Key points

• Balance date is when pasture growth rate increases to meet feed demand.
• Balance date should have the lowest average pasture cover (APC) of the season.
• Setting target balance date APC in the range 1900-2100kg DM/ha should ensure cows are adequately fed while maintaining good quality throughout the following months.
• Balance date APC can be calculated, then the number checked against these factors:
  • Stocking rate/feed demand – high vs low
  • Predictability of pasture growth after balance date – reliable v unreliable
  • Rotation length - faster or slower
  • Controlling surplus feed after balance date – focus on maintaining quality v shifting feed to another period to fill a deficit

Why is average pasture cover at balance date important?

• If average pasture cover is too low cows will be underfed and pasture growth reduced.
• If average pasture cover is too high, pasture quality will decline later in spring and production will suffer when cows are forced to graze to a lower residual than a previous grazing.

Target average pasture cover is dependent on the stocking rate and the pasture demand per cow (influenced by days since calving, production, breed and supplement fed). This should be the lowest that APC will reach all year and most farmers will set it within the range of 1900 – 2100 kgDM/ha.

Pasture cover targets and rotation length targets outside this range should be managed carefully.

Balance date is when pasture growth rate increases to meet feed demand. 

APC at balance date is required to set up the Spring Rotation Planner (SRP). The SRP is then used to monitor actual pasture cover against target pasture cover, allowing rotation length to be sped up or slowed down to bring the farm’s average pasture cover back on target.

Calculate average pasture cover target at balance date.

Download Average pasture cover at balance date (Farmfact 1-84) for a printable step-by-step guide.  

Is the calculated balance date APC number sensible for my farm and system?

Take care interpreting this figure, as the calculation can signal pasture cover targets and rotation length targets that are not appropriate for good management (i.e fast rotations for low covers, and slow rotations for high covers are not appropriate management at balance date).

Other considerations for your balance date cover include:

• If your stocking rate and/or pasture growth rate pattern mean that supply will be much larger than demand during the peak spring growth, set your APC at the low end of the 1,900-2,100 kgDM/ha range; and
• If your spring growth after balance date is unreliable, set your APC at the higher end of the 1,900-2,100 kgDM/ha range.

Ensure your fastest rotation length, used in this balance date APC calculation, is appropriate for optimum pasture growth and suits your farm system. The rotation length at balance date is usually 20-25 days. Lower stocked farms or farms using high amounts of supplements may go to an 18 day round. Farms that are subject to very volatile growth rates (one week 80 kg DM/ha the next week 20 kg DM/ha) tend to have a slower rotation (23-25 days) at balance date, as do high stocked farms.

For a discussion on rotation lengths in relation to ryegrass leaf stage click here. 

Table heading: Factors to consider when assessing how appropriate your balance date target is for your farm

Worked examples of balance date APC targets for two situations:

High Stocking rate= feed demand of 50kg DM/ha or more at balance date (3.1 cows/ha x16 kg DM/cow = 50 kg DM/ha /day. Rotation length 23 days= 2075 kg DM/ha average pasture cover)

Low stocking rate= feed demand of 42 kg DM/ha/day or less at balance date=(2.6 cows/ha x16 kg DM/cow=42 kg DM/ha. Rotation length 21 days= 1937 kg DM/ha average pasture cover)

If you would like assistance determining your APC at balance date contact your local DairyNZ consulting officer.

Easy Pasture Cover Assessment

Determine kg DM of paddocks with this easy-to-use pasture assessment form.

Easy Pasture Cover Assessment (PDF)