Chromium for dairy cattle: An essential nutrient

Abstract Text:

Although chromium (Cr) research dates back to the late 19th century, it wasn’t until approximately 50 years ago it was demonstrated that Cr was an essential mineral for rats and humans. Since then, there has been a plethora of research which has helped to explain the relevance of Cr in human and production-livestock nutrition. Chromium can exist in all oxidation states; however, the most common available forms are trivalent (Cr⁺³) and hexavalent (Cr⁺⁶). Trivalent Cr is most identified with digestibility markers and commercially available forms of Cr for livestock, while Cr⁺⁶ is associated with carcinogenic properties of Cr. Since bioavailability of inorganic forms of Cr are generally low (0.4 – 2.0%), organic forms of Cr⁺³ are now available which improve absorption and availability of Cr to the animal. Numerous studies have shown that Cr has a strong association to both glucose and lipid metabolism through insulin potentiation. As a result, production measures affected by insulin such as growth, milk production, and immunity are areas which benefit from Cr supplementation. Because of the relationship to insulin and insulin sensitivity, metabolic disorders related to the transition and early lactation periods have previously been identified as areas of opportunity for Cr supplementation. Additional research has recently demonstrated that Cr may also have significant benefits on reproductive indices. Bryan et al. (2004) observed a tendency for improved pregnancy rate in intensively grazed cows supplemented with Cr compared with cows not provided Cr. Additionally, in research done by Kafilzadeh et al. (2012), Holstein cows supplemented with Cr had fewer days to first service and days to first estrus compared with non-supplemented cows. It was speculated by both authors that increased insulin sensitivity may have affected granulose cell proliferation or perhaps increased ovulation rates as observed in swine fed Cr. Part of the improved response by Kafilzadeh et al. (2012) may have been related to improved immunity. Cows fed Cr had increased neutrophil and neutrophil to lymphocyte ratio during the prepartum period. Yasui et al. (2014) observed a similar immune response. Cows fed Cr tended to have a greater percentage of neutrophils as well as a decreased incidence of cytological endometritis compared with cows not fed Cr. Because of the relationship to insulin and related metabolic pathways, Cr supplementation has the potential to positively impact numerous production measures in dairy cattle. However, additional research needs to be completed to elucidate the exact mode of action.

Keywords: Chromium, dairy cattle, reproduction