Submitted to: Journal of Animal Physiology and Animal Nutrition
Publication Type: Review Article
Publication Acceptance Date: November 19, 2009
Publication Date: June 9, 2010
Citation: Pezeshki, A., Capuco, A.V., De Spiegeleer, B., Peelman, L., Stevens, M., Collier, R.J., Burvenich, C. 2010. An integrated view on how the management of the dry period length of lactating cows could affect mammary biology and defence. Journal of Animal Physiology and Animal Nutrition. 94:7-30.
The dry period is necessary to facilitate cell turnover in the bovine mammary gland and to optimize milk production in the next lactation. An eight-week dry period has long been the golden standard of management for dairy cows. Genetic improvements and new management technologies have led to higher milk production and a need for re-evaluation of the dry period length. The majority of recent studies continue to support the requirement of a 60-day dry period to maximize milk production. Inhibition of early events of involution in cows with short or eliminated dry periods is proposed in this review as an explanation for reduced milk yield in the next lactation. The influence of modified dry period length on the immune defense of the bovine mammary gland and the occurrence of new intramammary infections are poorly understood. The objective of this review is to discuss the bovine mammary gland biology, defense and systemic health when the dry period length is modified. Shortening or eliminating the dry period may minimize or remove the impact of milk accumulation at dry off, thereby lessening the immunodeficiency of the dam that is characteristic of this period. Composition of mammary secretions may change and the extent of tissue remodeling may be reduced when the dry period is reduced or eliminated. Additionally, impact of the dry period length on energy and nutritional status, and on hormonal and local regulatory factors, lead us to hypothesize that changing the dry period length might also affect intramammary infection. It is concluded that there is a need to integrate mammary gland biology and defense mechanisms in studies dealing with modified dry period lengths.