Flexible, collapsible, liquid-tight containers are described. The containers are typically formed of sheet material and having a pouring or dispensing spout with closure for same. The sheet material is preferably a laminate having at least three layers, including a central, heat-conductive layer, an outer layer of a polymer resistant to physical damage and an inner layer of a thermoplastic polymer which can be fused to another inner layer to seal the edges of the bag. Dispensing fixtures such as a nipple assembly and an esophageal feeder are described, and can be used in feeding calves and other young animals. Processes of heat treating liquids in the containers, including the pasteurizing of dairy products, are described. Methods of using the containers for feeding animals are also described.
