (P = 0.099) to affect H2S concentration where BSS and LSUL were 50 and 61% lesser when compared to HSUL, respectively. A tendency (P = 0.061) was also observed for concentration of NH3-N where HSUL and BSS were lesser than CTRL. There was also a tendency for a treatment effect (P = 0.082) where HSUL had a lower pH than LSUL with BSS being intermediate. Furthermore, treatment tended (P = 0.0712) to affect the concentration of acetate where HSUL was lesser than BSS. No effect of treatment (P ≥ 0.124) was observed on total VFA concentration nor concentrations of butyrate, propionate, or valerate (P ≥ 0.138). Treatment tended (P = 0.084) to affect branched chain VFA concentration where BSS decreased concentrations compared to LSUL. Molar proportions of the major VFA were not impacted by treatment (P ≥ 0.100). In conclusion, BSS appears to decrease H2S production in the rumen without having negative effects on the fermentation profile.