Ah summer!  Sunny days, cool drinks, relaxing on the beach… but don’t forget about your premixes. The heat and humidity of summer can speed up deterioration of labile ingredients such as vitamins, enzymes, direct fed microbials, and fat sources.  In fact, in the lab we consider 25C/77F with 60% relative humidity to be “long term” storage conditions—the type of climate your products may encounter in the warehouse or growout facility at any time of the year.  “Accelerated” conditions vary, but our standard protocol is 40C/104F and 75% RH—which sounds brutal until you consider normal warehouse or facility conditions in the summer in the SE US and for a few weeks in the Midwest.  Accelerated conditions shorten the incubation time needed to test formulations in the lab, and accelerated vs. long-term can increase the disappearance of modern beadlet A1000 by 2-8X in a choline-containing VTM within 3 months.  Here are some tips to consider when formulating premixes for the summer months.

1. It ain’t the heat, it’s the humidity!  If at all practical, reduce or remove choline from VTM’s in the summer months, and store it and add it separately.  Choline draws in active moisture, and under hot conditions can speed up decay reactions for vitamins, enzymes, and microbial products.  See figures 1 (winter months) and 2 (summer months) for a comparison of average vitamin A recoveries for poultry feeds submitted to the dsm-firmenich TMAS lab.  Note that the summer assays average about 10% lower than assays from the winter months, although it is encouraging that most of the submitted feeds exceeded 80% of vitamin A claim during the summer, and variability (as measured by coefficient of variation) was only slightly higher compared to the fall/winter samples.
2. Shorten your chain of custody.  Decrease storage/shipping/inventory time as much as possible.  That deal you got on dispersible A500 in May might not be as attractive by September if the product has to sit in a hot/humid warehouse.  Same thing with manufactured feeds.
3. Choose your sources wisely.  That includes trace minerals (see Digest article on trace minerals from Feb 2023), enzyme formulations, and your most reliable, stable vitamin sources.  Figure 3 below shows the range of reactivities for all the vitamins.  Note that Vitamin E and calcium pantothenate are on the stable end of the spectrum whereas vitamins A, K and thiamine are on the most labile end.
4. Consider feed intake.  Do your birds/pigs/cows consume less feed when it’s hot and humid?  Do their respiration rates go up?  It might be logical to adjust micronutrient concentrations upward based on expected lower feed intake or higher antioxidant need.
5. Quality assurance.  For quality assurance in the summer or any time during the year, you may want to analyze premix and/or the resulting feed in the field.  Consult with your dsm-firmenich representative for a good protocol, and samples can be submitted for lab analysis to make sure your straight product or premix is still “good”.  Feeds can also be sampled to assess accumulated storage, processing, and mixing losses and accuracy of mixing.  All vitamins are “fair game” for assessing premix stability, with the most labile expected to be vitamin A, Vitamin C, B1.  Vitamin E and Calpan are usually the most stable, with the lowest expected losses.  B vitamins can be analyzed from the premix, but may not be useful indicators of feed stability if the normal ingredient contribution (ex. pantothenic acid, niacin, thiamine) greatly outweigh the supplemental amount added by the premix.
6. Still have concerns?  Consult our Product Services team for special formulations, including carrier and source substitutions, possible antioxidant stability enhancers, and other hot weather recommendations.