Calcium propionate｜Improve metabolic diseases of ruminants
Calcium propionate is a kind of artificially synthesized organic acid salt, which has a strong activity of inhibiting the growth of bacteria and mold and sterilizing bacteria. Calcium propionate is included in the feed additive catalog in my country and is applicable to all farmed animals. As an organic acid salt, calcium propionate is not only used as a preservative, but also often used as an acidifier and functional nutritional additive in feed, which plays a positive role in improving animal production performance. Especially for ruminants, calcium propionate can provide propionate and calcium, participate in body metabolism, improve metabolic diseases of ruminants, and promote production performance.
After calving, dairy cows are prone to lack of propionic acid and calcium, which can easily lead to milk fever , resulting in decreased milk production and feed intake. Milk fever, also known as postpartum paralysis, is mainly caused by a large decrease in postpartum blood calcium levels in dairy cows. It is a common nutritional and metabolic disease in dairy cows during the peripartum period. The direct cause is the inability of intestinal absorption and bone calcium mobilization due to the beginning of lactation. Timely replenish the loss of blood calcium, and a large amount of blood calcium is secreted into the milk, resulting in a decrease in blood calcium levels and postpartum paralysis of dairy cows. Milk fever occurs mostly in high-yield multiparous dairy cows, and the incidence rate continues to increase with the increase of parity and lactation ability of dairy cows.
Both clinical and subclinical milk fever can reduce the performance of dairy cows, increase the incidence of other postpartum diseases, reduce reproductive performance, and increase the mortality rate. It is an important measure to prevent milk fever to improve bone calcium mobilization and gastrointestinal calcium absorption through various measures from peripartum to before and after calving . Among them, low-calcium diets and anion diets (diets that cause blood and urine to be acidic) during the peripartum period and calcium supplementation after calving are common methods to reduce the occurrence of milk fever.
Blood calcium level monitoring is the most basic method for the diagnosis of milk fever:
When the blood calcium level is less than 2.0mmol/L, it is diagnosed as subclinical milk fever;
Clinical milk fever was diagnosed when the blood calcium level was <1.5mmol/L.
(Remarks: The normal blood calcium level of dairy cows is 2.0-2.5mmol/L)
Pathogenesis of milk fever:
The body of an adult dairy cow contains about 10kg of calcium, more than 98% of which exists in the bones, and the remaining small amount exists in the blood and other tissues. The appetite and digestive function of dairy cows before and after delivery will decrease, and lactation will also lead to a large loss of blood calcium in dairy cows. If dairy cows cannot supplement in time to maintain the balance of calcium metabolism, it will cause a decrease in blood calcium levels.
The occurrence of milk fever in dairy cows is not necessarily due to insufficient calcium supply in the diet, but may be caused by the cows not being able to quickly adapt to the large calcium demand at calving (initiating the release of bone calcium into the blood), The main reason is that the sodium and potassium ions in the diet are too high, the magnesium ions are insufficient, etc. In addition, the phosphorus content in the diet is too high, which will also affect the absorption of calcium, resulting in hypocalcemia, but hypocalcemia caused by any reason , can be improved by postpartum calcium supplementation.
Symptoms and hazards of milk fever:
Milk fever is characterized by hypocalcemia, lateral recumbency, decreased consciousness, cessation of rumination, and eventually coma . Postpartum paralysis of dairy cows caused by hypocalcemia will increase the risk of cows suffering from metritis, ketosis, retained placenta, displaced abomasum, and prolapse of the uterus , thereby reducing milk production and service life of dairy cows, resulting in the death rate of dairy cows Increase rapidly.
(Liang et al.) estimated that the loss of clinical milk fever per cow was (246.23 ± 52.25) US dollars, and the death loss of milk fever was among the seven major postpartum diseases of dairy cows (hypocalcemia, left abomasum Lateral displacement, metritis, mastitis, lameness, ketosis, retained placenta) the most. Milk fever increases the incidence of ketosis in dairy cows, and (Rodriguez et al.) found that cows with milk fever were 5.5 times more likely to develop ketosis than normal cows. In addition, milk fever can also cause a decrease in the reproductive performance of dairy cows and an increase in the incidence of abomasum displacement.
The role of calcium propionate:
Calcium propionate can be hydrolyzed into propionic acid and calcium ions after entering the body of ruminants. Propionate is an important volatile fatty acid in ruminant carbohydrate metabolism. Propionic acid in the rumen is absorbed by the rumen epithelial cells, and 2% to 5% is converted into lactic acid. The main metabolic pathway of the rest of the propionic acid entering the portal vein in the liver is to generate glucose through gluconeogenesis or enter the tricarboxylic acid cycle for oxidation. can. Calcium propionate can not only provide energy substance - propionic acid, but also supplement calcium for dairy cows. Adding calcium propionate to the diet of dairy cows can effectively alleviate milk fever and ketosis in dairy cows.