Abstract
Chick Rescue TechniquesAn important aspect of hatching management is the ability to assist a developing embryo or hatching chick in trouble that would die of malpositioning or a disease process unless the aviculturist intervenes. This is an acquired skill that requires great experience and timing and has received little attention in the literature. The decision to intervene and to what degree is unique to each situation. The frequency for which embryo assistance is required is directly related to breeder flock and incubator management, as the most common causes are due to improper egg positioning, hen malnutrition, inappropriate incubator temperature and/ or humidity and lack of embryo development, including water loss rate. Transpiration Modification.
Once a discrepancy in water loss has been identified, either through weight loss measurement, decreased movement or inappropriate air cell changes, the breeder can promote or retard water loss by the egg in the following ways:
Many aviculturists will run two or three incubators simultaneously to accommodate normal, wet and dehydrated eggs where the relative humidities may be used to counter abnormal water status. Other techniques include sanding down the shell at the large end of eggs retaining water or even opening a small hole over the air cell and capping the hole with a piece of cellophane tape which may be pulled back or sealed as needed to expedite water loss. Sealing small portions of the shell pores by lightly painting the shell areas with paraffin wax will assist in decreasing transpiration when multiple incubators are not available. The first eggs of parrot clutches frequently have slightly thicker shells than the last eggs if clutch size is large. This is assumed to be a function for increased survival as the first laid eggs may lie unattended for several days until clutching is completed, and, therefore, will prevent excessive water loss. This may result in the eggs from a single clutch requiring different artificial hatching conditions. One highly respected aviculturist has been very successful in using a low tech approach to embryos with dehydration. Eggs found to be going light are kept in ziplock bags to reduce transpiration. Cotton balls wetted with distilled water will further enhance the water retention of the affected eggs.
For those eggs that are drying too quickly, especially noted when holes have been opened over the air cell and transpiration accelerated beyond normal, the albumen will thicken due to dehydration while the yolk sac absorption is retarded, leading to weak chicks forced to struggle in a viscous environment. Occasionally, it is necessary to artificially rehydrate the chick. Distilled water dropped onto the air cell membrane, one drop at a time every six to eight hours over a four or five day period, will successfully return the egg's hydration status to normal. Experimental efforts with saline and LRS have proven fatal and it is assumed that the introduction of additional electrolytes is responsible. Unlike dehydrated neonates or juveniles, there is no concurrent loss of electrolytes through the shell. Success is determined by reverse air cell drop and candling the egg for increased vigor of movements. Be very careful about the volume and frequency of distilled water addition, as over hydration is easy to achieve.
Embryonic Medicine and Surgery
The addition of antibiotics and antifungals by injection into the allantoic cavity and/or the yolk sac has been successfully used by several practitioners for bacterial and fungal infections. Pipercillen (200 mg/cc) injected into macaw eggs at 14, 18 and 22 days of incubation survived both needle intrusion and antibiotic complications. Cockatoo eggs injected in a similar fashion with a 27 gauge needle via the air cell also survived. Infections may be indicated by decreased chick movement or black discoloration of the egg. This should be differentiated from the dark brown color noted just prior to hatch where the membranous vascular system begins to cease to function. No strict dose recommendations can be made at this time due to the difference in physiology between embryos...