EXPERIMENTAL REPRODUCTION OF SEVERE HYPOGLYCEMIA AND SPIKING MORTALITY SYNDROME USING FIELD-DERIVED AND EMBRYO-PASSAGED PREPARATIONS

The clinical signs, enteritis, weight depression, and hypoglycemia of spiking mortality syndrome were experimentally reproduced in broiler b reeders and broiler chicks. Inocula included 1) virus-like particles f rom intestines of chicks with spiking mortality syndrome that had been banded in a discontinuous Renograffin(R) gradient, 2) homogenized dar kling beetles collected from litter of farms where spiking mortality s yndrome had occurred repeatedly, and 3) homogenized embryos which had been inoculated with the Renograffin-banded material. Arkansas variant infectious bronchitis virus and arenavirus-like particles were identi fied in the inocula. Serology on samples from surviving chicks suggest ed the presence of an avian encephalomyelitis virus in one of the inoc ula. One-day-old (n = 172) and 2.5-day-old (n = 30) chicks were inocul ated orally, and some were also injected intraperitoneally or subcutan eously, with 0.5 mi of the inocula. Twelve to fourteen days postinocul ation, chicks were fasted for 4-6 hours, then briefly stressed with a cool water spray. Within 1.5 hours, inoculated chicks began dying with severe hypoglycemia and clinical signs of spiking mortality syndrome. Body weights were significantly depressed. Uninoculated controls (n = 130) from the same hatches, also fasted and stressed, were unaffected clinically and were not hypoglycemic. One group (n = 52) of inoculate d chicks exposed to a controlled lighting program was unaffected clini cally, had significantly higher mean plasma glucose levels, and had si gnificantly less body weight depression than chicks exposed to continu ous lighting. We concluded that exposure to controlled amounts of ligh t/darkness can ameliorate much of the hypoglycemia, mortality and runt ing-stunting associated with spiking mortality syndrome of chickens. T he significance of the viruses and virus-like particles detected in th e inocula is currently under investigation.