Effects of bismuth subsalicylate and encapsulated calcium-ammonium nitrate on feedlot beef cattle production

Sulfur is an important element for the ruminant animal, this mineral occurs in essential amino acids such as cysteine, cystine, and methionine, and it is also important for the metabolism of a number of ruminal microorganisms. The effects of S on cattle health and performance have become a concern after the cattle industry started utilizing co-products from the ethanol sector to feed cattle. These coproducts carry levels of sulfur that can surpass the requirements of beef cattle, which can negatively affect performance and health in the feedlot. When cattle consume diets with high levels of dietary S, H2S occurs in the rumen that can enter the bloodstream after being inhaled, and can caused cellular necrosis in the brain, resulting in the expression of PEM. Additionally, dry matter intake can be reduced due to the discomfort created by high concentrations of H2S within rumen, and S can act as a trace mineral antagonist, which can create deficiencies. Many strategies have been investigated to combat the negative effects of S in beef cattle production. Nitrate has been primarily investigated as a CH4 mitigator in ruminants. When nitrate enters the rumen, it acts as a H2 sink, and reduces the substrate availability for methanogenesis. Bismuth subsalicylate has been observed to be an effective H2S mitigator when it has been provided to humans and rat. The results observed during the current study in in vitro ruminal fermentation indicate that bismuth subsalicylate and nitrate can be added in the diet of ruminants without affecting ruminal fermentation. During the in vivo portion of this study, nitrate showed a reduction of dry matter intake and average daily gain; however, feed efficiency was not affected. Final body weight was reduced by nitrate and as a result, hot carcass weight was also reduced. Digestibility of nutrient was only affected for dry matter and organic matter where bismuth tended to increased digestibility of these two variables. The data observed in this experiment also indicate that bismuth reduces the absorption of Cu; therefore, it is recommended to supplement cattle with Cu when bismuth is being administered. Some of the results observed in this study are in disagreement with previous data, therefore, more research should be performed to evaluate the effects of nitrate and bismuth subsalicylate within the rumen in order to elucidate some of the results observed in the feedlot.