Fascinating!
Empirically, I have found I need to feed 1.5 x the volume of Jersey milk to the sheep milk replacer we use, and using the figures in those references, that's about right!
The problem with feeding 1.5L per lamb per day, rather than 1L, is that really that's too much volume for three feeds until they're about 5-6 weeks old, so you end up feeding more often. So what time you save in mixing up the powder you lose in washing bottles! (I really ought to work out whether it's cheaper to feed the cow to produce the milk, or buy the milk powder...
)
Also, you don't want them full all the time or they don't get onto eating creep. So now I give them 100% sheep milk replacer for the first week, then mostly sheep's milk with a little Jersey milk (to get them used to it and because I think it helps them to have local antibodies in their milk) until about week 4, then roughly half-and-half for a week or two, then as they start eating creep properly, at about week 6, I move them onto 3 meals of Jersey milk (1L per day so they aren't always full, so want their creep), then down to 2 then 1.
All varied according to how they are batched and how much Jersey milk I have available. And when I say creep, it's a lamb finisher pellet actually, I've never found creep any more appealing to them and it's a heck of a lot more expensive to waste - which is what they do with most of it while they are learning to eat it!
People keep telling me I should wean earlier, not feed cows' milk, etc, but as long as the majority of my pet lambs grow and eventually sell for good money, I shall keep on doing it this way!