Resumen
This study was conducted to investigate the stability of five commercial vitamin A products in vitamin premixes and vitamin-trace mineral premixes. The five commercial products used were: Xinhecheng, Zhejiang medicine, Kingdomway, DSM, and BASF. The vitamin A products were stored in three vitamin premixes (for suckling, weanling, and finishing pigs) or in vitamin-trace mineral (VTM) premixes (for suckling, weanling, and finishing pigs). Vitamin premixes were stored in an environmentally controlled chamber set at 25 °C and 60% humidity. The VTM premixes were stored at room temperature (approximately 22 °C). Sampling was performed on d 0, 90, 180, 270, and 360. Stability was reported as the residual vitamin A activity (% of initial) at each sampling point. For the stability of vitamin premixes, all interactive and main effects of storage time and vitamin A product were not significant. For the stability of VTM premixes, there was no significant interaction effects between storage time, vitamin A product and main effect of vitamin A product, but the main effect of storage time was significant (p < 0.01). In conclusion, a longer storage time reduced vitamin A activity in VTM premixes but there was no difference in the stability of commercially available vitamin A.