Vitamin E is important in the body for its anti-oxidant activity and a deficiency can lead to oxidative stress and immune suppression in peripartum cows. The fatsoluble vitamin (which consists of a group of eight related compounds) is usually supplemented to dry cow diets to meet requirements and supplementation has been shown to improve reproductive performance in dairy cows (Moghimi-Kandelousi et al., 2020). Differences in dry matter intake between cows in a herd may, however, lead to variation in the vitamin status of animals around parturition.
The aim of our study was to assess the association between dietary intake and plasma concentrations of vitamin E in transition dairy cows. For this research, Royal GD and Schothorst Feed Research B.V. worked together to investigate how feed intake differences around parturition can influence the vitamin status of cows in the transition period.
Materials & Methods
The study was performed at the dairy farm of Schothorst Feed Research B.V. (Lelystad, the Netherlands). Sixty cows of all parities were enrolled in the study at approximately four weeks before the expected calving date. Animals were housed in a loose housing system equipped with individual feeding places and individual daily feed intake was registered from four weeks before the expected calving date until four weeks after calving. Animals had ad libitum access to a basal diet (~5% residuals) and water. The dry cow diet consisted of grass silage, corn silage, straw, a protein supplement, and 1 kilogram of concentrates per cow per day. The basal diet for lactating cows consisted of grass silage, corn silage, pressed beet pulp, and a protein supplement. Concentrates were fed to lactating cows according to a fixed scheme based on parity and days in milk.
Roughages were sampled once a week and pooled per batch for analysis. Concentrates were sampled at delivery. Vitamin E concentrations in feedstuffs were analysed using high-performance liquid chromatography. Total vitamin E concentrations were 108 IU/kg DM in the dry cow diet and 87 IU/kg DM in the lactation diet. Plasma samples were collected at approximately one week before the expected calving date and around four weeks after parturition. Vitamin E concentrations in plasma were analysed using highperformance liquid chromatography. Feed intake data were available for 57 out of 60 cows. Prepartum and postpartum plasma vitamin E concentrations were available for 56 and 54 cows, respectively. Descriptive statistics were performed and the association between the average dietary intake of vitamin E in the three weeks preceding the week of sampling and the vitamin E concentration in plasma of cows was assessed by linear regression using separate models for prepartum and postpartum data.
Descriptive data of intake and plasma parameters are shown in Table 1. There was considerable variation in the dry matter intake of transition dairy cows, even under conditions with unlimited dietary access via individual feeding places, as was the case in our study. As a consequence of these feed intake differences, there was also quite some variation in the dietary vitamin E intake of the animals (Figure 1). Plasma vitamin E concentrations were larger at four weeks after parturition than at one week before calving (P<0.001). Dietary intake of vitamin E was significantly associated with plasma vitamin E concentrations (P<0.01) in both prepartum and postpartum cows (Figure 2).><0.01) in both prepartum and postpartum cows (Figure 2).