To prevent milk fever in cows, you can use a special diet during late dry period.

Milk fever or hypocalcemia in cows after calving is one of the prevalent pathological conditions that prevent the owner from achieving the desired productivity from the cows and results in unplanned expenses on veterinary drugs. According to global sources, 50-70% of high-producing cows suffer from hypocalcemia. The greatest losses are caused by subclinical hypocalcemia, which does not have a pronounced clinical picture but manifests as retained placenta, metritis, displaced abomasum, and reproductive disorders.

A proper transition strategy from pregnancy to lactation is crucial for high productivity and reproductive system health in dairy cows. Conversely, an incorrectly chosen transition strategy often leads to significant economic losses for dairy farms due to disruptions in production plans and reproduction. Therefore, understanding the causes and consequences of metabolic changes in the transition period is essential for maintaining cow health after calving.

In dairy cattle, the period between 3 weeks before and 3 weeks after calving is called the transition period, which is one of the most critical physiological stages, as most metabolic and infectious diseases occur during this period.

Milk fever is the most common metabolic disorder in dairy cattle, resulting from a deficiency of calcium, also known as hypocalcemia. Milk fever is caused by a temporary deficit of calcium (Ca) in the blood, which occurs after calving. This deficit partly arises during late dry period when calcium is transported to the fetus, and at the beginning of lactation, when a large demand for calcium is necessary for colostrum production. Typically, milk fever occurs more frequently in high-producing dairy cows, but cows of any age can be affected.

Regulation of calcium metabolism:

In cows, only 8-10 g of calcium circulates in the blood, while the main mass is stored in the bones (6000 g) and intestines (80-100 g). Usually, when the blood calcium level drops, the parathyroid gland releases parathyroid hormone (PTH). Then PTH acts on osteoclasts to break down and transfer Ca from the bones into the bloodstream to raise the blood Ca level. PTH also acts on the kidneys, where 1,25-dihydroxyvitamin D3 is activated. 1,25-dihydroxyvitamin D3 stimulates the rumen to absorb more Ca to maintain an adequate Ca level.

Development Mechanism of Hypocalcemia:

After calving, lactation begins, and milk and colostrum remove calcium from the blood, and some cows cannot sufficiently quickly restore the concentration of calcium in the blood. Therefore, after the depletion of calcium reserves, subclinical hypocalcemia and clinical (milk fever) manifestations begin. The concentration of Ca in the extracellular fluid is also responsible for nerve impulse transmission, and hypocalcemia leads to spontaneous opening of voltage-gated ion channels, resulting in hyperactivity of nerve and muscle cells. Therefore, animals with clinical hypocalcemia experience tremors and are highly excitable. Hypocalcemia also leads to decreased muscle tone and contractility of many organs, including the cardiovascular system.

Provoking Factors for the Development of Hypocalcemia in Cows:

The age of the cow is an important factor because the risk of milk fever increases by approximately 9% per lactation. Hypocalcemia after calving is more common in high-producing cows that produce large quantities of colostrum. The predisposition of certain breeds, such as Jersey, under certain conditions, may be more prone to developing hypocalcemia even than Holstein. But the main provoking factor for the onset of milk fever is the animal’s diet. After calving, feed intake decreases, so calcium consumption also decreases. Calcium absorption from bones is suppressed when cows are fed diets with high levels of cations, such as feeds with high potassium (K) and sodium (Na) content. The cow should also not receive a diet with a high calcium (Ca) level during the dry period, as this reduces the ability to mobilize calcium from bones. Magnesium (Mg) also affects calcium absorption in the intestine, and low magnesium content reduces calcium absorption. Finally, the elevation of estrogen levels associated with calving inhibits calcium mobilization.

Hypocalcemia Prevention in Cows

Preventing hypocalcemia in cows involves the correct feeding strategy for cows in the 3 weeks before calving.

There are three main approaches to feeding:

1. Rations with low calcium content. Although this does reduce cases of hypocalcemia, it is challenging to implement on the farm. The main rule is to provide less than 20 g of available calcium. These rations often contain feeds of very low quality, which may limit dry matter intake.
2. Rations with low potassium content. Adding feeds with low potassium content (such as corn silage) to rations for dairy cows can reduce the likelihood of clinical hypocalcemia but not subclinical hypocalcemia. Changes in the dietary cation-anion balance (DCAB) may not be large enough to induce metabolic acidosis and prevent subclinical decreases in blood calcium concentration.
3. Feeding anionic salts for 21 days before calving: This is the most effective strategy for preventing hypocalcemia. Rations should be formulated to achieve a negative DCAB from -10 to -15 mEq/100 g dry matter using the most palatable anionic mineral supplements. From an economic point of view, this is the most costly method of prevention, but the reinvestment effect from increased milk yield and reduced veterinary costs will be from 1:2 to 1:5.

The feeding strategy for cows of VITAGRO Nutrition during the late dry period involves the use of quality hepatoprotectors, mycotoxin adsorbents, chelated forms of microelements and macroelements, fat-soluble vitamins, palatable anionic salts for metabolic acidosis to stimulate calcium metabolism. For the late dry period, a complex product called Vitamix Close Up 31 has been specially developed.

The purpose of using Vitamix Close Up 31 is to reduce the DCAB (dietary cation-anion balance), which stimulates the release of calcium from bone reserves before calving, preventing the development of hypocalcemia after calving. Vitamix Close Up 31 is a comprehensive product that also contains hepatoprotectors, mycotoxin adsorbents, antioxidants, chelated compounds of microelements, available macroelements, vitamins A, B, D, E, protected methionine. Together, this complex synchronizes the levels of Ca and Mg in metabolism and maintains the necessary level of these elements for a good lactation start. (Table 1)

Vitamix Close Up 31 – Vitamin-Mineral Complex for Cows in Late Dry Period

Vitamix Close Up 31 Dosage: from 500 g to 900 g per head per day. The final dosage is determined by urine pH. Mandatory urine pH control twice a week, at the same time, 6-8 hours after TMR feeding. Excellent results are achieved with an average urine pH of about 5.8-6.0.

You can check the correctness of the composed diet according to the principle of metabolic acidification using Table 2.

Indicators of the correctly chosen feeding strategy for 3 weeks before calving, Table 3.