Effects of a supplemental calcareous marine algae bolus
on blood calcium concentration in dairy heifers

Oral calcium (Ca) supplementation is common in dairy farms. The source and physical form of Ca greatly influence gastrointestinal absorption and consequently blood Ca responses. The aim of this study was to compare the effects of calcareous marine algae (CMA), calcium carbonate (CC) and calcium propionate (CP) on blood total Ca (tCa) and biologically active ionized form (Ca²⁺) concentrations in dairy heifers. Holstein Friesian heifers (n = 6), 14.8 ± 0.75-month-old, were used in a 3 × 3 repeated Latin square design of treatments. For each treatment, a daily oral bolus was administered for 7 days by balling gun, and serial blood samples were obtained on days 1 and 7. Serum tCa at day 1 was higher for CMA (2.41 mmol/l) in comparison to CC (2.38 mmol/l) and tended to be higher in comparison to CP (2.39 mmol/l). In addition, the area under the curve in the first 60 min (AUC_ab0-60) was increased by CMA as compared to both CP and CC, without any difference between the other two sources. Oral Ca bolus supplementation did not improve plasma Ca²⁺ concentration. Effects on mean blood tCa concentration and AUC_ab0-60 highlight the potential use of CMA as an oral Ca supplementation to promote a faster peak of blood tCa concentration than CC and CP.

ACKNOWLEDGEMENTS

The authors would like to thank Celtic Sea Minerals for the financial support of this project. Appreciation is also extended to Dr Giorgio Lonardi for his assistance during the trial.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interest.

METADATA IN OTHER LANGUAGES:

Chinese

补充海藻钙丸对奶用青年母牛血钙浓度的影响

血钙，海藻钙，钙丸，奶用青年母牛，低钙血症

奶牛场中给奶牛口服钙补充剂很常见。钙的来源和物理形态极大地影响胃肠道对钙的吸收，从而影响血钙响应。本研究旨在比较海藻钙 (calcareous marine algae, CMA)、碳酸钙 (calcium carbonate, CC) 和丙酸钙 (calcium propionate, CP) 对奶用青年母牛血液总钙 (total Ca, tCa) 和生物活性离子钙 (biologically active ionized form, Ca2+) 浓度的影响。采用14.8 ± 0.75月龄的荷斯坦青年母牛 (n=6) 进行3×3重复拉丁方试验设计。每一次处理中，每天使用口服投药器口服投药一次，持续7天，同时分别在第1天和第7天采集血样测定血钙。CMA组第 1天血清总钙含量 (2.41 mmol/l) 高于CC组 (2.38 mmol/l)，与CP组 (2.39 mmol/l) 相比也趋于升高。此外，与CP组和 CC组相比，CMA组增加了前60分钟曲线下的面积 (AUC_ab0-60)，而CP组和CC组之间没有任何差异。口服补充钙剂并没有改善血浆离子钙浓度。口服海藻钙制剂对平均血液总钙浓度和AUC_ab0-60的影响凸显了其比碳酸钙和丙酸钙口服制剂具有更快促进血液总钙浓度峰值的潜在利用价值。

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