Abstract
Meat and meat products are one of the largest contributors to vitamin D dietary intakes. Little is known, however, about how different animal husbandry practices and/or finishing diets might affect the vitamin D content of the animal. Therefore, this study aimed to investigate the effect of bovine finishing diet (grass vs. concentrate) on the 25(OH)D plasma concentrations of cattle and subsequent vitamin D content in beef. Cattle were fed grass (n = 7) or concentrate (n = 9) finishing diets for 15 weeks prior to slaughter. Bovine blood samples were collected at slaughter and plasma aliquots were stored (−80 °C) until analysis. Beef top rump from each animal was chilled for an ageing period of 21 days, then homogenised and frozen (−80 °C) until analysis. Bovine plasma samples were analysed for circulating 25(OH)D3, and 25(OH)D2 (nmol/L), and raw beef muscle (top rump) samples were analysed for vitamin D metabolites; vitamin D3, vitamin D2, 25(OH)D3 and 25(OH)D2 (µg/kg), all by LC-MS/MS. Total vitamin D activity was defined: [vitamin D3 + (25(OH)D3 × 5) + vitamin D2 + (25(OH)D2 × 5)]. Statistical analysis was conducted by SPSS with independent t tests used to compare groups; significance level p < 0.05. Data were presented as mean ± SD. A significantly higher plasma 25(OH)D2 concentration was observed in the grass finished cattle compared to the concentrate group (43.18 ± 11.75 vs. 16.56 ± 1.58 nmol/L, p < 0.002). No difference in plasma 25(OH)D3 concentrations was observed between groups. In beef top rump, the grass finishing diet resulted in a significantly higher mean ± SD vitamin D2 [0.07 ± 0.05 vs. 0.01 ± 0.01 µg/kg] and 25(OH)D2 [0.70 ± 0.16 vs. 0.25 ± 0.07 µg/kg] compared to concentrate finishing diet (both p < 0.001). Moreover, beef from grass finished cattle demonstrated a significantly higher total vitamin D activity compared to those in the concentrate group [9.52 ± 2.43 vs. 6.78 ± 2.00 µg/kg, p < 0.05]. No difference was observed for muscle vitamin D3 or 25(OH)D3 between groups. In conclusion, a more favourable bovine vitamin D profile, driven by vitamin D2 metabolites specifically (not vitamin D3), is reported from a grass-based finished system, compared to concentrate finishing. Further research is required to understand the impact of these findings for both agriculture practices and human nutrition.
Author Contributions
Conceptualization, K.P. and R.P.; methodology, E.R. and C.M.; formal analysis, E.R.; resources, C.M. and M.M.; data curation, E.R.; writing—original draft preparation, E.R.; writing—review and editing, E.R., C.M., R.P., S.S., M.M. and K.P.; supervision, K.P.; project administration, M.M.; funding acquisition, R.P., S.S. and M.M. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by TSB Innovate UK (ref: 132747).
Institutional Review Board Statement
All experimental procedures described were approved by the West of Scotland Research Committee with Ethics reference: 18/WS/0149.
Informed Consent Statement
Not applicable.
Data Availability Statement
The data presented in this study are available on request from the corresponding author (accurately indicate status).
Conflicts of Interest
The authors declare no conflict of interest.
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