Cow health is a challenge

Managing cow health is a challenge at the best of time, but the factors affecting it are exaggerated during the dry period as they approache calving.  However, maintaining good health at this time is critical to ensure both the delivery of a live, viable calf and a cow that can cope with the rigours of early lactation.  So altering the way that the dry cow is managed will have health implications and the length of the dry period could be especially significant.  Here, vet adviser at Intervet, Rosemary Booth offers a few pointers on what to consider.

The impact of changing the length of the dry period on the health of the cow are related to many specific and some rather general issues: -

• The impact on the cow of maintaining dry matter intake and improving the energy balance immediately before and during the critical first part of lactation
• The cow behavioural aspects of grouping and managing cows during the dry cow period become simpler and possibly less stressful
• The physical length and nature of the dry period could alter the performance of dry cow therapy and the cow’s responses to new mastits infection.  Included in this would be what happens to individual somatic cell counts.

Better energy balance

Shorter dry periods with a single ration being fed throughout will enable us to simplify dry cow feeding and minimise the fall in dry matter intake at the end of the dry period.  The cows basically stay more ‘switched on’ so there is less of a drop in energy intake and thus less negative energy balance in the immediate post-calving period. This produces: -

•  Less loss of body condition

•  Less mobilisation of body fat with NEFAs staying lower

•  Less fat laid down in the liver with lower triglyceride levels and thus less fatty liver disease

•  Greater health and better natural immunity at calving

All of this will reduce the risk of metabolic disease and the other conditions commonly seen in early lactation.

• Displaced abomasums
• Ketosis
• Retained foetal membranes
• Endometritis
• Mastitis

Different cows for different strategies??

The most difficult aspect of discussions about dry periods is that we have a dilemma.  Should we consider allocating dry periods according to cow characteristics e.g. length of previous lactation, previous mastitis history or parity number as all these things could have an input into the success or otherwise of their dry period?

• 1^st lactation cows appear to need longer dry periods so that the udder can continue developing.  Reducing the DP to 30 days can have a marked reduction in milk yield

• Cows with long calving intervals benefit from shorter dry periods as they are at risk of putting on too much condition  

• The relationship between calving interval and DP is more profound in older cows, again as they have an increased tendency to put on weight

On the other hand we need to set up protocols that are easy to apply in practice and with larger herds this means a “one size fits all” approach.  The distinctions described could become more important as we move towards more extremes of shortening the dry period.  However, at the more moderate level that most Cephaguard DC shorter dry period farms favour (40 days or so) it is likely that most of these individual issues will not have a significant role in the success of allocating a dry length.