Abstract
Serum vitamin B_<12> (B_<12>) contents in growing-fattening pigs and brood sows were measured by microbiological assay. B_<12> contents in each stage of the growing-fattening pigs were 230 pg/ml (1 week old), 260pg/ml (3 weeks), 284pg/ml (1 month), 364pg/ml(2 months), 383pg/ml(3 months), 343pg/ml(4 months), 295pg/ml (5 months), 268pg/ml (6 months), respectively. The B_<12> content significantly increased (P<0.05) with age and reached a peak at 3 months of age. Thereafter, it decreased significantly (P<0.05). B_<12> contents in nonpregnant pigs (virgin) were 240pg/ml. In pregnant pigs, B_<12> contents were 244pg/ml in an early stage (up to 30th day of gestation), 227pg/ml in a middle stage (from 30th to 80th days) and 210pg/ml in a late stage (from the 80th day of gestation to the day before parturition). After parturition, the b_<12> contents were 233pg/ml in the lactating pigs. Furthermore, we investigated the relationships between B_<12> content and litter size or parity. The B_<12> content was significantly low (P<0.01) in the mothers of higher litter size in contrast to those of lower litter size. B_<12> content was not affected by parity.
