EFFECT OF STORAGE TIME AND DIETARY ENZYME ON THE METABOLIZABLE ENERGYAND DIGESTA VISCOSITY OF BARLEY-BASED DIETS FOR POULTRY

The effect of barley storage time and dietary enzyme addition on the e nergy value of barley-based broiler diets was studied in two experimen ts. A two-rowed winter barley (Beka cultivar) was stored at room tempe rature for 0, 3, 6, 16, and 32 wk after harvesting. At these dates, di ets were formulated using 50% barley with and without the addition of a commercial beta-glucanase-based enzyme product. In Experiment 1,320 Arbor Acres chickens (eight replicates of three 10-d-old birds and eig ht replicates of one 30-d-old bird, per treatment) were fed the experi mental diets to determine the AME(n) following a 2 x 2 x 5 (age by enz yme by barley storage time) factorial design. At the end of the metabo lism trial, viscosity of the intestinal contents was determined in 30- d-old broilers. Total beta-glucan, nonstarch polysaccharides (NSP), in vitro viscosity, and endogenous enzyme activity of barley grain decre ased with increasing storage time. Dietary AME, increased. with barley storage time (from 2,755 to 2,939 kcal/kg DM, P < 0.001, for 0 and 32 wk of storage, respectively), with enzyme addition (2,861 vs 2,919 kc al/kg DM, P < 0.003), and with the age of animals (2,826 and 2,958 kca l/kg DM for 10-and 30-d-old chickens, respectively, P < 0.001). Intera ctions of enzyme and age by barley storage time (P < 0.02 and P < 0.00 1, respectively) were also detected. These data indicate that the mini mum time of: barley storage before its inclusion in broiler feed depen ds on the animals' age (more than 6 wk for 10-d-old chickens and 3 wk for 30-d-old chickens), and that the use of enzymes allowed a reductio n in the time of barley storage. Digesta viscosity decreased with barl ey storage time (P < 0.001), and with enzyme addition (P < 0.001), an interaction of storage time by enzyme addition was shown (P < 0.007). Digesta viscosity was also negatively related to the dietary AME(n) co ntent (r = -0.68, P < 0.01). In vitro barley viscosity explained 53 an d 90% of the variation in gut viscosity produced by unsupplemented and enzyme supplemented diets, respectively. In Experiment 2, the same di ets as Experiment 1 and the barley grain were intubated into 120 adult roosters (Hy-Line(R)) to determine TMEn. Dietary and barley TMEn valu es were not affected by barley storage time or enzyme addition (3,237 and 3,037 kcal TMEn/kg DM for diets and barley, respectively).