[The influence of infectious bronchitis virus on egg production, fertility, hatchability and mortality rate in chickens (author's transl)].
In 35 flocks comprising almost 100,000 White Plymouth Rock birds producing hatching eggs, infectious bronchitis (IB) caused a decline in production which appeared to be connected with the age of the birds, when the outbreak started (table I). In outbreaks of IB in pullets 3-4 weeks before they are ready to lay there is a considerable risk of delay of production and a generally too low yield (fig 1). Egg laying birds, 25-34 weeks of age, suffered a drop in production from 20-80% (on an average 40%) and normal yield was never regained. After 6-8 weeks the production rate usually stabilizes around 6-12% below normal production. IB outbreaks in the middle of the production period (35-45 weeks) resulted in a decline of egg production of 40-90% (on an average 55%). Recovery of production usually occurred after 6-8 weeks (fig. 2). Observations of clinically typical outbreaks without any laboratory verification indicate that IB outbreaks at the end of the egg production period resulted in irreparable decline of production. Marked alterations in exterior and interior quality of the egg have been observed. Both mishapen appearance, rough and thin shell, bleached shell color and watery albumen have occurred. These facts did sometimes cause transient increased "sorting out" of haching eggs. Also fertility rate was noticed to be affected temporarily during and after an attack of IB. In 17 flocks drops of 1.7-22.4% (on an average 7.4%) were registered (fig. 3). Also hatchability decreased 3.0-43.8% (on an average 13.7%) (fig. 4). In most of the registered outbreaks of IB the weekly mortality remained below 1%, but in single cases the figure could rise up to about 4% (fig. 5), most often in flocks where complicating factors such as secondary infections caused by E. coli or M. gallisepticum were present.
D000818:Animals; D001991:Bronchitis / Q000401:mortality / Q000662:veterinary*; D002645:Chickens; D004531:Eggs; D004971:Estrus; D005260:Female; D005298:Fertility; D001351:Infectious bronchitis virus; D011200:Poultry; D011247:Pregnancy; D014777:Virus Diseases / Q000662:veterinary*
Infektiøs bronchitis virus indflydelse på aeglaegning, befrugtnings og klaekningsprocent og afgang af høner