PRINCIPLES OF EX OVO COMPETITIVE-EXCLUSION AND IN OVO ADMINISTRATION OF LACTOBACILLUS-REUTERI

The data that have been presented indicate that the in ovo use of comp etitive exclusion (CE) agents is feasible for both chickens and turkey s. However, there are many pitfalls that await the use of in ovo appli cation of CE agents, including the use of nonspecies-specific intestin al microbes and the use of harmful proteolytic, gas-producing and toxi n-producing intestinal microbes. Of the potential CE agents that have posthatch application, only Lactobacillus reuteri has been shown to be safe and effective in terms of not affecting hatchability and in havi ng a prolonged effect in the hatched chick or poult. Lactobacillus reu teri administration in ovo increases its rate of intestinal colonizati on and decreases the colonization of Salmonella and Escherichia coli i n both chicks and poults. Additionally, mortality due to in-hatcher ex posure to E, coli or Salmonella is reduced with in ovo L. reuteri. Use of antibiotics in ovo may preclude the use of co-administered CE agen ts, but Gentamicin(R) and L, reuteri are a compatible mixture when adm inistered in ovo in separate compartments. Nevertheless, the intestina l morphology can be affected by both the CE agent and by antibiotics. Lactobacillus reuteri both in ovo and ex ovo will increase villus heig ht and crypt depth, and Gentamicin(R) in ovo causes a shortening and b lunting of the villus. Both Gentamicins and L, reuteri in ovo suppress potentially pathogenic enteric microbes, but with diminished antibiot ic effects shortening and blunting of the intestinal villi does not co rrect itself. Goblet cell numbers increase significantly on the ileum villus of chicks treated with Gentamicins in ovo, and this is presumab ly due to the increase in potentially pathogenic bacteria in the intes tinal tract. Diminishing antibiotic effects posthatch would then negat ively affect the absorption of nutrients and reduce growth at least in a transitory manner. Thus, L. reuteri administration in ovo singly or in combination with Gentamicin(R) followed by L. reuteri via drinking water or feed appears to have potential to control many enteric patho gens in poultry. Additional work in the use of in ovo CE cultures is m andated because there is a world-wide movement to reduce antibiotic us e in poultry due to increased microbial resistance to antibiotics. Use of naturally occurring intestinal bacterial cultures, either in mixed culture or as single well-defined cultures, has potential for immedia te use in the poultry Industry.