Iron carbonate supplementation to prevent reduced performance and health of wethers administered high-sulfate wate

Water is perhaps the most important nutrient for livestock. High concentrations of S in drinking water is frequently problematic for livestock produced in western regions of the U.S. High dietary S can cause decreased performance and health when reduced by ruminal microorganisms to toxic intermediates and end products. Monitoring and treating water for high concentrations of S is both expensive and impractical; therefore, an alternative method of controlling this problem is needed. Soluble Fe is routinely used in water treatment plants to bind S. We hypothesized that dietary supplementation with an Fe compound would bind excess S in ruminant animals, preventing the negative effects associated with high-S drinking water. This study used 80 wether lambs randomly assigned to one of four treatments in a randomized complete block design with 20 wethers per treatment replicated over 2 pens per treatment. Treatments included: 1) control feed and low-S well water (57 mg SO42-/L; 2) control feed and high-S water (2,250 mg SO42-/L); 3) low-Fe (250 ppm FeCO3) feed and high-S water (2,250 mg SO 42-/L); and 4) high-Fe (500 ppm FeCO3) feed and high-S water (2,250 mg SO42-/L). All wethers received ad libitum access to feed and water. Body weights and blood samples were taken on d -1, 25, and 50, and H2S gas in the rumen was measured on d -1 and 50, and liver samples were collected at slaughter. The results from this study indicate that supplementation of an Fe compound to ruminant animals exposed to high-S drinking water was not effective at preventing H2S gas accumulation in the rumen, and would likely not prevent the negative effects associated with high dietary S. Also, gene expression analysis revealed differentially expressed genes in the HSHI group that are involved in immune function, oxidative damage, apoptosis, tumor suppression, and tight junctions, suggesting that high dietary Fe, perhaps in combination with high dietary S, influences cellular functions in wethers consuming high-SO 42- water.