INTRODUCTION

The poultry industry is constantly optimizing production to achieve better economic results and produce safer food. Including functional foods such as prebiotics in diets enhances an animal's immune system. These foods improve productive variables, act against pathogens and environmental factors like stress, act efficiently in vaccinations, and improve nutrient digestibility ^1.2. They are classified by the Food and Drug Administration (FDA) of the United States as safe substances that depend on the balance of intestinal micro flora through beneficial microorganisms.

Available probiotics mainly consist of carbohydrates and are metabolized in the colon rather than the small intestine. They act as a source of energy and stimulate the growth of beneficial microorganisms and the accumulation of metabolites such as acetate, butyrate and propionate, which maintain dynamic and innate microbiota ¹.

In the composition most probiotics, two bacterial genera include, Bacillus and Bifidobacterium; these genres are highlighted by having resistance to low pH of the stomach and tolerance to bile salts ³.

According to the Brazilian Association of Animal Recycling (ABRA), Brazil produced about 12 million tons of animal waste in 2012 and generated 3.27 million tons of meals and 1.9 million tons of fat. Animal products such as viscera, meat and bone flour are often used in broiler diets as a source of protein, and can be used to substitute soybean meal ⁴. The aim of this study was to evaluate the use of probiotics in diets containing animal or vegetable ingredients on the productive variables of broilers from 1 to 42 days old.

MATERIALS AND METHODS

Study site and animals: The experiment was performed at the Experimental Aviary located in the Antonio Carlos dos Santos Pessoa Experimental Station at the State University of Western Paraná, Marechal Cândido Rondon campus (Paraná-Brazil), located at an altitude of 420 meters at coordinates 24°33'21 south latitude and 54°03'25" west longitude, with a humid tropical pre-mountain forest climate and an average temperature of 21°C, ranging from 16 to 27°C and 1700 mm annual rainfall.

The east-west facing experimental aviary has a concrete floor and clay tiles, and was divided into 48 boxes, 1.30 x 1.35m each. Each box had a feeder tray and a pressure bottle during the initial phase; for the other phases a semi-tubular feeder and Nipple water dispenser was used. The birds were kept warm with 250 watt infrared bulbs. The bedding material was recycled pine sawdust, covered with a centimeter of new sawdust.

Were used 1056 male broilers, day-old Ross 308. Their initial weight was 40.45g, from 39 week old matrices. The birds were vaccinated in the hatchery against Marek, Fowl Pox and Infectious Bronchitis. The chickens were individually weighed and randomly distributed between the experimental units.

Treatments: The experimental diets were calculated according to the feed composition and nutritional requirements proposed by Rostagno ⁵.

Nutritional composition and centesimal are found in Table 1. Treatments are described as follows:

DAA: Animal diet with antibiotics - diet with animal products supplemented with antibiotics until 35 days.

DVA: Vegetable diet with antibiotics - diet with vegetable products and supplemented with antibiotics until 35 days.

DACN: Animal diet, negative control - diet with animal products without growth promoters.

DVCN: Vegetable diet with negative control - diet with vegetable products without growth promoters.

DAPA: Animal diet with Probiotic A - diet with animal products supplemented with Probiotic A (0.005%) from 1 to 42 days.

DVPA: Vegetable diet with Probiotic A- diet with vegetable products supplemented with Probiotic A (0.005%) from 1 to 42 days.

DAPB: Animal diet with Probiotic B - diet with animal products supplemented with Probiotic A (0.04%) from 1 to 42 days.

DVPB: Vegetable diet with Probiotic B - diet with vegetable ingredients supplemented with Probiotic A (0.04%) from 1 to 42 days.

The antibiotics used in the DAA and DVA treatments were: Lasalocid 15% (0.03%), avilamycin 10% (0.005%) and colisitin 8% (0.0094%) for the pre-initial phase; lasalocid 15% (0,06%), avilamycin 10% (0.01%) and colisitin 8% (0.0188%) for the initial phase and narasin 10% (0.08%), avilamycin 10% (0.008%) and colisitin 8% (0.0125% for the growth phase. Promoters were substituted in relation to inert material in the diet.

For treatments with probiotic (Bacillus subtilis), 2 products of different brands were used, one for DAPA and DVPA diets and one for DAPB and DVPB diets. Probiotics were included to replace inert material.

Sampling: At 7, 21 and 42 days all birds and feed leftovers were weighed to evaluate production parameters. Weight gain, final weight, feed intake, feed conversion and mortality were determined from 1 to 7 days, 1 to 21 days, and 1 to 42 days. Data obtained were used to calculate the index of production efficiency (IEP) at 42 days.

The maximum, minimum and current temperature and relative humidity were observed daily at 0800 h and 1800 h using two thermohygrometers installed inside the shed 5 centimeters above the birds. The lighting program was constant, with 24 hours of light (natural and artificial light).

Experimental Design: A completely randomized experimental design was used with a 2x4 factorial arrangement, two types of diets (animal and plant), and four different growth promoters (antibiotics, two promoters and a negative control) with 6 replicates and 22 birds per experimental unit.

The results of the production parameters were analyzed in a SAEG statistical program; joint analysis of variance and a SNK 5% test were performed.

RESULTS

From 1 to 7 days there was no interaction (p>0.05) between types of diet and growth promoters for final weight, weight gain and feed intake (Table 2). Birds fed diets containing animal products had a higher (p<0.05) final weight, weight gain and feed consumption from 1 to 7 days (Table 2).

There was interaction for feed conversion (p<0.05) between the type of diet and growth promoter, where the animal diet with probiotic A showed better feed conversion (CA) when compared to the vegetable diet. Among the different growth promoters, antibiotics added to vegetable diets provided better CA (p<0.05) when compared with other treatments.

From 1-21 days no interaction (p>0.05) on productive variables between the types of diet and growth promoters was observed (Table 3).

Final weight, feed intake and weight gain during 1-21 days of age was lower (p<0.05) and feed conversion was worse for diets containing probiotic B when compared with other treatments. Mortality for this period was higher (p<0.05) for birds fed animal ingredients.

From 1-42 days no interaction (p>0.05) between the type of diet and growth promoters used (Table 4) was observed. Higher mortality (p<0.05) at 42 days for animals that received diets containing animal products was observed.

Viability at 42 days of age was higher (p<0.05) for birds fed vegetable products, regardless of the growth promoter used. The production efficiency factor (IEP) was affected by the type of diet (Table 5).

Birds fed diets of animal products and probiotic A and the negative control group had the highest (p<0.05) levels of production efficiency, while diets containing animal products with antibiotics and probiotic B had the lowest IEP.

DISCUSSION

Higher values obtained for final weight and weight gain for birds fed diets containing animal products may be due to the fact that these diets adequately address nutritional requirements and the nutrients are used more effectively from 1 to 7 days ⁶.

Improvement observed in birds supplemented with antibiotics during the first 7 days may be because these additives benefit the host, provide intestinal microbial balance, and act on the immune system ⁷.

The effects of probiotics on productive variables from 1 to 7 days obtained in this study were similar to those observed by Applet et al ⁷, who evaluated probiotics in diets with animal and vegetable products in broilers, and Bellaver et al ⁸, who replaced animal meal with vegetable products, and Carvalho et al ⁴, who evaluated animal meal, and Rigobelo et al ⁹ and Rocha et al ¹⁰, who evaluated probiotics in broilers.

The results for feed conversion may be due to the innumerable benefits of probiotics in the pre-initial stage, such as the best intestinal microbial balance and modulatory action ⁷. Improved conversion of birds fed with animal products is due to the high nutrient density and the availability of nutrients for the birds. One factor that affects production parameters of diets containing vegetable products is the content of non-starch polysaccharides which reduce digestibility and increase viscosity and intestinal motility ¹¹.

Similar results were observed by Applet et al ⁷, who observed improved CA in birds fed diets containing probiotics and animal products.

Results obtained using probiotic B on productive parameters from 1 to 21 days may be due to several factors, including the development of the intestinal tract of the birds, which can be affected by the presence of additives. Additionally, we must consider that the efficiency of probiotics depends on the qualitative and quantitative characteristics of microorganisms. The amount used may also interfere with the action of the probiotic ¹². Some species, such as Bacillus subtilis, colonize with a larger number of microorganisms than, for example, Lactobacillus acidophilus, mainly due to its spore form and because it is not destroyed when manufacturing diets ¹³.

Similar results were obtained by Bittencurt et al ¹⁴, who evaluated the effect of probiotics on the performance of broiler chickens. The results of feed conversion were similar to those obtained by Appelt et al ⁷ from 1-21 days.

The absence of interaction between diets and growth promoters from 1-42 days indicates that the productive response does not depend on the use of probiotics or antibiotics ¹⁵. However, other factors that can influence the productive response are hygiene in the environment, bedding quality, health status of the animals, and the concentration and composition of microorganisms.

The lower rate of productive efficiency in animal diets with probiotic B and antibiotics may be due to the high mortality that occurred with these treatments. This mortality may be associated with metabolic problems that may be related to the higher genetic potential for growth and feed efficiency of broilers. These metabolic problems usually affect birds with increased productivity and are associated with cardiovascular deficiencies and cause sudden death ¹⁶.

In conclusion, using probiotics stimulates a similar effect than that of antibiotics and a diet free of growth promoters, and can be used in broiler diets without affecting productive parameters. Diets with vegetable products are more viable in comparison with diets containing animal products.