Critical batches, locations and moments

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Eggshell temperature is key

Which measurement is correct?

Measure the eggshell temperature at the equator of the egg and not at the top, otherwise you will measure the temperature near the air cell. Air has an insulating effect, so you could measure a different value than the actual embryo temperature. If you do this manually, don’t wait too long to measure: after opening the door, the eggshell temperature will drop.

Because it is difficult to measure the embryo temperature, the eggshell temperature (EST) is measured. The EST differs approx. 0.1-0.2°C (0.20.4°F) from the embryo temperature, depending on the stage of incubation. At the start of incubation, when the eggs must be warmed, the embryo temperature is lower than the eggshell temperature. In a further stage of embryonic development, the embryo produces more heat and the embryo temperature will be higher than the EST. The heat that the embryo produces has to be removed. The same applies to the relationship between the eggshell temperature and the temperature in the incubator. Many other influences play a role, such as air velocity and evaporative heat. The eggshell temperature is therefore not the same as the air temperature in the incubator! In practice, each hatchery uses its own program. The eggshell temperatures affect the body weight and feed conversion rate of the day-old chick posthatch. The temperature in the incubator is often already reduced a long time prior to transfer of the eggs, otherwise the chick embryos could overheat between day 14 and day 18. At the end of the incubation period, the embryo temperature can exceed 40°C (104°F). And, at some locations, the variation in embryo temperature can increase by more than 2-3°C (4-5°F), depending on the position in the incubator, especially in places with little air movement and close If the incubation temperatures are persistently too high or too low, there to the spray nozzles. will be higher mortality in the first week and a lower chick weight after a week. The chick yield (chick weight/egg setting weight) is slightly higher at a lower incubation temperature, but within a week this positive effect has disappeared.

E ect of egg shell temperature on hatching results

7 day weight (g) Chick yield (%) 7 day mortality (%) 98.5°F 36.9°C 99°F 37.2°C 99.5°F 37.5°C 100°F 100.5°F 37.8°C 38.0°C Eggshell temperature 101°F 38.3°C

101.5°F 38.6°C copyright protected

Which temperature measurement is corret?

T = ?

T = ? T = ?

Heat production is highest towards the end of incubation. Any mistakes in temperature measurement must be avoided. After day 14, you should take a few temperature readings on each egg to avoid wrong measurements. Low temperatures may be caused by insufficient contact of the embryo with the eggshell; the highest reading is the correct value. The air cell is also getting larger and may have shifted a little to the left or right (incorrect turning angle?). Maintain a constant embryo temperature of 37.8°C (100°F). Check the temperature using an infrared thermometer. Make sure the tip of the thermometer is flat against the equator of the egg.

Incubation temperature

Based on average values, embryonic development is optimal during the first 18-19 days at an embryo temperature of 37.8°C (100°F). After internal, and then external, pipping, the temperature of the embryos may gradually increase from day 20 to 39°C (102°F). As a rule of thumb, aim for a range in which 95% of the eggs/day-old chicks are no more than 1% below or above the optimal value: 1% of 37.8°C rounds off to 0.4°C. More than 95% of the eggs should therefore be in the range between 37.4-38.2°C. Note: this applies to the Celsius scale. At Fahrenheit you can stick to: between 99.3 and 100.7°F.

Variation inside the incubator

There are always some cold spots and hot spots in an incubator. Cold spots occur in places such as close to the floor, the walls, the point where fresh air reaches the eggs first and around the sprayer or humidifier. Cold spots at the start of the incubation process, and hot spots at the end of the incubation process are places where there is generally little airflow. Some brief variations are not usually an immediate cause for concern. In natural conditions, the hen also occasionally leaves the nest to eat or drink towards the end of the brooding process. Prolonged deviations from optimal conditions may negatively affect embryonic development (and uniformity). Ensure proper incubator maintenance to avoid structural deviations.

Embryo temperature during the incubation process (°F/°C)

Min Optimal Max

Day 1-19 99.3 / 37.4 100.0 / 37.8 100.8 / 38.2 After pipping, day 20 101.5 / 38.6 102.2 / 39.0 102.9 / 39.4 Dry chick 103.1 / 39.5 104.0 / 40.0 104.9 / 40.5

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During the maturation stage (approx. from day 16), the embryo can respond slightly to the ambient temperature. If the temperature is too low, the heart rate decreases so the metabolic heat produced by the embryo is not released through the eggshell, but stays ‘inside’ the egg, with the embryo. The opposite also occurs: the embryo responds to ‘feeling’ too hot by increasing its heart rate so that more blood flows along the eggshell. This releases heat to the environment around the egg and allows a higher intake of oxygen. This thermal image shows that the eggs in the centre of the setter tray are much warmer than the eggs at the sides. During incubation, the aim is to create the most uniform possible temperature in the whole incubator. However, the temperature can vary between different parts of the incubator. This is caused by different air velocities and using humidification sprayers.

The most important thing is to maintain a constant, uniform temperature for all the eggs, particularly at the start of incubation. The ventilation is reduced to an absolute minimum (air inlets closed) to ensure the most uniform possible temperature in all the eggs and prevent cold air flowing into the incubator. If the air used to ventilate can be properly conditioned (pre-heated) this is not such a problem.

Index

Abnormalities Air cell Air temperature Air velocity Airflow Airport Altitude Arrival check Artificial incubation Aspergillus Bacterial load Bangers Beak Belly Biomarkers Biosecurity Biosecurity zones Breakout Breeds Broilers Calibration

76, 168, 171 38, 49, 85 133 41, 101 102 184 41 189 22, 23 75, 93, 142, 149 53 90 167 164 124, 125 62 64, 65 113, 129 29 29 98 Candling 112, 113, 115-117 Carbon dioxide (CO2) 35, 39, 104, 159, 181 Cargo area climate 181 Celsius 7 Chick delivery 186 Chick length 159, 160 Chick quality 148 Chick temperature 154 Chick transport 178 Chick weight 159 Chick yield 155 Cleaning 73, 74 Climate conditions 101 Cloaca 163 Cloaca sexing 173 Colour sexing 175 Condensation 17, 40, 59, 77, 80, 100, 133 Condensation point 77 Cooling 40, 46, 47, 102, 106 Cracks 52 Critical batches 15 Critical locations 15 Critical moments 16, 17 Dew point 77 Dirty eggs 50, 53 Disinfectants 93 Disinfection 57, 63, 75, 90-93 Downgraded chicks 172 Dry bulb temperature 78, 79 Drying off 156 Drying out 156 Early feeding 143, 153, 157 Early mortality 46 Egg grading 48 Egg handling 44, 49 Egg inspections 83 Egg quality 44, 50 Egg shape 49 Eggshells 49, 149, 150 Egg size 49, 51, 97 Egg weight 49, 51, 97 Eggshell temperature 30, 45 Embryo position 135 Embryonic development 20, 21, 45, 95 Employees 71, 72 External pipping 137 Fahrenheit 7 Feather sexing 174 Feathering 165 Filling 99, 101 Floor eggs 54, 55 Floor quality 67 Fluff 134, 139 Formalin 75, 91, 92, 93 Fumigation 91 Gas exchange 26 Gender reversal 125 Hatch moment 139 Hatch of fertile 119 Hatch of set 118 Hatch of transferred 119 Hatch peak 134 Hatch window 138 Hatcher baskets 131, 144 Hatchery manager 8-10 Hatching 132 Hatching egg 19 Hatching systems 143 Heat distribution 106 Heat production 25, 33, 39,181 Heating 102 House inspection 189 Humidification 103, 134 Humidity 59, 134 Humidity peak 134 Hygiene 53, 69, 128, 130, 187 Incubation temperature 31 Infection pressure 152 Infertile 112, 115-117 Information exchange 11, 12 In-ovo sexing 123 In-ovo vaccination 120, 121, 122 Integration 5 Internal pipping 136 International transport 183 Jolts/vibrations 81 Key indicators (KPI) 118 Laying date 97 Laying hens 29 Legs 166 Litter 147 Logistics 82 Long storage 87 Long transport 185 Measuring 34, 38, 154 Meconium 153 Mixing 95 Moisture loss 27, 37, 38 Monitoring 110, 111 Mortality 190 Multi-stage 7, 42, 43 Natural brooding 22, 23 Navel 163 On-farm hatching 145 On-farm traying 48 Origin 96 Oxygen (O2) 39

Packing 47 Paper egg flats 47, 146 Parent stock age 97 Pasgar score 170 Personnel 69 Physiological zero 45, 46 Pipping 136, 137 Pipping height 151 Pipping line 151 Placing chicks 188 Planning 9 Plastic tray 47 Point setting 60 Preparation 98 Pre-warming 100 Pull time 138, 140 Pulp tray 47, 146 Red hocks 14, 166 Relative Humidity (RH) Residual yolk/yolk sac Routing Scoring system Selection criteria Setter trays Setting Sexing Signals concept Single-stage Slow-growing broilers Spectroscopy SPIDES Storage (chicks) Storage (eggs) Storage conditions (eggs) Storage duration Take-off table Temperature Temperature development Temperature requirements Temperature settings Temperature variation Tona score Track and tracecopyright protected 36, 37, 105 19, 157, 158 65 169, 170 162 82 94, 99 173 13 7, 42, 43 28 123 58, 89 179 58, 76, 84 58, 59, 85 86 161 25 46, 78 25 32 31, 32 169 61 Transfer 114, 126 Transition 102 Transport 144 Transport (chicks) 180 Transport (eggs) 76, 126 Transport conditions 80 Trolley cover 80 Turning 88, 107-109 Unhatched eggs 141, 142 Uniformity 12, 27, 31, 51 Urates 150 Vaccination 120-122, 176, 177 Variation 12, 27, 31, 51 Vent sexing 173 Ventilation 34, 39 Ventilation (transport) 182 Washing 56 Weight loss 27, 37, 38 Wet bulb temperature 78, 79 Yolk Free Body Mass (YFBM) 159 Yolk sac/residual yolk 19, 157, 158