**5. Limitations on the use of probiotics in broilers**

The limitations surrounding the application of probiotics are several, however those inherent in the breeding environment are those described here, among which are summarized below.

#### **5.1 Absence of a pattern in the effect of probiotics**

The absence of a common pattern in the effect of probiotics and their probiotic potential is directly connected to particular species, not to the genus or species of a microorganism. Studies with *Bacillus subtilis*, analyzing from performance to biochemistry parameters showed variable results [21, 24, 62–64].

Using Probiotics based on *Bacillus subtilis*, bone growth in broilers under an episode of cyclic heating was induced, which was attributed to the inhibition of bone resorption, resulting from the negative regulation of circulating TNF-a and CTX, [32, 65].

In chickens challenged with *C. perfringens* tested strains of *Bacillus subtilis*, they showed no significant difference in the ability to degrade proteins and carbohydrates and inhibit the growth of *C. perfringens* in vitro, when compared to the control without probiotics, [21]. Already combined with *L. amiloquaficiences*, the results demonstrate the suitability of the combination of multi - strains of Bacillus evaluated as an effective probiotic.

A study by Liang [64], showed that probiotics *(Bacillus subtilis* and *Lactobacillus acidophilus*) in isolation, were not effective in controlling *E. coli* infection in broilers and did not lead to significant weight gain. In addition, 75% of the mortality was obtained in treatments with the application of these probiotics. The combination of these probiotics with flavonoids (Taraxacum) improved indicators of diarrhea [64].

According to assessments made on the use of probiotics in animals by FAO the effects of probiotics seem to result from their interaction with the host. Such interaction is likely to define the mode of action of probiotics, which may be similar in different probiotics, or a specific strain may function through various mechanisms and several strains of probiotics have similar effects on the gastrointestinal microbial population [20].

#### **5.2 Post-marketing handling and conservation**

The stability of the probiotic in the storage time is one of the criteria of useful technology established to demand from formulators [66]. However, situations of inadequate handling or conservation after acquisition are more likely to happen and may result in inactivating their effect, and consequent absence the effect now expected, since it is a live microorganism.

The probiotic formulas, depending on the species and age of the host animals, can be administered as a powder, suspension, capsules, pellets, gel or paste [67]. In broiler chickens the most usual form of administration depends on the manufacturer, usually applied via injection (in eggs); via litter; via suspension and also orally.

In oral application conventionally made by means of food or water, the probiotic may be subject to loss of viability in contact with water disinfectants (chlorine) or by interaction with other substances contained in feed. Probiotics are not always effective in reducing microbial load in the same proportion, their effectiveness under commercial conditions is not guaranteed [68].

Eggs injected with probiotics before incubation to verify the effect on their hatchability, had unsatisfactory results, in which no protective effect was obtained [30].

#### **5.3 Existence of internal animal or environmental challenges**

Several factors can induce stress in chickens, which results in a reduction of beneficial microorganisms throughout the intestinal tract and their inefficiency in their protective action. The same analogy is used in the administration of the probiotic, in minimum concentration values it is necessary to ensure that they are available until reaching the site of action in the intestinal tract.

With the chicken's intestinal microbiota variable, due to factors such as geographic location, breed, temperature and dietary ingredients, it is very possible that other commensal bacteria can nullify, reduce or amplify the effects that probiotics can have on animal behavior and neurochemical metabolism [69].

The use of combined probiotic *(L. plantarum, Lactobacillus rhamnosus, Enterococcus faecium, Candida pintolepesii, Bifidobacterium bifidum* and *A. oryzae)* had no statistical difference when compared to the control without probiotic, did not affect the performance, internal organs and blood parameters of the chickens challenged with *Clostridium perfringens* [34]. However, in preliminary in vitro studies, this same mixture of strains showed abilities to inhibit the growth of the pathogen.

The mechanism by which the effects of stress or challenge are reversed are associated with the stimulation of the immune system, which in turn activates the nervous system and occurs the restoration of body balance and the fight against the pathogen [46].

#### **5.4 Lack of suitability of the probiotic manufacturer**

There seems to be no rule for combining probiotic strains in a formulation, nor an indication of the expected effect of such a mixture to treat a specific problem, which strengthens the use of probiotics as prophylactics rather than as therapeutic. [19, 20, 69, 70].

Information about the formulation is extremely important, especially for commercial broiler production farms or other animals that routinely use probiotics or other prophylactics (live, inactivated, and similar subunits) in their animals without knowing if there is an improving or canceling the effects of each other [69].

Some commercial formulas of probiotics combined, are still sold with indefinite constitution of the strains. A study was carried out with probiotic compounds with undefined strains that were purchased from authorized local stores. That, tested in the treatment of broilers challenged with *Salmonella enteritidis*, the positive effect

**153**

*Probiotics as a Promising Additive in Broiler Feed: Advances and Limitations*

minimum viable quantities must be respected and declared.

was only in the first 5 days [46]. There is an assumption that probiotic strains reduce the concentration over time throughout the intestine [70] and, for the best effect, continuous inoculation is necessary to maintain the optimal levels of the probiotic load, capable of competing favorably [18]. Even so, the possibility of dishonesty on the part of the manufacturer is not ruled out. According to the established standards FAO [9, 20] for the manufacture of probiotics, species and strains, as well as

Studies carried out due to the performance of tests to confirm the information contained in the label of probiotics of several commercial brands, it was found that there were numerous irregularities, highlighting whether (1) existence of strains different from those declared; (2) Encapsulation material not suitable for animal consumption or to maintain viability within the stated period; (3) association of species or strains other than those declared and (4) non-viable microorganisms in

If there are inconsistencies in the results of probiotic research, information on the safety of a specific microorganism should not be applied to other closely related

The absence of clinical side effects is an important benefit of using probiotics. However, some of the species and/or bacterial strains can present risks, they can be responsible for a series of problems to animal, human health and the environment, causing mild reactions or serious and potentially fatal infections [20]. In addition,

Risk reports on the use of probiotics are scarce. However there is a probable risk of transmission of antibiotic resistance (eg, *Enterococcus* genus) to pathogenic

In the USA, probiotics and other microorganisms used as food additives must have the status of Generally Regarded as Safe (GRAS), regulated by the FDA. In Europe, the use of the term Qualified Safety Assumption (QPS) has been regulated by EFSA. Crucial criteria for the selection of probiotic microorganisms in animals were jointly established by (WHO), (FAO) and EFSA, where they stand out:

Security - stipulates that the origin of the strain to be used as a probiotic must be from the intestine of this animal species; whose antibiotic resistance profile must be non-existent; in addition to the need for a total absence of association with patho-

Functionality- as an important criterion, functionality is about the viability of the strain within the conditions of the intestine, which must be greater; in addition to the efficiency in adherence to epithelial cells, reduced intestinal permeability of

Technological utility - no influence of probiotic microorganisms on the sensory properties of meat or meat products should be observed. Phage resistance is also an important property in this criterion, as well as the guarantee of viability of the microorganism during processing, and good stability in the product and in the

Current levels of information about probiotics are not sufficient to declare any group of probiotics completely safe without a case-by-case risk assessment. The results of the studies do not allow establishing the existence of a real risk for

microbiota or enterotoxin production (eg, *Bacillus cereus* strain) [19].

*DOI: http://dx.doi.org/10.5772/intechopen.97957*

packaging within the time limit [71–75].

**6. Risks inherent in the use of probiotics**

no probiotic can be considered 100% safe or at zero risk.

Security, functionality and technological utility [19].

the mucosa and proven immunomodulatory effects.

probiotics, but they also do not guarantee total safety.

microorganisms.

genic cultures.

storage time.

#### *Probiotics as a Promising Additive in Broiler Feed: Advances and Limitations DOI: http://dx.doi.org/10.5772/intechopen.97957*

*Advances in Poultry Nutrition Research*

under commercial conditions is not guaranteed [68].

also orally.

obtained [30].

pathogen.

pathogen [46].

therapeutic. [19, 20, 69, 70].

The probiotic formulas, depending on the species and age of the host animals, can be administered as a powder, suspension, capsules, pellets, gel or paste [67]. In broiler chickens the most usual form of administration depends on the manufacturer, usually applied via injection (in eggs); via litter; via suspension and

In oral application conventionally made by means of food or water, the probiotic may be subject to loss of viability in contact with water disinfectants (chlorine) or by interaction with other substances contained in feed. Probiotics are not always effective in reducing microbial load in the same proportion, their effectiveness

Eggs injected with probiotics before incubation to verify the effect on their

Several factors can induce stress in chickens, which results in a reduction of beneficial microorganisms throughout the intestinal tract and their inefficiency in their protective action. The same analogy is used in the administration of the probiotic, in minimum concentration values it is necessary to ensure that they are

With the chicken's intestinal microbiota variable, due to factors such as geographic location, breed, temperature and dietary ingredients, it is very possible that other commensal bacteria can nullify, reduce or amplify the effects that probiotics

The use of combined probiotic *(L. plantarum, Lactobacillus rhamnosus, Enterococcus faecium, Candida pintolepesii, Bifidobacterium bifidum* and *A. oryzae)* had no statistical difference when compared to the control without probiotic, did not affect the performance, internal organs and blood parameters of the chickens challenged with *Clostridium perfringens* [34]. However, in preliminary in vitro studies, this same mixture of strains showed abilities to inhibit the growth of the

The mechanism by which the effects of stress or challenge are reversed are associated with the stimulation of the immune system, which in turn activates the nervous system and occurs the restoration of body balance and the fight against the

There seems to be no rule for combining probiotic strains in a formulation, nor an indication of the expected effect of such a mixture to treat a specific problem, which strengthens the use of probiotics as prophylactics rather than as

Information about the formulation is extremely important, especially for commercial broiler production farms or other animals that routinely use probiotics or other prophylactics (live, inactivated, and similar subunits) in their animals without knowing if there is an improving or canceling the effects of each

Some commercial formulas of probiotics combined, are still sold with indefinite constitution of the strains. A study was carried out with probiotic compounds with undefined strains that were purchased from authorized local stores. That, tested in the treatment of broilers challenged with *Salmonella enteritidis*, the positive effect

hatchability, had unsatisfactory results, in which no protective effect was

**5.3 Existence of internal animal or environmental challenges**

available until reaching the site of action in the intestinal tract.

can have on animal behavior and neurochemical metabolism [69].

**5.4 Lack of suitability of the probiotic manufacturer**

**152**

other [69].

was only in the first 5 days [46]. There is an assumption that probiotic strains reduce the concentration over time throughout the intestine [70] and, for the best effect, continuous inoculation is necessary to maintain the optimal levels of the probiotic load, capable of competing favorably [18]. Even so, the possibility of dishonesty on the part of the manufacturer is not ruled out. According to the established standards FAO [9, 20] for the manufacture of probiotics, species and strains, as well as minimum viable quantities must be respected and declared.

Studies carried out due to the performance of tests to confirm the information contained in the label of probiotics of several commercial brands, it was found that there were numerous irregularities, highlighting whether (1) existence of strains different from those declared; (2) Encapsulation material not suitable for animal consumption or to maintain viability within the stated period; (3) association of species or strains other than those declared and (4) non-viable microorganisms in packaging within the time limit [71–75].

If there are inconsistencies in the results of probiotic research, information on the safety of a specific microorganism should not be applied to other closely related microorganisms.
