Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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Aspergillosis and Ascites in Broilers K. McMillan
History On February 6,1995, a flock of broilers was placed into three barns on one premises. They appeared to start well and looked quite good during the first week. First week mortality was as follows: Barn 1 2 3 Placed 8,000 10,000 16,000 % Mortality to 7 days 0.78 0.91 0.88 On the 7th day mortality began to increase and by the morning of day 11 the owner became concerned and took some of the dead birds to the Lab. Discussion was held later in the day with the owner and with the Lab. The Lab reported that they had observed little in the specimens outside of some retained yolk sac and had made preliminary diagnosis of Omphalitis, pending culture test of selected tissue. Flock Visit: That evening a visit was made to the flock. Barn conditions were good; the litter (straw) was dry. Temperatures were appropriate for age and there were 2 exhaust and 3 circulating fans operating. Many dead birds were found scattered throughout the barns. There were also a significant number of moribund birds present. Barn mortality during the time period from 8 am through 7 pm was a follows: Barn 1 2 3 Mortality 8 am – 7 pm 12 14 37
Necropsy: Pericarditis/peritonitis 5 N.V.L. 8 Starveout/dehydration 9 S.D.S. 3 Yellow plaques in airsacs/lung 36 Ascites 2 One bird had prominent blue black (1cm d) mold growth in the right abdominal airsac. A diagnosis of Aspergillosis was made and the owner advised that he might expect the mortality to continue for a few days and might possibly see an increase in the incidence of Ascites in the flock later on. No treatment was considered, but the owner agreed to treat the litter with a mold inhibitor the next day. The straw litter did not show evidence of mold. The straw had been baled right behind the combine, but the owner indicated the grain crop had been subjected to heavy rains while in the swath and the straw had deteriorated in quality. Mold culture plates placed in barn #3 the next day showed a very high number of airborne Aspergillus spores, which were likely enhanced by the air currents from the circulating fans. The flock was revisited at day 18. The overall mortality of the combined barns had risen to 28.6%. Dead birds were collected and examined on necropsy: S.D.S. 5 Culls 3 Ascites 22 The Ascites was found to range from early stages of right ventricular hypertrophy and pericardial fluid through to extensive accumulations of abdominal fluid. Yellow plaques of Aspergillus growth could be found in some of the airsacs and lungs of the Ascites birds. Because of the still increasing mortality, arrangements were made to move the flock to market at Cornish weight (28 days of age). By market time the accumulated mortality had reached 52.3%. As expected, slaughter condemns were very high at 8.7% of which 6.9% were for Ascites and Cyanosis. Conclusions: It is believed that the Aspergillosis infection contributed significantly to the development of Ascites in this flock. The broiler grower has since abandoned the straw supply and has raised his birds on shavings litter without further problems. Interestingly an almost identical problem occurred two weeks earlier on another premises some 15 miles away. The straw litter used on that premises had visible mold present. Losses in that flock only reached 27% by broiler market age, but again the prominent feature was the development of clinical Ascites following exposure to Aspergillus in moldy straw. |
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