Transition cows

A cow's transition period is generally three weeks pre- until three weeks post-calving, and is one of the most important periods of a dairy cow's life. During the transition period, a cow moves from late pregnancy into lactation.

Dairy cows face many physiological challenges during this time. Appropriate management is vital to ensure a successful transition from late pregnancy to early lactation. This will optimise performance (health, milk production and reproduction) in the season ahead. Use the checklist below to stay on track.

Ensure all cows are at target body condition score (BCS) two to three weeks before calving.
- Aim for 5.5 BCS units for first- and second-calvers and 5.0 for mixed-age cows.
- It’s very difficult to change BCS in the last month before calving, as the cow partitions much of her energy and nutrient intake to her growing calf.
- Use a certified assessor to BCS your cows.
Identify at-risk animals.
- This includes all animals that are ’above’ or ’below’ BCS targets.
- The risk of metabolic disorders (e.g. milk fever and ketosis) increases in cows above BCS targets. The risk of infectious diseases (e.g. metritis and mastitis) increases in cows below their target BCS.
Allocate feed to cows according to their BCS (see Feeding the transition cow).
- Cows at or above target BCS should be fed 90 percent of their daily energy requirements for two to three weeks before calving.
- Cows that are below target BCS should be fed 100 percent of their daily energy requirements.
Supplement all cows with magnesium pre- and post-calving.
- Dry cows require 0.4 percent of dry matter (DM) magnesium in the diet for two to three weeks pre-calving.
- Lactating cows require 0.3 percent of DM magnesium for four months post-calving.
Keep dietary calcium levels low pre-calving.
- The risk of milk fever is reduced if dietary calcium levels can be maintained below 0.5 percent of DM before calving.
Supplement all colostrum cows with calcium.
- All cows should receive at least 100 grams (g) of lime flour daily during the colostrum period.
- Give more (300g) to at-risk cows, e.g. older cows, Jerseys, or those above BCS 5.5 at calving.
Maintain dietary phosphorus between 0.25 and 0.45 percent of DM pre-calving.
- Avoid pre-calving feeds high in phosphorus (e.g. palm kernel extract).
- Supplement with phosphorus if cows have a diet consisting of low-phosphorus feeds (e.g. fodder beet).
Avoid grazing effluent or recently fertilised paddocks as these can contain high levels of potassium.
- Research shows that potassium levels in pasture ranging from 1.0 to 4.5 percent of DM do not increase the risk of milk fever.
- However, effluent or fertilised paddocks can have higher potassium levels and increase the incidence of milk fever.