Incorrect feed allocation is most commonly caused by an incorrect break size. Knowing the crop yield ikely utilisation, animal requirements and crop ME is vital to set the right break size.

 

Crop utilisation

Not all of a forage crop is eaten, particularly in wet weather. Utilisation also depends on animal performance goals, and for high weight gains, lower utilisation must be accepted, e.g. maintenance utilisation of kale might be 80-85%, but needs to be <75% for body condition gain.

 

Typical winter crop utilisation rates (vary widely

 

Stock requirement example

When winter crop yield is measured, a sample of what will be grazed should be sent for ME analysis. Next, you need stock ME requirements, which are available - see table below. In this example, dairy cow ME requirement depends on liveweight, and changes during pregnancy.

 

Cow ME requirements for 1 body condition score gain in 60 days (MJ ME/cow/day)

 

 

Example of crop allocation 

In this example, 100 cows (450 kg/head LW), 12 weeks pre-calving, are to be break fed kale, with the aim of adding 1 BCS over winter. Kale will comprise 70% of their diet and baleage the rest. The crop yields 14 t DM/ha, utilisation is estimated at 85% and feed quality is 11.5 MJ ME/kg DM. The width of the crop paddock is measured at 200 m.