Hi FH, someone with more knowledge will follow up my post

I know.....I was a bit confuzzled when i first started with my sheep. From what i understand its more to do with the nutrient levels in the feed rather than how the feed is presented, although in saying that I think generally the pencils/nuts tend to have different levels than the coursemix, no matter what 'brand' you use.
So, pencils/nuts look like nuggets and have the feed value spread evenly throughout.
...... coursemix looks like a muesli type of mix and each componant will be different, but as a total gives the feed value stated on the bag. I mention this because I have noticed that when fed coursemix different ewes will prefer different parts and will pickout their favourite bits. Sometimes they will all leave certain bits (the pellets) for the birds. Logic would suggest that this means they are not getting a true ballance! On the other hand coursemix seems to be more mollassesy (sp!!) and will tempt fussy eaters.
I am not sure what 'cake' is.... could it be the highenergy feedblocks which can be left in the field for the ewes to lick whenever they want.
i think also different things get called different names, depending on what part of the country you are in. (eg i went round to my neighbour to let him know one of his ewes was cast....he was very confused -telling me there cant be any cast because none were in lamb!!!- this caused me even more confusion.....eventually we realised the confusion was caused by 'Cast' meaning aborted in his lingo!! whereas for me it means 'stuck on her back')
Anyway back on topic....Your feed merchant should be able to advise what they hold in stock, what they can get in for you, and what sheep the feeds are designed for. for example some feeds are not suitable for tups and tup lambs yet are Ok for the ewes (this depends on the breeding) due to natural copper levels in the feeds.
Hope this helps a little bit..Emma T