W.P. Weiss, J.S. Hogan, and K.L. Smith
Department of Animal Sciences
Cows and heifers (Holstein and Jersey) were assigned to one of three treatments starting 60 days before anticipated calving. Treatment 1 approximated NRC recommendations for vitamin E (100 IU of supplemental vitamin E per day). Treatment 2 was based on our current recommendations (1000 IU/day during the dry period). Treatment 3 was 1000 IU/day during the first 7 weeks of the dry period and 4000 IU/day during the last 2 weeks of the dry period. All diets contained 0.1 ppm of supplemental selenium. The percentage of quarters infected at calving was not different between treatment 1 and 2 (32%) but was reduced by treatment 3 (11.8%). The prevalence of clinical mastitis was 25% of quarters for treatment 1, 17% of quarters for treatment 2 (33% reduction), and 3% of quarters for treatment 3 (88% reduction from treatment 1). Dietary supplementation of high levels of vitamin E during the last 2 weeks of the dry period had a substantial positive effect on mammary gland health.
A substantial amount of research has found that supplemental vitamin E reduces the prevalence of mastitis in dairy cows. Research conducted at OARDC has determined that vitamin E is especially critical during the peripartum period. The prevalence of mastitis is high during the first few weeks of lactation. This period is also the time when plasma vitamin E concentrations are very low. Feeding 1000 IU of supplemental vitamin E per day lessens the decrease in plasma vitamin E that occurs around calving but does not eliminate it. We have found that injecting vitamin E shortly before calving increases the concentration of vitamin E in plasma and improves the killing ability of neutrophils. The objective of this experiment was to learn whether feeding high amounts of vitamin E elevated plasma vitamin E concentrations in cows during the peripartum period and improved mammary gland health.
Sixty-six cows and heifers (51 Holsteins and 15 Jerseys) were assigned to one of three treatments 60 days before anticipated calving. Treatments were blocked by calving date, parity, and breed. All cows were fed a typical dry cow diet [55% grass silage, 25% grass hay, and 20% concentrate, dry matter (DM) basis]. The diet for treatment 1 was supplemented to provide 100 IU of supplemental vitamin E per day (all-rac alpha-tocopheryl acetate) during the dry period. Treatment 2 provided 1000 IU of supplemental vitamin E per day during the dry period. The diet for treatment 3 was formulated to provide 1000 IU of vitamin E per day during the first 46 days of the dry period and 5000 IU/day during the last 14 days of the dry period. Based on assay results from feed samples, actual intakes of supplemental vitamin E were 140 IU/day for treatment 1, 1000 IU/day for treatment 2, and 1000 IU/day during the early dry period and 4000 IU/day during the last 2 weeks of the dry period. All diets contained 0.1 ppm of supplemental selenium. Blood plasma was sampled at dry-off, 14 days before calving, at calving, and 7 and 30 days postpartum and analyzed for alpha-tocopheryl and selenium. Blood neutrophils were sampled at dry-off, calving, and 7 days postpartum and analyzed for alpha-tocopheryl. Quarter foremilk samples were cultured before dry-off, the day of drying off, 30 days into the dry period, the day of calving, and 3 and 7 days postpartum. The prevalence of clinical mastitis (abnormal milk) was monitored the first 7 days of lactation.
Concentrations of plasma selenium were low in all cows (0.05 µg/ml) and were not affected by treatment. Treatment 3 prevented the normal decline in plasma alpha-tocopheryl concentrations normally observed at calving (Figure 1). Treatment 2 elevated plasma alpha-tocopheryl concentrations above treatment 1, but plasma concentrations still decreased. Treatment 3 increased (P < 0.10) the concentration of alpha-tocopheryl in neutrophils (6.5 ng/106 cells) on the day of calving. The concentrations of alpha-tocopheryl in neutrophils were not different between treatments 1 and 2 (3.5 ng/106 cells).
Figure 1. Concentrations of
alpha-tocopheryl in plasma of cows fed 100 IU of vitamin E/day (open ball line); 1000 IU/day during the dry period and 500 IU/day
during lactation (closed ball line); or 1000 IU/day during the first 46 days of
the dry period, 4000 IU/day during the last 14 days of the dry period,
and 2000 IU/day during lactation (triangle line).
Figure 2. Prevalence of intramammary gland
infections in cows fed 100 IU of vitamin E/day (100); 1000 IU/day during
the dry period and 500 IU/day during lactation (1000); or 1000 IU/day
during the first 46 days of the dry period, 4000 IU/day during the last
14 days of the dry period, and 2000 IU/day during lactation (4000).
Figure 3. Prevalence of clinical mastitis in cows
fed 100 IU of vitamin E/day (100); 1000 IU/day during the dry period and
500 IU/day during lactation (1000); or 1000 IU/day during the first 46
days of the dry period, 4000 IU/day during the last 14 days of the dry
period, and 2000 IU/day during lactation (4000).
The percentage of quarters infected during the first 7 days of lactation was higher in first lactation animals than in multiparous cows (Figure 2). Cows (all parities) fed treatment 3 had about 50% less (P < 0.01) infections than cows in the other two treatment groups. Clinical mastitis during the first 7 days of lactation also was higher in first lactation cows than in multiparous cows (Figure 3). First lactation cows fed treatment 1 had more than twice as much clinical mastitis as did treatment 2 cows (P < 0.01). No clinical mastitis was observed in first lactation animals fed treatment 3. No difference in the prevalence of clinical mastitis in multiparous cows was observed between treatments 1 and 2, but treatment 3 reduced the prevalence about 70%. When all parities were combined, 25% of all quarters had clinical mastitis during the first 7 days of lactation in treatment 1, 16.7% of quarters for treatment 2, and 2.6% of quarters for treatment 3. Cows that had plasma concentrations of alpha-tocopheryl less than 3 g/ml were nine times more likely to have clinical mastitis than were cows with plasma concentrations greater than 3 µg/ml. Dietary supplementation of vitamin E above 1000 IU/day was necessary during the peripartum period to maintain adequate plasma concentrations of alpha-tocopheryl.