Serum samples from 15 suckling foals, 119 days of age, of Quarter Horse and Thoroughbred breeding, that were weaned at either 140 days of age (EW) or 182 days of age (LW) were used to measure changes in vitamin K status over time and to assess the effect of age at weaning on vitamin K status. Jugular venous blood samples were collected from each foal at the start of the experiment and 21-day intervals thereafter, with the exception of a one-week interval post-weaning in both groups. The study continued for 84 days post-weaning in both groups. Serum was analyzed for total osteocalcin and hydroxyapatite binding capacity of serum osteocalcin (HABOC) which was calculated as follows: HABOC = [(total serum osteocalcin - serum osteocalcin following extraction of serum with hydroxyapatite)/total serum osteocalcin]×100. Osteocalcin's capacity to bind hydroxyapatite is vitamin K-dependant and, therefore, is used as a marker of vitamin K status. Hydroxyapatite binding capacity of serum osteocalcin increased (quadratic; P<0.01) over the experimental period regardless of weaning age, indicating an increase in vitamin K status in both weaning groups. In addition, there was a tendency for an age at weaning by time interaction (P = 0.056) on serum HABOC. This tendency was due to significantly higher HABOC at 182 days of age for EW as compared to LW (P<0.05). After 182 days of age, HABOC was not different between EW and LW. Serum osteocalcin decreased (linear; P<0,01) in both weaning groups over the experimental period. In conclusion, vitamin K status increased and serum osteocalcin decreased with age. In addition, vitamin K status tended to increase at a greater rate in foals weaned early as compared to those weaned late.
|Number of pages||4|
|Journal||Journal of Equine Veterinary Science|
|State||Published - Nov 2000|
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