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United States Department of Agriculture

Agricultural Research Service

2008 Annual Report

1a.Objectives (from AD-416)
Compare the microbiology of eggs obtained from caged Leghorn hens and cage-free floor housed Leghorn hens with both naturally contaminated and artificially inoculated environments.

1b.Approach (from AD-416)
Day of age Leghorn pullets will be obtained and reared in a confinement rearing facility set up to industry standards until the birds reach sexual maturity. At this time, a confinement housing facility would be set up to simulate a commercial Leghorn setting where the hens are housed in cages versus a confinement rearing facility where Leghorn hens are housed on the floor and eggs collected from nest boxes. To test the microbiology of the eggs from the two laying areas, an assortment of microbiological analyses (i.e. total aerobic plate count, Enterobacteriaceae count, E. coli count, Campylobacter, and Salmonella) of the eggs from both groups will be performed. In addition, another set of experiments will be conducted where the Leghorn hens are inoculated and colonized with a Naladixic acid resistant Salmonella and analysis of the eggs conducted.

3.Progress Report

This progress is related to objective 3 of inhouse project: Qualitatively and quantitatively idenfity and compare selected microbial populations in the chicken gastrointestinal and reproductive tracts and in the internal organs of healthy and of diseased birds.

This research quantifies the bacteria levels recovered from table eggs produced in three laying environments prior to and following eggshell sanitization and has implication for foodborne pathogens associate with table eggs.

Hy-Line International hatching eggs were obtained from both the W-36 (White) and Brown layer strains from flocks at 56 weeks-of-age. Eggs were set at the University of Georgia hatchery on December 24, 2007 and hatched on January 15, 2008. Hatchability for the White strain was 90.6% and resulted in #220 female chicks. Hatchability for the Brown strain was 78% resulting in #177 female chicks. Pullets were reared intermingled in a single environmentally controlled closed brood/grow-out facility to 15 weeks-of-age under photoperiod restriction. Samples of 40 pullets have been weighed every two weeks and at 13 weeks-of-age body weight averaged for the White pullets at 1,025 g and for the Brown pullets at 1,161 g. These body weights are on target according to the Hy-Line management guide standards: 1,030 g for the White and 1,130-1,250 g for the Brown. Pullets were moved into the laying facility at 15 weeks-of-age, on May 2, 2008. Pullets were moved at this age to maximize the potential for nest box familiarization prior to the onset of egg laying, hopefully resulting in a minimum number of floor or slat eggs through the life of the flock. The White pullets obtained a body weight of 1,270 g (2.8 lbs) at 18 weeks-of-age and increasing photoperiod to induce the onset of egg production was initiated and will continue to increase until 14 hours is attained. We have prepared duplicate pens for housing 45 or 54 laying hens in 9-colony cages (5-pullets per cage for Brown and 6-pullets per cage for White). For the elevated wire slats and wood shavings pens, 54 White or 54 Brown pullets were placed into each pen. All pullets were housed within the same room, fed ad libitum the same feed, water provided by enclosed nipple drinkers, and exposed to the same circulating air flow, environmental temperature and relative humidity profiles. Pullets housed on shavings or slats have been provided roll-out nest boxes at a density of 4.5 pullets per nest (12 nests / 54 pullets). Pullets housed in cages are provided trough feeders and hens on slats or shavings are provided tube/pan feeders. Access to perches has continued to be provided for pullets on slats or shavings. At the time of moving pullets into the laying facility, 15 weeks-of-age, flocks had maintained Salmonella and Campylobacter negative status, as determined by litter sampling with stepped-on-drag swabs. The first progress report was submitted on May 1, 2008. The first egg was laid May 23, 2008.

Scientist attended and participated in quarterly meetings and biannual site visits to discuss and monitor research activities.

Last Modified: 7/26/2016
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