Once you start creep feeding you are adding enormous overheads. Much better if you can take them straight off the grass.
I am always disappointed.
You ever think there's cause and effect there?
I agree, of course, that feeding adds costs. But let's do some sums. Let's say we feed a basic 16% feed, like Champion Tup & Lamb, at half a pound per head per day for a month. That's 30 x 0.25kgs = 7.5kgs. That'll cost about £3. It should give the lamb a bloom so the punters should pay at least an extra 10ppk. Assuming you're selling at around 40kgs, that extra 10ppk adds £4. That's without accounting for the extra weight it puts on - should be at least another kilo, and/or you get it away sooner, which may or may not translate into money on your farm, depending on how you use your land. Also, by getting it away earlier, you may be selling when prices are a bit higher, before everyone else's lambs are ready off grass, too.
I could go on... by feeding lightly, the lambs are kept in tip-top condition, more likely to withstand any setbacks, infections, etc. This may translate into more lambs away earlier (in addition to the effect of the feed on weight and condition) or could even mean less losses. The lambs' demands on their mothers will be a little less, so their mums are less likely to get mastitis, and will carry a bit more condition, which again would translate into greater resilience, less losses, less costs of feeding up for culls, possibly higher lambing percentages next year...
I don't diss grass-fed systems. But it is not correct to state that feeding erodes profit. Done intelligently, it can and should maximise profit.