Group 1 - The article emphasizes that high protein content in pet food is not always beneficial and can lead to health issues such as kidney disease if consumed in excess [2][5] - It highlights the importance of evaluating the digestibility and quality of protein sources rather than just the crude protein content [5][7] - The article discusses that "grain-free" pet food is not necessarily healthier for all pets and that food allergies can vary among individual animals [7][11] Group 2 - Key nutrients such as vitamins A, D, calcium, and phosphorus are crucial for pet health, and their appropriate levels should be ensured in pet food [11][29] - The article mentions that there are no clear national standards for "organic" pet food, while "natural" pet food must adhere to specific regulations regarding ingredient processing [13][15] - It advises pet owners to pay attention to the ingredient list and nutritional balance when selecting pet food, ensuring that high-quality protein sources are prioritized [25][32]