Sunday, 20 July 2014

The Ins and Outs of Emu Egg Hatching - Part 2

Source: Backyard Chickens, Corny Caleb NJ Mar 26 2014
In part one of The Ins and Outs of Emu Egg Hatching we reviewed the natural development of the embryo as it is incubating. Now we are going to look at the environmental conditions necessary to bring that developing chick to successful hatch. There are four main principles to incubation.

The first principle is to maintain a constant temperature throughout the incubator. Emu eggs are incubated best at temperatures between 97.0F-97.5F ( see chart 1 below). This will allow for healthy embryo development and a usual hatch time of about 50-52 days. Commercial incubators allow for even air temperature to be circulated around all the eggs from top to bottom.  Other styles that have a fan located at the top of the units might require homemade defectors on the glass at the front to redirect warm air evenly to the bottom shelves. It is a good idea regardless of how sophisticated the incubator to have at least a couple of additional thermometers monitoring the inside temperatures. High temperatures during incubation cause more harm than low temperatures.  RT8100MAT
We use Thermoworks thermometers as they are    handy and accurate in our experience.

Access to a generator is a must if power outages are a possibility and a supply of spare parts for the incubator ensures quick reaction time.

The second principle is to maintain constant fresh air exchange in the incubator room and hence in the incubator itself. As the emu eggs incubate they expel carbon dioxide which needs to be exhausted from the incubator. Fresh air can be brought in passively through a cracked window from the outside avoiding a direct draft to the incubator air intake.

Apollo 7 - 24 Hour Digital Timer

We use a ceiling exhaust fan to circulate the air and exhaust the CO2. One that has a timer will give the flexibility to adjust for local outside weather conditions. We use the one pictured here from Home Depot.

The third principle is to adjust humidity when required

Oxygen in the air is absorbed through the shell as the emu embryo develops over an incubation period about 2.5 times that of a chicken (as noted above the resultant CO2 will be expelled).  The air cell starts out small and increases to approximately 1/3 of the egg capacity by hatch time (see update). This predictable air cell growth can be monitored using a candling device.  Due to the thickness of an emu shell a simple chicken candler will not be useful. Specialized candlers have been developed and can possibly be sourced over the internet. We have an Emu Vision 2000 stand alone candler but haven’t used it enough to give an expert opinion. It has a video monitor and an infrared light source. Commercial emu egg incubators such as Hatchrite have a candler device included.  As the air cell growth is monitored adjustments to the incubator humidity can be made to speed up or slow down the growth if needed.  Due to the limited transparency of the emu egg shell we will look at another facet of egg incubation.

Air In....... Moisture Out

As the emu embryo develops moisture from inside the egg is expelled through the pores in the shell. The air coming in weighs less than moisture going out so the emu egg will decrease in weight. The ideal rate of weight loss for emu eggs is15% of the original egg weight for successful hatch. This weight loss can be monitored and is the measurement most commonly used by emu farmers.

As the weight loss (ie evaporation rate) is determined adjustments to the humidity conditions in the incubator can be made to speed up or slow down the developmental process.

In summary:

  • When the air cell growth is too slow then the evaporation rate in the egg is too low and can be identified as a slower than ideal rate of weight loss.
  • When the air cell growth is too fast then the evaporation rate in the egg is too high and can be identified as a faster than ideal rate of weight loss.
  • So the goal is to maintain the egg weight loss at an ideal of 15% and within a range of 13-17%. At 10% weight loss (or 20% on the other end of the scale) the conditions for proper chick development are severely jeopardized.

Click image to enlarge

A. Measuring weight loss
Good record keeping is the key to this process. As each egg is collected from the nest its breeder pen ID is noted on the egg with a china marker ie 3/mar 4 means breeder pen 3 and lay date of March 4. When ready to incubate a batch each egg is weighed and recorded on the shell of the egg as well as on a paper/computer record for future comparisons. An accurate scale is necessary when weighing incubating eggs. It must be able to measure in tenths of a gram rather than in pounds.

A simple set of formulas is applied to the weight of each egg. To monitor a 15% weight loss progress use the following example:

·         original egg weight of 641g

·         2nd day egg weight of 637g

·         total length of incubation is 50 days

Start Wght  Predicted Final Wght  Predicted Daily Wght Loss     Actual Wght Loss

641g                 641–(641 x .15)=545g      (641 x .15)/50 days=1.9g     (641-637)/2 days=2.0g  

Some emu farmers weigh their eggs every day for the first week to ensure the ideal weight loss and then randomly for the remainder of the hatch. Others measure every week for the first 3 weeks. As critical embryo development occurs in the first third of the hatch it is this farmer’s opinion that the first option is the safest.

B. Measuring the humidity in the incubator
Taylor® Mason’s Hygrometer

Emu eggs develop best at humidity readings between 24 and 35% (see charts 1 & 2 below). These conditions are a little more flexible than temperature readings and can be adjusted.

Incubators frequently have digital readouts to show the humidity conditions under which the eggs are incubating. To back up this technology we use a manual system with the aid of a hygrometer. Hygrometers measure dry and wet bulb temperature conditions. We use the Taylor version.

Chart 1 to the left explains the ideal conditions for incubating emu eggs. The hygrometer  should read 97.5 deg dry bulb and 70-75 deg wet bulb. To enlarge this chart click on it, search for the pdf and the information is on page 6.

Chart 2 to the right then converts those ideal dry and wet bulb readings to the % humidity range of 24-35.

So if the emu egg weight loss is out of spec ie below 13% (1) or above 17% (2) the incubator humidity is:

(1) lowered closer to 24%
(2) raised closer to 35%

There are other options available if raising or lowering humidity is not getting the results that you need:
(1) move the egg away from the humidity source, dehumidify the incubator room, move egg(s) to another incubator with a lower humidity setting
(2) tape off (using electrical or duck tape) some of the pores on the shell, humidify the room

The fourth principle is to turn eggs (in a rocking motion) through 180 degrees frequently per day.

In the natural setting a male emu will move the eggs that he is incubating many times during the day. This instinct ensures proper contact by the embryo with the food material contained in the egg. In artificial incubation conditions the egg must be rocked back and forth through 180 deg. It is never fully turned through 360 deg. as this will disorient the growing chick. Ideally this rocking is done as frequently as every two hours to a minimum of 3 times in 24 hours so that the egg isn't in the same position through the long period at night.

Well that's a lot of detail to digest.  Keep in mind that there are just four main principles to successful emu egg incubation.

Three of them are defined:
  • temperature holds at 97.0-97.5 degrees
  • constant fresh air needs to be available
  • eggs need to be rocked through 180 deg (not 90 deg as with other eggs)
The fourth is intended to be flexible to ensure ideal egg weight loss by making humidity adjustments early on in the incubation period.

Incubating emu eggs is not a difficult process but does require attention to detail and good equipment and record keeping. Good luck with your endeavours and enjoy the rewards!

Source: Wikipedia