A bottle assembly comprising: a container comprising an open end, a closed end, a base portion, a neck, and a rim on the neck of the container and defining the open end of the container, the container having a central axis; a vent assembly positionable at least in part on the rim of the container to permit venting of the container during use and comprising at least one lateral vent extending other than parallel to the central axis of the container when the vent assembly is positioned on the rim of the container; and a collar assembly generally defining a closure for the container and being releasably engageable with the neck of the container over the open end thereof, the collar assembly and vent assembly being configured relative to each other to permit selective configuration of the bottle assembly between: a first configuration in which upon releasable engagement of the collar assembly with the neck of the container when the vent assembly is on the rim of the container, the collar assembly urges the vent assembly into substantially sealing engagement with the rim of the container such that at least a majority of a cross-section of the lateral vent is disposed below the rim; and a second configuration in which upon releasable engagement of the collar assembly with the neck of the container when the vent assembly is omitted from the bottle assembly, the collar assembly substantially sealingly engages the rim of the container. a container comprising an open end, a closed end, a base portion, a neck, and a rim on the neck of the container and defining the open end of the container, the container having a central axis; a vent assembly positionable at least in part on the rim of the container to permit venting of the container during use and comprising at least one lateral vent extending other than parallel to the central axis of the container when the vent assembly is positioned on the rim of the container; and a collar assembly generally defining a closure for the container and being releasably engageable with the neck of the container over the open end thereof, the collar assembly and vent assembly being configured relative to each other to permit selective configuration of the bottle assembly between: a first configuration in which upon releasable engagement of the collar assembly with the neck of the container when the vent assembly is on the rim of the container, the collar assembly urges the vent assembly into substantially sealing engagement with the rim of the container such that at least a majority of a cross-section of the lateral vent is disposed below the rim; and a second configuration in which upon releasable engagement of the collar assembly with the neck of the container when the vent assembly is omitted from the bottle assembly, the collar assembly substantially sealingly engages the rim of the container. a first configuration in which upon releasable engagement of the collar assembly with the neck of the container when the vent assembly is on the rim of the container, the collar assembly urges the vent assembly into substantially sealing engagement with the rim of the container such that at least a majority of a cross-section of the lateral vent is disposed below the rim; and a second configuration in which upon releasable engagement of the collar assembly with the neck of the container when the vent assembly is omitted from the bottle assembly, the collar assembly substantially sealingly engages the rim of the container.