Effects of an Outbreak of Avian Encephalomyelitis (Epidemic Tremor) in a Breeding Flock

Abstract

DURING a period in which hatching eggs were collected for experimental incubation at Berkeley in April, 1953, it became apparent that many hens were pausing for short periods of time. Examination of daily production records gave evidence of a sharp decline in egg production in pens H4 and H5 of one house (Figure 1). Pens H2 and H3, containing birds of the same age in another house, exhibited production curves nearly identical with those of pens H4 and H5, excepting that the pausing period was five days later. Inspection of the birds in these pens revealed no detectable symptoms of any disorder. Recovery from the low point in the production curve was rapid and nearly all hens returned to their normal rates of egg production. Upon completion of the incubation period of the eggs set (Hatch 33), it was noted that hatchability in both control and experimental lots of eggs …