No Grass! HELP!

Hello i have a welsh mountain pony at a livery yard and the feilds have barely any grass left in them...i have noticed he has lost a small amount of weight, i got told it would be a good idea to add a small amount of pony cubes a day (1.5kg). Just been flicking through a few sites and read that adding pony cubes could cause colic...has anyone ever heard of this? At the moment he is out all the time and only comes in to be ridden. The livery yard owner only gives him about 2 haynets weighing 6kg per week. He is ridden every day and im not sure if this is enough food for him...could anyone advise on what i should add, this is our 1st pony so just want to get it right
Thanks

Sounds like he is not getting enough hay/roughage. I was feeding my boys 6kg of hay a day and then a hard feed as well as pasture time. They really should have access to hay if there is no grass in the pasture.

Personally, I prefer upping the actual loose hay/roughage before using cubes or other processed feeds. Have you spoken to the livery owner about increasing the hay or being able to provide your own for your pony?