Geographical Variations in Egg Nutrient Density: A Comparative Study of Ohio and Indiana Layer Hen Systems in Late Fall and Early Winter Months

Results: We identified and screened 76,587 articles, of which 10,884 were included.Research addressed agricultural processes for crops (73% of articles), seafood (21%) and meats (8%) from more than 140 countries.Most research assessed cadmium (68%), followed by lead (44%), arsenic (24%), and mercury (15%).Most articles on crops (57%) focused on soil, soil amendments, and fertilizer.Whereas most articles on seafood (49%) and meat (39%) were related to weather and the environment, including pollution.Five agricultural process categories from each domain were determined to be research gaps.For crops, these were planting and field maintenance (6% of articles), microbial inoculation (5%), harvesting (2%), washing, storage, and waste management (2%), and pest control (1%).Gaps for seafood were on feed (9%), medications and feed additives (3%), chemotherapeutants in water (1%), fertilizer (0.4%), biologics and hormones to induce spawning (0.1%).For meats, gaps included egg production (4%), housing (3%), milk production (2%), reproduction (1%), and farm management, waste, and production scale (0.4%).Conclusions: Our study identified several research gaps warranting further investigation, as well as areas where existing evidence might be sufficient to warrant systematic review to inform future policies related to reducing heavy metal contaminants in the global food supply.