Vitamin prices go up and down; this is just the nature of doing business at an international level. Users of vitamins are either animal producers or premix companies. Both buy from vitamin manufacturers, mix vitamins into a premix, and use or resell. The fine details of design for such premixes differ according to the nature of the user. A feed producer will need different design principles compared to a premix manufacturer, but both users tend to adjust vitamin concentrations according to prices, and this is something that entails certain dangers.
I recall a tale about a premix manufacturer who used to “delete” vitamins when they would become too expensive, and another story about an animal farmer who would ask for the premix to have the same price no matter how vitamin concentrations would change to accommodate price fluctuations. Luckily, such objectionable, if not illegal, practices are just tales of old, but there is still the trend for knee-jerk reactions when vitamin prices spike. For example, it has been related to me that during the last World Pork Expo, pork producers who cut vitamin premix use felt their animals were not doing as great. Perhaps it's a coincidence, or just farmers being worried. Time will tell…
I have always argued that we need to keep evaluating vitamin levels — and additives and everything else, but it is one thing to use correct levels, adjust safety margins or even up certain vitamins for certain productivity reasons. I have always recommended this be done by a highly qualified nutritionist (not me, this is not solicitation for work!) who has considerable experience on vitamins (and trace minerals, as these always go together).
So, if you have recently changed your vitamin levels because prices went up, there is good news: prices are back to normal. So, remember that vitamin functions are unique and irreplaceable, go back to your original levels and then find a nutritionist to evaluate your premixes. This is a lengthy and time-consuming process, and it is best done when things (prices) are calm. And, now is the time!