PSVIII-A-1 - Effect of source of trace mineral and bismuth subsalicylate on growth, ruminal H2S, and trace mineral status of growing heifers

Abstract: This study evaluated the effects of providing inorganic, chelated, and inorganic plus injectable trace mineral supplementation strategies with or without the inclusion of bismuth subsalicylate (BSS) on dry matter intake (DMI), water intake, ruminal hydrogen sulfide (H₂S) concentration, and trace mineral status of growing beef heifers provided high sulfate (5,055 ± 228 mg/L) water. This study consisted of an 84-d feeding period with a 2×2+1 factorial treatment arrangement conducted using 2 blocks. Beef heifers (n=15/block; 367 ± 33 kg BW) in each block were stratified according to their initial liver copper concentration. Mineral treatments included inorganic [added CuSO₄ (7.76 mg/kg), ZnSO₄ (22.92 mg/kg), MnSO₄ (15.28 mg/kg)], chelated (100% of the Cu-methionine (7.68 mg/kg ), Zn-methionine (22.89 mg/kg), and Mn-methionine (15.27 mg/kg), and injectable trace mineral (15 mg/mL Cu, 10 mg/mL Mn, 60 mg/mL Zn) provided in combination with the inorganic mineral treatment. The BSS treatments were 0.0 (CON) or 0.2% (BSS) on a DM basis. Feed and water intake (weekly), ruminal H₂S concentration (d 42 and 84), and liver (pre-study, d 42 and 84) and serum trace mineral concentrations (d 1, 28, 56, and 84) were evaluated. Initial liver trace mineral concentration was used as a covariate. Dry matter intake tended to be greater (mineral × BSS, P = 0.05) for heifers provided chelated minerals and fed CON, compared to BSS, and tended to be less for heifers fed inorganic and CON than BSS. Heifers fed chelated minerals drank 6.1 L/d more (P < 0.05) water than those provided inorganic minerals. Injectable trace-mineral provision did not affect DMI or water intake. Ruminal H₂S was not affected by mineral type or BSS (P ≥ 0.33). The inclusion of BSS reduced (P < 0.01) liver Cu concentration from 60.5 to 31.3 ppm. Heifers provided the injectable minerals had greater (P < 0.01) liver Cu concentration than the inorganic without BSS treatment. Serum copper was not affected by BSS or mineral treatment (P ≥ 0.44). The liver concentration of Se was reduced (P < 0.01) by the inclusion of BSS. The serum Se concentration was not affected by mineral type, BSS, time, or any two- or three-way interactions (P ≥ 0.24). Bismuth subsalicylate did not affect ruminal H₂S, and negatively affected liver Cu concentration. The use of organic trace mineral supplementation strategies did not affect the trace mineral status of beef heifers drinking high sulfate water, but use of an injectable trace mineral supplement increased liver Cu.