Knowing how much feed is on offer, and how quickly it is growing, is the basis for all stocking rate and rotation decisions. Herbage mass estimates do not need to be precise — a usable estimate is better than no estimate at all.
Dry matter estimation — practical methods
Visual disk pasture meter (rising plate meter): The most common on-farm tool. Drop a weighted disk onto the pasture; the height the disk rides reflects pasture density. With a calibration specific to your pasture type, this gives kg DM/ha. A trained operator can estimate a paddock in 15–20 minutes with 50–100 readings.
Clipping: Cut 3–5 representative 0.25 m² quadrats to ground level, dry in a microwave or oven, and weigh. Multiply by 4 to get kg/m², then by 10,000 for kg/ha. Slow but accurate; useful for calibrating visual estimates.
Comparative visual estimation: Match the paddock to standard photo reference sets calibrated to kg DM/ha. Useful for experienced operators making rapid decisions in the field.
Converting herbage mass to grazing days
Apply a utilisation factor of 30–40% (leaving the rest for ground cover and recovery). Divide by daily intake per animal. Daily intake for beef cattle is approximately 2–2.5% of body weight as DM:
- 450 kg cow: 9–11 kg DM/day
- 300 kg weaner: 6–8 kg DM/day
Seasonal growth rates
Carry capacity is not static. During peak wet season growing conditions, well-managed C4 tropical pastures in 700+ mm rainfall country can grow 30–60 kg DM/ha/day. In the dry season, growth may be zero. Factor this into rotation planning — paddocks that appear empty in the dry will fill rapidly once the wet starts.