It is common for dairy cows in farms to suffer from hypocalcemia during their perinatal period. The perinatal period of dairy cows refers to a period of 21 days before and 21 days after production. Female cows will be affected by physiology, environment, and feed, and abnormal conditions such as delivery and lactation will occur. Their nutritional metabolism, endocrine, and other changes will occur. So it's more prone to this kind of disease. In this paper, the author's experience of perinatal hypocalcemia control measures to reduce the incidence of dairy cows, as a reference.
1. Harm
Perinatal hypocalcemia in dairy cows can weaken the elasticity of muscle tissue, and affect the cardiovascular system, reproductive system, lactation system, and digestive system function. After delivery, the incidence of ketosis, mastitis, true stomach displacement, and other common diseases increases, causing economic losses to farms.
2. Influence factor
Age: There is no milking fever in young cows, but it will occur with the increase of age, and the intestinal receptors in cows decrease gradually.
Breed: Juanshan cattle have the highest incidence of perinatal hypocalcemia, probably because of its high calcium level in colostrum and normal milk, less 1,25-dihydroxy vitamin D receptor in the intestine and poor regulation of calcium level, so its incidence is higher than other dairy cattle.
Diet: Metabolic alkalosis is a very great cause of hypocalcemia. It is necessary to prevent metabolic alkalosis in the prevention and treatment of hypocalcemia. The higher the cationic content in the feed, the more cations, the stronger the alkalinity. The sodium and potassium ions in the feed can be absorbed, and the blood alkalinity is stronger. Perinatal dairy cows can not absorb calcium and magnesium ions well, which leads to hypocalcemia when the level of sodium and potassium ions in feed is high.
Hypomagnesemia: Hypomagnesia is another cause of the disease. Hypomagnesia reduces PTH secretion, changes its conformation and reduces PTH sensitivity in target tissues.
3. Prevention
Using a low-calcium diet: In dairy farms, dairy cows need to continue feeding 15 g/d of calcium 10 days before production, the incidence of the disease declines, and the calcium homeostasis regulation mechanism can be activated during lactation. In production, it is difficult to prepare low calcium feed that meets the requirements.
Oral Calcium Preparations during Calving: Calving cows with oral Calcium Preparations during calving can reduce the incidence of the disease. This method has some drawbacks, high cost, and risk of inhalation pneumonia.
Supplementation of exogenous vitamin D and parathyroid hormone: feeding or injecting a large dose of VD (more than 10 million IU) to dairy cows within 10-14 days before delivery can increase the absorption of calcium in the intestine and prevent hypocalcemia. This disease is similar to a poisoning dosage, so it should be used cautiously. Low dosage can cause hypocalcemia. High level of 25-OH vitamin D and 1,25-dihydroxy vitamin D feedback inhibits PTH secretion and kidney synthesis of endogenous 1,25-dihydroxy vitamin D. Prenatal treatment of dairy cows with 1,25-dihydroxy vitamin D or its analogs or PTH has achieved good results, but its treatment dose is close to the toxic dose, there are still some problems such as drug administration and stopping time control, treatment cost and so on.
Reduce the content of sodium and potassium in the diet: During the perinatal period, there are many potassium ions in the feed, but sodium ions can not be added. Corn and barley are recommended as feed instead of alfalfa.
Mild (compensatory) acidosis induced by adding anionic salts: Dietary anion-cation balance (DCAD) refers to the difference between the contents of major cations (Na+, K+, Ca2+, Mg2+) and major anions (Cl-, S2-, PO 43-) and their millimoles (mmol) in the diet of dairy cows. DCAD directly affects electrolyte balance in the digestive tract and body of dairy cows. DCAD changes, osmotic pressure, acid-base balance, water, and salt metabolism and physiological and biochemical indicators will change in dairy cows.
Improving the level of magnesium in diet: The absorption and utilization of magnesium ions should be considered in the feed mixing. Hypomagnesia results in decreased PTH secretion by the parathyroid gland and affects calcium metabolism. The feeding of 0.35%~0.40% magnesium to dairy cows before delivery can avoid the decrease of blood magnesium concentration after production, ensure enough magnesium ions, enable the rumen to absorb and utilize magnesium ions, penetrate the rumen wall, and do not rely on active transport to make magnesium through the rumen wall. The process of magnesium transport may be inhibited by dietary potassium. There is no readily available magnesium storage in the body, so the daily intake of magnesium through the diet must meet the needs.
Control of dietary phosphorus content: 40-50 g of phosphorus per cow per day can meet the needs of phosphorus. The daily phosphorus intake of each cow is less than 25 g, which may cause hypocalcemia. When the daily phosphorus intake of each cow is higher than 80 g, hypocalcemia can be induced.
There are many causes of hypocalcemia in dairy cows during the perinatal period (21 days before delivery to 21 days after delivery). Its physiological status, feed ratio, and environmental changes will have a greater impact. Therefore, cattle breeders should understand the perinatal status of dairy cows. If the management is not in place, the nutritional problems of dairy cows will not be paid attention to. It can lead to hypocalcemia in the perinatal period of dairy cows, and it can also cause a series of other reproductive diseases, which will damage the economic benefits of dairy farming. In the process of cattle farm management, we should use various ways to adjust the health status of dairy cows during the perinatal period, prevent the occurrence of diseases, and ensure the health of dairy cows, so that the farm can obtain high profits.
