Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2009
Publication Date: 11/19/2009
Citation: Nonnecke, B.J., Reinhardt, T.A., Waters, W.R. 2009. Short Communication: The Preruminant Calf as a Model for Characterizing the Effects of Vitamin D Status in the Neonate. Journal of Dairy Science. 92(11):5692-5696. Interpretive Summary: Effects of vitamin D status on the growth and health of the preruminant, milk-fed dairy calf are not well described. Justification for the current NRC recommendation of 600 IU of vitamin D/kg DM of milk replacer or the substantially higher concentrations typically found in commercial milk replacers is limited. To enhance our understanding of the impact of vitamin D on the neonatal calf, a method to manipulate predictably vitamin D status from birth to weaning needs to be developed. The objective of this study was to determine if vitamin D status could be controlled experimentally so as to establish two groups of calves; one representing low vitamin D status and the second representing high vitamin D status. All dairy calves were fed a milk replacer without vitamin D during the experimental period. Vitamin D status was regulated in a predictable fashion by subcutaneous administrations of 25-hydroxyvitamin D3, the circulating form of vitamin D. Results demonstrated that it is possible to manipulate predictably the vitamin D status of the preruminant calf. This approach could be used to characterize more extensively the effects of vitamin D on the growth and health of the neonate.
Technical Abstract: The objective of this study was to evaluate the feasibility of using the preruminant dairy calf as a model for evaluating effects of vitamin D status in the neonate. Because the newborn calf can be sustained during the first weeks of life solely on a fluid diet having a defined composition, has documented nutritional requirements, and is minimally impacted by repeated samplings of peripheral blood it has the potential to serve as a model for characterizing nutrient specific effects on the growth and health of the neonate. Colostrum-fed Holstein bull calves (n = 13) entered the trial at approximately 4 days of age. All calves were fed a custom-formulated milk replacer devoid of vitamin D. Plasma 25-hydroxyvitamin D3 concentrations in all calves were determined on a regular basis beginning at d 0. Using this information, low and high status groups of calves were established by subcutaneous administration of 25-hydroxyvitamin D3. To maintain targeted plasma 25-hydroxyvitamin D3 concentrations in low (< 30 ng/mL) and high (> 60 ng/mL) vitamin D status calves, low status calves received a total of 8,600 IU (2,225 IU/wk) of vitamin D during the experimental period and high status calves received 54,000 IU (13,500 IU/wk). 25-hydroxyvitamin D3 concentrations in low status calves averaged 27 ng/mL compared to 78 ng/mL in high status calves and were lower at all sampling times from d 7 to d 28. 1,25-Dihydroxyvitamin D3 and 25-hydroxyvitamin D3 concentrations were not correlated. Calcium, magnesium, and phosphorous concentrations were unaffected by 25-hydroxyvitamin D3 administration; however, plasma calcium and 1,25(OH)2D3 concentrations were correlated. Calcium and Mg concentrations decreased with age but remained within normal ranges for dairy cattle. These results indicate that it is possible to control predictably vitamin D status over a 28 d period and suggest that the preruminant calf may be useful as a model for studying effects of vitamin D on growth, development, and immune function in the neonate.