Objective—To assess the effects of electromagnetic (EM) field modification by use of Nufield EM field modification (NEFM) units on egg-laying hens in commercial flocks as indicated by production measures, including hen-day mortality rate (HDMR) and eggs per hen housed (EHH).
Animals—16 commercial flocks of egg-laying hens.
Procedure—5 caged commercial table egg layer flocks (Single Comb White Leghorns) successively housed at the same location during a 6-year period were exposed to NEFM. There were 7 hens/cage (317 cm2 of floor space/bird). At the same site, 11 concurrent non–NEFM-exposed flocks (4 genetically different strains) were sequentially housed. All 16 flocks underwent the same feed and management practices. For each NEFM- and non–NEFM-exposed flock, HDMR and EHH were compared with their respective national breeder goals (BG), defined as the reasonable genetic potential expressed under optimal management and environmental conditions. Furthermore, the HDMRs and EHHs of the NEFM- and non–NEFM-exposed flocks were compared.
Results—Mean HDMR and EHH of the NEFMexposed flocks was 36.9% less and 4.96% greater than the relevant BG, respectively. Mean HDMR and EHH of the non–NEFM-exposed flocks was 12.6% and 0.49% greater than the relevant BG, respectively. Compared with the 11 non–NEFM-exposed flocks, the NEFM-exposed flocks collectively had a 47.6% decrease in HDMR and 1.33% increase in EHH.
Conclusions and Clinical Relevance—Results strongly suggest that application of NEFM in commercial egg-layer flocks improves production measures, which has important welfare implications as well as gross economic advantage. (Am J Vet Res 2005;66:1425–1429)