Materials and Methods
The first experiment used 15 sows and measured liver GLO activity and ascorbic acid concentrations in fetal pigs at 60, 80, 100, 107, and 111-day postcoitum. Three sows were killed at each designated treatment day. The livers of three randomly selected fetal pigs were obtained from the litters of each sow. The collected livers were frozen and stored for later determination of GLO activity and their ascorbic acid concentration.
The second experiment was designed as a 2 X 2 factorial arrangement of treatments in a split plot design. The first factor evaluated the pigs from sows induced to farrow early (113 day) by injecting 200 mg of Lutalyse ® while the other set of sows were allowed to farrow normally (115 d). The second factor evaluated pig birth order (either 1st and 2nd or 7th and 8th pigs) from all sows. A total of 24 pigs from 6 sows were therefore used in this experiment with neonatal pigs killed prior to co lostrum consumption. Liver samples were subsequently collected, frozen, and stored for later GLO activity and ascorbic acid analysis as in the previous experiment.
The third experiment evaluated liver GLO activity and the ascorbic acid concentrations of young pigs at 0, 3, 7, 14, 21, 28, 35, and 42 day of age. Pigs were allowed to nurse their dams 14-day period and then weaned and fed typical starter diets devoid of supplemental ascorbic acid Three pigs were killed at each designated treatment day with livers collected for the determination of GLO activity and ascorbic acid concentration.
The fourth experiment determined the effect of three different weaning ages on liver GLO enzyme activity and ascorbic acid concentration. Weaning ages of 10, 17, and 24 days were evaluated. A total of 45 crossbred pigs were used in the experiment with the study being conducted in a randomized complete block design.
The measurement of the liver GLO enzyme was based on the colorimetric procedure of Dabrowski (1990). Ascorbic acid concentration was determined by the dinitrophenyl-hydrazine (DNPH) method outlined by Dabrowski and Hinterleitner (1989).