J. Appl. Poult. Res.
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J APPL POULT RES 2007. 16:52-61
© 2007 Poultry Science Association
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Research Reports

Evaluation of a Feed-Grade Enzyme in Broiler Diets to Reduce Pododermatitis

M. Nagaraj, J. B. Hess and S. F. Bilgili1

Department of Poultry Science, Auburn University, AL 36849

1 Corresponding author: bilgisf{at}auburn.edu


   SUMMARY
TOP
 SUMMARY
DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Nutritional and management interventions are needed to reduce the incidence of pododermatitis in poultry. In this study, enzyme (Allzyme Vegpro) supplementation of corn-soybean meal-based broiler diets was evaluated in an effort to reduce total N and NH3 production and its effect on pododermatitis in broiler chickens. A total of 1,600 mixed-sex chicks were raised on floor pens in a design involving 2 x 2 x 2 arrangement of protein level [high or low], protein source [all vegetable (Veg) or vegetable plus animal (Veg + Ani)], and enzyme [with or without enzyme supplementation (0.06%)], on a 4-stage feeding program (4 replicate pens/treatment; 50 birds/pen). In addition to live performance, the feet were scored for incidence of lesions on all birds on 28, 42, and 57 d of age, and the severity was recorded as none, mild, and severe. Pooled gut samples were collected at 57 d of age to determine viscosities of fore- and hindgut contents. Pooled litter samples were analyzed for moisture, total N, and NH3 production at 14, 28, 42, and 57 d of age. Live performance of birds did not vary among the treatments (P > 0.05). The incidence of pododermatitis was significantly affected by protein source at 42 d (P < 0.05), with birds fed all-vegetable diets showing higher incidence and severity than those fed vegetable plus animal diets. At 57 d of age, birds reared on all-vegetable diets with enzyme supplementation showed a lower incidence of mild footpad lesions compared with other treatments. Enzyme supplementation reduced viscosity of the gut contents irrespective of the protein level or protein source. Higher levels of litter NH3 were observed with high-protein diets (28 and 42 d), all-vegetable diets (28 d), and with enzyme supplementation (28 and 42 d). In this study, enzyme supplementation had little effect on litter total N and NH3 production levels, but reduced viscosity of the gut contents and severity of pododermatitis in older birds.

Key Words: broiler • footpad quality • pododermatitis • protein level and source • enzyme


   DESCRIPTION OF PROBLEM
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Over the past decade, the poultry industry has benefited from growing domestic and international markets for chicken feet (paw) as a profitable commodity [1]. Insight into the causes of downgrading is required to develop wholesome chicken feet [2, 3]. Pododermatitis, a type of contact dermatitis [4, 5, 6], is a common cause of condemnation and downgrading of chicken feet [7]. In addition, the incidence and severity of pododermatitis has been an animal welfare issue in recent years [8, 9, 10, 11]. Feed composition and programs have been implicated as an important factor in the etiology of pododermatitis. The use of high nutrient-density diets [12, 13], high protein [14, 15], and high levels of soybean meal inclusion [15, 16, 17] in broiler diets have been implicated to cause a higher incidence of pododermatitis. High-protein diets lead to excessive N excretion and, subsequently, result in high NH3 levels in the broiler house. The nonstarch polysaccharide (NSP) fraction of the soybean meal has poor digestibility that results in sticky and potentially irritant droppings and wet litter conditions. [16, 18]. These conditions could certainly predispose birds to contact dermatitis and other ulcerative lesions [16, 19, 20].

Peptic polysaccharides comprise the major fraction of NSP in soybean meal. These include 1–4 ß-arabinogalactans; 1, 2-1, 4-ß-rhamnoga-lacturonans, and {alpha}-galactosides [21]. The dietary soluble NSP hinder the digestibility of lipids, protein, and starch [22, 23] and also reduce nutrient absorption [24]. In young birds, limited amounts of endogenous enzymes [25, 26] limit digestibility of carbohydrate and vegetable protein diets [27]. Researchers have shown that use of exogenous enzymes can improve digestion [28] by breaking the polymers, inactivating the antinutritional factors, supplementing endogenous enzymes, manipulating gut microflora populations [29], and reducing the digesta viscosity [30].

Until recently, enzyme supplementation was assumed to have a limited value in corn-soybean meal rations. Now, many commercial exogenous enzymes are being marketed for use in corn-soy diets to further improve animal performance and meat yield. The common enzymes used are protease and carbohydrase [31], {alpha}-amylase [32], and multienzyme preparations containing xylanase, ß-glucanase, arabinofuranosidase, glucosidase, galactosidase, cellulose, and polygalacturonase [33].

Previous research has shown that proportion and severity of pododermatitis can be induced by feeding broilers high-protein and all-vegetable diets [15]. It was our hypothesis in this study that the of use of a feed-grade enzyme (Allzyme Vegpro) [34] designed to target the NSP fraction of soybean meal in broiler feeds might help in reducing the incidence and severity of pododermatitis in broiler chickens.


   MATERIALS AND METHODS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
A total of 1,600 one-day-old straight-run broiler chicks were randomly allotted to 32 different pens in a curtain-sided, naturally ventilated concrete floor house. The cement-floored pens were bedded with 8 cm of new pine shavings as litter. All the pens were equipped with tube feeders and bell drinkers. There were 50 birds of mixed sex/pen and 8 replicate pens/each treatment [35]. Experimental design included a 2 x 2 x 2 arrangement of protein level (high or low), protein source [all vegetable (Veg) or vegetable plus animal (Veg + Ani)], and enzyme [with or without enzyme supplementation (0.06%)]. The nutrient and ingredient composition of the experimental diets is shown in Tables 1Go and 2Go. The level of poultry by-product meal was kept constant for each feed, and the soybean meal levels were adjusted to attain the desired protein levels. The enzyme was supplemented at a recommended level of 0.06% [34]. The experimental diets were provided on a 4-stage feeding program consisting of crumbled starter (0 to 14 d of age), pelleted grower (15 to 28 d of age), finisher (29 to 42 d of age), and withdrawal (43 to 57 d of age) diets. Birds were reared on a 23L:1D lighting program, in which they received feed and water continuously. All birds were weighed on a per-pen basis at 14, 28, 42, and 57 d of age, and average BW, feed conversion, and mortality were determined.


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  		Table 1. Composition of experimental diets1
 

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  		Table 2. Inclusion levels of soybean meal (SBM), poultry by-product meal (PBPM), and enzyme in the experimental diets (%)
 
On 57 d of age, 8 birds were randomly sampled from each treatment of intestinal viscosity measurements. The birds were killed by CO2, and foregut (gizzard to Meckel’s diverticulum) and hindgut (Meckel’s diverticulum to ileoceco-colic junction) segments of the intestine were collected. A small (1.5 g) sample of the intestinal contents was placed in a microcentrifuge tube and centrifuged [36]. The supernatant was collected and stored at 4°C until further analysis. Viscosities were measured in centipoises using a Brookfield DV-E viscometer [37] following the procedure described by Bedford and Classen [38].

The incidence and severity of pododermatitis were recorded on 28, 42, and 57 d of age by a visual ranking system [39]. Litter samples were collected from each pen and pooled by each feeding program for litter moisture [40], total and NH3-N analysis on d 14, 28, 42, 57 [41, 42]. The data were statistically analyzed by the GLM procedure of SAS [43, 44, 45]. All percentage data were transformed to arcsine values before analysis, and the significance level was set at P < 0.05.


   RESULTS AND DISCUSSION
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
This was a mixed-sex trial in which the sex ratio was not equalized. Total mortality at 57 d of age was higher than normal, but no differences (P > 0.05) were detected in mortality among the treatments throughout the course of the study (Table 3Go). This could be attributed to the high environmental temperatures during the experimental period (July and August). Both protein level and source had a significant effect on BW, but only at 14 d of age, when birds raised on high-protein diets and vegetable diets had high BW. High-protein diets improved feed efficiency on 28 and 42 d of age. A significant (P < 0.05) protein level x protein source interaction at 28 and 42 d of age showed that birds reared on low-protein and vegetable plus animal diets had a depressed weight compared with other treatments (Figure 1Go). This was consistent with a previous study [15], but the effect was not seen at 57 d of age.


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  		Table 3. Influence of protein level, protein source, and enzyme on broiler performance1
 

Figure 1
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  		Figure 1. Protein level x source interaction for BW (P < 0.05). Veg = all-vegetable protein (only soybean meal); Veg + Ani = vegetable plus animal protein (poultry byproduct meal).

 
Interestingly, the performance of birds fed with enzyme-supplemented diets was similar to the birds that received diets without enzyme at 14, 28, and 42 d of age. This was in contrast to other researchers’ findings, in which they have observed significantly better feed efficiency with enzyme supplementation [23, 24, 27]. This could be due to the variability in nutrient density and the corn-soy used to formulate the diets. It is also reported that a certain extent of enzyme denaturation may occur due to the acidic pH of the stomach, resulting in minimal improvements in live performance. Smiricky et al. [46] concluded that there may be other antinutritional factors apart from oligosaccharides that potentially inhibit efficient soy protein utilization in the gut, even with enzyme supplementation. Given the array of commercial enzyme products available, further research is required to explore the ideal enzyme combination that targets the highly indigestible oligosaccharides and other antinutritional factors present in corn-soy diets. At 57 d of age, a significant protein source and enzyme interaction was present for feed conversion ratio. It was observed that enzyme supplementation in all-vegetable diets showed improved feed efficiency in birds compared with other treatments (Figure 2Go). This finding suggests that the enzymes could help in improving live performance in older birds. However, caution should be exercised in interpreting the live performance data of mixed-sex trials, because additional variation may be introduced from variable sex ratios.


Figure 2
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  		Figure 2. Protein source x enzyme interaction for feed efficiency at 57 d of age (P < 0.05). Veg = all-vegetable protein (only soybean meal); Veg + Ani = vegetable plus animal protein (poultry by-product meal).

 
Gut viscosity was significantly affected by protein source and enzyme supplementation (Table 4Go). A significant protein level and source interaction was observed in foregut viscosity. Feeding all-vegetable diets increased gut viscosity significantly as compared with those fed Veg + Ani diets. However, foregut viscosity did not differ between the 2 protein sources in birds fed low-protein diets (Figure 3Go). A significant protein level and enzyme supplementation interaction was present for hindgut viscosity. As compared with other treatments, birds on high-protein diets with enzyme supplementation showed low viscosity of hindgut contents (Figure 4Go). In the hindgut, the interaction was due to the magnitude of differences between the high- and low-protein diets.


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  		Table 4. Effect of enzyme supplementation on gut viscosity1
 

Figure 3
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  		Figure 3. Protein level x source interaction for gut viscosity at 57 d of age (P < 0.05). Veg = all-vegetable protein (only soybean meal); Veg + Ani = vegetable plus animal protein (poultry by-product meal).

 

Figure 4
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  		Figure 4. Protein level x enzyme interaction for hindgut viscosity at 57 d of age (P < 0.05).

 
The incidence and severity of pododermatitis were significantly affected only by protein source at 28, 42, and 57 d of age in this study. Birds reared on all-vegetable diets showed higher incidence and severity of lesions (Table 5Go). In contrast to a previous study [15], no effect of protein level or gender was observed in this trial (P > 0.05). The absence of effect of protein level on incidence and severity of pododermatitis was unexpected. The explanation for this could be due to excessive wetting of litter due to excessive thirst in response to high environmental temperatures during the study, thus masking the effects of protein level on the footpad lesions. The effect of gender was consistent with the findings of Berg [47], in which no conclusive association between gender and the incidence of pododermatitis was observed among different broiler chicken flocks.


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  		Table 5. Influence of protein level, protein source, and enzyme on the incidence of pododermatitis1 (%)
 
A significant interaction between protein source and enzyme supplementation was detected for mild footpad lesions at 57 d of age. This interaction was due to a slight improvement in lesions with enzyme supplementation in birds reared on all-vegetable diets (Figure 5Go). Nairn and Watson [4], Jensen et al. [16], and Boling and Firman [18] suggested that the complex carbohydrates of soybean meal that are not vulnerable to the endogenous enzymes were associated with footpad dermatitis in turkey poults. The reduction in the severity of lesions in the current experiment suggests that appropriate exogenous enzymes, when added in commercial broiler diets formulated with soybean meal, may help alleviate pododermatitis in broilers at an older age.


Figure 5
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  		Figure 5. Protein source x enzyme interaction for mild lesions at 57 d of age (P < 0.05).

 
Litter quality also plays a significant role in the etiology of pododermatitis [19, 20, 48]. In this study, litter moisture varied little among the dietary treatments (P > 0.05; Table 6Go). Litter total N and NH3-N were significantly affected by protein level and enzyme supplementation at 28 and 42 d of age and by protein source at 28 d of age (Table 7Go), in which analysis of litter samples from pens with high-protein, all-vegetable, and enzyme-supplemented diets showed a higher percentage of total N and NH3 excretion. It is reported that use of enzymes in broiler feed improves utilization of protein. But the actual mechanism by which it enhances nutrient utilization is still unclear. The antinutritional factors in soybean meal may also interfere with digestibility of nutrients, thus excreting nutrients directly into the litter. This could be a possible explanation for higher total N excretion by birds into the litter and thus higher NH3 production in enzyme-supplemented diets.


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  		Table 6. Moisture levels (%) of litter from different treatments
 

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  		Table 7. Influence of protein level, source, and enzyme on litter total and NH3-N concentration
 
It is clear from the results of this study that pododermatitis is a common problem seen in fast-growing broiler chickens. The etiology is thought to be multifactorial. Our hypothesis that supplementation of exogenous enzymes in broiler diets may ameliorate this condition was not clearly proven, although an improvement in footpad quality was seen at later stages of life. Further research is needed on other enzyme preparations that can be used in corn-soybean meal diets that help improve feed utilization, reduce total N excretion into litter and NH3 emission, and reduce the incidence of pododermatitis in broilers.


   CONCLUSIONS AND APPLICATIONS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES
 

  1. Gut viscosity was reduced significantly by enzyme addition irrespective of protein level or source.
  2. No protein level effects on footpad lesions were observed in this experiment.
  3. Enzyme supplementation in all-vegetable diets reduced the incidence of mild lesions at 57 d of age.
  4. Litter total and NH3-N levels were affected by protein level (high > low), protein source (Veg >Veg + Ani), and by enzyme supplementation (with enzyme> no enzyme).
  5. A feed-grade enzyme may play a role along with other nutritional and management programs to control footpad lesions in broilers.


   REFERENCES AND NOTES
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 

  1. Christensen, H. 1996. PRESTO! An insatiable market in southern China and Hong Kong changes a chicken by-product into a snack food. Poultry Marketing and Technology. April/May:38.
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  11. Haslam, S. M., S. N. Brown, L. J. Wilkins, S. C. Kestin, P. D. Warriss, and C. J. Nicol. 2006. Preliminary study to examine the utility of using foot burn or hock burn to assess aspects of housing conditions for broiler chicken. Br. Poult. Sci. 47:13–18.[Web of Science][Medline]
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  13. Bilgili, S. F., M. A. Alley, J. B. Hess, and M. Nagaraj. 2006. Influence of age and sex on foot pad quality and yield in broiler chickens reared on low and high density diets. J. Appl. Poult. Res. 15:433–441.[Abstract/Free Full Text]
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  34. Allzyme Vegpro, Alltech, Nicholasville, KY 40356. Allzyme Vegpro contains a combination of protease, cellulase, pentosanase, {alpha}-galactosidase and amylase enzymes. Added at a rate of 1.2 lb/ton or 0.06%. Active constituents: 7,659 hydrolyzing units of trypsin units/mL of fungal protease.
  35. There were 50 birds of either sex/pen and 8 replicate pens/treatment. The pens were 1.70 x 2.30 m in dimension with a final stocking density of 12.14 birds/m2.
  36. IEC Micro-MB, International Equipment Co., Needham Heights, MA. The samples were centrifuged at 12,700 x g for 5 min.
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  39. The footpad lesions were assigned to 1 of 3 values: 0 = footpads with no lesions, dermal ridges intact within the central plantar footpad surface, with or without discoloration; 1 = footpads with mild lesions, dermal ridges not intact within a central, round to oval ulcer on the central plantar footpad surface, roughened lesion surface with small tag of crust <1.5 cm in diameter; and 2 = footpads with severe lesions with large brown discolored ulcers of >1.5 cm in diameter.
  40. Hoskins, B., A. Wolf, and N. Wolf. 2003. Dry matter analysis. Recommended Methods of Manure Analysis (A3769). I-2/2003. http://learningstore.uwex.edu/pdf/A3769.pdf Accessed Jan. 2007.
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  43. The statistical model consisted of 2 x 2 x 2 factorial arrangement of protein level, protein source, and sex. The data were analyzed for main effects, 2-way and 3-way interactions between the protein levels, sources, and enzyme.
  44. On d 57, the footpad lesions were analyzed for protein level, protein source, sex, and enzyme supplementation.
  45. SAS Institute. 2002–2003. SAS/STAT Users Guide for Personal Computers. Release 9.1. SAS Inst. Inc., Raleigh, NC.
  46. Smiricky, M. R., C. M. Grieshop, D. M. Albin, J. E. Wubben, V. M. Gabert, and G. C. Fahey. 2002. The influence of soy oligosaccharides on apparent and true digestibilities and fecal consistency in growing pigs. J. Anim. Sci. 80:2433–2441.[Abstract/Free Full Text]
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