Evaluation of the nutrient utilization in starter broilers fed corn based diets added with different exogenous enzymes.

Introduction. The use of exogenous enzymes directed to the hydrolysis of non-starch polysaccharide (NSP) to increase the extraction of available nutrients is an effective strategy to increase the economic benefits even from highly digestible feedstuffs. The NSP in the cell wall of the cereal grains such as corn is complex and differ in their composition and properties. To ensure maximum profits from exogenous enzymes it is necessary to evaluate their effectiveness in cereal grains of different chemical composition. Therefore, the objective of the study was to evaluate the effect of adding blends of amylase, xylanase and glucanase in diets including two sources of corn on the apparent ileal digestibility and the fecal apparent retention of nutrients.

 

Materials and methods. From 16-22 days of age, 1200 broilers were allocated in groups of three in cages and randomly assigned to 10 treatments given by the combination of 2 Corns (1 and 2) and 5 enzyme treatments: None, no enzymes added; 133 ppm of HiStarch (?-amylase activity); 100 ppm of Multigrain (mainly xylanase and ?-glucanase activities); 50 ppm of WX (xylanase activity); and 133 ppm of HiStarch + 50 ppm of WX. A dose of 1000 FYT/kg of phytase (HiPhos) was included in all diets. Titanium oxide was added to the diets (0.3 %) to estimate the apparent fecal retention of crude protein (AFRCP), fat (AFRFat), energy (AFRE), phosphorus (AFRP), calcium (AFRCa) and the apparent metabolizable energy adjusted to a cero nitrogen balance (AMEn). In addition, partial excreta sampling was used to estimate the apparent partial fecal retention of energy (APFRE). Excreta were obtained from days 19-21. At day 22, the ileal digesta was collected to estimate the apparent ileal digestibility of crude protein (AIDCP), energy (AIDE), phosphorus (AIDP) and calcium (AIDCa). The data was subjected to ANOVA using the GLM procedures of SAS under a complete randomized block design. There were 10 replicates/treatment and each replicate had the samples (excreta or ileal content) of 12 chicks.

 

Result and discussion. The main chemical difference between the corns was that Corn 1 had lower total and soluble CP and higer insoluble CP than Corn 1; these differences probably caused lower (P < 0.01) AIDCP, AIDE, AFRCP, and APFRE in Corn 1 compared to Corn 2. In addition, in Corn 1 the Enzyme treatments improved the AFRE and AMEn compared to Corn 2 (interaction of Corn and Enzyme treatments, P < 0.01); the lower values were observed with None (80.96% and 2874 kcal/kg) and the higher were seen with HiStarch+WX (83.68% and 2971 kcal/kg); in Corn 2 no differences were detected in the AFRE and AMEn among the enzymes. Furthermore, the AIDE and AIDP were lower (P < 0.01) in None compared with all the Enzyme treatments. The AIDCa was lower (P < 0.01) with None, intermediate in Multigrain and WX, and higher with HiStarch and HiStarch+WX. The AFRCa was lower (P < 0.01) with None, intermediate with WX, and higher with HiStarch, Multigrain and HiStarch+WX.

 

Conclusions. The AFRE and AMEn were improved by 3.4% in Corn 1 with the combination of HiStarch+WX. Additionally, the AIDE in Corn 1 and 2 was improved with the addition of any of the enzyme treatments by about 3.5% compared to the None treatment.

 

Implications. The energetic value of the corn can be enhanced, regardless of its quality, by the addition of exogenous enzymes, especially by the combination of HiStarch and WX.