Calcium dynamics in post-parturient dairy cow

T. K. S. Rao, Shashipal, Hemant Kumar, Tripti Kumari, Dhirendra Kumar

College of Veterinary and Animal Sciences, 855107 Kishanganj, Bihar Animal Sciences University, 80014 Patna  

Calcium dynamics in dairy cow describes the changes in blood calcium level and effect of these changes on their health and milk yield. 

Blood calcium dynamics during early post-partum: Post-parturient inflammation leads to reduced blood calcium level in dairy cows. Blood calcium concentration classically decreases around the parturition, however, recover rapidly. Cows with milk fever have a more profound decrease in blood calcium concentration characteristically below 5.5 mg/dL due to sudden increase in calcium release from 10 to 30g per day.

            Calcium homeostasis is challenged after calving in cows. Improving blood calcium after calving may be a useful strategy to reduce incidence of post calving disorders in order to improve performance of cows throughout the production.  Milk calcium measurement is claimed to be effective to assess blood calcium level after calving in multiparous dairy cows as higher correlation was observed between plasma and milk calcium especially on 3^rd and 4^th day of calving (Aubineau et al., 2021). Serum calcium concentration in multiparous cows increases from day 1 to 3 after parturition, while it decreases in primiparous cows.

Voluntary oral aqueous calcium suspension or drink resulted in a relatively stable calcemia in cow after parturition as compared to solid calcium or bolus (Wilms et al., 2022).

Calcium dynamics during transition phase: When dairy cow transition from pregnanacy to lactation, she need more calcium to support milk production. This may some time lead to drop in blood calcium level, which can put the cow at risk of hypo-calcaemia. At start of lactation excretion of calcium increases from about 10g to 30g on daily basis. 

Four types of calcium dynamics in post parturient cows (Seminara et al., 2023):

1. Normocalcemic: Sub clinical hypo-calcemia at no days in milk
2. Transient hypocalcaemia: Sub clinical hypo-calcemia at one day in milk
3. Delayed hypocalcaemia: Delayed sub clinical hypo-calcemia at four days in milk
4. Persistent hypocalcaemia: Sub clinical hypo-calcemia at both one and four days in milk

Plasma calcium concentration at calving vis-a-vis fertility: Management approach which minimize the reduction in blood ionized calcium concentration in the periparturient dairy cow are likely to improve reproductive outcomes like time of first service, time to conception and should be considered as a part of multifactorial protocol to optimising dairy cow fertility (Mahen et al., 2018).

 Concept of negative energy balance (NEB): After parturition energy released in form of milk (energy output from cow unit) is more as compared to energy intake inform of food (energy input to cow unit)thus newly calved cow reaches a state of negative energy balance. In severity fatty acid released from adipose tissues leading to elevated level of NEFA (non-esterified fatty acids) and BHBA (beta hydroxy butyric acid) and finally it may cause metabolic disorder such as fatty liver and ketosis. Further inflammation and immune activation are additional cause of negative energy balance in fresh cows.

Immunity status: Hypocalcaemia decreases response of immune cells. It impaired neutrophil function and changed metabolism. Moreover, hypocalcaemia could be alleviated using calcium administration in cows challenged by lipopolysaccharide. While formulating on farm nutritional strategies, calcium metabolism and its critical role in fresh cow’s immune function should be considered.   

Normal healthy cows: In normal healthy cow blood calcium concentration is typically between 2.1 – 2.5 millimoles per liter. Calcium deficiency in cow leads to muscle tremors, weakness depression, moreover, cow more likely to get metabolic and infectious diseases. Calcium deficiency in cow supported by signs low appetite, cold ears, muscle tremors, weakness and depression. Common health issues caused by calcium deficiency include metritis, mastitis and left displaced abomasum (LDA).  Other effect on health include stunted growth, delayed maturity, reduced fertility, lowered milk yield, fragile bones and paralytic warning sign.  

Mastitis: Mastitis can causea reduction in calcium in cow milk (Venjakob et al., 2021). The CACNA2D1 is voltage dependent calcium channel gene considered a candidate gene which influence mastitis.  

Lameness: Calcium deficiency due to high production can cause a number of problems including lameness, especially in young animals. Serum calcium level was lower in lame cows as compared to healthy cows. Typical lame cows showed concentration of calcium as subclinical hypocalcaemia.   

Factors affecting calcium dynamics in cow:

1. Age: Older cows are less able to mobilize calcium from the skeleton system to blood.
2. Breed: Incidence higher in Jersey and Guernsey breeds 
3. Estrogen: High level of Estrogen around calving inhibits calcium mobilization.
4. Calving: Feed intake decreases around calvingwhich ultimately reduces calcium intake. 
5. Lactation: During lactation release of calcium through milk increases from 10-30 gm per day. A litre of cow milk with 4% fat contains about 1.22 grams of calcium. Cows entering in third or later lactation are more susceptible to milk fever.
6. Hypocalcaemia: It is also described as milk fever. If calcium intake is severely deficient cattle may develop rickets, weak skeleton or bone fracture due to fragile weak bones.   
7. Parturient paresis: Disease of adult dairy cows with flaccid paralysis, condition occurs when blood calcium fall below 5.5 mg/dL.
8. Serum calcium concentration: Normal serum calcium concentration for normal healthy cow is between 2.1-2.5 millimoles per liter. Serum concentration below 2.0 mmol/L considered as hypocalcaemia. Serum calcium concentration can be affected by time, parity, metritis etc. including other factors like dietary, physiological and environmental conditions.  

Essentiality of Calcium in cow:

1. Bone health: Calcium is important component of bones therefore young animals require adequate calcium for proper growth.
2. Milk production: Calcium is essential for milk production.
3. Muscle activity: Calcium is essential for muscle activity.

Clinical vs. Subclinical hypocalcaemia: Symptoms of clinical hypocalcaemia include weakness, depression, muscle tremors or sternal recumbency. Moreover, subclinical hypocalcaemia diagnosed with blood test but the cow did not show clinical signs. 

Signs and symptoms of calcium deficiency in cow: Sign and symptoms of calcium deficiency in cow include-

1. Anorexia:
2. Confusion:
3. Dry-muzzle:
4. Subnormal body temperature:
5. Cold extremities:
6. Low heart rate:
7. Decreased intensity of heart sound:
8. Weak peripheral pulse:
9. Inability to urinate:

Calcium channels: In cow calcium channels are found in the plasma membrane of cells. It is protein complexes which regulates the flow of calcium ions into cells.

Inflammation vs. calcium concentration: Systemic inflammation led to reduced blood calcium concentration in dairy animals (Neves, 2023).

Milk and blood calcium association: Milk calcium measurement is effective technique to assess blood calcium levels after calving in cows especially multiparous (Aubineau et al., 2021).  

Role of parathyroid in calcium balance: When parathyroid gland senses low blood calcium, it increases parathyroid hormone (parathormone) secretion which ultimately increases calcium release from bone and calcium absorption through intestine and decreases calcium excretion from kidney.   

Source Photograph: https://www.horiba.com/

Improving calcium in cow: Cattle may be offered legume fodders, maize fodders, tree leaves in food items. Mineral mixture may be included in drinking water to improve calcium status in body of animals. Access to sun is provided during cool hours in order to produce Vitamin D. Feeding green grass adlib after milking is common practice to overcome calcium deficiency in cow. Feeding acidogenic diet before parturition is most common practice to avoid calcium deficiency in blood.

Calcium supplementation bolus vs. liquid: Cow can be given supplements as oral liquid are more stable as compared to bolus.

Injectable calcium therapy: Cows in stage 2 or 3 of milk fever can be injected with calcium intravenous, however, too much of calcium given too quickly may results in heat attack. In order to avoid heart attack due to calcium drip Avil injection may be given intramuscular prior to intravenous calcium drip.

Calcium carbonate in feed and serotonin in blood: Calcium carbonate can be added to the feed in order to improve bone mineral density, prevent bone disorders and promote skeletal integrity. Moreover, elevation of circulating serotonin improves calcium dynamics in peripartum dairy cows (Weaver et al., 2016).   

Reducing dietary cation-anion difference (DCAD) and using calcium binders: Reducing DCAD include reducing potassium and sodium and increasing chloride and sulphur in diet and adding anionic salts or increasing dietary acidity.  

Urine & blood pH of cow: Urine pH should be (reduced from 8.0) checked and maintained between 6.0-6.8. moreover, blood pH should also be reduced slightly from 7.46 to 7.38.