I have discovered the reason for sliminess.... let me explain. I live in Turkey in a very small village and buy my milk each day from the neighbour who spends each day, every day with her two cows, moving them along the green pastures like the shepherds would have done hundreds of years ago back in England. I have learnt to speak Turkish and chat regularly with the village ladies. The last 3 times I have made yoghurt, it has been very slimy and I thought it was my mistake somehow with the weather having warmed up a lot lately and possibly leaving my pot too long in its blankets to set. However, today I spoke to the villagers and they explained to me that the cow is pregnant and this is the reason the milk has become slimy and this is how they first learn that a cow is pregnant. I just thought this was quite fascinating and thought it was worth passing on to others who have also been affected by this. Some of the villagers actually prefer this slimy texture and consider it delicious, but actually I have chosen to purchase my milk from the other neighbour for the next 5 months until the calf is born.