My horse I posted a pic of up there was moved to a farm about a half hour from here. That farm lost ALL of their baby DONKEYS to a pack of dogs the year prior. Same pack came back in and killed an adult mini horse not long after I moved my horse there. They had to put a mule in with their mini donkeys to protect them when one foaled out later on.
A donkey with a baby is probably going to protect your sheep less than a single donkey. The whole idea behind keeping a donkey with sheep is that the donkey thinks of the sheep as its "herd" and will protect them as it would its "own". Once you have multiples, I believe you have less of a chance of the donkey associating the sheep as her "own" and a better chance the donkeys will band together and leave the sheep to their own devices.
How many sheep are you getting? Do you really need all 4 acres fenced? Your best bet would be to use woven wire to fence in a smaller area, use wire as multiple people have said in this thread, top strand to keep jumpers/climbers out, bottom outside strand to keep diggers out and a single middle strand inside to keep leaners from damaging it. You really need a smaller area in addition anyways, in case they need locked up or more easily caught (shearing, trimming, etc). I would create a small "pen" so to speak to keep them in......and as you have money, slowly fence in a larger area.
A donkey with a baby is probably going to protect your sheep less than a single donkey. The whole idea behind keeping a donkey with sheep is that the donkey thinks of the sheep as its "herd" and will protect them as it would its "own". Once you have multiples, I believe you have less of a chance of the donkey associating the sheep as her "own" and a better chance the donkeys will band together and leave the sheep to their own devices.
How many sheep are you getting? Do you really need all 4 acres fenced? Your best bet would be to use woven wire to fence in a smaller area, use wire as multiple people have said in this thread, top strand to keep jumpers/climbers out, bottom outside strand to keep diggers out and a single middle strand inside to keep leaners from damaging it. You really need a smaller area in addition anyways, in case they need locked up or more easily caught (shearing, trimming, etc). I would create a small "pen" so to speak to keep them in......and as you have money, slowly fence in a larger area.