Transitioning drought feeding into calving season

As we move through May, most spring-calving herds are entering their final trimester. While cows have had relatively stable energy requirements since weaning, this is about to change rapidly.

Energy & Protein Demand – What’s Coming

For a 600 kg Angus cow:

Stage	ME Requirement (MJ/day)	Crude Protein (%)
Mid-pregnancy (now)	~70 MJ	7–8%
Late pregnancy (last 6–8 weeks)	~90 MJ	9–10%
Early lactation (peak demand)	~120++ MJ	11–13%

Key point:

➡️ Energy demand increases by at least 60% from mid-pregnancy to peak lactation

➡️ Protein demand rises in parallel, particularly for milk production

Visualising the Energy Shift

ME (MJ/day)
120 |                          ████ Peak Milk
100 |                        ████
90 |                   █████
80 |              █████ Late Pregnancy
70 |         █████
60 |    █████ Mid Pregnancy
--------------------------------
May      June      July

What Does This Actually Look Like ?

Assuming approximate values (as-fed basis):

• Good cereal hay: ~7–8 MJ/kg

• Whole cottonseed: ~10 MJ/kg

• TMR Grain mix: ~11–12 MJ/kg

To meet maintenance energy of ~120 MJ/day (peak lactation target) with minimal paddock feed:

A) Good cereal hay only

• ~15 kg/day➡️ Thats about 3 big square 500kg bales a day for 100 cows!

B) Cottonseed

• ~12 kg/day➡️ Safer energy + protein source, good fibre contribution

C) Full TMR grain mix (for those with the feedlot infrastructure)

• ~10 kg/day➡️ Must be processed properly and introduced gradually; risk of acidosis if unmanaged

  
  

Practical Feeding Strategy

Most systems will require a combination approach, ie:  moderate levels ME fed out AND cows will mobilise body weight to meet deficits in peak lactation,

BUT this only works if they have condition to loose. Now is our last chance to maintain/add to BCS before lactation starts.

We need to enter calving at BCS 3 or better. 

Body Condition Score (BCS) Economics

For a 600 kg Angus cow:

• 1 BCS ≈ 60 kg liveweight

• There is ROUGHLY 30 MJ per kg live weigh change gain or loss

  
  

  What does that mean?

• If we need them to gain 1 BCS before calving in 3mo, they need to gain 0.7 kg per day. So they need 21 extra MJ per day ON TOP of maintenance. EG: 80 + 21 = 101 MJ per day. That looks like 12.5 kg of hay right now. 

• AND, if we are comfortable with them then loosing just 1 BCS over early lactation they can slip only 1 kg per day for 2mo. More than this risks milk production and calf quality as well as return fertility. 

➡️ Condition loss in late pregnancy = doesn't provide the buffer we need for lactation

➡️ Excessive condition loss during lactation will reduce milk yield and delay or prevent good cycling for our subsequent joining

Key Takeaways

• Energy demand spikes at least 60% from now to peak lactation

• Feed to this spike and maintain cows to BCS 3 or better at calving for optimal  milk production (calf quality) and fertility 

Early planning now prevents production losses later. Matching feed supply to demand over the next 8–12 weeks is critical for both cow and calf performance.