1. Contamination: When a bird pierces the bottle top, it creates an opening that allows air and potentially harmful bacteria to enter the milk. Birds can carry various microorganisms, including Salmonella and E. coli, which can contaminate the milk and cause foodborne illnesses.
2. Spoilage: The presence of bacteria can accelerate the spoilage of milk. Bacteria can multiply rapidly at room temperature, causing the milk to spoil more quickly and become unsafe for consumption.
3. Altered taste and quality: The piercing of the bottle top can also affect the taste and quality of the milk. The exposure to air can cause the milk to lose its freshness and develop an off-flavor or smell.
4. Risk of injury: There's a risk of small plastic particles or sharp edges from the pierced bottle top entering the milk. Consuming these particles can cause injury to your mouth, throat, or digestive tract.
If you notice that the bottle top of your milk has been pierced by a bird, it is best to discard the milk and get a fresh bottle to ensure your safety. To prevent such incidents, it's advisable to store milk in a secure location and avoid leaving it exposed to birds or other potential sources of contamination.