The dry period (of a dairy cow)

“Management by neglect” were the harsh words of PhD. Robert J. Van Saun about dry cows in his 1991 paper on dry cow nutrition [1]. Over the past three decades, the dairy industry has undergone significant changes. Higher-producing cows and the growing need to manage metabolic diseases have pressured dairy farmers to focus more on the care and management of dry cows.

Even though a dry cow is not giving milk, she is far from resting. The dry period is crucial for a dairy cow for several reasons. First and foremost the dry period is used to heal the udder from existing issues and to prevent new infections. A study performed at Wageningen University in the Netherlands showed that among cows with a high cell count, only 50% recovered without a dry period, whereas 92% recovered when getting a dry period. [2] Furthermore, the dry period is needed to provide nutrients to the fetus, and to ensure optimal milk production and health during the following lactation. The drying off is also a great moment to trim hooves [3].

A period of 40 to 60 days is often seen as a sufficient dry period to prepare the dairy cow for an optimal milk production [4]. In a survey of dry cow management on 148 commercial dairy farms in the United Kingdom, the median length of the dry period was 56 days [5]. Cows without a 50- to 60-day dry period produce only 75% of the milk they would have produced if they were allowed a dry period [6].

The dry period comes with a lot of challenges such as the extra stress during the drying-off itself, change of feed, feed restrictions, and change in social groups [5] The feeding strategies should focus on obtaining maximum milk production in the next lactation, minimizing the chances on disorders such as milk fever, and ketosis and fertility. Even though dry cows are growing a calf, they need a lower feed amount as they are not giving milk. The exact needs depend largely on the body condition of the cow [6]. However, lower needs does not mean poor quality feed. Dry cow diets lacking nutrients like selenium, vitamin E, and magnesium have been linked to more health problems around calving. Good nutritional management during the dry period is paramount for a successful lactation. The dry period is “lactation-preparation” [1].

Vitamins and trace elements during the dry period

From A to Zinc, vitamins and trace elements play an essential part during the dry period. The supplementation of vitamins and trace elements in the dry period decreases number of diseases and other problems around calving.

Trace minerals such as iron (Fe), copper (Cu), cobalt (Co), iodine (I), manganese (Mn), selenium (Se), and zinc (Zn) are crucial for the health and development of both the mother and the fetus during pregnancy. During the close-up period (2-4 weeks before calving) the requirements for vitamins and trace-elements are higher as 60% of the weight of the fetus is gained in the last 3 weeks [7].

The transfer of trace-elements between the mother and the calf (passive immunity) also has an interesting additional benefit. Fetal tissues, particularly the liver, often accumulate higher concentrations of trace minerals compared to the mother's body during pregnancy. This storage of trace minerals in the fetal liver serves as a reserve that can be used during periods of mineral deficiency after birth. Essentially, the fetus is "stockpiling" essential trace minerals to ensure adequate supply during early life when dietary intake might be insufficient. After birth, these reserves are replenished even more through the colostrum. [1].

Around calving, the immune system of the dairy cow is suppressed which increases the risk of infections. This weakened immune system is partly because of a decrease in blood concentrations of vitamins A and E, selenium, and zinc. These deficiencies have also been proven to lead to mastitis, metritis, and retained placenta [8]. When selenium deficient dry cows where supplemented with selenium and vitamin E 20 days before calving, the incidence of retained placenta lowered from 50% to 10%. Insufficient vitamin A also results in retained placenta, but can even lead to abortion or the birth of weak or death calves [3].

Table 1: Parturient disorders and associated nutrients [9]

The administration of antioxidant vitamins and trace elements also positively influence energy metabolism, by reducing the need for excessive lipomobilization (fat breakdown), as evidenced by the lower BHB levels in treated cows. High BHB levels indicate energy metabolism issues, such as when glucose demand exceeds the liver's ability to produce it, leading to lipomobilization [10].

Infertility or poor reproductive performance are also linked deficiencies in trace minerals and vitamins. Several studies show quicker recovery and readiness for reproduction after calving, and improved conception rates thanks to trace minerals [11].

Dry cow bolus

Source list

[1] J. Van Saun, R. (1991). Dry cow nutrition: The key to improving fresh cow performance. Vetrinary Clinics of North America: Food Animal Practice, 7(2), 599–620.

[2] Van Hoeij, R., Lam, T., De Koning, D., Steeneveld, W., Kemp, B., & Van Knegsel, A. (2016). Cow characteristics and their association with udder health after different dry period lengths. Journal Of Dairy Science, 99(10), 8330–8340.

[3] Thatcher, C. D. (1986). Effects of nutrition and management of the dry and fresh cow and fertility. The Bovine Practitioner, 172–179.

[4] Agriculture and Horticulture Development Board. (2021). Dry cow management: A practical guide to effective mastitis control.

[5] Fujiwara, M., Haskell, M. J., Macrae, A. I., & Rutherford, K. M. D. (2018). Survey of dry cow management on UK commercial dairy farms. Veterinary Record, 183(9), 297.

[6] Extension Alabama A&M & Auburn Universities. (2021). Managing and caring for the dry cow.

[7] Nowak, W., Mikuła, R., Zachwieja, A., Paczyńska, K., Pecka, E., Drzazga, K., & Ślósarz, P. (2012). The impact of cow nutrition in the dry period on colostrum quality and immune status of calves. Polish Journal Of Veterinary Sciences, 15(1).

[8] Meglia, G., Holtenius, K., Petersson, L., Öhagen, P., & Waller, K. P. (2004). Prediction of Vitamin A, Vitamin E, Selenium and Zinc Status of Periparturient Dairy Cows Using Blood Sampling During the Mid Dry Period. Acta Veterinaria Scandinavica, 45(2).

[9] Swecker, W. S. (1995). Trace Elements and Vitamins for Dry Cows. American Association Of Bovine Practitioners Proceedings Of The Annual Conference, 50–51.

[10] Omur, A., Kirbas, A., Aksu, E., Kandemir, F., Dorman, E., Kaynar, O., & Ucar, O. (2016). Effects of antioxidant vitamins (A, D, E) and trace elements (Cu, Mn, Se, Zn) on some metabolic and reproductive profiles in dairy cows during transition period. Polish Journal Of Veterinary Sciences, 19(4), 697–706.

[11] Ballantine, H., Socha, M., Tomlinson, D. A. D., Johnson, A., Fielding, A., Shearer, J., & Van Amstel, S. (2002). Effects of Feeding Complexed Zinc, Manganese, Copper, and Cobalt to Late Gestation and Lactating Dairy Cows on Claw Integrity, Reproduction, and Lactation Performance. The Professional Animal Scientist, 18(3), 211–218.