et al., 2011) have documented that blood concentrations
of -tocopoherol can decrease dramatically in dairy cows
during the periparturient period. The lowest concentrations
are generally observed between 1 week pre-partum
and 2 weeks post-partum. This decline is partly a result of
directing -tocopherol to colostrum production. Colostral
-tocopherol is found to be about three times higher than
milk -tocopherol in ewes (Njeru et al., 1994). The decline
can also be attributed to metabolic stressors associated
with parturition, such as negative energy, protein and calcium
balance (Goff and Stabel, 1990).
The difference in serum concentration of -tocopherol
after lambing between ewes with or without stillborn
lambs, found in ewes having ≥3 lambs, only, suggests that
low level of vitamin E in blood is detrimental for ewes having
large litters. Naziroglu et al. (1998) examined the level
of -tocopherol in plasma of ewes that aborted their lambs,
and found a significant lower level in ewes that aborted
(1.11 mg/L) than in control ewes (1.54 mg/L).
4.3