Tackling Hypocalcemia and Systemic Inflammation During the Transition Period
Calving is essential in dairy cattle for both initiating lactation and producing the next generation of heifers. However, the peri-partum period is a challenging time for dairy cows, as they have to cope with physiological challenges that increase the risk of diseases (Drackley, 1999). During and shortly after calving, dairy cattle experience systemic inflammation and high calcium demands, which are considered part of the normal cow physiology. Nevertheless, some animals may experience a higher inflammatory response or higher decrease in circulating calcium, which has been associated with a greater risk of developing metabolic and infectious diseases.
Hypocalcemia, also known as milk fever (clinical presentation), is one of the most common post-partum metabolic disorders in dairy cattle. Hypocalcemia is characterized by a sudden and drastic decrease in the serum concentration of calcium after calving, following the onset of lactation and colostrum production. While only approximately 5% of cows in the US may be affected by clinical hypocalcemia (milk fever), almost 50% of periparturient cows may experience subclinical hypocalcemia (Reinhardt et al., 2011). Hypocalcemia not only can negatively affect the productivity and fertility of the herd, but it is also considered as a gateway factor that predisposes cows to a wide range of other metabolic and infectious diseases (e.g., clinical metritis, ketosis). It has been estimated that one case of hypocalcemia alone had an upfront cost (veterinary and labor) of approximately $102.00 and an additional $161.00 (culling risk, fertility, production) of future losses (Liang et al., 2017).
A recent study proposed to classify hypocalcemia in transient (low blood calcium only the first day after calving), persistent (low blood calcium on the first and second day after calving) or delayed (low blood calcium only the second day after calving) based on the duration of the decrease in blood calcium concentrations (McArt and Neves, 2020). In this study, authors reported that primiparous and multiparous cows that had transient hypocalcemia produced more milk compared to cows with normal levels of calcium in the blood. On the other hand, either primiparous or multiparous cows with persistent hypocalcemia or delayed hypocalcemia were more likely to have an adverse event compared to normocalcemic cows. These finding suggest that hypocalcemia should be monitored for the first two days after calving, and only the cows that have persistent or delayed hypocalcemia, regardless of lactation, should be considered for preventative treatment and close monitoring to prevent further losses. Although this monitoring protocol may not be applicable on daily basis in conventional dairy farms since it may be time consuming and costly (lack of cow-side on-farm tests), it could be used on monthly or bi-monthly basis to assess overall hypocalcemia status in the herd and assess if management can be improved.
The systemic inflammation around calving is one of the newest cow physiology findings in the transition dairy cows. The triggering events of this inflammation are not uncovered yet, but it has been associated with the drop in dry matter intake and mobilization of fat tissues that cows experience during this period. It also has been suggested that this inflammation may be caused, in part, by the dry-off process. Previous literature has described that this inflammatory process starts around 14 days before calving, peaking around calving and decreasing around one to two weeks after calving. However, our lab has found that this inflammatory process may start even earlier than 21 days before calving (Figure 1). As mentioned above, this process is part of the normal physiology of the transition cow; however, animals that have exacerbated inflammation were found to have higher incidence of diseases and lower milk production. Unfortunately, there is not yet a cow-side on-farm systemic inflammation assessment test that could be used to monitor inflammation in cows around calving in order to determine which cows may benefit from anti-inflammatory treatment. However, it has been reported that over-conditioned cows (≥3.75 pts.) and cows that had calving disorders (dystocia, twins, stillbirth) may experience a higher inflammatory response. Hence, these groups of animals can be targeted as high-priority groups for preventive therapies (e.g., anti-inflammatory management) and closer monitoring.
Our lab is running a study that is focused on tackling these two physiological challenges (hypocalcemia and systemic inflammation) with calcium and anti-inflammatory treatments in high-priority cow groups (picture 1). A total of 354 multiparous Holstein cows were randomly allocated into four treatment groups: 1) ASA [n=84]: 2 oral administrations with aspirin after calving 24 h apart (125 g/cow/d; 4 480 grain/bolus), 2) ASA+Ca [n=90]: 2 oral administrations with aspirin (125 g/cow/d; 4 480 grain/bolus) and calcium (43 g/cow/d; 2 Ca boluses) after calving 24 h apart, 3) Ca [n=93]: 2 oral administrations with calcium (43 g/cow/d; 2 Ca boluses) after calving 24 h apart, and 4) UNT [n=87]: cows remain untreated. Some of the preliminary results from this study suggest that cows treated with a combination of aspirin and calcium may have a lower concentration of ketone bodies in the first 21 days in milk. On the other hand, cows treated with only oral calcium may have lower incidence of subclinical ketosis in the first 21 DIM compared to untreated cows; while cows treated with only aspirin produced around 2.55 kg/d more milk in the first 60 DIM compared to untreated cows. These preliminary findings are promising and support previous literature regarding the effects of aspirin on milk production (Barragan et al., 2020b; a).
Hypocalcemia and systemic inflammation are part of the normal physiology of the transition cow. However, when exacerbated, these physiological processes can increase the risk of animals becoming sick and having low performance. Better diagnostic tools are yet to come to help identify high-risk animals for hypocalcemia and systemic inflammation and adjust farm management for this susceptible population. Meanwhile, monitoring body condition score and calving disorders can be used to selectively implement preventative strategies, such as the one mentioned in this article, and improve cow health and performance.
References
Barragan, A.A., L. Bauman, L. da Costa, J. Velez, J.D.R. Gonzalez, G.M. Schuenemann, B. Menichetti, J. Piñeiro, and S. Bas. 2020a. Administration of acetylsalicylic acid after parturition in lactating dairy cows under certified organic management: Part I. Milk yield, milk components, activity patterns, fertility, and health. Journal of Dairy Science 103:11697–11712. doi:10.3168/jds.2020-18388.
Barragan, A.A., E. Hovingh, S. Bas, J. Lakritz, L. Byler, A. Ludwikowski, S. Takitch, J. Zug, and S. Hann. 2020b. Effects of postpartum acetylsalicylic acid on metabolic status, health, and production in lactating dairy cattle. Journal of Dairy Science 103:8443–8452. doi:10.3168/jds.2019-17966.
Drackley, J.K. 1999. Biology of Dairy Cows During the Transition Period: the Final Frontier?. Journal of Dairy Science 82:2259–2273. doi:10.3168/jds.S0022-0302(99)75474-3.
Liang, D., L.M. Arnold, C.J. Stowe, R.J. Harmon, and J.M. Bewley. 2017. Estimating US dairy clinical disease costs with a stochastic simulation model. Journal of Dairy Science 100:1472–1486. doi:10.3168/jds.2016-11565.
McArt, J.A.A., and R.C. Neves. 2020. Association of transient, persistent, or delayed subclinical hypocalcemia with early lactation disease, removal, and milk yield in Holstein cows. Journal of Dairy Science 103:690–701. doi:10.3168/jds.2019-17191.
Reinhardt, T.A., J.D. Lippolis, B.J. McCluskey, J.P. Goff, and R.L. Horst. 2011. Prevalence of subclinical hypocalcemia in dairy herds. The Veterinary Journal 188:122–124. doi:10.1016/j.tvjl.2010.03.025.
