Bacillus thuringiensis var. israelensis em dietas para frangos de corte

Abstract

Through the present study, was evaluated the effect of supplementation with Bacillus thuringienis var. israelensis, on the performance of organs and carcass, meat quality, intestinal morphometry, hematological parameters and morphometry of seminiferous tubules of broiler chickens The experiment was conducted in the bioterium of the Laboratory of Zootechnical Teaching and Experimentation Prof. Dr. Renato Rodrigues Peixoto – UFPEL/Pelotas -RS, Brazil. A total of 288 one-day-old male and female Cobb strain broilers were housed in boxes The birds were randomly distributed into four treatments, with 12 replicates of six individuals each. The treatments consisted of supplementation or not with Bacillus thuringienis var. israelensis (Bti), in each gender. A food program was used considering the phases: initial, growth and final. Bacillus thuringiensis var. israelensis was added to the diets in the amount of 1x108 CFU per gram of feed, daily, for 42 days. For performance evaluations, the following variables were considered: weight gain, feed intake and feed conversion. For the evaluations of organ and carcass yield, meat quality, intestinal morphometry and hematological parameters, 12 birds per treatment were euthanized at 42 days of age, representing the boxing average. For the morphometry of the semiferous tubules, male testicles were collected from individuals euthanized at 42 days. Data were submitted to analysis of variance and means were compared using Tukey's test (P≤0.05). Male broilers obtained greater weight gain in the periods from 1 to 21 days (701 g), from 21 to 42 days (1496 g) and from 1 to 42 days (2197 g), higher feed intake from 1 to 21 days (1038 g), from 21 to 42 days (2735 g) and from 1 to 42 days (3773 g). They showed better feed conversion from 1 to 21 days (1.49). At 42 days, they had higher liver weight (38.2 g), higher live weight (2319 g), higher thigh weight (116.6 g), higher drumstick weight (132 g) and higher percentage of cooking loss (29.4%). There was a significant interaction between Bti:Gender for the cooking loss variable (P<0.05), where non supplemented males had the highest loss (31.2%) and non-supplemented females the lowest (25.9%). A significant interaction was also observed between Bti:Gender for the variable b*skin (P<0.05), where the use of Bti produced lower b*skin in males (20.5) and higher in females (24.0). The Bti-supplemented group had a lower duodenal crypt depth when compared to the non-supplemented group (684 vs 762 µm; P<0.05). The inclusion of Bacillus thuringiensis var. israelensis in broiler diets did not improve performance variables, organ and carcass yield, meat quality, hematological parameters and seminiferous tubule morphometry. In intestinal morphometry, it provided a reduction in duodenal crypt depth.