Jun 11
19
Yolk Sac Infection and Retention in Ostrich Chicks
When ostrich farming developed globally yolk sac infection was commonly identified as the cause of death for many chicks. The reason for this was the variable yolk sacs witnessed. One ostrich veterinary book even suggested that yolk sacs with some green colouration may be yolk sac infection as they were so unused to seeing the green yolk sacs. In fact the green colouration is correct and the sign of a healthy chick with excellent bile production to assist in the digestion on the fats in the yolk sac.
The picture illustrates 3 baby chicks during autopsy. No 1 and No 2 are about 10 days of age and No 3 was only 1 day old. No. 2 was a healthy chick euthanized for the purpose of a study to illustrate how a healthy yolk sac should look.
None of these chicks have Infected Yolk Sacs even though all look very different. These variations are all caused by nutritional deficiencies in the diet of the hens that produced the eggs. No. 3 was one of a number of chicks autopsied that day. They were all different, with extremely large yolk sacs and variable internal organ development. No. 3’s yolk sac was twisted – the photograph was taken after untwisting.
During the South African investigation on Chick Mortality, personal communication with a vet involved in the study mentioned testing many chicks for yolk sac infection as he saw similar extremes variations as illustrated above. He was unable to identify any particular bacteria causing any major infection.
As the pictures illustrates, there are problems with the yolk sacs, but infection is not the cause.
Yolk sac retention is another condition often reported in ostrich chicks. As can be seen Chick No. 2, at 10 days old, is using the yolk sac well and was likely to be totally absorbed during the next week. As mentioned above, the green in the yolk sacs is bile. Bile is required to aid the digestion of the fats in the yolk sac. Chick 1 also has a liver that is extremely yellow rather than the natural brown as seen in Chick 2 and Chick 3. Chick 3 had other issues apart from the twisted yolk sac.
The purpose of the yolk sac is to provide the chick with adequate nutrients while the digestive system develops. It is essential to provide food and water to the chicks as quickly as practical after hatch. When a chick is hatched with internal organs that have not developed properly, such as the yellow liver, the chick has a battle to simply survive, let alone grow and develop. Chick 1 was unable to win that battle.
The main cause of yolk sac abnormalities at this time remains breeder nutritional deficiencies. Farms experiencing these problems will usually experience reduced egg fertility and hatchability. Addressing the cause of this problem is essential for commercial success in ostrich farming.
To avoid the mistakes of many past ostrich farmers, and to save you time and money, check out “How to Start A Successful Ostrich Farm“.
