A study was conducted with laying hens to evaluate the effects of cholecalciferol (CC), 25-hydroxycholecalciferol (25-OH-CC) and 1α-hydroxycholecalciferol (1α-OH-CC) on calcium absorption, intestinal and uterine calcium-binding protein (CaBP), and egg shell quality. Calcium absorption was significantly higher in 1α-OH-CC-fed hens during periods of egg shell formation when compared with CC- or 25-OH-CC-fed hens. During periods of uterine inactivity there were no significant differences in calcium absorption between the groups. Intestinal CaBP was significantly higher in 1α-OH-CC fed hens as well. Uterine CaBP was not affected by vitamin D source.
Feed consumption was lower in the 1α-OH-CC than in the CC- or 25-OH-CC-fed hens. The 1α-OH-CC-fed hens had significantly lowered egg weights and daily egg mass. Shell weight and shell density were not affected by vitamin D source. 25-OH-CC did not affect any of the parameters measured.
The results show that neither 25-OH-CC nor 1α-OH-CC affects uterine calcium transport when used at physiological levels, although the latter stimulates calcium absorption considerably.
A study was conducted with laying hens to evaluate the effects of cholecalciferol (CC), 25-hydroxycholecalciferol (25-OH-CC) and 1α-hydroxycholecalciferol (1α-OH-CC) on calcium absorption, intestinal and uterine calcium-binding protein (CaBP), and egg shell quality. Calcium absorption was significantly higher in 1α-OH-CC-fed hens during periods of egg shell formation when compared with CC- or 25-OH-CC-fed hens. During periods of uterine inactivity there were no significant differences in calcium absorption between the groups. Intestinal CaBP was significantly higher in 1α-OH-CC fed hens as well. Uterine CaBP was not affected by vitamin D source.
Feed consumption was lower in the 1α-OH-CC than in the CC- or 25-OH-CC-fed hens. The 1α-OH-CC-fed hens had significantly lowered egg weights and daily egg mass. Shell weight and shell density were not affected by vitamin D source. 25-OH-CC did not affect any of the parameters measured.
The results show that neither 25-OH-CC nor 1α-OH-CC affects uterine calcium transport when used at physiological levels, although the latter stimulates calcium absorption considerably.