IMPACT OF CORN GRIND DIAMETER AND HOUSING ENVIRONMENT ON PERFORMANCE AND PRESENCE

White Leghorn hens will be housed in either conventional layer hen battery cages, in a quad-deck system with 10 layer hens/cage (403 cm2/bird) or housed free range housing with floorpens on litter with access to roosts or suitable free-range environment. FDA AHU assistance willnot be required for this collaborative study. Piedmont Research Station, North CarolinaDepartment of Agriculture and the Department of Poultry Science, North Carolina StateUniversity will provide experimental animals (White Leghorn Hens), experimental diets, housingand animal care over the 6 week experimental time frame. Also, all animal husbandry (feeding,providing water, maintenance of housing) will be provided by Piedmont Research Station, NCDept. Agriculture, which will perform the collection and recording of weekly bodyweights. Theexperimental design consists of a 2 X 2 factorial experimental design with variables of feed grainsize (fine versus coarse) in a mash diet and housing (conventional cages versus free-range) for 8weeks (20 weeks to 28 weeks of age). The experimental diets will be formulated using least-costlinear programming to meet or exceed NRC (1994) nutrient requirements for layer hens. Thecorn included in the feed will be either ground fine or coarse for experimental dietary treatments.The corn in the finely ground mash diet will be ground in a hammermill equipped with a 3-mmscreen with an average particle size of 560 yen¿. Coarsely ground corn utilized in the alternativediet will be prepared by grinding using a 4-mm screen with subsequent sieving in a 60 in.separator using a 16-mm sieve with an average particle size greater than 3000 yen¿. These dietarytreatments will not contain antimicrobials or coccidiostats. Laying hens will be inspected dailyand birds with visual health problems or poor body condition will be humanely euthanized bycervical dislocation and recorded for mortality rates. Eggs collected from production hens willbe stored at 4¿¿C for a maximum of 24 hours and subsequently, processed at the Department ofPoultry Science, for analysis. At week 6, all hens will be euthanized by cervical dislocationperformed by animal husbandry team at Piedmont Research Station, Salisbury NC and thefollowing tissues will be aseptically collected: spleen, hen reproductive tract (ovaries and/oruterovaginal region) and cecum. These tissues will be stored in sterile ice cold buffered peptonewater in stomacher bags and processed at the Department of Poultry Science, for analysis formicrobial analysis for Salmonella. Additionally, environmental microbial analysis will beconducted on samples collected from each experimental housing type (conventional cage versusfree range roost), drinking water and feed. Environmental testing will be conducted at the onsiteof the experimentation, at week 3 of experiment, and at week 8 of experimentation (termination).