What is probiotics?
Probiotics are defined as live microorganisms causing no pathological disorders and promoting enteric microbiota balance (Ohimain and Ofongo, 2012), optimizing function of enteric epithelia and mucosal immunity, which is an important first line of defense against the intrusion of enteric pathogens (Fagarasan, 2006).
Its appearance can be powder,granule,coated granule,micro-capsule. It can be a single strain, multi-strain, a combination with other ingredients.
Most commercial probiotic products fall into two major categories, Sporulated Bacillus spp. and Lactic acid producing bacteria . Here is an overview of the major probiotic bateria species which consists of the probiotics product.
|B. subtilis, B. licheniformis
|L. acidophilus, L. bulgaricus, L. reuteri, L. salvarus, L. sobrius
|B. animalis, B. bifidum
Can probiotics keep stable in heat treatment?
This is an FAQ by customers whether probiotics can withstand the heat treatments being used in normal feed production practices.
Some probiotic companies claim that sporulated bacteria such as Bacillus spp. and Clostridium spp. are less heat sensitive than non-sporulated bacteria such as lactic acid producing bacteria and Bifidiobacterium spp. This in itself is true, but it is not a complete answer, because:
Protection from oxygen sometimes required
Bifidiobacterium spp. are obligate anaerobes, meaning they cannot grow in the presence of oxygen, and therefore need to be protected from air in order for them to survive. Certain coating technologies offer protection against the normal heat and steam treatments currently used in feed manufacture, which can have additional stabilizing effects for survivability of obligate anaerobic bacteria. However, these protective coatings need to be adapted to the species, and even the specific strain’s needs, in order to warrant proper protection during the pelleting process.
Probiotics delivered to animals at an early age can help establish a beneficial gut microbiota and set them on the right path for development. Application of probiotics in adult animals also provides benefits including resistance to health challenges and better flock uniformity.
Probiotics can be used to address several challenges in commercial production of food-producing animals, such as:
- Opportunistic bacterial challenge
- Heat stress
- Antibiotics reduction
Bacteria, such as Salmonella, Clostridium, Escherichia coli, and other opportunistic microorganisms have the capability of causing chronic mucosal enteric damage disturbing not only gut integrity but also the overall physiology of the animals.
The outbreak of these microorganisms bring several consequences, such as enteric epithelia cells destruction, decrease on nutrient digestion and absorption capacity (Kaldhusdal et al., 2001). In addition, Salmonella, E. coli and Campylobacter carcass contamination are negative bacteria causing enteric disorders not only in animals but also in humans.
Global warming has brought environmental temperature stress problems on animal production around the word . Birds expose to heat stress can result on poor performance in broilers, as high morbidity and mortality in layers (Mcgeehin and Mirabelli, 2001) due to impairment to their endocrine system (Rozenboim et al., 2007), electrolytic unbalance (Teeter et al., 1985) and immune system suppression (Mashaly et al., 2004). These disorders can affect microbiota eubiosis and villus morphology (Burkholder et al., 2008).
Why are pigs so sensitive to heat stress?
Pigs are much more sensitive to heat than other animals during periods of hot weather due to pigs do not sweat and have relatively small lungs.Becuase of these physiological limitations and their relatively thick subcutaneous fat, pigs are prone to heat stress.Bigger pigs are more prone to heat stress and the reduction in growth performance is greater than for smaller pigs.
What does current research say about heat stress?
A recent publication by Pearce et al. (2013) examined what happened to the intestinal structure when pigs were exposed to heat stress. The research showed that exposure to 35°C for 24 hours significantly damaged the intestinal defence function and also increased plasma endotoxin levels. The authors explained that when pigs are exposed to heat stress (even for as little as two to six hours) their intestinal defence systems are significantly compromised and this provides opportunity for infection as pathogenic bacteria can invade the body more easily. Therefore, heat stress can create secondary infection if sanitary conditions are poor.
Prolonged exposure to heat stress increases corticosteroids secretions (Sapolsky et al.,2000) affecting enteric epithelia integrity. Corticosteroids secretion breaks down tight junction proteins promoting bacterial translocation and metabolic disorders. Once these anatomic structures of the enteric epithelia are affected and the physical barrier is more permeable. Therefore, bacteria and toxins can go from the lumen of the gastrointestinal tract to the blood stream. This phenomenon may lead to reduction on feed intake and digestion capability (Zhang et al., 2012) reducing performance efficiency (Azad et al., 2010).
How does probiotics impact controlling of heat stress?
Heat stress as any other stress stimulate corticosteroid secretion by the suprarenal gland (Shini et al., 200), then corticosteroid secretion is linked to the ratio of hetherophyls and lymphocytes, which is use as stress indicators (Gross and Siegel, 1983). The over secretion of corticosteroid induce the break down of tight junctions proteins leading to, not only, bacteria translocation, but also digestion and absorption disorders. Probiotics can potentially reduce the impact of extreme environmental temperature, improve feed efficiency and enhance growth rate (Eckert et al., 2010) through the down-regulation of corticosteroid secretion, resulting in an enhanced intestinal barrier and positively influenced immune response (Ng et al., 2009).
Antibiotics reduction and antibiotic-free feeding
Antibiotic-free feeding (ABF) programs is not only an antibiotics reduction or replacement strategy, but a comprehensive program that includes strengthening of biosecurity measures and progressive inclusion of feed additives alongside pharmaceutical components, such as such as vaccines, enzymes, acidifiers, phytogenics, probiotics and prebiotics in order to enhance immune system capacity to face challenges on the field.
The right probiotics are considered a useful tool to be included in antibiotic free production program (Gustafson and Bowen, 1997), this scientific development not only can enhance the immune response against vaccine antigens (Patterson and Burkholder, 2003), but also to decrease the impact of environmental conditions and infectious diseases (Willis and Reid 2008).
probiotic are very useful alone or in combination with other antibiotic-alternatives for the control of infection due to Gram+ and – bacteria . The use of these alternatives result not only in the control of pathogenic outbreaks but with the right approach serve as natural growth promoters and used as alternative to antibiotics as growth promoters, as well as to decrease the use of antibiotics for treatments (Willis and Reid 2008). A very important clue to determine if either probiotic could be part of this kind of programs is a correct diagnostic and to determine if the probiotic mode of action may contribute to diminish the impact of the most common factors modifying animal performance.
How to choose the right poultry probiotics ?
How to choose the right pig probiotics ?
There are several alternatives of probiotics in the market, all with inherent advantages and disadvantages depending on the nature of the organisms and the treatment that the final product receives.
Several criteria can be used to select probiotics including:
- Product composition / choice of strains*
- Documented mode of action*
- Stability vs efficacy
- Defined vs undefined cultures
- Sporulated vs non-sporulated
* Regarding the first two criteria, buyers should be aware of what they’re buying and to what extent scientific studies document the effects is.
Stability vs. Efficacy
Customers often have to choose between these two criteria. However, from customer’s point of view it may be safer to select efficacy over stability for a simple reason: it is easy to check for stability and it can be demanded to the probiotic manufacturer. If the manufacturer claims a certain amount of viable colony-forming units (CFU) after pelleting or after 6 months of storage the producer is only a few samples away from the truth.
On the other hand, there is no insurance for efficacy. There are too many factors that can compromise efficacy of a product in the field: diseases, nutrition, immune status of the flock, and stress factors in general; as a consequence it is difficult for the poultry producer to evaluate the real efficacy of a given product under field conditions.
Sporulated vs. Non-Sporulated Probiotics
Sporulation confers an excellent method to protect bacteria against physical damage. From this starting point several advantages can be surmised. For instance, the issues of shelf life and storing conditions seem irrelevant when considering that spores can remain viable for hundreds of years. One main advantage of spores is that they can be easily incorporated into feed tolerating pelleting process with minimal reductions in viability.
Similarly, passage through the stomach should not be a problem for a spore. However, all those advantages seem to pale if the natural habitat of the most currently used sporulated bacteria is considered: Bacillus sp. are well recognized as environmental bacteria. This apparently simple statement draws a question mark on most scientific evidence supporting the effect of the vegetative form of these bacteria against pathogens.
By definition, a dormant life form does not utilize a lot of environmental resources and thus not very many biochemical reactions are taking place.
Competition for available nutrients, production of antibacterial substances, direct inhibition of pathogens, and probably even active attachment and competition for binding sites are all doubtful in case spores are not able to transform into vegetative cells inside the intestinal tract. Valid scientific evidence should address possible mechanisms of action in vivo.
In contrast to spores, when considering long storing periods, pelleting, and passage through the stomach, the non-sporulated bacteria seem fragile. Some of these weaknesses can be partially solved by a coating treatment if the bacteria are to be mixed in feed that will be pelleted.
Quality of the coating will determine the cell viability after pelleting and after passage through the stomach. Despite all these weaknesses, when vegetative probiotics (of intestinal origin) reach the intestine they are “at home”. If the probiotic strains originate from a compatible animal —or even better from the same animal species— there will be no better place for these bacteria to grow, replicate, compete for nutrients, attach to cellular receptors, and to interact with the host than in the intestine.
From this point of view there is a huge potential for future development of probiotics. It is very likely that in the in vitro process of screening we have lost excellent candidates due to our current inability to create a model that closely resembles the intestinal tract. It is becoming increasingly clear that interaction between bacteria and their environment is very important when analyzing the efficacy of probiotics.