Transition is the critical time when a cow is preparing for calving and the next lactation, and once she calves, establishing a new lactation.
There is a lot happening during this critical time.
In the final weeks of the dry period, a cow’s udder begins to produce colostrum, the vital first milk that is rich in antibodies and other valuable nutrients that will set a calf up for lifelong success if it receives enough high-quality colostrum as soon as possible after birth.
Because a cow’s placenta does not allow antibodies to pass directly from her bloodstream to the calf, the failure to provide enough colostrum in the critical first few hours of life will result in a failure of the passive transfer of immunity from the cow to the calf and a calf that is at greater risk of disease.
Research consistently supports the fact that improving our efforts to achieve this passive transfer will have both immediate and lifelong benefits to the calf.
The other important considerations that need to be addressed in the vital last few weeks of the dry period is rumen adaption to the lactation diet and managing the risk of metabolic diseases like milk fever and ketosis.
A common strategy that is often very successful is the use of ‘lead feeding’.
This is a sometimes confusing term because it is not always clear whether the lead feed is being fed to manage milk fever, adapt the rumen or do both of these important roles.
With the development in recent years of alternative lead feeding strategies to the typical anionic salt DCAD diets, I see a bit of confusion in the field as to exactly what is the best lead feeding strategy, how long it should go for and how we can monitor the success or otherwise of the transition feeding.
In short, the best lead feeding strategy that you can implement is one that will work with your particular farming system and infrastructure.
There are several options that you might consider after discussion with your herd’s nutritional adviser and veterinarian, but the bottom line is that there are very few circumstances where some type of transition or lead feeding strategy will not benefit the cows, as long as it is done well.
The benefits in reduction of metabolic diseases are often the most visible and obvious (less milk fever cows treated) but the biggest financial gains can be in the reduction of the sub-clinical milk fever and immune suppression that contributes enormously to what I usually refer to as the ‘transition diseases’ — retained membranes (RFM), dirty cows (metritis and endometritis) , ketosis and LDA.
There will be improvement in early lactation performance leading to higher peak production and milk yield and a significant gains in subsequent fertility is also associated with a smooth transition
Any disease event that occurs in those critical early weeks of lactation can set in chain a series of events that can have serious long-term implications for the cow’s health and the farm’s profitability.
Even a lameness or mastitis event in early lactation will have serious impacts on how a cow performs for the whole lactation.
A cow whose transition is interrupted by metabolic disease, poor rumen adaption to the lactating diet, sickness or illness will have a reduced feed intake and this will lead to her being in a state of negative energy balance.
This negative energy balance will cause her to mobilise her body fat reserves, causing body condition loss and putting her liver and already depleted immune system under considerable stress.
The more body fat she mobilises to make up the shortfall between her intake and the output in milk and activity will determine the consequences.
In worst cases, she can develop a fatty liver and/or ketosis which will often lead to displaced stomach or death. In most cases, however, the ketosis is mild and the real cost is the reduction of potential lactation performance, reduced fertility, increased lameness and increased transition sickness.
Transition management is another example of where proactive health care is far superior to reacting to diseases that occur.
I encourage you to consider discussing with your herd health veterinarian how you might be able to improve the management of your transition cows to reduce the risk of those critical few weeks of every cow’s life.
Dr Rob Bonanno is a ProDairy regional veterinary lead based in Gippsland, Victoria.
