Typical feeding ingredients for pet foods should contain adequate folic acid. As an example, common, commercial cat feeds usually contain from 2 to 25 mg/kg folic acid, with high amounts from the Torula yeast, fish and organ meat components of these diets. Also, for most species, including dogs and cats, substantial quantities of folic acid are provided through microbial synthesis. Thus, the diets normally fed dogs and cats meet the requirements for folic acid. However, when dogs and cats are treated with antibiotics that destroy the intestinal microbes that synthesize folic acid or other disease states exist, concern should be given to having adequate amounts of folic acid in the diet and also adequate amounts of other dietary components such as choline, methionine, and vitamin B12, because of their interactions with this vitamin (Ralston Purina, 1987).
Processing of dog and cat foods, which involves high temperatures for prolonged periods in the presence of atmospheric oxygen, may destroy some of the folic acid present. In addition, more folic acid may be lost in the processing fluid if this is not retained in the final product. The presence of ascorbic acid will inhibit the oxidative destruction of folic acid, but this vitamin is not usually present in significant quantities in the feedstuffs used for commercial dog and cat foods.
Gadient (1986) considers folic acid very sensitive to heat and light, slightly sensitive to moisture and insensitive to oxygen. Folic acid can be lost during storage of premixes, particularly at elevated temperatures (Frye, 1978). After three months of room temperature storage, 43% of the original folic acid activity was lost. Verbeeck (1975) found that folic acid is stable in premixes without trace minerals but that there may be as much as a 50% loss in a premix with trace minerals stored at room temperature for three months. Adams (1982) reported only 38% retention of folic acid activity in a premix without trace minerals after three weeks of storage at 45°C; however, 57% retention of activity was retained after three months of storage at room temperature. After six months of storage in a vitamin premix, 97% of folic acid was recovered, but only 43% was recovered in a vitamin premix combined with choline and trace minerals.
