Abstract: An experiment was conducted to study the influence of different levels of Brewers Spent Grain (BSG) and Enzyme Supplementation (ES) in the diet on the productive performance and digesta viscosity of broilers from 7-42 day of age. Six treatments were arranged factorially with 3 levels of BSG (none, 7.5 and 15%), unsupplemented and supplemented with 0.05% enzyme. Treatments were formulated with the same AME_n and protein. Each treatment was replicated four times (consist of 12 chicks per replicate). During the experimental period daily weight gain, feed conversion and feed intake evaluated. At 21 and 42 days one bird from each replicate killed for measuring digesta viscosity. The results indicated a significant reduction in weight gain, feed intake and increase in feed conversion in broilers by feeding 15% BSG at during the starter period in comparison of control group (p<0.05). ES improved body weight, feed intake and daily weight gain in starter period (p<0.05). Digesta viscosity in broilers decreased with feeding 15% BSG in starter period (p<0.05). It was concluded that broiler performance is improved by ES at early ages. Also, BSG may be used up to 7.5 and 15% of the diets of broilers at starter and grower period, respectively.

INTRODUCTION

Brewery Waste (BW) is a by product of beer making and contains 21-29% crude protein on DM basis (Su and Heng-Chun, 1995; Westendorf and Wohlt, 2002). BW consists largely of structural carbohydrates and the protein remaining when barely is malted and mashed to release sugars for brewing. It is a concentrated source of digestible fiber, with good amino acid, B-vitamin and phosphorus contents but is low in other minerals. The results show that traditionally BW has only been used for feeding ruminants, due to the high level of fiber (Cromwell et al., 1993; Shurson, 2003). However, research has shown that BW can be successfully fed to poultry (Parsons et al., 1983; Noll et al., 2001). Brewers Spent Grain (BSG), the main by-product of the brewing industry, is rich in proteins and dietary fiber (Mussatto et al., 2006). The composition of BSG varies with barley variety, time of harvest, adjuncts added and brewing technology (Santos et al., 2003). During malting, barley proteins are in part degraded to amino acids and small peptides by a range of proteolytic enzymes (Baxter, 1981; Enari and Sopanen, 1986; Jones, 2005). Nutritional evaluations of BSG have been reported by Celus et al. (2006), who stated that the typical crude protein content (DM basis) of BSG was 26%. In practical diet formulation of broilers inclusion rates up to 20% of BW did not depress gains or feed conversion during early growth (0-4 and 4-8 weeks) and rates of up to 30% were not observed to decrease performance in broilers from 8-12 weeks old (FAO, 2005). Celus et al. (2006) reported that β-glucan content decreased withBaxter malting but amount of arabinoxylans increased extremely which are known to have an anti-nutritive effect on broilers and to decrease energy and nitrogen availability. Valverde (1994) found that BSG is rich in cellulose (17%) and non-cellulosic polysaccharides (mainly arabinoxylans) (39%). Soluble Nonstarch Polysaccharides (NSP) present in viscous grains increase digesta viscosity which interferes with the activity of intestinal enzymes in the gastrointestinal tract. As a consequence, feeding barley increases the incidence of sticky droppings, reduces the extent of digestion and absorption of nutrients and impairs broiler performance (Annison and Choct, 1991). Increases in intestinal viscosity reduce macronutrient digestibility, digestive enzyme activities (Smits et al., 1997), ability of the gut to vigorously mix intestinal contents and the rate of passage of digesta through the intestine (Salih et al., 1991). Deleterious effects associated with increased intestinal viscosity are more pronounced in younger birds (Almirall et al., 1995). Enzymes reduce viscosity and improve nutrient digestibility and feed intake (Lazaro et al., 2003a, b). Therefore, the objectives of this study were to examine the influence of ES on the productive performance and intestinal viscosity of broilers fed different levels of BSG.

MATERIALS AND METHODS

Birds, diets and enzyme: About 1 day old male (Ross 308) broiler chicks were obtained from a local commercial hatchery. The birds were fed commercial chick starter diet (21% CP) for a 7 days pre-experimental period. At 7 day of age, 288 of the birds were selected according to body weight (145±2 g) and randomly distributed among the 6 treatments, using 12 birds per pen and 4 replicate pens per treatment.

Table 1:	Composition and nutritive value of the experimental diets1
1Supplied kg-1 of diet: selenium, 0.15 mg; iodine, 2 mg; cobalt, 0.2 mg; copper, 6 mg; iron, 30 mg; zinc, 50 mg; manganese, 80 mg; retinyl acetate, 7,500 IU; cholecalciferol, 1,500 IU; dl-tocopheryl acetate, 7.5 IU; riboflavin, 5.3 mg; pantothenic acid, 8 mg; pyridoxine, 1.8 mg; folic acid, 0.5 mg; menadione sodium bisulfite, 2 mg; vitamin B12, 12.5 mg; niacin, 24 mg; choline, 350 mg, ES have been added to each diet as supplement with two ration of 0.0 and 0.05%

The experiment was of 6 weeks (7-42) duration. All chicks received an isocaloric and isonitrogenous starter feed (21% CP and 2950 kcal ME kg^-1) during the 7-21 day followed by a grower feed (Table 1). All diets were formulated to meet or exceed requirements by the National Research Council (NRC, 1994) for broilers. The 3x2 factorial arrangement included three levels of the BSG (none, 7.5 and 15%), unsupplemented and supplemented with 0.05% enzyme included in experimental diets. BSG was obtained from commercial malting company. The commercial enzyme preparation (Endofit WNC, Biform Canada) used in this study was contained 440 IU of β-glucanase and 1200 IU of arabinoxylanase per gram. The composition of the experimental diets is shown in Table 1.The birds had free access to water and feed and were provided with continuous light. Body weight and feed intake was monitored weekly with pen as the experimental unit. Mean weight gain, feed intake and feed-to-gain ratio were used to determine the growth performance.

Viscosity: At 21 and 42 day of age, one chick per replicate cage were randomly selected and killed by cervical dislocation. The jejunum, defined as the region from the pancreas tail to the Meckel’s diverticulum was dissected and the content collected as described by Bedford et al. (1991). The viscosity (centipoise, cP) of a 0.5 mL aliquot obtained from the supernatant solution was determined by using a Brookfield digital viscometer.

Statistical analysis: Statistical analysis of results was performed using the GLM procedure of the SAS software (SAS, 1990). Productive performance data were analyzed as a randomized complete design and main effects (level of BSG and enzyme) and their interactions were studied. All differences were considered significant at p<0.05. According to the following general model:

Where:

RESULTS AND DISCUSSION

Performance: No significant differences were observed in feed intake of birds by feeding BSG as compared to control grope. Enzymes significantly improved feed intake at 14-21 day (63.4 vs. 65.4 g day^-1) (p<0.05) (Table 2). Exogenous enzymes have been shown to dramatically improve the use of certain feedstuffs such as barley, wheat, rye and oats, especially in poultry (Marquardt et al., 1994; Zhang et al., 1997). The study showed improved growth performance when ES was included. No significant differences were noted for bird feed intake in grower periods by ES (21-42 day).

Table 2:	Daily feed intake (g day-1) of broilers fed different levels of BSG1 (%) diets with or without ES2 (%)
1Brewers spent grain; 2 Enzyme supplementation (Endofid W GNC, Biform Canada); 3There were four replicate cages per treatment and the number of birds per cage was 12 from 7-21 day and from 21-45 days a-bMeans within the same column with different superscripts differ significantly (p<0.05)

Table 3:	Weight gain (g/d) of broilers fed different levels of BSG1 (%) diets with or without ES2 (%)
1Brewers spent grain2, Enzyme supplementation (Endofid W GNC, Biform Canada), 3There were four replicate cages per treatment and the number of birds per cage was 12 from 7-21 days and 11 from 21-45 days. a-bMeans within the same column with different superscripts differ significantly (p<0.05)

There were no significant treatment effects on feed consumption through the end of the experiment. Treatment effects on BW in the end of the starter period by enzymes supplementation was due to increase in feed consumption (p<0.05). Table 3 is a results of body weight gain determined at 14, 21, 28, 35 and 42 day of age. There were no significant treatment effects observed on body weight gain by ES on day 42 but the enzyme treatments improved body weight gain at 21 day of age. Table 4 feeding 0.05% ES during the starter period may be more beneficial than thereafter, as observed in the trial. It is possible that at early ages the beneficial effects of ES on nutrient retention overwhelmed the negative effect of the higher soluble NSP content and viscosity in the gut. The improved performance observed at early ages with ES are consistent with previous research with young chicks fed barley diets (Vranjes and Wenk, 1995). Villus height and surface area increased with ES and improvements in nutrient retention and productive performance detected (Viveros et al., 1994). Bedford et al. (1991) reported that viscosities were significantly correlated only with carbohydrate fractions that existed as complexes >500,000 Da. It’s seemed that high concentration of arabinoxylans of BSG degraded to small units <500,000 Da in malting process that resulted to no increase of intestinal viscosity or reduced performance.

Intestinal viscosity: Intestinal viscosity was not affected by enzyme supplementation but tended to decrease with age an observation consistent with previous results (Petersen et al., 1999). Water to feed intake ratio increases with age and as a consequence, DM and viscosity of the intestinal content is reduced. Moreover, Petersen et al. (1999) speculated that the decrease in viscosity with age observed in broilers may be a consequence of acclimatization to diet, including an alteration in the microflora. feeding 15% BSG decreased Intestinal viscosity (p = 0.05) (Table 5). The major endosperm cell wall NSP are the β-glucans in barley (Cambell and Bedford, 1992) But β-glucan content decreased with malting but amount of arabinoxylan increased extremely (Celus et al., 2006). In the current study, the soluble NSP of BSG had no detectable viscosity effects. The results of these studies indicate no negative effect of feeding 15% BSG throughout the broiler growth period.

Table 4:	FCR of broilers fed different levels of BSG1 (%) diets with or without ES2 (%)
1Brewers spent grain; 2Enzyme supplementation (Endofid W GNC, Biform Canada); 3There were four replicate cages per treatment and the number of birds per cage was 12 from 7-21 days and from 21-45 days; a–b-cMeans within the same column with different superscripts differ significantly (p<0.05)

Table 5:	Viscosity of intestinal content of broilers
1Brewers spent grain; 2Enzyme supplementation (Endofid W GNC, Biform Canada); 3 3There were four replicate cages per treatment and the number of birds per cage was 12 from 7-21 day and 11 from; a,bValues within a rows with unlike superscripts differ significantly (p<0.05)

The results of the present experiment clearly indicate that BSG may be used up to 7.5% of the diets without having adverse effects on broilers performance. The use of enzymes in diets for broilers based on BSG is recommended at early ages. But more studies are needed to evaluate the beneficial effects of enzymes on broiler productivity.

CONCLUSION

The results indicated a significant reduction in weight gain, feed intake and increase in feed conversion in broilers by feeding 15% BSG at during the starter period in comparison of control group (p<0.05). ES improved body weight, feed intake and daily weight gain in starter period (p<0.05). Digesta viscosity in broilers decreased with feeding 15% BSG in starter period (p<0.05). It was concluded that broiler performance is improved by ES at early ages. Also, BSG may be used up to 7.5 and 15% of the diets of broilers at starter and grower period, respectively.