You can give your baby a 5 day old breast milk that was store properly in the fridge or in the freezer.
According to the 5 5 5 rule if the breast milk is in the refrigerator the 5 5 5 rule states that the refrigerated breast milk should be used within 5 days so if the breast milk is only 5 days old in the fridge it can be used and if it was frozen it can be used up to 5 months later.
The reason why you can't store breast milk in bottles with nipples is because the nipples are not airtight due to the opening in the nipple.
The nipple opening can expose the breast milk in the bottles to bacteria and contaminants from the air and potentially compromise the breast milks safety.
When storing breast milk it's best to use bottles that have secure lids to properly seal the milk when storing it.
However if the bottles have a cap that seals over the top of the nipple then you can safely store the breast milk in the fridge with the cap over the nipples and the nipples in place.
You can also use breast milk storage bags for better storage of breast milk or use bottles with secure lids.
Always sterilize any containers or bottles before storing breast milk.
Be sure to refrigerate any breast milk that is not being used to prevent spoilage.
There's also another rule for breast milk storage and breast milk which is known as the 5 5 5 rule.
The 5 5 5 rule for breast milk is a guideline for breast milk being stored at room temperature, in the refrigerator and in the freezer.
The 5 5 5 rule for breast milk states that if the breast milk is at room temperature the breast milk should be used within 5 hours.
If the breast milk is in the refrigerator the 5 5 5 rule states that the refrigerated breast milk should be used within 5 days.
If the breast milk is kept in the freezer and frozen the 5 5 5 rule states that the breast milk should be used within 5 months of freezing.