Bloat is very obvious, it's sudden and they seem in distress and can die. Getting to be a bit of a porker (politely called 'in good condition') is a slower process
For sudden bloat, treat with vegetable oil and baking powder instantly - see below.
To avoid it in the future, add live yoghurt to the milk (8oz pot to 2 litres milk replacement), feed it much cooler than you'd think and if necessary split back to more, smaller feeds.
It can be a killer - dad lost a lamb the other day, fed it, 2 hours later, dead with bloat. So don't delay in treating it.