Traditionally the period from three to four weeks before calving through to three to four weeks following calving has been considered the transition period.
This period is when as much as eighty percent of the herd's disease costs are generated and where up to four percent of cows are culled from the herd as a consequence of problems arising at this time. We are now being encouraged to think of this as a 90 day period extending from 60 days prior to caving through to 30 days following calving.
Given the close connection between metabolic diseases, reproductive performance, efficient rumen function and immune suppression, a carefully planned and executed transition feeding programme is now seen as a prime opportunity to set the herd up for a successful season. Information from Dairy Australia would indicate that the return on investment is likely to be $4.00 to $5.00 per $1.00 spent!
For the dairy cow, numerous changes are occurring as they prepare to dry off and then set up for another birth and then a fresh lactation - changes such as:
- The cessation of milking at dry-off
- Changes in their environment and their ration
- Rapid foetal growth
- A decline in dry matter intake just prior to calving
- The start of colostrum production
- Rapid changes in blood hormonal levels
- The process of giving birth
- A rapid increase in milk production
A further complication to these changes is that this year many cows will need a longer dry period with ad-lib feeding throughout in order to provide the opportunity for facial eczema damaged livers to heal and for sufficient weight gain to occur so that target body condition scores can be reached by the start of calving.
A well managed transition period will set the scene for top milk yeilds and maximal fertility. Conversely, if not well managed, production will be curbed and herd fertility will be adversely affected.
The focus of the transition period is to:
- Help prepare and adapt the rumen for the high intakes required of the milking cow diet - the quicker a cow reaches her peak intake following calving the less weight she will lose, with the obvious flow-on effect into increased production and improved fertility.
- Help prepare the cow to manage her blood calcium levels. Low blood calcium at the time of calving is most obviously seen as milk fever but this is just the tip of the iceberg - remember that for every case of milk fever that you treat there will be 15 or 16 other cows in the herd that will be suffering from a reduced appetite ultimately leading to lost production and reduced fertility. Added to this there will be the increased risk of disease through a suppression of their immune system.
There are now a number of tools available as well as a range of products that can assist the herd manager to fully prepare cows to successfully transition from late pregnancy and to become the highly efficient "athlete" required on the modern dairy farm - talk it over with your vet sometime soon!