Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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Investigation to Determine Cause of Embryo and Early Chick Mortality of Ratites Dr. Detlef K. Onderka, Alberta Agriculture Food and Rural Development Animal Health Laboratories Branch
Introduction Over the last few years the ratite industry in Alberta has been expanding rather rapidly. More and more producers either acquired breeding birds or had birds that recently matured to breeding age. As a result, considerable reproductive activity has taken place in the last two years. As might be expected in a young growing industry, there were considerable trials and errors particularly in the area of egg handling, incubation, hatching and early chick management. In order to identify major problem areas, the Alberta Agriculture Animal Health Laboratories, in cooperation with the Alberta Ratite Research Foundation conducted this project. The ostrich breeding season was already somewhat advanced, therefore, the number of specimens were limited.
Results Eggs Fourteen (30%) of the ostrich embryos developed to the piping stage, but were too weak to hatch. In these birds, there was extensive accumulation of fluid under the skin particularly on the neck, inner thighs, and down to the toes. This condition is called anasarca and is known in the industry as "wet chicks". The average moisture loss in eggs with wet embryos was 13.3%. The range of weights of 29 African Black eggs was 1206-1486 grams with an average of 1317 grams. This weight omits two unusually small eggs of 868 and 991 grams respectively. A second prominent problem was bacterial contamination. It occurred in 14 (30%) of the eggs. Contamination was seen in both fertile and infertile eggs. When it occurred in fertile eggs, the embryo usually died about midway through incubation with a few eggs showing embryo mortality already after the first week. There was no correlation between washed and unwashed eggs (about half and half) or the storage time (4-7 days) and contamination. Most nests were lined with sand and a few laid the eggs on soil. Again there was no difference in contamination rate. Bacteria isolated from those eggs were primarily E. coli, Pseudomonas spp, Lebsiella spp, and Aeromonas spp. These bacteria are environmental contaminants, no specifically associated with ostriches or eggs. Another significant category was infertility, which was seen in 26% of the eggs submitted. Malposition and miscellaneous findings were of minor importance. Chicks A significant proportion of the chicks submitted (32%) died with a fairly sudden onset of gut infection (enteritis). This usually affected the large intestine causing severe damage to the gut lining cells. The intestines were reddened, slightly ballooned and in many cases had pale necrotic areas. It was associated with the heavy proliferation E. coli, Clostridium spp of Klebsiella spp. In one case CORONAVIRUS was involved. Twenty five percent of the birds died with emaciation. These chicks either never did go on feed, could not utilize their yolk sac as a nutrient source or did not eat sufficient quantities for sustained growth. They usually were sick for one week or longer and continuously lost weight. By the time the chick had lost about 20% of its body weight, it would be beyond any hope of recovery and went on to die. Infected yolk sacs were relatively uncommon occurring only in 14% of the birds submitted. Pneumonia was seen in a small percentage of the chicks. This was related to litter quality and resulted in either bacterial or fungal (Aspergillus) pneumonia. A small proportion of chicks had peritonitis or retained yolk sacs. Normal yolk sacs at about one week of age were found to be 14-16% of the total body weight. In cases of malabsorption of the yolk, the yolk sac was about 33-48% of the body weight. |
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