I breastfed my daughter until she was just over 13 months old. She never took a bottle and I was never able to get her to drink breastmilk out of a sippy. However, we had been giving her small amounts of juice in a sippy to eliminate constipation after she started eating solids. Once her pediatrician cleared her for whole milk at her 12-month appointment, we started putting trace amounts of whole milk with juice in her sippy. I gradually increased the amount of milk until she was pretty much getting whole milk with a trace amount of juice, while I was slowly eliminating one feeding at a time. Within a month, she was down to nursing only before bed time, and drinking 100% whole milk out of the sippy. Once I was satisfied that she was getting close to 16-24 oz of whole milk per day, I cut out the night time nursing.
Oh yeah, I tried heating the milk, even tried heating it with fresh bananas and stawberries then straining it, for a sweet bedtime treat and my little one didn't like it. She pretty much has gone for milk straight out of the fridge.