Interpretive Summary: Impact of storage conditions and premix type on phytase stability.
By: Dr. Emily Taylor
Phytase is an enzyme used to release phosphorus from phytate in cereal grains. The use of phytase as a direct ingredient in animal diets, or in a vitamin or trace mineral premix is common practice. Unfortunately, bacteria and viruses such as PEDV and ASFV, have been shown to survive in some feed ingredients and additives under certain transport conditions.
Researchers have demonstrated that a medium-chain fatty acid blend can effectively mitigate PEDV in feed ingredients. Moreover, the use of a combination of temperature and exposure time has also been shown to eliminate pathogens. Therefore, a recent article published in Translational Animal Science investigated the effects of using a medium-chain fatty acid blend, as well as varying temperatures and exposure times on the stability of phytase.
For experiment one, vitamin and vitamin trace mineral premixes were blended with 1% inclusion of medium-chain fatty acids or mineral oil and stored for 0-, 30-, 60-, or 90-d. These samples were then exposed to varied environmental conditions – room temperature, temperature-controlled laboratory (22 ⁰C), or an environmentally controlled chamber set at 40 ⁰C and 75% humidity. There were no four- and three-way interactions among premix type (PT), oil type (OT), storage condition (SC), and storage time (ST) for phytase stability. There were two-way interactions for PT × SC and SC x ST. The OT did not affect phytase stability when premixes-containing phytase was added as either mineral oil or medium-chain fatty acids.
For experiment two, a sample from each treatment was heated in an environmentally controlled chamber at 60 ⁰C and 20% humidity for 11 h and 48 min. No differences were found in phytase stability between PT and OT, vitamin premix and vitamin trace mineral premix-containing phytase heated at 60 ⁰C, and between premixes-containing phytase mixed with 1% mineral oil or medium-chain fatty acids.
In conclusion, when phytase was added to both vitamin and vitamin trace mineral premixes, phytase stability was not impacted at 22 ⁰C. However, when exposed to 40 ⁰C and 60 ⁰C, phytase stability was dramatically decreased. Also, phytase stability during storage up to 90 d and heated was not effected by medium-chain fatty acids. Authors believe that if both medium-chain fatty acids and heat pulse treatment have similar efficiency at neutralizing or reducing the target pathogen, the process of chemical treatment could become a more practical practice.