How much feed is too much for one sitting?

[RubyFrench]

Im feeding calm and condition with a handful of chaff. The c&c recommends I feed 0.5-1.5kg for rest/light work. Sometimes it is impossible for me to get up the yard twice a day so was wandering what the maximum would be to give in one bucket feed?

 

[FairyLights]

2 kg (4 lb) is the maximum for a horse. rather less for a pony.

 

[RubyFrench]

Thankyou!