Antioxidant supplementation strategies for periparturient dairy cows

By Caio Figueiredo, Veterinary Medicine Extension

In another article from this newsletter, we highlighted the differences in antioxidant status associated with the occurrence of diseases, milk production, and reproductive performance of dairy cows. Considering the detrimental impacts associated with oxidative stress described previously, the aim of this article is to discuss some of the benefits of supplementing vitamin E and selenium (antioxidants) on dairy cow health and performance.

Vitamin E and selenium are supplemented in the diets of dairy cattle to combat reactive oxygen species and their detrimental effects (Figure 1). The main mode of action of Vitamin E is to prevent the spread of free radicals in membranes and in plasma lipoproteins, while the functions associated with selenium are attributed to its role as a co-factor for selenoproteins, countering oxidative stress and modulating immunity of dairy cows. Studies related to vitamin E supplementation in the transition period have highlighted its many benefits, including the reduction of disease occurrence and improved reproductive performance. For instance, a meta-analysis published in 2007 reported that vitamin E supplemented in the dry-period reduced the occurrence of retained fetal membranes (RFM; Bourne et al., 2007). In that study, both the natural (α-tocopherol; odds ratio = 0.49) and synthetic form (odds ratio = 0.53) of vitamin E yielded reduced odds of RFM in lactating dairy cows. A more recent meta-analysis depicted the benefits of vitamin E to reduce the occurrence of RFM in lactating cows, in addition to several benefits on reproductive performance, such as reduced calving to estrus interval, days open, and number of services per conception (Table 1; Moghimi-Kandelousi et al., 2020). The same study also reported that the supplementation of vitamin E and selenium together have been associated with greater benefits on reproductive performance and reduction of RFM occurrence compared with vitamin E alone. Regarding the relationship between Vitamin E/selenium and udder health and milk production/composition, the outcomes are variable within the literature. For example, although no differences were observed by Moghimi-Kandelousi et al. (2020), other studies have reported small differences in milk production and somatic cell counts (Abuelo et al., 2014). Altogether, the supplementation of vitamin E and selenium in the diet of transition dairy cows has been positively associated with cow health and reproductive performance; however, it is important to keep supplementation within recommended doses, as over supplementation was previously associated with excessive reactive oxygen species production.

Figure 1. Schematic illustration of the interplay between antioxidant supplementation, metabolic stress, dysfunctional inflammation and presented health disorders. NEFA = Non‐esterified fatty acids; BHB = β‐hydroxybutyrate; ROS = Reactive oxygen species; NFκB = nuclear factor kappa B; TNFα = tumor necrosis factor alpha; IL‐6 = Interleukin 6. (Image taken from Abuelo et al., 2014).