Red No. 2 and Violet No. 1 were banned by the FDA in mid-1970s as possible carcinogens, but prior to that they were widely used in pet foods. The sugar adds palatability and moistness and aids in preventing bacterial contamination. But the amount of sugar used in commercial foods is definitely not needed by most birds and can stress the pancreas and adrenal glands, causing diabetes or other problems. Completely devoid of protein, vitamins and minerals, for many birds sugar is, literally, empty calories.
Salt is added to many foods as a meat preservative.
Too much salt can irritate the digestive system and cause a mineral imbalance because the salt itself can upset the calcium-potassium balance. Quality Biological value. The biological value of the ingredients are a key to good nutrition. The biological value of a food is a measure of how complete the amino acids are in the proteins contained in the food. Eggs have a biological value of 100 percent.