Calcium deficiency comes from the dry period ration<\/h3>\n
Milk fever, also called parturient paresis, is caused by a calcium level in the blood that is too low. It can occur from 1 to 2 days before calving until a few days after calving, but the first day in particular is a critical moment. As colostrum production starts a few days before calving, calcium is drawn from the blood, so the blood calcium level drops. A cow that produces 10 litres of colostrum needs 23 grams of calcium for the first colostrum milking. On average, the cow then needs 9 times more calcium than is available as plasma calcium in the blood.<\/p>\n
“At the first colostrum milking the cow needs 9 times more calcium than is available in the blood.”<\/em><\/h4>\nTo prevent a calcium deficiency just before calving, it is important that cows can draw calcium from their own reserves. This depends on how active bone mobilisation (releasing calcium from the bones) is. The dry period ration can steer bone mobilisation through the cation-anion balance. This balance should be negative, meaning there are fewer positively charged elements (potassium and sodium) and more negatively charged elements (sulphur and chlorine) in the dry period ration. This stimulates bone mobilisation, so that cows facing a calcium shortage can take calcium straight from their own reserves.<\/p>\n
If the calcium level stays too low for a longer time, this can have serious consequences for the cow. The cow can then develop problems with muscle and nerve function in particular. Cold ears and no longer being able to stand are the main symptoms of milk fever. Besides the skeletal muscles, the muscles of the organs also receive only a minimal amount of calcium, which can lead to problems with the heart, the digestive tract (feed intake) and the uterus (ease of calving and retained placenta).<\/p>\n
![\"\"](\"https:\/\/www.topro.nl\/wp-content\/uploads\/23-07-Topro-koe-calciumhuishouding-groot-1024x660.png\")
Figure 1. Schematic view of calcium metabolism when the blood calcium level is low. PTH activates vitamin D and drives bone mobilisation and calcium retention in the kidneys. Vitamin D improves calcium absorption in the intestines. Together with bone mobilisation, calcium retention in the kidneys and stimulated uptake of Ca in the intestines, the blood calcium level will rise. Potassium has a negative effect on magnesium, and magnesium stimulates PTH. Phosphorus has a negative effect on the activation of vitamin D. However, the cow can become short of phosphorus when colostrum production starts in the dry period. It is then important that the cow still takes in enough phosphorus to avoid a phosphorus deficiency.<\/p><\/div>\n
Energy balance in cows: how did that work again?<\/h3>\n
Ketosis, called “slepende melkziekte” in Dutch, is a result of the negative energy balance (NEB) around calving. NEB means that the energy needed for milk production cannot be fully covered by the energy taken in through feed; almost all cows go through a NEB at the start of lactation. This is because cows normally eat less in the last few days, as the calf presses on the digestive tract and the cow has less room for feed. On top of that, the cow is preparing for calving and her hormone levels shift, which also strongly reduces appetite.<\/p>\n
At the same time, the cow badly needs that energy, because the rising milk production demands a lot of energy. Energy demand is then higher than oral energy intake and the cow turns to other energy sources: the rate of fat breakdown increases. This releases NEFAs. The liver can convert a certain amount of NEFAs into usable energy, but once that limit is reached, NEFAs are converted into ketone bodies that end up in the blood. Ketosis occurs when there is an excess of ketone bodies in the blood, which makes the cow feel unwell, eat less and take in even less energy. The cow ends up in a downward spiral with all the consequences that follow.<\/p>\n
Ketosis occurs later in the cow’s lactation, usually a few weeks to months after calving. In Dutch it is called “slepende” (lingering) milk fever because the symptoms are often less obvious and the cows often do not look as ill as with milk fever. Instead, they show subtle signs of illness, such as reduced appetite, lower milk production and a sharp drop in BCS. These symptoms resemble those of other problems, which is why ketosis can sometimes be hard to recognise.<\/p>\n
Calcium deficiency and energy deficiency go hand in hand<\/h3>\n
It is important to know that these two conditions are not completely separate from each other. Milk fever and ketosis share a common cause: a disturbance in calcium metabolism. Cows that have had milk fever run a higher risk of also developing ketosis later in lactation. This is because feed intake is lower with milk fever, so the cow also takes in less energy and ketosis is lying in wait.<\/p>\n
Figure 1. Schematic view of calcium metabolism when the blood calcium level is low. PTH activates vitamin D and drives bone mobilisation and calcium retention in the kidneys. Vitamin D improves calcium absorption in the intestines. Together with bone mobilisation, calcium retention in the kidneys and stimulated uptake of Ca in the intestines, the blood calcium level will rise. Potassium has a negative effect on magnesium, and magnesium stimulates PTH. Phosphorus has a negative effect on the activation of vitamin D. However, the cow can become short of phosphorus when colostrum production starts in the dry period. It is then important that the cow still takes in enough phosphorus to avoid a phosphorus deficiency.<\/p><\/div>\n
Energy balance in cows: how did that work again?<\/h3>\n
Ketosis, called “slepende melkziekte” in Dutch, is a result of the negative energy balance (NEB) around calving. NEB means that the energy needed for milk production cannot be fully covered by the energy taken in through feed; almost all cows go through a NEB at the start of lactation. This is because cows normally eat less in the last few days, as the calf presses on the digestive tract and the cow has less room for feed. On top of that, the cow is preparing for calving and her hormone levels shift, which also strongly reduces appetite.<\/p>\n
At the same time, the cow badly needs that energy, because the rising milk production demands a lot of energy. Energy demand is then higher than oral energy intake and the cow turns to other energy sources: the rate of fat breakdown increases. This releases NEFAs. The liver can convert a certain amount of NEFAs into usable energy, but once that limit is reached, NEFAs are converted into ketone bodies that end up in the blood. Ketosis occurs when there is an excess of ketone bodies in the blood, which makes the cow feel unwell, eat less and take in even less energy. The cow ends up in a downward spiral with all the consequences that follow.<\/p>\n
Ketosis occurs later in the cow’s lactation, usually a few weeks to months after calving. In Dutch it is called “slepende” (lingering) milk fever because the symptoms are often less obvious and the cows often do not look as ill as with milk fever. Instead, they show subtle signs of illness, such as reduced appetite, lower milk production and a sharp drop in BCS. These symptoms resemble those of other problems, which is why ketosis can sometimes be hard to recognise.<\/p>\n
Calcium deficiency and energy deficiency go hand in hand<\/h3>\n
It is important to know that these two conditions are not completely separate from each other. Milk fever and ketosis share a common cause: a disturbance in calcium metabolism. Cows that have had milk fever run a higher risk of also developing ketosis later in lactation. This is because feed intake is lower with milk fever, so the cow also takes in less energy and ketosis is lying in wait.<\/p>\n
![\"\"](\"https:\/\/www.topro.nl\/wp-content\/uploads\/krant-16-schema-calcium-bladzijde-2.png\")