Addition of enzyme to starter and grower diets for ducks.

The growth performance and nutrient utilization responses of White Pekin ducks to a commercial enzyme preparation were investigated. The enzyme contained 4,000 units amylase, 12,000 units protease, and 1,600 units xylanase per gram. Twelve pens of 10 ducks were fed diets based on corn and soybean meal and wheat middlings. The diets contained the enzyme mixture at 0, 0.375, or 0.5 g/kg in a growth study for 42 d. At the end of growth study, four ducks from each of eight pens per diet were retained and continued their respective diets containing 2.5 g Cr2O3/kg for 7 d. Intestinal content was sampled to determine ileal digestibilities of energy, nitrogen, and amino acids. One duck from each pen was selected at the end of the growth study and was fitted with retainer rings around the vent for the attachment of an excreta collection apparatus; these ducks were maintained on their respective diets containing 2.5 g Cr2O3/ kg to determine dietary nitrogen, amino acids, and energy retention. Results from the performance study showed a 6 to 8% increase (P < 0.05) in BW gain for birds fed diets containing the enzyme. There was also an enzyme-related improvement in feed efficiency (P < 0.05) over the 42-d study. Ileal nitrogen digestibility was highest (P < 0.05) for ducks fed diets containing the enzyme preparation at 0.5 g/kg, but ileal digestibility of energy was not affected by enzyme supplementation of diets. Apparent nitrogen retention was greater (P < 0.05) in ducks that received enzyme at 0.5 g/kg diet than in ducks fed diets without the enzyme. Energy retention (AME and AMEn) of diets was not affected by the addition of enzyme to diets. Excreta amino acid digestibilities were found to be consistently higher than ileal estimates. The mean ileal amino acid digestibility coefficients in diets with enzyme at 0, 0.375, and 0.5 g/kg were 86.94, 88.82, and 88.87%, respectively. The addition of enzyme improved (P < 0.05) ileal amino acid digestibility and apparent amino acid retention. The study indicates that dietary enzyme supplementation improved growth performance, nitrogen, and amino acid retention of White Pekin ducks.