Occurrence of Salmonella spp.: a comparison between indoor and outdoor housing of broilers and laying hens
It is beneficial to view the results of this 9-year study in conjunction with extensive published reviews that concluded that there is no consensus regarding the impact that cage, barn and free-range egg production has on Salmonella contamination of eggs (Holt et al 2011 and Whiley et al 2015). An Australian report indicated that fewer free-range flocks than indoor flocks were found to be environmentally Salmonella positive (Safe Food Qld 2015). Another (NSWFA 2013) reported that single tier cage farms were with the lowest Salmonella prevalence (10%), followed by free-range farms with moveable sheds (34%), free range fixed sheds (50%), multi-tier cages and barn (100%). Among other variables, the type of the indoor housing (e.g. multi-tier vs single tier) and the outdoor housing (e.g. fixed vs moveable) as well as the ventilation system (controlled environment vs natural ventilation) may play a role. The current considerable evidence does not support the perceived higher risk associated with outdoor systems. All layer hens regardless of their housing should be regularly monitored. Should we be reminded that the epidemics of Salmonella enteritidis emerged long before the trend towards a better welfare outcome for hens? References 1. Holt et al (2011) Poultry Science, Vol 90, Issue 1, https://academic.oup.com/ps/article/90/1/251/1513625 2.Whiley et al (2015) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4377917/ 3. Safe Food Qld (2015) Salmonella survey of the Queensland egg production environment http://esvc000111.wic055u.server-web.com/images/PDF/2015%20Microbiological%20survey%20of%20Queensland%20egg%20farms.pdf 4. NSWFA (2013) Baseline evaluation of the NSW Egg Food Safety Scheme – microbiological survey of egg farms in NSW http://www.foodauthority.nsw.gov.au/_Documents/scienceandtechnical/egg_baseline_micro_survey.pdf
Actually the climatic condition of the study area is not stated, but the environment has a great effect on the survival of the pathogens. The environment should be considered. Environmental (tropic and temperate) comparative study is required to conclude. Thanks. Dr. Asheikh
