Review/Oorsig Volume 22, Issue 02 - Page 27

Volume 22 • Issue 02 • 2018 incidence of post-calving mastitis cases and even vaginal and uterine prolapses can all be linked to low blood calcium levels, namely subclinical hypocalcaemia. And because of this effect on the digestive tract, DMI (Dry Matter Intake) drops, and ketosis and fatty liver syndrome are all possible consequences of a high producing dairy cow that is not eating enough (low DMI) in the first few days after calving. are relatively well absorbed but take a longer time to do so without being longer acting (e.g. calcium propionate). Others are very effective at being absorbed quickly, the only downside being that they do not last very long (e.g. calcium chloride); while others take slightly longer to make a contribution to blood calcium levels, but then go on to do so for many hours (e.g. calcium sulphate). For cows whose blood calcium levels are low, but are still standing and able to swallow, oral calcium supplementation is often the best approach. Intravenous (I/V) calcium in cows still standing, walking and swallowing is not recommended because I/V calcium causes a rapid increase in blood calcium levels, often to potentially dangerous levels. Often, for cows that have gone down and cannot stand up due to milk fever, only very careful I/V calcium treatment will actually save her life. After the necessary and successful treatment with I/V calcium, the cow is normocalcaemic (i.e. normal blood calcium levels) but for 4-6 hours only, as a result, these animals can experience relapses. These relapses can either be seen as her going down again, or more commonly, the blood calcium levels drop to above the level where she would have gone down again, but still well below the level of where the knock-on problems occur again (rumen and intestines not working, as well as uterus and teat sphincter muscles not working too) – again, all without being visible to the farmer or vet! No matter how good all the various supplements on the market are, nutrition, both pre- and post-calving, remains the most important – no question. And dietary acidification creates an ideal pH in the cow’s body in which the hormone responsible for efficient calcium usage and absorption (PTH) can function optimally. The cow will now be able to: a) draw on calcium reserves from her own bones; b) she will be efficiently absorbing the calcium in her ration or grazing and, c) her kidneys will be reabsorbing any calcium ‘attempting’ to leave her body via her urine. Treatments for Hypocalcaemia Subcutaneous Calcium Treatment In cows that are not already already down (severely hypocalcaemic) and dehydrated, subcutaneous calcium is well absorbed initially - however blood concentrations of calcium are increased, but again only for 4 to 7 hours! And whether it’s clinical milk fever or subclinical hypocalcaemia, one would ideally aim to supplement these cows with a calcium source that would raise blood calcium levels for as long as practically possible within the first 24 hours after calving. Types of Oral Calcium Supplementation Supplementing calcium either: routinely post- calving (in cows 2nd lactation/calf and older); or as a follow-up after life-saving I/V calcium, certain oral formulations serve this purpose well. One should familiarise yourself with the type of calcium supplemented: some are poorly absorbed (e.g. calcium carbonate); some Beyond the Calcium Type and Quantity Calcium Bolusses Bovikalc is a combination of calcium chloride and calcium sulphate, combining the fast, high availability of calcium chloride, with the longer acting, sustained release contribution of calcium sulphate. Once the bolus is in the rumen the blood calcium levels show an 7&V6RvF3C֖WFW2B6FVW2F6FfVǒ&6R&@66VWfV2f""W'2"&RFW&VgFW"6&FbV67Fr6&VBvF7W7FVB&VV6RखFFFF&fFrFR6rvFvW"Ц7Fr66V6G&'WFFR&W2266FvV2v62&VV&fVF6W6RFP6rFgW'FW"G&rW"v66V&W6W'fW2FR&W226FVBFW"bvFBFR7vvr&6W72B62&W7VBFW0BfRVV6BF7FRF֖7FW&r&W22f7FW"B&R6fVVBF7@FW"66V7WVVFFF֖7G&FWFG2B26Vff6VB&W7VFr7Bv7FvRBbFR&GV7B&VfW&V6W2f&Rg&WF #p