Effect of a Combination of a Probiotic Strain and an Exogenous Enzyme Blend on Broilers Carcass Yield

INTRODUCTION

Improving the efficiency of the use of nutrients and causing a formulation to be more precise are the most effective methodologies intended to reduce losses of nutrients and improve performance parameters.

According to GUENTER (2002), enzyme supplementation to animals is intended to remove or destroy anti-nutritional factors of grains and increase total digestibility of feeds. Exogenous enzymes increase the availability of surplus polysaccharides, fats and proteins, protected from digestive activity, by cell wall polysaccharides, in addition to minimizing the negative effects caused by anti-nutritional factors present in sundry ingredients and optimizing endogenous enzyme activity, especially in young animals holding immature enzyme systems.

Jointly with the role of the digestive enzymes, another aspect several researchers have been interested in is the use of probiotics in broilers feed. Such organisms are introduced as feed additives and contribute to a better establishment and maintenance of microbial populations in the animal’s digestive tract, which will compete with undesirable microorganisms, especially pathogens, for space and nutrients. Probiotics, added to poultry feed, increase feed efficiency, provide better feed quality, operate as natural promoters of growth, as well as reduce losses due to infectious diseases and stress symptoms (KOZASA, 1989).

Therefore this study was intended to assess the yield of broiler chickens’ carcass and parts, as raised from 1 to 42 days of age, being fed diets containing probiotic (Bacillus subtillis) and exogenous enzymes (phytase, protease, xylanase).

MATERIALS AND METHODS

An experiment was conducted including 900 broiler chicks (Cobb®) as raised from 1 to 42 days of age, distributed in 36 boxes, in a wholly casual design, containing 4 treatments, 9 replications with 25 birds. The treatments consisted of different diets for broiler chickens containing exogenous enzymes and Bacillus subtillis, whose formulation was based on corn and soy mash, supplemented with minerals, vitamins and amino acids, in order to meet the nutritional requirements according to ROSTAGNO et al. (2005) recommendations. A nutritional matrix of each enzyme was used to ensure the proper diet formulation. The added Bacillus subtillis is present in a commercial product currently tested in birds.

Treatments were as follow: a negative control (NC, a control diet without feed additives); probiotic (PRO, the NC diet + 500 ppm of a product containing Bacillus subtilis); exogenous enzyme blend (ENZ, the NC diet + 20 ppm of a blend of phytase, 200 ppm of protease and xylanase); and a treatment combine both feed additives in the NC diet (P+E).

At 42 days of age, birds were segregated (2 birds/replication) according to each portion’s average weight, within a variation interval of 10% up and 10% down of each portion’s average weight. Birds were individually identified, weighed in and segregated in boxes. After an 8 hour feed fast, birds were once again weighed in to calculate the carcass and parts yield. The birds were then desensitized with CO (carbon monoxide) and slaughtered through bleeding by cutting their jugular vein, and then they underwent scalding, defeathering and evisceration.

Animals’ feet, heads and necks were removed in order to calculate the carcass yield, thereby resulting in the slaughter weight. The yield of the parts (chest, thighs, upper thighs, wings and dorsum) will be calculated based on their respective weights, according to MENDES (2001).

Then the data underwent variance analysis by employing the General Linear Model (GLM) procedure through the software SAS ® (SAS Institute, 2002). Averages were then compared based on Tukey test with a significance level of 5%.

RESULTS AND DISCUSSION

Table 1 contains the data on the carcass and parts yield.

In this study, it was observed there were no significant differences (P>0.05) in the carcass yield, but it was observed the parts yield was only significant (P<0.05) between the treatments, concerning the yield of the broiler chickens’ chest meat. In this regard, it was observed the animals fed diets containing P + E (38.78%) evidenced higher yield of chest (P = 0.009) than NC (37.04%), PRO (38.39%) and Enz (38.02%), not statistically differing from the animals fed PRO and ENZ.

Table 1. Averages, F and P values and variation coefficient for carcass and parts yield feature (thighs + upper thighs, chest, dorsum and wings) (%), related to broiler chickens fed probiotic (Bacillus subtillis) and exogenous enzymes (phytase, xylanase and protease).

Effect of a Combination of a Probiotic Strain and an Exogenous Enzyme Blend on Broilers Carcass Yield - Image 1

One can observe that the availability of nutrients can be scaled up upon the use of enzymes in combination with a probiotic, increasing their absorption in the gastrointestinal tract, improving chickens’ chest yield. That could not be observed upon the isolated use of Bacillus subtilis and enzyme complex by some authors.

ZANELLA (1998) did not observe any significant difference in any of the features of carcass and parts yield when only the enzyme supplementation was tested in processed soy and corn-based diets in comparison with a witness feed. The same could be observed by MAIORKA et al. (2001) and CORRÊA et al. (2003) with the isolated addition of a probiotic (Bacillus subtillis) to broilers chicken diet, they observed it did not change the carcass and parts yield against the control feed without additives.

Bacillus subtillis, whenever added singly or associated with enzymes and other agents to birds’ diets, is intended to help the colonization of lactic acid-producing bacteria (MARUTA, 1993), thereby triggering a reduction in the intestinal pH, causing the environment to be improper for the multiplication of pathogen agents. As a consequence, they increase enzyme activity and the absorption area in the gastrointestinal tract, thus improving feed efficiency and animals’ protein gain.

CONCLUSION

The study findings suggest the use of probiotics and exogenous enzymes in broiler chickens’ diets can produce better economic results to the poultry industry.

THANKS

DSM for the donation of probiotic and exogenous enzymes. To FAPESP for the scholarship and financial support to the project.

REFERENCES

CORRÊA, G. S. S., GOMES, A.V.C. and CORRÊA, A. B. et al. (2003) Efeito de antibiótico e probióticos sobre o desempenho e rendimento de carcaça de frangos de corte. Arquivo Brasileiro de Medicina Veterinária e Zootecnia, v. 55, n.4, p. 467-473.

GUENTER, W. (2002) Pratical experience with the use of enzymes. Capturado de http://www.idrc.ca/books/focus/821/chp6.html.

KOZASA, M. (1989) Probiotics for animal use inJapan. Revue Scientifique et Technique de L Office International dês Epizooties, v.8, n.2, p.517-531, 1989.

MAIORKA, A., SANTIN E., SUGUETA, S.M., GODOI, J.A. and MACARI M. (2001) Utilização de prebióticos, probióticos ou simbióticos em dietas para frangos. Revista Brasileira de Ciência Avícola.

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MENDES, A. A. (2001) Jejum Pré-abate em Frangos de Corte. Revista Brasileira de Ciência Avícola, v.3, n.3, p.199-209.

ROSTAGNO, H.S. et al. (2005) Tabelas brasileiras para aves e suínos: composição de alimentos e exigências nutricionais. 2.ed. Viçosa: Universidade Federal de Viçosa, 2005. 189p.

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ZANELLA, I. (1998) Suplementação enzimática em dietas a base de milho e sojas processadas sobre a digestibilidade de nutrientes e desempenho de frangos de corte. 187f. Tese (Doutorado em Zootecnia) - Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista.