I just wrote:

>Equaling out the missing energy:
>To eat the whole kangaroo you would need at least 19390*2 = 38780
>28780-14890 = 13890  kcal from other sources, lets assume tubers.
>This are from carots 13890/270 = 51  kg
>or from salsify      13890/645 = 21  kg

Just a little update to the tuber amount required (due to a typo):

To eat the whole kangaroo you would need at least 19390*2 = 38780
38780-14890 = 23890  kcal from other sources, lets assume tubers.
This are from carots 23890/270 = 88 kg
or from salsify      23890/645 = 37 kg

These carots already had =  880*1   = 880 g protein
or from salsify             370*1.4 = 518 g protein.

Tubers increase,
conclusion remains.

Amadeus