Roughage level and supplemental fat for newly received finishing calves: effects on growth performance, health, and physiological responses

A high fat to vitamin E ratio in the feed protects and improves uptake of the natural form of vitamin E in postweaning calves

In postweaning calves, it is a challenge to maintain the plasma vitamin E level at or above the recommended level (3 µg/mL), which is linked to a good immune response. It has been unclear until now why the provision of solid feed with concentrations below 200 mg/kg feed of vitamin E is ineffective in maintaining the plasma vitamin E level of calves above the recommended plasma level postweaning. The present study was conducted to investigate if a high fat to vitamin E ratio in the concentrate could protect and improve the delivery of the natural form of vitamin E (RRR-α-tocopherol) to calves postweaning. Thirty calves were included in the experiment from 2 weeks preweaning until 2 weeks postweaning (Weeks -2, -1, 0 [weaning], 1, and 2 relative to weaning) and fed one of three concentrates in which lecithin mixture provided the fat supplement: control (77 mg/kg of vitamin E and 4.9% DM of crude fat; CONT), medium level of vitamin E supplemented (147 mg/kg of vitamin E and 7.7% DM of crude fat; MedVE) or high level of vitamin E supplemented (238 mg/kg of vitamin E and 12.4% DM of fat; HiVE). Thus, there was a comparable ratio of fat to vitamin E (520-630) in the three concentrates. During the 2 weeks postweaning, final body weight (92 ± 2 kg), average daily gain (917 ± 51 g/day) and concentrate intake (2.2 ± 0.09 kg/day; mean of treatment ± standard error) were unaffected by treatment and the interaction between treatment and week. There was an interaction between treatment and week for vitamin E intake pre- (p < 0.001) and postweaning (p < 0.001). There was an interaction between treatment and week (p < 0.001) for plasma vitamin E level postweaning, and it was 2.5, 3.1, and 3.8 µg/mL in CONT, MedVE, and HiVE, respectively, at Week 1 postweaning. In addition, plasma vitamin E levels at Week 2 postweaning were 2.6, 3.6 and 4.8 µg/mL in CONT, MidVE and HiVE respectively. The results show that 147 mg/kg of lecithin-protected vitamin E in the concentrate is needed to secure a plasma vitamin E level well above the recommended level. In addition, lecithin-protected vitamin E elevated the plasma level of triglycerides and nonesterified fatty acids.