Evaluation of alternative disinfectants to formaldehyde for treating broiler eggs in a commercial hatchery

Abstract

Omphalitis (mushy chick) is a significant cause of early chick mortalities on commercial chicken farms. While there are many factors that affect the incidence of mushy chicks, egg hygiene and handling practices on breeding farms as well as in hatcheries has a significant effect on this incidence. Disinfection of eggs at the breeding farm and/or the hatchery is crucial to decrease the number of bacteria, viruses and fungi on the egg shells which may affect not only the survival of the embryo, but also affects chick quality and performance through chick mortality, leg problems (bacterial femur head necrosis), absorption of the yolk, immune status, growth and feed conversion. During the 18-week trial period, 17 280 000 broiler eggs were exposed to three different disinfectants during the final three days of incubation in a broiler hatchery. Thirty-seven percent liquid formalin served as the control and were compared to Virocid, a glutaraldehyde and quaternary ammonium compound disinfectant and Imazigard, a disinfectant with polyhexamethylene biguanide and imazilil as the active ingredients. Application time for formalin was continuous through evaporation from days 19 to 21, while Virocid and Imazigard were applied once a day for two minutes as liquids through a cold fogger on days 19 and 20 of incubation. The trial was performed in 3 hatcher bays in the same hatchery, with each bay receiving a specific chemical treatment for 6 weeks before rotating to another product. Bacterial (Total Viable Counts, Escherichia coli and Pseudomonas) as well as fungal (yeasts and moulds) counts on fluff from hatchers were used as a direct measure of efficacy of disinfection. Seven-day mortality data from broiler chicks were used as an indirect indicator of efficacy of egg disinfection. Fluff E. coli counts from the Virocid group were significantly lower (p<0.01) compared to the formalin control group. All other bacteriology and mycology on fluff samples showed no statistically significant differences in the counts between the treatment groups and formalin with p values >0.05. There was no statistically significant difference in cumulative mortalities up to 7-days between Virocid (p=0.58) and Imazigard (p=0.45) chicks when compared to chicks emanating from eggs that were treated with formalin. Comparing the cost of formalin versus the treatment groups was imperative to establish the financial impact of using alternative disinfectants. While the price of a liter of liquid formalin is less than a liter of either Virocid or Imazigard, the price to disinfect an egg during the trial was approximately four times less for each of these disinfectants when compared to formalin. This is because the products are diluted to 2% (Imazigard) and 4% (Virocid) while the formalin is used undiluted. In conclusion, considering the highly irritant nature of formalin for hatchery personnel as well as newly-hatched chicks, the research has proven that good alternatives exist to effectively and cost effectively disinfect poultry eggs in hatcheries.