Probiotics in broiler production – a review

In 1988–1989 as a result of a public food poisoning from infections with S. interitidis eggs in England, egg consumption decreased within a short time by 90%. This caused a very serious economic loss for the government and the producers of about 70 mil. £ Sterling, and lead to a culling of a vast number of birds (North and Gorman, 1990). For the period March 1989 until December 1990, 1,700,000 infected birds have been killed. During that disaster, the question regarding Salmonella resistance arose. Different analyses revealed that 67% of the feed containing animal proteins and 69% from the mixtures at the feed factories were contaminated with Salmonella (Public health Services laboratory, 1991). For the rapid colonization of the intestinal tract of newly hatched chicks with useful intestinal micro-flora different biological products are used. Due to the politics of banning growth promoters (feed antibiotics), the group of probiotics faced increasing interest in the past. Probiotics are biological products, which stimulate the immunity system and increase its defensive activity against pathogenic bacteria. Probiotics competitively exclude the Salmonella bacteria from the intestinal tract of the treated chickens. The auspicious effect of probiotics over the organism is due to the better adhesion of the lactic acid bacteria to the intestinal epithelium in comparison to the pathogenic bacteria, and stopping the implementation of that bacteria over the mucosa of the intestine (Fuller, 1989). Probiotics stimulate the natural resistance of the organism by increasing the number of antibodies and increasing the effectiveness of macrophages (Goldin and Gorbach, 1984b). Usually probiotics contain one or more types of bacteria depending on the media of their growth. The idea of using pure cultures of microorganisms for prophylaxis against gastrointestinal infections appeared during the past century. In 1889, Brudzinski recommended the prophylactic use of coli bacteria cultures, Peretz (1932) curatively used coli bacteria cultured in sterile milk for gastrointestinal infections and named this preparation “Colibacterin” (Colicin; Gratia and Frederica, 1925). For the first time Metchnikoff (1961) used lactic acid bacteria for suppressing the growth of putrefactive and pathogenic bacteria in the chicken’s intestinal tract, the preparations were called “Lactobaciline”: fermented milk with L. bulgaricus and lactic acid streptococci. Different substances containing defined bacteria have a protective effect in the organism of the bird. Filtrates without containing bacteria obtained from fermented cultures of material taken from intestinal or caecum suspension – have no protective effects (Rantala, 1976; Snoeyenbos et al., 1978; Soerjadi et al., 1978). The principal effect and the greatest value of probiotics is derived from reducing colonization of chicks by Salmonella, thereby reducing the prevalence of Salmonella at slaughter and reducing the risk of Salmonella poisoning for consumers. The cost of Salmonella poisoning to the Canadian economy is in the region of $ 1,344,000,000 per annum. In the UK in 1993, it produces a staggering total cost of over 6 billion £ Sterling. The potential economic impact of probiotics may be demonstrated by the observation in Sweden, where 179 high risk, commercial broiler flocks were treated with CE and only one of those was subsequently found to be contaminated with Salmonella. In Finland from the broiler’s flocks received Broilact only in 0.4% of the flocks were found Salmonella (Wierup et al., 1992). Furthermore, Broilact1 treatment may significantly increase the performance of broilers, which means a clear profit to the producer. Considering prevailing poultry meat and feed prices this was worth approximately £ 22 per 1000 birds after subtracting the cost of Broilact1 (Broilact Newsletter, 1994). Growth-promoting antibiotics are much cheaper than probiotics, their use costs about one third of a Sterling penny per bird, but most of them favour colonization of the gut by Salmonella and they are unpopular by consumers. Probiotics cost one Sterling penny per bird, but provide the additional benefits stated above.