Aerobic spoilage of total mixed rations (TMR) during the summer months is a problem that is commonly observed in the Danish dairy industry. However, problems with aerobic spoilage vary considerably among herds. In some herds, aerobic spoilage might be apparent on only a few days in a year and other herds have pronounced spoilage for months, if the TMR is not treated with appropriate additives. Any heating of TMR in the bunk is to be considered as an important feeding problem and it is strongly recommended to check leftovers for heating on a regular basis during summer.
If a ration has been extensively mixed e.g. Compact TMR (Kristensen 2017), the feed can be warm already when unloaded, however, this should not be confused with aerobic spoilage because it is caused by friction in the mixer and not microbial spoilage.
Sodium benzoate is not approved for use in TMR, it is only approved for treatment of silage. Many farmers have wondered why the substance is not allowed for use in TMR when it legally can be used in food and is extensively used by the food industry. The aim of the present study was to test the efficacy of Sodium benzoate when compared to other additives used for the prevention of aerobic spoilage in TMR. It was also the aim of the study to compare “dry acid products” Salvana TMR and FreshFOSS with propionic acid.