The effect of contact time between an exogenous enzyme and broiler starter feed

 

In Venezuela, one of the most important protein supply sources for the population is broiler meat, representing 65% of the total animal protein intake (Fenavi 2007). From an economical standpoint, feed represents 60 - 70 % of broiler production cost, according to the United Nations Organization for Food and Agriculture (FAO) (2003). The use of exogenous enzymes (amylases, xylanases, proteases) in the feed, is made in an attempt to improve the utilization of all dietary components, since they result in increased nutrient digestibility and broiler productive performance while making possible the use of lower quality ingredients (Cuts et al., 2002, Wu and Ravindran, 2001; Brenes et al., 1996). The enzymes produced by solid state fermentation (SSF) are an enzyme complex containing cellulases, pentosanases, pectinases, amylases, proteases, beta-glucanases and phytases, produced by an Aspergillus niger strain under a SSF system (Alltech, 2009). Gonzalez (2008) added 200 g/ton SSF to corn-soy broiler diets resulting in 1.9 % improved live weight, as compared to the basal diet, while production costs per kg of feed were reduced by 2.3 and 2%  in the grower and finisher, respectively, as compared to the control.

Devegowda & Ramesh (2005) point out that the inclusion of 0.002% SSF, increased body weight gain by 3.79% when compared to the controls, contrary to that, Bol & Bohorquez (2009) determined that the inclusion of SSF did not affect productive parameters. The fact that the SSF complex is produced at humidity conditions similar to those in the feed, opens the possibility that it can act on feed components, even before it reaches the digestive tract of birds. Based on the fact that the time elapsed from the inclusion of the enzyme in the diet and its use in Venezuela is variable, we think it will be useful to verify if this could increase the efficiency of the action of SSF on the.

The essay took place in the Poultry Laboratory Section, Faculty of Agronomy, Central University of Venezuela, located at an altitude of 455 meters over sea level,  with an average temperature of 25° C and an average annual relative humidity of 75% (INIA, 2010). Six hundred (600) hybrid, one-day-old  Cobb broilers of both sexes were selected from a population of 1,000 birds. A 6 m wide x 64 m long shed was used with two pen lanes, of which 30 were used for this study. Birds were subjected to 24/24 h lighting, the bed consisted of ground rice hulls. Feed was supplied through hopper feeders and one gal drinkers. After day 18, the curtain of the shed was lifted to allow for greater ventilation and fresh air during the day time. The animals were weighed by groups and the feed supplied vs. feed left overs was properly accounted for each post on the days 7, 14, 21 using an electronic scale (Kem, model FBK) with 65 kg capacity  and 1 kg precision. Using the ratio between these two variables, the feed conversion rate was obtained. On day 9, Newcastle disease (Avinew) and Gumboro disease (Bursa Vac 3) vaccines were applied, both of them by the ocular route of administration. Using a completely-at-random design, birds were allotted to 3 treatments and 10 replicates, for a total of 30 experimental units.

Table 1. Descripcion de los tratamientos incluidos para evaluar el efecto de la permanencia de la enzima exogena y el alimento para los pollos de engorde en las etapas de iniciacion 7-21d

The feeding system used was : commercial prestarter (0 - 7 days), and starter (7 - 21 days) in mash form mixed at the Poultry Laboratory Section, in accordance with a commercial formulation (Table 2) and each treatment foreseen. Feed and water were offered ad libitum. The diets were prepared with the same raw materials used at the beginning, which were stored under ideal conditions in aims to maintain their maximum nutritional quality. A contact time range was established in view that in actual practice it is impossible to prepare diets daily.

Table 2. Percent feed composition and bromatological analysis (both estimated and actual) performed in the laboratory for the starter feed (7 - 21 days)

For the analysis of the data, ANAVAR test was applied and when significant differences were found, mean Fischer''''s test was applied. Results were obtained with values of mean, standard deviation and probabilities (p<0.05) for each variable.

Average feed intake in the initial phase (0 - 7 d) was 170 g, while in the growing phase (7 - 21 d) significant differences existed as shown in Figure 1 (p = 0.01) in T1 with respect to T2 and T3 (6.2 g/group/bird) less in average with respect to T1 and the differences observed between T2 and T3 were 3.8 g/group/bird less feed intake with respect to T2, which indicates that CT between the enzyme and the feed seems to have a positive effect on feed intake, since feed intake was lower in the treatment with longer CT (T3). It is worthy to point out that in these studies CT was not considered, therefore no references in this area are shown. The results of this research were similar to those reported by Sitthigripong (2000), Jimenez (2009) and Perez (2009) who did evaluate the effect of adding or not SSF and enzymes, indicating that feed intake was reduced in the treatments where the enzymes were added, and whose response could be conditioned by the beneficial effect of the enzyme to improve diet digestibility, as reported by Wu and Ravindran (2001).

 

 

 

 

 

 

 

 

 

In the results obtained by the above-mentioned authors, enzyme-feed CT is not reported. Perhaps the differences in such CTs could explain why in some cases the effects of the enzyme are not shown and in others not on feed intake. With regard to live weight, no statistically-significant differences were found in the initial phase (0-7 days). In the growing phase (7-21 days) no significant differences were observed between the treatments, considering an average weight of 180.94 g/bird at 7 days and 713.89 g/bird at 21d. It is worthy to point out that the expected weight for this hybrid in the different phases (start, growth) is 164g and 843g respectively (Cobb500, 2008), which indicates that the live weight reported in this study in the starter phase is 16 g higher than those reported in the Manual, and regarding the live weights in growing phase the aforementioned results are 130g underneath such average, for this genetic strain, in accordance with Cobb''''s Manual. These values explain that broiler starter feeds fall within the acceptable range for this period. Regarding feed conversion rate (FCR), in the growing phase (7-21d) (Figure 2) significant differences exist (p=0.01) between T1 (FCR 1.52 ) and T2 (FCR 1.55) and T3 (FCR 1.46) where evidently T3 FCR 0.999 is lower than T1 FCR, which shows that the enzyme-feed CT tends to improve the FCR, since it was lower in the treatment with longer CT (T3). It is worth to point out that in these studies CT was not considered and therefore no references are shown in this area, in coincidence with the results obtained by Devegowda and Ramesh (2005) where the addition of SSF to corn flour/soy-based feeds for Cobb broilers allowed for increased weight and and reduced FCR.

Extended contact times (from 1-7d to 28-35d) between the SSF enzyme and the feed resulted in reduced feed intake and significantly improved feed conversion rate, without affecting live weight during the starter phase (7-21d) in broilers.

Alltech. 2009. Allzyme. SSF. En linea. Consultado el 10 Junio 2010. Disponible en: http://www.alltech.com/es/brands/Paces/AllzymeSSF.aspx.

Bol C & Bohórquez N. 2009. Efecto del allzyme SSF en dietas con base de maíz, soya y granos secos  de destilería con solubles (DDG''''s) sobre el desarrollo y características de la canal en pollos de engorde. Tesis de postgrado. Zamorano, Honduras. 23pp.

Brenes A, Lázaro R, García M, Mateos GG. 1996. Utilización Práctica de Complejos Enzimáticos en Avicultura. En: XII Curso de especialización FEDNA. Avances en Nutrición y Alimentación Animal. Madrid, España. p.135.

Cortés CA, Águila SR, Ávila GE. 2002. La Utilización de enzimas como aditivos en dietas para pollos de engorda. Vet. Méx. Universidad Nacional Autónoma de México. México D.F. 33:1.

Devegowda G & Armes K. 2005. Effect of enzyme complex (Allzyme SSF TM) on performance, intestinal viscosity and toe ash of broiler chickens fed corn-soybean meal based diets. En línea consultado el 25 Julio 2010. Disponible en: http://www.poulvet.com/poultry/articles/feed_additives/152.php.

FAO, 2003. Manual sobre la aplicación de análisis de peligros y de puntos críticos de control (APPCC) en la prevención y control de los micotóxicos. Estudio FAO Alimentación y Nutrición 73:132.

FENAVI, 2007. Lo nuestro producción 100% Venezuela. Material divulgativo de estadísticas. IX Congreso Avícola, Hotel Caracas Milton. 11 al 14 de mayo, 2005.

González A. 2008. Efecto de la reformulación de una dieta con un complejo enzimático de fermentación en estado sólido sobre parámetros productivos y viscosidad intestinal en pollos de engorde. Tesis de pregrado. Facultad de Agronomía. Universidad Central de Venezuela. 16pp.

INIA. 2010. Unidad Agroclimatológica. Instituto Nacional de Investigaciones Agropecuarias. Reporte de estación climatológica. Maracay, Venezuela.

Jiménez M. 2009. Efecto de la adición de enzimas en dietas para pollos a base de sorgo sobre parámetros productivos. Tesis de pregrado. Facultad de Agronomía. Universidad Central de Venezuela. 25pp.

Manual Cobb. 2008. Guìa de Manejo de pollos Cobb 500. Disponible en línea: htpp://www.avicolacolombiana.com/content/view/164/98. Acceso: junio 14,2010.

Pérez C. 2009. Efecto de la adición de complejos enzimáticos en dietas a base de sorgo sobre la integridad intestinal de pollos de engordes. Tesis de pregrado. Facultad de Agronomía. Universidad Central de Venezuela. 27pp.

Sitthigripong,R. 2000. Efectos de Allzyme vegpro sobre rendimiento, contenido de humedad de las excretas y economía de la producción de pollos parrilleros en Tailandia. Departamento de producción y tecnología animal, King Mongkut''''s Institute of Technology Chaokuntanham Landkrabang, Thainland. Manual de clientes , Allzyme vegpro, trabajos de investigación. 41p.

Wu Y & Ravindran V. 2001. Expanding the potential of enzymes to release nutrients: a unique microbial phytase produced by solid state fermentation. New Zeland. 123-124p.