A COMPARISON OF ENZYME PREPARATIONS TO LIBERATE FOLIC-ACID FOR THE MICROBIOLOGICAL ASSAY OF FEED INGREDIENTS

Microbiological assays were conducted to determine the level of total folate in feed ingredients using Lactobacillus casei (ATCC 7469). Fift y-seven samples of feedstuffs were collected from several locations in the southeastern USA by a major broiler producer. Folic acid contents of samples pretreated before assay with three enzymes (conjugase, cr- amylase, a mixture of protease (Pronase (R)) were 22.86 +/- 1.99 (mu g per 100 g +/- SD) for corn (N = 14), 22.01 +/- 1.18 for fish meal (N = 7), 29.34 +/- 0.55 for mile (N = 4), 25.80 +/- 6.93 for bakery meal (N = 5), 56.76 +/- 4.97 for meat and bone meal (N = 4), 85.14 +/- 2.56 for wheat middlings (N = 5), and 193.97 +/- 11.19 for soybean meal (N = 18). Predigestion with conjugase, alpha-amylase and Pronase (R) lib erated folic acid and increased values by 22.3% compared to conjugase predigestion alone (P < 0.05). This study shows that the traditional c onjugase pretreatment does not completely free folate from complex fee d ingredients for microbiological analysis.