Hypocalcemia is a disorder in dairy cows caused by lower than normal blood calcium concentrations. There are two forms of the disorder, clinical and subclinical. Clinical hypocalcemia, more commonly referred to as clinical milk fever (MF), is defined as a cow having a total blood calcium concentration below 5.5 mg/dl and showing physical signs of the disorder (muscle tremors, drop in body temperature, laterally recumbent). Subclinical hypocalcemia (SCH) is defined by a total blood calcium concentration ranging from 5.6 to 8.5 mg/dl and showing no physical signs of the disorder.
Cows affected by subclinical hypocalcemia (SCH) are less productive and less profitable, with an estimated cost to dairymen of approximately €112.00 per case. Since more cows are affected by SCH (> 50%) than MF (typically, < 5%), SCH has a larger negative impact on dairy profitability.
(Oetzel, G.R. 2012. An update on hypocalcemia on dairy farms. Proceedings of Four-State Dairy Nutrition & Mgmt. Conf.)
The prevalence of subclinical hypocalcemia (SCH) in a herd can be determined by measuring blood calcium concentrations between 48 and 72 hours following calving. Before doing so, it is necessary to establish a threshold level of blood calcium concentration that is considered “normal”. It is generally accepted that a value above 8.5 mg/dl is normal.
DCAD stands for “Dietary Cation-Anion Difference”. It is a measure of the milliequivalent difference between positively charged minerals, or cations (predominantly potassium and sodium), in relation to the negatively charged minerals, or anions (predominantly chloride and sulfur), in a ration. DCAD is calculated using the molecular weight and charge of these four minerals.
Regardless of age, all prepartum dairy cows are susceptible to hypocalcemia due to the rapid increase in calcium requirements around calving. Cows that are hypocalcemic have increased odds of developing retained placenta, metritis, mastitis and displaced abomasum which can lead to reduced milk yields and decreased fertility. Feeding a negative DCAD diet to cows prior to calving helps reduce the risk of developing hypocalcemia.
Negative DCAD diets work by causing a moderate, compensated metabolic acidosis and aciduria. This is accomplished by feeding elevated levels of anionic minerals containing chloride and/or sulfur. The compensated metabolic acidosis lowers blood pH and, through the actions of parathyroid hormone and vitamin D, enhances the cows’ natural physiological mechanisms for maintaining normal blood calcium concentrations. These include dietary calcium uptake by the gut and bone release of stored calcium. Aciduria induces urinary excretion of calcium prepartum therefore increasing the flux of calcium through the exchangeable calcium pool.
No. When cows are fed diets that are over-acidified (this varies by farm) they will adjust dry matter intake downward to prevent over-acidification.
No. It is estimated that the amount of calcium stored in bone in the adult dairy cow ranges between 7.8 to 8.5 kilograms. During the late gestation and early lactation periods a dairy cow will support the requirement for milk calcium in two ways. First, by increasing the amount of calcium absorbed from the diet and secondly, by releasing calcium from bone, a process known as lactational osteoporosis. These combined processes typically occurs over a 6 to 8 week period during early lactation at which point the cow returns to a positive calcium balance (Hibbs and Conrad, 1983). The significantly shorter period of time that a cow may be fed an acidogenic diet (21 to 28 days) does not pose a threat to depletion of bone calcium.
No. For negative dietary cation-anion difference (DCAD) diets to work you must feed enough anions to lower urine pH significantly below a urine pH of 7.5. Most researchers agree that a diet resulting in a urine pH below 6.8 must occur to have any positive effect. However, diets that induce a moderate compensated metabolic acidosis and aciduria, resulting in urine pH values from 5.5 to 6.0 work best.
AniStart helps to optimise calcium metabolism around calving which may result in healthier, more productive dairy cows.
AniStart dietetic complementary feed for particular nutritional purposes in ruminants is manufactured with proprietary technology that results in a product that is highly concentrated and highly palatable.
The proprietary manufacturing process used to make AniStart, incorporates mineral salts into a fat matrix, making AniStart highly concentrated and palatable.
Calcium is a critical mineral involved in many biological functions including muscle contractions, nerve conduction and immune cell function. Feeding a properly balanced acidogenic DCAD diet can result in reductions in clinical and subclinical hypocalcemia, displaced abomasum, retained placenta and metritis.
AniStart is a mixture of two mineral salts manufactured with a proprietary process resulting in enhanced palatability. Feeding a combination of chloride and sulfur leads to better DCAD diet results. Magnesium chloride and calcium chloride are single source mineral salts that can be unpalatable and do not supply any sulfur. Maintaining high dry matter intake during the close-up period has positive benefits to the cow both prior to and following calving. Choosing an anionic mineral product that is palatable helps to achieve high dry matter intakes during the close-up period.
The amount of AniStart to feed to dairy cows will vary between farms but will always be the amount needed to result in a urine pH range from 5.5 to 6.0. This is typically from 0.35 to 0.45 kg per day.
Learning if the proper dietary cation-anion difference (DCAD) level is being fed can be determined by measuring urine pH. Properly formulated and fed negative DCAD diets result in urine pH values from 5.5 to 6.0. The best time to monitor urine pH values is 6 to 9 hours after the delivery of feed.
Research has demonstrated that feeding high levels of dietary calcium (> 180 g per head per day) result in greater amounts of available calcium (Amundson et al., 2018. J. Anim. Sci. 96:5010; Glosson et al., 2020. J. Dairy Sci. 103:7039), and greater pregnancy rates at first timed AI (Ryan et al., 2020. Theiogen. 142:338) compared to a similar DCAD diet with low dietary calcium.