Effect of water sulfate and dietary bismuth subsalicylate on feed and water intake, ruminal hydrogen sulfide concentration, and trace mineral status of growing beef heifers.

In the Northern Great Plains, cattle may be exposed to water with elevated sulfate concentrations resulting in ruminal hydrogen sulfide (H2S) production and risk of copper deficiency. There are currently few strategies available to help mitigate effects arising from high sulfate water. The objective of this study was to evaluate the effects of feeding a moderate forage diet with or without bismuth subsalicylate (BSS; 0.0 vs. 0.4% DM basis) when provided water with a low (LS; 346 ± 13) or high (HS; 4,778 ± 263 mg/L) sulfate concentration on feed and water intake, ruminal H2S concentration, and liver and serum trace mineral concentrations. Twenty-four Limousin × Simmental cross beef heifers (221 ± 41 kg) were stratified based on initial liver Cu into a completely randomized block design with a 2 × 2 factorial treatment arrangement. Feed and water intake (measured weekly), ruminal H2S concentration (measured on d 42 and 91), and liver (measured on d -13 and d 91) and serum trace mineral concentrations (measured on d 1, 28, 56, and 91) were evaluated. Initial liver trace-mineral concentrations were used as a covariate in the statistical model. Water intake tended to be reduced with the inclusion of BSS (P = 0.095) but was not affected by water sulfate (P = 0.40). Water sulfate and BSS did not affect DMI (P ≥ 0.89). Heifers consuming HS had ruminal H2S concentration that was 1.58 mg/L more (P < 0.001) than LS. The inclusion of BSS reduced (P = 0.035) ruminal H2S concentration by 46% (2.3 vs. 1.4 mg/L). Regardless of the water sulfate concentration, heifers fed BSS had lesser liver Cu concentration (average of 4.08 mg/kg) than heifers not provided BSS, and when not provided BSS, HS had lesser Cu than LS (42.2 vs. 58.3; sulfate × BSS, P = 0.019). The serum concentration of Cu did not differ over time for heifers not provided BSS; whereas, heifers provided BSS had lesser serum Cu concentration on d 91 than d 28 and 55 (BSS × time, P < 0.001). The liver concentration of selenium was reduced (P < 0.001) with BSS inclusion but the selenium concentration in serum was not affected by sulfate, BSS, or time (P ≥ 0.16). Bismuth subsalicylate reduced ruminal H2S concentration, but depleted liver Cu and Se. Moreover, sulfate concentration in water did not appear to affect DMI, water intake, or growth, but increased ruminal H2S and reduced liver Cu concentration.