[Physiological processes in the mammary gland tissue of dairy cows during the dry period]

The dry period is essential for the bovine mammary gland to regenerate after the previous lactation. This period is necessary to render an appropriate milk yield during the subsequent lactation. Furthermore, the dry period allows the cure of existing infections of the mammary gland, but also bears an increased risk of new infection. The physiological processes within the bovine mammary gland can be devided in the following way: During the first days of active involution, a change in the cellular architecture is suggested, possibly caused by the high intra-alveolar pressure. Extensive histological changes affecting the capability of synthesis and secretion of milk components are also observed. During the involution, there is a loss of integrity of the mammary epithelial and various substances enter from blood into the mammary lumen. The histological and morphological changes continue during the steady state involution and the period of neolactogenesis. Hence, the composition of the secretion produced by the mammary epithelia changes markedly. Furthermore, the phases of the dry period differ in regard to the susceptibility towards intramammary infections. Therefore, it is necessary to consider the physiological processes during dry cow management. This literature survey describes the essential findings about the changes within the mammary tissue during the dry period.