I’ve attached a photo of how I make sure the wee-est of my litters get fed. Your best chance to save wee ones is early intervention, as follows: because rabbits feed only once or twice a day, it is safe to keep nest out of mom’s cage and in a safe location within your home. At feeding time, but before mom feeds entire litter, identify which rabbit or rabbits from your litter that need this extra help (at this point I usually put them in a little straw lined box so I don’t confuse them with the rest of the litter), next, bring mom in and place her on her back (some people do this upon their lap, but I have found that method to be difficult and unsafe for the babies so I place mom in a baby blanket lined plastic dishpan, her feet towards me as shown in the photo I have include, this way she and I can see each other, I can sooth her, have free hand to pickup and place babies on her for feedin, keep them on her, etc). To avoid accidents, I recommend no more than 2 babies on mom at one time because they squirm and slip. The babies will root around from one nipple to another, sometimes quite frantically. I’ve come to realize this helps stimulate a milk letdown in mom (letdown is when the tiny milk sacs in her breasts contract to allow the milk to go to the nipple). in this regard, sometimes when I have only one struggling kit, I’ll add the second smallest kit from the litter just to have this stimulating activity. but not alway…you kind of learn the more you do this. After this feeding, place the fed kits back into the nest box with the litter, mom back in her cage, take nest box to cage and mom will happily feed the entire litter for the day. When she’s done, pull nest box again to keep inside until tomorrow’s feeding, repeat process. I’ve found a need to do this only about 3 days to get kits over the hump and strong enough to compete. They will always be smaller than the rest of the litter, as they are usually the runt, and should not be bred. I raise for meat, so to me the extra work is worth it to assure even the runt lives to fulfill its purpose as a meal for my family.
In the photo I’ve attached, there is only one kit and the situation was very different. They were born Monday and on the 6th day I found this kit out of the nest box crouching in the corner of the cage. I don‘t know how long it was there because I had neglected to check on this litter on the 5th day to be sure all were present, but it had obviously missed at least one feeding (perhaps that morning’s feeding), so I brought mom in for this feed to be sure.