Impact of fever on the lifetime performance of your dairy cows

ilk fever is a metabolic lead to a long-term disturbance or production deficiency, further threatening the Mdisease of dairy cows that economic profitability. Hence, the generally occurs just before, or soon prevention of milk fever and long- after, calving due to low calcium term calcium deficiency is key in the levels in the blood. It is associated dairy industry. with the drain of calcium within the foetus and milk during pregnancy and calving, respectively. Milk fever Milk fever has both direct and indirect economic impacts on the dairy Milk fever (also called parturient industry. paresis or parturient hypocalcaemia) is one of the production diseases which primarily occur among older by Dr Maurice Verschaeve, high-yielding dairy cows during the Veterinary Surgeon, period around calving. The increased Kathleen Verschaeve, Pharmacist, demand for calcium at parturition milk yield (cows with higher yield are The role of calcitriol Jonas De Roo, Biologist & due to the onset of may more predisposed than cows with Dr Glenn Verstraete, Pharmacist, result in a calcium deficiency lower yield), breed, body condition, Calcitriol or 1.25-dyhodroxyvitamin Emma Nutrition. situation potentially provoking the length of dry period and diet D3 is a metabolite of vitamin D3. www.emma.be outbreak of milk fever in dairy cows. composition. Unlike vitamin D3 that needs to be Milk fever generally occurs when transformed in the liver and , calcium blood plasma concentration calcitriol works directly on the The most important direct is lower than 8mg/dL (i.e., 2.2 Long-term hypocalcaemia vitamin D3 receptors in the intestinal economic losses due to milk fever mmol/L). Such a low calcium blood wall, bones and kidney having the are losses due to reduction in milk plasma concentration has As mentioned earlier, high yielding following effects: production of affected cows, loss of consequences for many nerve and dairy cows suddenly experience a l Intestinal wall: animals through death and culling, muscle functions. high demand of calcium during Calcitriol is able to activate the and the cost of treatment. Milk fever is an economically parturition. calcium-binding proteins increasing In addition, the excessive drop in important disease due to milk Calcium is necessary for the calcium absorption rate from the calcium levels around calving can secretion that can reduce the contraction of the uterine wall gut to the blood vessels. productive life of a dairy cow. Milk muscle and milk production. The l Bones: fever incidence has remained steady natural regulation systems in the Calcitriol activates the vitamin D in some countries at about 10%. dairy cow can not always cope with receptors in the bone cells increasing Milk fever affects about 6% of this sudden increase in calcium calcium deposition or release from dairy cows in the United States each demand. As a result, calcium blood the bones, depending on the year, according to the 1996 National plasma levels can drop significantly. concentration of calcium in the Animal Health Monitoring Survey. If Depending on the severity of this blood plasma. left untreated, about 60-70% of the drop in calcium levels this can lead l Kidney: affected cows may die. to a long-term calcium deficiency Calcitriol stimulates the resorption There are some factors which and thus a persistent lack of of calcium from the urinary tracts to influence incidence and severity of appetite, hypersensitivity, weakness the blood vessels Single dose Green Bolus that can milk fever. These are: age (older cows and, if left untreated, even paralysis Taking all the above-mentioned slowly release calcitriol-glycoside. are more sensitive than younger), and mortality. into account, it can be stated that Long-term hypocalcaemia also has calcitriol can increase the absorption some widespread effects that and regulation rate of calcium thus Fig. 1. Impact of gastrointestinal residence time (days) on bolus weight (g). predispose to other periparturient maintaining an optimal calcium level diseases such as mastitis, ketosis, in the blood plasma. In addition, displaced abomasum and retained calcitriol is known to have a similar 120 placenta. Even if no visible effect on phosphorus absorption 100 symptoms are observed, long-term and regulation, positively affecting 80 hypocalcaemia can lead to a the immune system and improving decrease in production and fertility. the suppression of pathogens. 60 Even successful treatment of 40 hypocalcaemia does not eliminate further complications associated Advantages of Bolus weight (g) Bolus weight 20 with milk fever, which results in calcitriol-glycoside 0 further economic losses. This 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 stresses the demand for an effective The binding of calcitriol to a Gastrointestinal residence time (days) prevention: administration of glycoside is known to improve calcitriol. Continued on page 14

International Dairy Topics • Volume 20 Number 2 13 Continued from page 13 disintegrating bolus that should only Calcium concentration in blood (mmol/L) stability and increase bioavailability be administered once (approximately T0 T1 (due to better absorption through 1-2 days before calving). Cow the intestinal wall). Calcitriol- As listed in Table 1 and displayed in (when applying bolus) (24 hours after calving) glycoside can be found in dried Fig. 2, this unique patented formula 1 2.33 2.13 leaves of the plant Solanum allows farmers to easily increase Control 1.83 glaucophyllum (containing a calcitriol blood concentration 8-10 2 1.93 standardised concentration). hours after oral administration. (2.93 - 24 hours after Green Bolus) Studies with herbal calcitriol- Furthermore, it was found that 3 1.87 2.47 glycoside added to the feed of calcium concentration in blood ruminants show a significant increase could be kept above 2.2 mmol/L 4 1.98 2.16 of calcitriol in the blood levels. (i.e., 8.8mg/dL which is the 5 1.96 2.16 Furthermore, it was observed that a recommended minimum calcium Green single high dose of herbal calcitriol- blood plasma concentration to 6 2.51 2.16 Bolus glycose around calving could result prevent milk fever and long-term 7 2.10 2.21 in a major increase in both calcium hypocalcaemia). and phosphorus blood levels. Therefore, one might assume that 8 2.20 2.25 hypocalcaemia could still be 9 2.24 2.33 countered even in case the Green Slow-release Bolus is administered just before or Table 1. Impact of Green Bolus administration on calcium concentration in calcitriol-glycoside after calving. Finally, it was observed the blood of Holstein-Friesian cattle. that the administration of Green Considering calcitriol-glycoside as an Bolus could positively affect effective substance to prevent phosphorus levels. As a result of the Conclusion hypocalcaemia and milk fever, hypocalcaemia, it was of the highest excellent in vivo performance, Emma resulting in a higher economic importance for Emma Nutrition to Nutrition’s Green Bolus was officially Emma Nutrition successfully yield. n search for the most convenient and recognised in 2020 as a highly developed a single dose calcitriol easiest way of administration. effective diet food for the glycoside bolus (Green Bolus) that is As displayed in Fig. 1, Emma prevention of long-term officially recognised as a diet food References are available Nutrition developed a slowly hypocalcaemia and milk fever. to prevent dairy cows from from the authors on request

Fig. 2. The impact of Green Bolus administration on cholecalciferol (left) and calcium, phosphorus and magnesium levels (right).

250 4 l Calcium l Phosphorus l Magnesium (Bolus (Bolus 200 administration) (calving) administration) (calving) 3 150 2 100

(mmol/L) 1 50

in blood (mmol/L)

Concentration in blood Concentration 0 0

Cholecalciferol concentration Cholecalciferol 0 10 24 72 7 10 0 10 24 72 7 10 hours hours hours hours days days hours hours hours hours days days Time Time

14 International Dairy Topics • Volume 20 Number 2