Effect of hoof bath formulations on manure digester methanogenic bacteria

Objectives

Foot bath formulations that are used for the prevention of hoof diseases are typically discarded in the manure pit after use. It has previously been demonstrated that copper sulphate has a negative effect on digester performance. Therefore, it is important to evaluate the effect of foot bath formulations on a manure digester. Manure digesters use methanogenic bacteria for the production of biogas. The goal of this study was to investigate the effect of two-foot bath products (Intra Hoof-fit Bath and Intra Eco-Bath) on the growth rate of methanogenic bacteria.

Materials and methods

Experiments were performed by Opure BV (Ede, The Netherlands). Test concentrations were calculated based on worst-case practical conditions (i.e., a small digestor and long retention time). A weekly 200-liter hoof bath with 5% product solution would then results in a product concentration inside a digestor of 60 mg/l. Therefore, product concentrations of 10, 20, 50, 100 and 250 mg/l were evaluated.

Methanogenic bacteria were grown in anaerobic reactors with acetic acid as the main substrate at 35°C. Bacteria were incubated for 5 days at low substrate levels in the presence or absence of product concentrations. The amount of produced methane was measured to calculate the Chemical Oxygen Demand (COD) and reactor feed COD was adjusted daily to compensate. [...]