**3. Probiotics for animal use**

The use of growth promoters permit to improve animal performance. Initially, a great variety of antibiotic function substances, particularly penicillin and tetraclines, were used to improve performance of birds, swines and cattle. The use of antibiotics as feed additive showed great benefices to animal production, mainly expressed in an improvement of weight gain and feed conversion. Antibiotics were used for many years, but they are being banned from animal production activities especially because of risks presented by resistant bacteria, which can result in problems to animal and human health. Therefore, probiotics are receiving special attention by animal nutrition researchers, who search for alternatives to the traditional use of growth promoters.

Probiotics have been incorporated through diets, with the objective to keep intestinal microbiota balance of animals, preventing digestive tract diseases, improving feed digestibility, leading to a greater use of nutrients and improving animal performance (Fuller, 1992).

Overall, effects of probiotic addition tend to be more outstanding in inadequate production conditions or in stress conditions, in which microbiota are unbalanced, especially in young animals. The most commonly highlighted factors among those previously cited are: temperature below or above thermal comfort zone; presence of pathogens; deficient sanitary conditions; management stressing conditions; change in feeding; weaning; transportation; high stock density; post-antibiotics treatment; sudden environment change. Regarding the results obtained in experiments with probiotics, those can be affected by factors as for example: type of probiotic microorganism; method and administered amount; host condition; intestinal microbiota condition; age of the animal.

#### **3.1 Probiotic in aquaculture**

Probiotics in aquatic organisms can act similarly to terrestrial animals. However, the relationship between aquatic animals and cultivation environment is much more complex than that involving terrestrial animals. Because of this closer relationship between animal and cultivation environment, the traditional definition of probiotics is insufficient for aquaculture. Therefore, Verschuere et al. (2000) suggest a broader definition: "it is a microbial supplement with living microorganisms, with beneficial effects on the host, by modifying its microbial community associated with the host or its cultivation environment, by ensuring improved use of the artificial feed or its nutritional value, by

The administration of *Lactobacillus* GG in pregnant women, nursing mothers and babies in the first months of life was associated with a decrease in the occurrence of topic eczema in children at risk of developing allergies compared to a placebo group at the end of a year of life (Kalliomäki et al., 2003). Another two controlled studies showed improvement of atopic dermatitis in children after use of *L. rhamnosus* and *L. reuteri*, and children with atopic eczema and allergy to cow's milk responded more effectively to a hydrolyzed formula supplemented with *Lactobacillus* GG (Majamaa et al., 1997; Rosenfeldt et al., 2003). These results are promising for the use of probiotics in allergies, but more studies are needed to

The use of growth promoters permit to improve animal performance. Initially, a great variety of antibiotic function substances, particularly penicillin and tetraclines, were used to improve performance of birds, swines and cattle. The use of antibiotics as feed additive showed great benefices to animal production, mainly expressed in an improvement of weight gain and feed conversion. Antibiotics were used for many years, but they are being banned from animal production activities especially because of risks presented by resistant bacteria, which can result in problems to animal and human health. Therefore, probiotics are receiving special attention by animal nutrition researchers, who search for alternatives to the

Probiotics have been incorporated through diets, with the objective to keep intestinal microbiota balance of animals, preventing digestive tract diseases, improving feed digestibility, leading to a greater use of nutrients and improving animal performance

Overall, effects of probiotic addition tend to be more outstanding in inadequate production conditions or in stress conditions, in which microbiota are unbalanced, especially in young animals. The most commonly highlighted factors among those previously cited are: temperature below or above thermal comfort zone; presence of pathogens; deficient sanitary conditions; management stressing conditions; change in feeding; weaning; transportation; high stock density; post-antibiotics treatment; sudden environment change. Regarding the results obtained in experiments with probiotics, those can be affected by factors as for example: type of probiotic microorganism; method and administered amount; host

Probiotics in aquatic organisms can act similarly to terrestrial animals. However, the relationship between aquatic animals and cultivation environment is much more complex than that involving terrestrial animals. Because of this closer relationship between animal and cultivation environment, the traditional definition of probiotics is insufficient for aquaculture. Therefore, Verschuere et al. (2000) suggest a broader definition: "it is a microbial supplement with living microorganisms, with beneficial effects on the host, by modifying its microbial community associated with the host or its cultivation environment, by ensuring improved use of the artificial feed or its nutritional value, by

confirm this property.

(Fuller, 1992).

**3. Probiotics for animal use** 

traditional use of growth promoters.

**3.1 Probiotic in aquaculture** 

condition; intestinal microbiota condition; age of the animal.

enhancing the host response towards diseases and by improving the quality of its ambient environment."

Microorganisms in the aquatic environment are in direct contact with the outer part of the animals, as for example gills and with the supplied feed, with easy access to the digestive tract of the animal. Among those microorganism present in the aquatic environment are the potentially pathogenic ones, which are opportunists, that is, they take advantage of some stress situation of the animal (high density, deficient feeding), causing infections, which can worse animal performance and even death. *Vibrio* sp., *Plesiomonas shigelloides*, in addition to *Aeromonas* sp. are the main agents causing death in aquaculture, and they can also cause feed infections in human beings. Thus, the objective of using probiotics by aquatic organisms is not only the direct beneficial to the animal but also its effect in the environment (Verschuere et al., 2000).

The interaction between environment and host in an aquatic environment is complex. Microorganism in the water influence host intestinal microbiota and vice-versa. Makridis et al. (2000) showed that supply of the bacteria strains through the feed and direct in the cultivation water, in turbot (*Scophthalmus maximus*) larvae incubators, promoted their maintenance in the environment, and they also promoted colonization of the digestive tract of the larvae.

Changes in the salinity, temperature, dissolved oxygen variations, alter conditions of the environment, which are propitious to different organism, with consequent changes in the dominant species, which may lead to a efficacy loss of the product. Thus, addition of a probiotic into the cultivation water must be constant, because the medium conditions undergo periodical changes. So, when choosing the pro biot to be used in aquaculture, variety of the microorganism present in the medium must be taken into account.

Intensive cultivation systems use high stock densities, among other stressing factors (for example: management), which result in low growth rates and feeding efficiency, a fragility in the immune system, making those animals susceptible to the presence of opportunist pathogens present in the cultivation environment. Thus, the effect of the probiotics on the immune system has led to a great number of studies with results beneficial to the health of aquatic organisms, although the way they act have not been clarified, yet. Gram et al. (1999) showed that the use of *Pseudomonas fluorescens* AH2 as probiotic, reduced mortality of rainbow trout (*Oncorhynchus mykiss*) juveniles exposed to *Vibrio anguillarum*. The joint administration of *Lactobacillus fructivorans* and *Lactobacillus plantarum* through live or dry feeding promoted colonization in intestine of *sea bream* (*Spaurus aurata*) larvae and the reduction of animal mortality during larva culture and nursery (Carnevali et al., 2004). Kumar et al. (2006) observed a greater survival in *Labeo rohita* carp fed *Bacillus subtilis*, submitted to intraperitoneal injection with *Aeromonas hydrophila*.

Regarding cultivated shrimp, bacterial illness are considered the greatest mortality cause in larvae. The administration of a bacterium mixture (*Bacillus* sp. e *Vibrio* sp.) influenced positively survival and presented protection effect against *Vibrio harveyi* and the white spot virus (Balcázar et al., 2006). In the clam *Argopecten purpuratus*, an *Alteromonas haloplanktis*, able to reduce larva mortality when submitted to challenge with *Vibrio anguillarum,* was isolated (Riquelme et al., 1996).

The Benefits of Probiotics in Human and Animal Nutrition 85

*Lactobacillus casei*, *Lactobacillus plantarum* and *Enterococcus faecium* at 106 UFC egg-1, at 16 days of incubation and the performance of challenge of chicks at one day of age via stomach with 13.6 x 106 UFC mL-1 of *Salmonella enteritidis*, improved performance of animals fed probiotics when compared to control treatment (Leandro et al., 2004). Moreover, in the same experiment, authors observed that from 7 to 21 days of age, *Salmonella* sp. was identified only in challenged animals which were not fed probiotic. It is suggested that probiotic

In chicks emerging from incubators, pH concentration and the presence of volatile fatty acids, which are one of the main protection barriers of the animal organism, are not sufficiently chemically to avoid that pathogens enter in their organism. Moreover, the small variety of the birds' intestinal microbiota in this phase is considered as a limiting factor for the digestion and for the possibility of intestinal colonization by enteric pathogens. Thus, probiotic supplementation seems to be a beneficial action for the animal performance and

An efficient immune response is related to the presence of immunomodulaters in the diet, which will act by reducing immune stress and then reducing nutrient mobilization to activities which are not related with production (meat or eggs), permitting in addition to a

The use of yeast *Saccharomyces boulardii* in the diet for broiler chickens reduced the level of *Salmonella* sp. from 53.3% to 40.0% at stress conditions in transportation to slaughter (Line et al., 1998). The used of yeast *Saccharomyces cerevisiae* var. *chromium* reduced negative effects of

The results of studies with probiotics in poultry production have been showed to be rather contradictory regarding to its efficiency. Not always are positive results observed by using probiotics. Those vary with age of the animal, type of probiotic used, viability of the microorganisms, storage conditions, level and manner of administration, in addition to the low challenge in relation to the experimental condition concerned to sanity, management and other stressful conditions. Some researchers have stated that the addition of probiotics into the diet did not improve animal performance in broiler chickens. Estrada et al. (2001) observed that the administration of *Bifidobacterium bifidum* did not alter significantly animal growth. But, according to Zulkifli et al. (2000), even by observing an increase in the feed intake, there was no reduction in feed efficiency in broiler chickens when *Lactobacillus* sp.

On the other hand, several studies have shown extremely interesting results on adition of probiotics into diets for broiler chickens. The addition of *Bacillus subtilis* into the diet increased weight gain and feed conversion (Fritts et al., 2000). The addition of *Lactobacillus*  increased weight gain and improved feed conversion of supplemented animals (Kalavathi et al., 2003). The use of yeast *Saccharomyces boulardii* in *Salmonella enteritidis* infected broiler chickens improved feed efficiency by 10% when compared to control treatment, and by 12%

Concerning to carcass quality of broiler chickens, the beneficial effect of probiotic use was also observed. The addition of *Lactobacillus acidophilus* e *Streptococcus faecium* reduced plasma protein concentration, levels of total cholesterol and HDL in addition to an increase

in animals supplemented with *Bacillus cereus* var. toyoii (Gil de los Santos, 2004).

in the protein content of probiotic supplemented animals (Pietras, 2001).

greater survival in stress situations, the non-harmful effect on animal performance.

avoided bacterium colonization in the gastrointestinal tract of the birds.

health of birds from commercial incubators.

caloric stress on broiler chickens (Guo & Liu, 1997).

was administered in the diet.

Probiotics can also be used to promote growth in aquatic organisms, either by a direct help in nutrient absorption or by supplying them. Lara-Flores et al. (2003) concluded that the use of *Saccharomyces cerevisiae* yeast as probiotic for Nile tilapia (*Oreochromis niloticus*) alevino as growth promoter, resulted in a greater growth and feed efficiency, suggesting that yeast is a proper growth promoter in the tilapia farming. Lin et al. (2004) used *Bacillus* sp. in the diet of shrimp *Litopenaeus vannamei* improving feed digestibility indices. Ziaei-Nejad et al. (2006) added probiotic *Bacillus* sp. in the cultivation of shrimp *Fenneropenaeus indicus* larvae and observed that in addition to the increase of survival, there was an increase in the activity of enzymes lipase, protease and amylase in the digestive tract of shrimp, which may stimulate the better use of the artificial feed.

However, addition of probiotics *Bacillus subtilis* at different doses (2.5; 5.0 and 10 g kg-1 of diet) in diets for bullfrog (*Lithobates catesbeianus*) with initial weight of 3.13g did not improve weight gain, apparent feed conversion and survival when compared to control treatment (without addition of probiotic), but the immunostimulatory effect was evidenced through the increase of phagocytic capacity in the animals (França et al., 2008).

Another aspect of using probiotics in aquaculture is the improvement of the water quality in culture ponds. Reduction on nitrogen and phosphate compounds in the water used in *Litopenaeus vannamei* shrimp cultivation was observed when commercial probiotics were added into the water (Wang et al., 2005). Similarly, it was observed an improvement in the water used for cultivation of *Penaeus monodon* shrimp when *Bacillus* sp. was used as probiotic (Dalmin et al., 2001).

The conditions in which animal are submitted during cultivation can influence directly efficiency of probiotics. Thus, when they are not submitted to stressing situations, the obtained results many times do not show significant effect of probiotics on animal performance, so, more scientific studies should be conducted to know better interactions between those factors with the animals.
