Metabolic challenges in the transition period: Milk fever explained

During the transition period, a cow faces major changes and challenges. That is why the transition period is of critical importance for dairy cow health, production and profitability. Due to the start-up of colostrum and milk production, there is a sudden increase in nutrient demand, which can be as much as three times higher than before calving, right at the time when dry matter intake is a reduced, leaving nutrient supply behind (Dekkers & Sorensen, 1999; Mezzetti et al., 2021). When a cow is not supported sufficiently or correctly during this period, the slightest issues can push her over the edge and be the cause of major metabolic challenges.

The transition period involves a complex interplay of metabolic and hormonal adjustments and immune activation. These changes necessitate adequate provision of nutrients to make sure the cow’s needs are met for the final stage of calf growth and the start of a successful lactation. Insufficient support during this period can lead to health and developmental challenges for both cow and calf.

There are many challenges that can potentially arise from the metabolic, hormonal and energy adjustments that a cow undergoes in the transition period. But there is also an indirect risk of other health challenges, such as silent heats, heavy calving or challenges regarding locomotion and reproduction (Lührmann, 2011). In this article the focus will be on one of these health challenges, namely milk fever. More will be explained about the disorder in general, its cause, symptoms and costs related to milk fever.

Milk Fever

Milk fever, or subclinical hypocalcaemia, around calving is a health challenge dairy cows might face due to insufficient support during the transition period (DeGaris & Lean, 2008). Milk fever is one of the most common mineral-related metabolic conditions that impact cows around calving (Fikadu et al., 2016).  In early lactation, the energy requirements rise to about 300% and the calcium requirements to over 65% to support (the start-up of) milk production (Drackley, 1999). This leads to a dramatic increase in the cow’s demand for mineral (calcium, phosphorus, magnesium) and energy reserves. If these needs are not met, a cows is at risk of developing milk fever.

Figure 1: Visualization of amounts of net energy required, consumed and utilized by lactating mammary gland of healthy dairy cows at 4 days postpartum (Drackley, 1999).

Figure 2: Visualization of amounts of metabolizable protein required, consumed and utilized by lactating mammary gland of healthy dairy cows at 4 days postpartum (Drackley, 1999).

Figure 1 shows the amounts of net energy required, consumed, and utilized by the mammary gland by healthy cows at 4 days postpartum. The requirements for net energy exceeded the intake by 26% respectively. Furthermore, the calculated use of net energy by the mammary gland for milk production was, respectively, 97% of the intake, leaving little to meet the maintenance needs. Figure 2 shows the amounts of metabolizable protein required, consumed, and utilized by the mammary gland by healthy cows at 4 days postpartum. These cows had a metabolizable protein requirement that exceeded their intake by 25%. Moreover, the calculated utilization of metabolizable protein by the mammary gland for milk production was 83% of intake, leaving little to fulfil maintenance needs (Drackley, 1999).

The incidence of clinical milk fever generally ranges from 0 to 10% on an average dairy farm, but it can range up to 25% of cows calving. However, research has shown that the incidence of subclinical milk fever can affect up to 80% of cows calving (DeGaris & Lean, 2008). Additionally, the risk of milk fever increases with age, as milk fever generally affects older, high producing cows. About 50% of the dairy cows in their second lactation and greater have blood calcium concentrations that fall below the subclinical hypocalcaemia threshold after calving. Insufficient blood calcium levels can lead to a cow’s inability to stand up, as calcium is crucial for nerve and muscle function (Frikadu et al., 2016). Furthermore, lacking calcium in the blood can lead to reduced rumen function, as contractile strength of the rumen decreases as calcium concentration decreases. In case of clinical milk fever, ruminal contractions can even disappear (Huber et al., 1981).

Symptoms

A cow suffering from milk fever can be recognised by low appetite and low activity. As a result of hypocalcaemia often the cow’s ears are cold. Also the calcium deficiency in the blood causes the muscles to stop working properly. For example, when it affects the skeletal muscles it can be a reason to why a cow is no longer able to get up properly, or in more severe cases it can lead to downer cows. Another example is that when it affects the uterine muscles it can cause retained placenta. If the muscles are affected it can have far-reaching consequences for calving and when closing the cervix, but it also can affect other organs such as the heart and the rumen. Statistically, more than 5% of cows die from milk fever.

Figure 3 offers a schematical overview of the consequences of milk fever (when it causes decreased muscle function and/or increase immune function). It shows that the milk fever, or hypocalcaemia, can have a widespread effect on body and organ function.

Figure 3: Consequences of milk fever (Mulligan, 2006).

Costs

Milk fever is one of the most common mineral-related metabolic diseases in dairy cows. Economically, milk fever can cause the dairy cow’s productive life to be reduced by 3.4 years. Economic losses resulting from clinical milk fever are substantial and include losses from deaths (8% of affected cows), premature culling (12% of affected cows), treatment costs, and decreased milk production (in the subsequent lactation). On average a cow suffering from milk fever has a milk loss of 36.42 litres during the period of illness (Engdawork, 2019; Bzuneh et al., 2020).

The costs of subclinical cases of milk fever are often much higher than expected. Our own research shows that the estimated costs of clinical milk fever on an average Dutch dairy farm with 103 dairy cows is about €4,860.07 a year. Subclinical milk fever, as described above, can affect up to 80 percent of the herd, leading to economic losses almost four times greater than those associated with clinical milk fever (DeGaris & Lean, 2008; Guard et al., 1996).

Table 1: Estimated economic impact of clinical milk fever on an average Dutch dairy farm with 103 cows.

To prevent (or at least reduce the risk of) milk fever, extra attention is needed to prevent the mineral and energy deficiencies as discussed earlier in this article. Although treatment with intravenous infusion of calcium salt solutions cures most clinical cases of hypocalcaemia, it has been suggested that a specific control programme should be implemented when the incidence of milk fever increases to more than 10% in high risk cows; i.e. cows entering the third or later lactation period. Strategic prevention of milk fever is economically important for the dairy farmers because of the minimal production loss, mortality and veterinary costs associated with cases of clinical milk fever (Frikadu et al., 2016).

Using AHV StartLac

AHV StartLac is a dietetic feed and provides support around calving to prevent insufficient blood calcium levels. It does this by incorporating active vitamin D3, which promotes faster and more efficient absorption of calcium from blood, muscles and bones. So it stimulates the body to resume these processes by itself. The product also contains magnesium and phosphorus that have an additional positive effect on calcium absorption, which is needed for calving, colostrum and milk production. Furthermore, it contains inulin, which supports energy utilisation, and yeasts, to support digestion.

StartLac is available in two forms, namely a paste and tablet form. The AHV StartLac Tablet, one tablet should be administered directly after calving and a second tablet 12 to 24 hours after calving.

The AHV StartLac Paste is given immediately after calving for support the lactation start and mineral and energy replenishment. The StartLac Paste can also be used as a way of reactive mineral support. In that case, one tube should be gives at first and then be repeated every 12 hours (for reduction of the risk of milk fever and subclinical hypocalcaemia).

Applying AHV StartLac Tablet and StartLac Paste truly prepares the cow for an improved start of lactation. Thereby allowing here to maintain production levels, to reach a proper health status and to reach productive success.

Both StartLac Tablet and StartLac Paste are part of several AHV programmes to support Transition and Uterine Health & Fertility. To speak to an AHV Consultant in your area or our Veterinary Technical Manager please fill out our short contact form below.

Sources

Bzuneh, E., Alemneh, T., & Getabalew, M. (2020). Milk fever (parturient paresis) and its economic impact in dairy cattle production. Journal of Veterinary Medicine and Research, 7(3): 1191.
DeGaris, P. J. & Lean, I. J. (2008). Milk fever in dairy cows: A review of pathophysiology and control principles. The Veterinary Journal, 176(1), 58-69.
Dekkers, J. C., & Sorensen, D. (1999). Persistent effects of lactation on somatic cell count. Journal of Dairy Science, 82(7), 1454-1461.
Drackley, J. K. (1999). Biology of dairy cows during the transition period: The final frontier?. Journal of Dairy Science, 82(11), 2259-2273.
Engdawork, A. (2019). Review: Milk fever and its economical impacts in commercial dairy cattle production. International Journal of Agriculture & Agribusiness, 2(2), 221-242.
Fikadu, W., Tegegne, D., Abdela, N., & Ahmed, W. M. (2016). Milk fever and its economic consequences in dairy cows: A review. Global Veterinaria, 16(5), 441-452.
Huber T.L., Wilson R.C., Stattelman A.J., Goetsch D.D.. Effect of hypocalcemia on motility of the ruminant stomach (1981). American Journal of Veterinary Research, 42(9), 1488-90. Lührmann B. (2011). Fruchtbarkeit- Rechnet sich das? [PowerPoint slides]. Bezirksstelle Osnabrück der Landwirtschaftskammer (LWK) Niedersachsen. http://www.lkvmv.de:8080/examples/Information/!Fachtagung%20der%20Landwirte%20und%20Tieraerzte/29FT/Fruchtbarkeitskosten%20Vortrag%20LKV%20M-V%2012-10-2011.pdf
Mezzetti M., Cattaneo L., Passamonti M.M., Lopreiato V., Minuti A., Trevisi E. (2021). The Transition Period Updated: A Review of the New Insights into the Adaptation of Dairy Cows to the New Lactation. Dairy,  2(4), 617-636.
Mulligan, F., O’Grady, L., Rice, D., & Doherty, M. (2006). Production diseases of the transition cow: Milk fever and subclinical hypocalcaemia. Irish Veterinary Journal, 59(12), 697-702.