Bacillus amyloliquefaciens CECT 5940 (Ecobiol®) go beyond performance in broilers under enteric pathogen challenge compared to antibiotic growth promoter and other commercially available probiotics

Coccidiosis is a common problem in broiler production, resulting from the development and reproduction of Eimeria species that can infect specific areas of the gut and cause tissue damage in the intestinal epithelial cells (Ritzi et al., 2014; Ritzi et al., 2016). In general, producers have been using anticoccidians to control Eimeria and avoid further development of enteric diseases such as necrotic enteritis arising from intestinal overgrowth of Clostridium perfringens (Awad 2017). In this context, antibiotic growth promoters (AGP) have been also used to control the growth of pathogenic bacteria while improving performance and gut health. However, concerns over antibiotic resistance led to regional bans in order to reduce AGP use in poultry feed. Consequently, the use of probiotics has received special attention as potential alternatives to replace AGPs since they may provide similar improvement in performance. Probiotics are living microorganisms provided in the feed, which are able to reduce pathogen load by competitive exclusion and can enhance health and nutrient absorption in the host. Ecobiol® is a probiotic product containing Bacillus amyloliquefaciens  CECT 5940 strain, which is a naturally occurring strain with fast growing characteristics and high tolerance to gastric and bile secretions. Bacillus amyloliquefaciens  CECT 5940 is able to improve feed conversion and reduce pathogenic bacteria in the intestine (Facts & Figures n°15160). Other commercially available probiotics are based mainly on Bacillus subtilis strains, which may have different mode of action compared to Bacillus amyloliquefaciens strains but, at the end, promote performance and improve gut health as well. Therefore, this study was conducted in order to evaluate the efficacy of Bacillus amyloliquefaciens  CECT 5940 (Ecobiol®) in promoting both performance and gut health compared to AGP and other commercially available probiotics in broilers under challenge condition. This trial was conducted by Dr. Nilva Kazue Sakomura at “São Paulo State University (UNESP)” in Brazil.

One thousand eight-hundred thirty-six day-old male chicks (Cobb 500) with an average initial weight of 50.2 ± 0.1 g were randomly assigned to one of the six dietary treatments with nine pen replicates of 34 birds each. The basal diets composed by corn-soybean-meat and bone meal were formulated to meet Evonik amino acids recommendations (AMINOChick® 2.0) for starter(day 1-13), growerI (day 14-21), grower II (day 22-35) and finisher (day 36-42) phases with all diets provided in mash form. The treatments consisted of non-challenged group receiving a basal diet without feed additives; Challenged group receiving a basal diet without feed additive; Challenge + 0.05 g/kg BMD (Bacitracin methylene disalicylate); Challenge + 1g/kg Ecobiol® (1 x 10⁶ CFU/g of Bacillus amyloliquefaciens CECT 5940); Challenge + 0.100 g/kg Competitor A (1 x 10⁶ CFU/g of B.subtilis DSM17299) and Challenge + 0.05g/kg Competitor B (1 x 10⁵ CFU/g of B. subtilis PB 6). The enteric pathogen challenge consisted of inoculation by oral gavage on day 17 with 1mL of Eimeriamaxima (5.0 X 10⁴ CFU/g) and Clostridium Perfringens (2.5 X 10⁶ CFU/g) on days 18, 19, and 20. Feed and water were provided ad libitum during the experimental period.

Body weight and feed intake were recorded on days 21, 35, and 42 of the experimental period for calculation of weight gain and feed conversion ratio. Cause, date andweight of dead birds were recorded daily. Score of litter moisture (0 = Dry friable; 1 = Dry with very fine texture; 2 = Sticky on compression or crumbles; 3 = Clod on compression; 4 = Wet; 5 = Drops of water come out on compression), fecal (0 = Solid with white cap; 1 = Bulckyand moist; 2 = Watery; 3 = No consistency, watery, mucus, undigested feed, sloughed mucosa, foamy) and cecal droppings (0 = Black to brown and firm, 1 = Lack consistenceand foamy; 2 = watery and foamy; 3 = Foamy like mousse, spread, liquid) were evaluated at day 28. Two birds from each pen were randomly selected and sacrificed on days 21 and 28 to evaluate general intestinal health and to collect digestasamples from ileum and cecum for further analysis. The score evaluation of the intestinal health considered the presence (1) or absence (0) of the following parameters: ballooning, Muscle tone, thin or fragile, abnormal content (excessive slime, water, gas, greasy aspect or mixture of these), swollen or red, sloughed mucosa or presence of undigested feed. The contents of the ileum and cecum were collected and stored at −20°C for Clostridium perfringens counts. Quantitative PCR targeting the 16S rRNA genes of C. perfringens was used in the quantification. Body weight uniformity, footpad lesions (0 = none; 1 = mild; 2 = moderate; 3 = Severe; 4 = extreme), hock burn (0 = none; 1 = mild; 2 = moderate; 3 = Severe; 4 = extreme), carcass and breast meat yields were evaluated on days 42. Treatments were statistically analyzed using one-way ANOVA procedure in SAS v9.4 software followed by mean comparison with SNK (Student-Newman-Keuls) test at 5% of probability and frequency of the scores were evaluated using a non-parametric Kruskal-Wallis test followed by Dunn-Bonferroni test at 5% probability.

The results of the performance are presented in Tables 1. Feed intake was higher in the challenged group receiving B. subtilis B compared to the non-challenged group and the group receiving Ecobiol® (P < 0.05), but no significant differences were observed when compared to the challenged group without additives and the groups receiving BMD or B. subtilis A (P > 0.05) on day 21. Feed conversion ratio and weight gain were not significantly different between the treatments at 21 days (P > 0.05), which was the day right after the challenge. On the other hand, feed intake and weight gain were significantly lower in the challenged groups compared to the unchallenged group at 35 and 42 days (P < 0.05). The birds undergoing the enteric pathogen challenge had significantly better feed conversion ratio when fed any of the feed additives on day 35 compared to the challenge group without feed additives (P < 0.05). The challenged birds receiving Ecobiol®, BMD or B. subtilis B had significantly better feed conversion ratio compared to the challenge group without feed additives (P < 0.05) on day 42. The improvement with B. subtilis A was not enough to provide a significant difference on day 42 compared to the challenged group without additive (P > 0.05). Mortality was not significantly different between the treatments (P > 0.05).