Influence of hen age and molting treatments on shell egg exterior, interior, and contents microflora and Salmonella prevalence during a second production cycle.

The objective of this study was to determine if increasing hen age and 3 different molting treatments influenced the total microflora counts or the prevalence of Salmonella spp. on the exterior of the egg shell, within the interior shell, or in the contents. Eggs from Hy-Line W-98 and Bovans White layer strains were sampled approximately every 28 d from 70 to 114 wk of age, with the molting period from 66 to 70 wk of age. Layers were utilized from the 35th North Carolina Layer Performance and Management Test and managed under identical husbandry practices. This study consisted of nonfasted, nonmolted, and feed-restricted treatments with the use of 135 eggs per layer strain, for a total of 270 eggs sampled per period. The exterior, interior shell, and contents were spiral plated onto plate count agar to calculate the total aerobic counts. Additional preenrichment, enrichment, conformational, and biochemical procedures were performed to test for the presence of Salmonella spp. Hen age and molting treatment significantly (P < 0.05) affected the microbial loads on all 3 egg components. Exterior, interior, yolk, and albumen counts increased during the molt period to as much as 1 log unit higher than the highest countable plate, which was 10(5). Exterior, interior, and contents counts significantly increased (P < 0.05) during period 15, with a significant increase (P < 0.05) in the interior also in period 14, and in the contents in periods 14 and 17. There were a total of 360 egg pools, and of those, 4 were positive Salmonella samples. Both the interior and exterior shell components and 2 of the 3 molting treatments had positive samples. Of these positives, 4 were confirmed as Salmonella Braenderup. Three positives were associated with the interior component, whereas 1 positive was associated with the exterior shell component. Three of the 4 samples were related to the nonfasted treatment, whereas the remaining positive was found in the non-molted treatment.