24 Nov 2015
Ceva Animal Health
Job Title
Find out more about the different dry off methods and their impact on udder health, management and welfare of cattle.
Presented below is an excerpt from the publication The dry period: where everything starts by Ana I de Prado, corporate technical manager, Ceva Santé Animale (France).
This publication highlights the critical importance of the dry period in dairy cattle. An explanation about the different dry-off methods and their impact on the management, udder health and welfare of cows is also provided to better understand why the dry off is not the end of the current lactation but the beginning of the next one.
The dry period is an important resting period for the dairy cow. The average duration of the dry-period is 45-60 days. It is crucial to maximise productivity in the following lactation as the preparation of the next lactation starts here.
Anatomical physiological and immunological changes happen in the mammary gland during this period, especially in the early dry period (active involution) and the time immediately prior to and after parturition (colostrogenesis).
In the early dry period, the mammary gland should quickly involute to maintain udder health and optimise milk production in the next lactation. Typically, this phase (udder involution phase) has a high risk of new intramammary infections (IMI) and it is thought to take 3-4 weeks to complete.
In the fully involuted state (between active involution and colostrogenesis) the mammary gland is considered very resistant to new infection and the duration of this state will be determined by the overall length of the dry period allowing for the processes of involution and colostrogenesis. One or two weeks before calving, the risk of new IMI is high again.
The importance of the dry period in the epidemiology of mastitis at calving has been studied for years. Some studies in the 1980’s demonstrated new infection rates by environmental organisms as 10 times higher than during lactation.
UK studies also examined the role of the dry period in mastitis epidemiology. It was demonstrated that in low bulk milk somatic cell count herds (< 250,000 cells/mL ) using blanket antibiotic treatment, there was a significant rise in the prevalence of IMI between drying off and postcalving.
Experimental trials performed by the same authors and using the latest molecular techniques confirmed that over 50% of all environmental mastitis occurring in early lactation (first 100 days in milk) resulted from infections acquired during the dry period.
It was also proved that infections from quarters that became infected during the dry period were significantly more likely to succumb to clinical mastitis with the same pathogen in the subsequent lactation than uninfected quarters.
The acquisition of new IMIs in the dry period can have a dramatic impact on the incidence and distribution of clinical mastitis in the subsequent lactation. In fact, much of the peak in clinical mastitis seen in early lactation can be attributed to dry period infection.
It is also important to remember that infections acquired in the late dry and transition periods are more likely to have a major influence on clinical mastitis in the subsequent lactation than those acquired shortly after drying off.
One important objective of the dry-off is to minimise the risk of intramammary infections. However there are two other aspects equally important and very much related to the udder health. These aspects or axes are cow management and welfare.
The genetic potential for milk production has increased during the last decades, as a result of that it has become a management challenge to stop milk production in high yielding cows at the moment of dry-off. Large amounts of milk in the udder lead to udder engorgement. Udder engorgement causes discomfort and pain and there is a reduction in total lying time and the average duration of lying bouts.
A good way to evaluate the relationship between three axes is through these key dry-off indicators: the incidence of milk leakage, the incidence of new intramammary infections and udder pain.
The two most common methods used to stop milk production at the end of lactation are abrupt dry-off and gradual dry-off. Abrupt dry-off implies an abrupt cessation of milking without any intended variation in the milk production of the lactating cow prior to that moment. This means no change in the quantity and quality of feeding, water availability, or milking frequency.
Any other dry-off method that aims to reduce the level of milk production of the cows in the days before the dry-off is performed, such as reducing milking frequency or food restrictions, is referred to as a gradual dry-off method. Most farmers prefer to use the abrupt dry-off method as the management is easier. However, with the increase in genetic potential for milk production, drying off has become a challenging moment for dairy cows.
High producing cows are difficult to dry-off abruptly as they produce more milk and are also more prone to milk leakage with an increased risk of new IMI. Thus, the National Mastitis Council (NMC) recommends stopping concentrate feeding of high producing cows two weeks before the anticipated drying off to reduce daily milk production to less than 15kg per day before the dry-off.
Intermittent cessation of milking has been shown to decrease milk production by 22% to 47% during the last week of lactation. As this management procedure reduces milk production, it results in a reduction in economic income.
In a study, cows offered 8kg of dry matter/day during the seven days before drying-off, produced 34% less milk than those offered 16kg of dry matter/day. However, this reduction in nutrients at drying off may lead to metabolic problems, especially among high-yielding cows and may cause hunger. An increase in NEFA levels can cause a suppression in immune function and therefore the cow can be more susceptible to infection.
Lowering milk production before dry-off has been found to be beneficial from the udder health perspective. However there are concerns about the effects of both feed restrictions and reduced milking frequency on the welfare of dairy cattle. Furthermore, these methods involve higher labour costs than the abrupt dry-off.
Download the full publication to continue reading about the impact drying off can have on the management, udder health and welfare of cattle.
