Beta-carotene: an Essential Nutrient for Horses?

Beta-carotene (ß-carotene) is one of many carotenoids found in nature. In the human nutrition field, evidence suggests that higher blood levels of ß-carotene as well as other carotenoids such as alpha-carotene, lycopene, lutein, zeaxanthin, and ß-cryptoxanthin may be associated with lower risk of several chronic diseases. ß-carotene, a-carotene, and ß-cryptoxanthin have pro-vitamin A activity, while the other carotenoids have no pro-vitamin A activity (DRI, 2000). Earlier publications on nutrient requirements of horses (NRC, 1961) suggested that horses had both a carotene and vitamin A requirement; however the latest edition (NRC, 1989) has published only a vitamin A requirement and not a carotene requirement for all horse classes. Thus, nutritionists typically do not consider the intake of carotenoids when formulating rations for horses. Do all horse classes only need pre-formed vitamin A and not ß-carotene, or is there also a need to supplement some classes of horses with ß-carotene as well as vitamin A?