5.05 - Weaning age and projected liveweights

The following table shows weaning and projected live weights for three target growth rates relative to pasture quality in British breed cattle.

Projected growth rate to weaning (kg/day) Pasture quality (MJ ME/kg DM) Assumed birth weight (kg) LW at 100 days of age (kg) LW at 150 days of age (kg) LW at 200 days of age (kg) LW at 250 days of age (kg)
1.1 12.0 (80% digestibility) 36 146* 201 256 311
0.9 10.5 (70% digestibility) 34 124 169 214 259
0.7 9.0 (60% digestibility) 31 101 136 171 206
LW = liveweight
* Calculated as (1.1 × 100) + 36 = 146kg
Source: data extrapolating from results of the high, medium and low pre-weaning pasture treatments used in the crossbreeding research project conducted by NSW Agriculture at Grafton, NSW.

Note: These are averaged projections over the whole pre-weaning period. There will be a range in weaning weights either side of these values, and the range will be greater in herds with extended mating seasons. As such, earlier weaning at an age of 100–120 days (and a minimum liveweight of 100kg) can be successful for calves grazed on the high quality pastures (greater than 11.5MJ/kg DM). Earlier weaning should be managed carefully, particularly if calves are grazed on lower quality pasture to weaning. Ensure that they are heavy enough, and that there is an adequate supply of high quality feed for these calves during and after weaning.