Getting the transition period right
Date: 1 Jun 2026
Transitioning from a dry cow to a lactating cow is the single biggest stress point in the annual calendar for our dairy cows. It is the time when we see the greatest losses, the most disease, and the biggest workload in our herds. Getting transition right is important.
What do we mean by “getting it right?”
Simply put, we want cows to get through the transition period free from disease and eating at least as well as they were before calving by Day 4 after calving. Keeping calcium metabolism fully functional throughout the transition and avoiding appetite suppression from ketosis are the most important aspects of getting the transition right.
Assuming a baseline of feeding cows to reach >BCS 4.5 by halfway through their dry period, the following are most important for a successful transition:
Sufficient magnesium in the diet. This is important to ensure that calcium metabolic pathways function well. Generally, magnesium supplementation is required from two weeks before calving. While this is the case, it can be overdone, so aim to provide the equivalent of 12-20g of elemental magnesium down the throat per day. The form of magnesium and the wastage rates of different forms of feed vary. Keep this in mind when formulating your ration.
Calcium levels in the diet. While it is true that cows need calcium approaching calving, activating the mechanism to release calcium from bone is required for them to meet that need. This is often best achieved by limiting the calcium intake in the two weeks before calving to ~0.5-0.7% of the diet. Higher levels of calcium can be fed, but only under the advice of your veterinarian or nutritionist. Increasing calcium above these levels, all else being equal, is associated with an increased incidence of milk fever.
BCS and energy balance. Getting cows to a BCS of 5.0 at calving gives the optimal balance between lower disease risk, milk production, and improved reproduction. Cows calving fatter than this can be at risk of ketosis and appetite suppression if not managed well. Cows calving lighter than this are more likely to have poorer reproduction, production and health outcomes. It doesn’t matter whether cows have gained BCS slowly or quickly over the dry period. What matters is that they get to BCS 5 at calving.
Dietary-cation-anion-difference (DCAD). Once the above factors are optimised, DCAD becomes an important aid to improving production and further reducing disease at calving. Any transition diets must be palatable, measurable, and fed for as close to the optimum window of 14 days +/- 4 days as possible. Cut cows into the springer mobs frequently, based on their expected calving dates, to avoid them eating transition diets for longer than 21 days.
Water intakes. Cows approaching calving will reduce their water intake in the 24 hours before calving, but will increase it following calving. Individual cows vary substantially in their water intake (25 to 80 litres) but typically drink 15 to 20 litres at a time following calving, on two to three occasions in the first 24 hours. Have plenty of clean water to hand in the springer and colostrum mobs.
Rumination minutes and rumen fill. Use your wearables to ensure that cows recover pre-calving rumination minutes by 4 days post-calving. If you don’t have wearables, assessing rumen fill is a useful tool. At the end of the colostrum mob, cows should have full rumens and be ruminating well. If they are not, there is something wrong. Check the cow, administer fluids and electrolytes (e.g., Selekt pump), and provide pain relief.
Our veterinary team can help de-risk the transition with a Herd Efficiency Transition Plan. Call if you would like us to optimise this season’s transition.
Dr David Hawkins BVS, Farm Vet & Consultant, Taupiri
