Effect of Bacillus Toyoi in Broiler Chicken Production
Published: December 8, 2013
By: Katia Pedrosa (MSc. Technical Manager at Lohmann Animal Health GmbH & Co. KG), Roser Dolz Pascual and Marisol Castillo£ (DVM, PhD, CReSA, Campus Universitat Autònoma de Barcelona, £
DVM, PhD, Rubinum SA)
Summary
It is common to use bacteria resident of the intestinal microflora such as lactobacilli, bifidobacteria and enterococci as probiotics. Currently in the European market the strains approved as probiotics are Bacillus, Enterococcus, Clostridium, Pediococcus and Lactobacillus. In fact, Bacillus species are indigenous to soil, capable of anaerobic growth and fermentation of a wide range of carbohydrates. They withstand elevated as spores and therefore it makes them especially useful as feed additives. Spore of probiotic strains must germinate in the intestinal tract first and be transformed into vegetative cell to have a positive influence.
In order to prove the probiotic effect of Bacillus toyoi an in vivo experiment was performed in 264 one day old male broiler chickens. Animals were randomly distributed into two experimental groups: control group (without probiotic) and a treatment group (with supplementation of probiotic Bacillus toyoi). At the end of the trial, supplemented animals with the probiotic had higher body weight and average daily gain during the first period (0 to 21 days), improved feed conversion ratio in 5,6% and 10,9% (day 21 and 35, respectively) compared to the control group, improved gut architecture and at last improved response to vaccination.
The use of spores as probiotics particularly Bacillus toyoi has clearly proven its efficacy and reinforced its ability to be used as feed additive.
Introduction
Feed additives are popular for their diverse activity via different modes of action. Probiotics as feed additives are currently widely utilized in order to modify the microbial population in the digestive tract.
According to FAO probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. They require several days to indirectly induce an alteration in the dynamic microbial equilibrium and they are known to aggregate with pathogenic organisms, attach to receptors on the gut willing competition with pathogenic organisms, compete with undesirable microbes for specific nutrients, lower pH through acid formation and modulate the intestinal epithelium.
A great number of microorganisms are used as probiotics such as lactic acid bacteria, non-lactic acid bacteria and yeasts and only few microorganism-preparations are authorized in the EU for the use in poultry mainly for broilers but some also for layer hens or turkeys.
The extensive research and field work conducted with Bacillus Cereus var. toyoi in several animal species has proven to be remarkable agent in improving feed intake, feed efficiency and growth performance in poultry, swine and ruminants.
The objective of the present study was to explain the mode of action of bacterial spore formers as probiotics (Bacillus Cereus var. toyoi) in poultry production and prove the efficacy of such probiotic in feed efficiency, histology and gut modification of broilers chickens and response to vaccination.
Material and methods
A total of 264 one day old male broiler chickens (Ross 308) were allocated in two pens, containing 22 birds each and 6 replicates. The animals were divided in two groups and had ad libitum access to a standard diet.
The control group was free of probiotic and the treatment group was supplemented with Bacillus toyoi at 1000 g/ton of feed and both groups were evaluated during two experimental periods (from 0 to 21 days and from 21 to 35 days).
Feed intake and individual animal weights was weekly registered per each pen on days 7, 14, 21, 28, and 35 and were necropsied to take samples (2 birds per pen).
At day 7, four birds per pen were selected, to get enough amount of gut digesta. Birds with the highest and lowest body weight in each pen were selected.
Histology
After fixation in 10% neutral buffered formaline and embedding in paraffin, tissue sections of ileum and caecum were processed routinely for haematoxilyn/eosin. For each section, villus length, crypt depth, intraepithelial lymphocytes and globet cells quantification were carried out.
Serology
Antibody titres against IBD virus and IB virus were determined by using a commercial ELISA.
Results and Discussion
A significant decrease on the average daily feed intake of the animals receiving probiotic was significantly lower in the second part of the experimental period (21 to 35 days) and in the overall trial (-13.60% decrease) (Figure 1).
Figure 1 - Average daily feed intake (g) of the two experimental periods
On the other hand, there was a significant improvement of FCR on treated birds with the probiotic. FCR was improved by 5.6% on the first 21 days and by 10.9% during the all experiment (day 0 to 35) (Figure 2).
Figure 2 - Feed conversion ratio of the two experimental periods
Histology
The ileal villus height and crypt depth was improved in birds of the treated group at day 7 and therefore, the ileal villus height:cryipt depth ratio was also higher in the probiotic group.
Figure 3 and 4 - Ileal villus height and crypt depth and ileal villus height:cryipt depth ratio at day 7
Serology
IBD titers observed until 14-21 days were maternal antibody titers. Surprisingly, no seroconversion was observed for any of the treatment groups, which indicate a poor vaccine administration or the use of an in ovo recombinant vector vaccine. Feeding the probiotic supplemented diet, a
n increase of the number of antibodies against IBD on day 35 was observed compared to control diet (P<0.05) (Figure 5).
Figure 5 – Count of Infectious Bursal Disease antibody titers
Regarding IB titers, again, the seroconversion observed at 21, 28 and 35 days of age was very poor, what it is expected for this vaccine, as it mainly induces mucosal immunity. At day 14, statistical differences were also observed between IB antibody titers of chickens fed with T1 and T5 (P<0.05) (Figure 6).
Figure 6 – Count of Infectious Bronchitis antibody titers
Conclusion
Bacillus Cereus var. toyoi has clearly proven its efficacy in what concerns feed efficiency by improving FCR; improved the gut architecture by increasing the ileal villus height and crypt depth and therefore ileal villus height:cryipt depth ratio and at last but not least showed a strong and improved response to vaccination against Infectious Bursal Disease and Infectious Bronchitis. In this way, Bacillus toyoi is considered an efficient strain to be used as feed additive.
This paper was presented at the 3rd International Veterinary Poultry Congress, February 22-23, 2012- Tehran, Iran.
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16 de diciembre de 2013
It would be more convincing if authors presented data on Bacillus toyoi viable counts obtained from gut digesta of necropsied birds at days 7,14,21,28 and 35 since the authors themselves stated that the bacillus spores must germinate and transform into vegetative cells to exert their positive effects.The addition of 1 g bacterial spores per kg of feed is a lot of additional protein on the feed of treated birds. Could the observed FCR and lower feed intake in treated birds be due to different CP content?
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