ISSUE FOCUS FEED & ADDITIVE MAGAZINE May 2023 21 Moulds reduce the nutritive value of feeds, reduce the palatability of feeds, and the spores may cause an immune response. Some moulds, such as Aspergillus, Fusarium and Penicillium, produce secondary fungal metabolites called mycotoxins. These mycotoxins may accumulate in the liver and long exposure to low levels will negatively impact animal production. THE PROLIFERATION OF MICROORGANISMS Bacterial pathogens and moulds are widespread and cannot be entirely eliminated. They have adverse effects on animal health and performance resulting in financial losses, and can be transmitted to humans. It is important that these organisms are controlled from pre-harvest right up until the animals consume the feed. The rate at which moulds and bacteria grow during feed processing and storage depends on factors such as pH, temperature, oxygen availability, and most importantly, water activity of the feed. Moisture content of feed merely describes how much water is in the product. Water activity describes how much of that water is free and therefore available to microorganisms for growth. Hot temperatures cause water to migrate during storage, while humid conditions will result in condensation, both resulting in higher activities of free water. The growth of microorganisms will be hindered when the water activity of a feed reaches below 0.9 for most bacterial pathogens and below 0.6 for most moulds. By managing the water activity of feed during processing and storage, we can reduce the proliferation of microorganisms and ensure feed safety. Heat-treatment steps can kill bacterial pathogens such as Salmonella, but moulds are stable and won’t be destroyed. This has necessitated the need for alternative solutions. SMARTMOISTURE: MANAGING MOISTURE IN FEED PRODUCTION Shrinkage and milling loss results in huge financial losses for feed mills. Animal feed can lose up to 3% moisture during processing, so moisture management is vital. Untreated free water cannot simply be added to animal feed during processing as it will not be optimally absorbed by feed particles and will be easily driven off creating problems such as feed build-up. Free water will also increase water activity levels making the environment more favourable for microbial growth. The use of organic acids as preservatives is well researched. As these products suppress mould and bacterial pathogen growth, they maintain the nutritional value of feed as well as improve nutrient digestibility. Organic acids make a fundamental contribution to feed hygiene and safety, animal health and performance. Devenish has developed two moisture managing products, SmartMoisture and SmartMoisture S. OUR PATENTED SOLUTION SmartMoisture and SmartMoisture S consist of a combination of propionic acid esterified to glycerol, buffered organic acids, and surfactants. It is 30% more concentrated than any other product on the market due to the stability of the glycerol esters. The propionic acid esterified to glycerol is a novel process used to buffer and stabilise propionic acid (Figure 1). It increases retention time of propionic acid in feed ensuring longer lasting microbial inhibition. Glycerol acts as a humectant and emulsifier and can hold up Figure 1. Stability of propionic acid from SmartMoisture
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