Chick Length and Organ Development
Experimental design
Chicks of a breeder flock of 33 weeks old, were selected for this trial. Birds were housed at a broiler farm of 9.000 birds and were fed a starter diet. At the day of hatch, chick length and weight was measured and sixty birds were selected and divided in three groups. The largest group contained chicks with a length between 20,0-20,6 cm, the middle group between 19,2-19,8 cm and the small group between 18,2-18,8 cm. At day 7, chicks were weighed again and the weight of the residual yolk, bursa of Fabricius, liver, heart, spleen and length of the intestines was measured.
Results
The correlation coefficient (R) of chick length at day 0 and chick weight at day 7 was positive again (R= 0,68; pThere was hardly any residual yolk found after 7 days. In 42%, 59% and 20% of the chicks of respectively the large, middle and small group was some residual yolk found. The amount of residual yolk varied between 0,03 and 0,32 grams.
The weight of the heart and liver was significant different between the large and small group. The weight of the spleen was significant different between all three groups. The chick with the largest chick length at day 0 had the heaviest heart, liver and spleen. There was no difference found between the weight in the bursa of Fabricius and the length of the intestine between the three different groups (Table 1).
| Chick length day 0 (cm)* |
Heart (gr)* |
Liver (gr)* |
Spleen (gr)* |
Bursa (gr)* |
Intestine (cm)* |
|
| large chick length group | 20,2a | 1,49a | 7,78a | 0,149a | 0,30 | 92,56 |
| middle chick length group | 19,6b | 1,43a | 7,71a | 0,122b | 0,28 | 92,31 |
| small chick length group | 18,6c | 1,25b | 6,51b | 0,120c | 0,26 | 88,85 |
| significant difference (p<0,05) | Yes | yes | yes | yes | no | no |
There was a positive relation between chick length at day 0 and chick weight at day 7. The heart, liver and spleen were better development at day 7 in the large chick length group compared to the small chick length group. The difference in heart and liver weight was not significant different between the largest and middle chick length group, probably due to the small difference between the group in chick length.
The heart is an important organ for blood supply with oxygen and nutrients for the main organs. The heart can contribute to an optimal development and growth of the chicks, which helps expressing the genetic potential. The liver and spleen are important organs as well for development and growth of the chick. The liver is the largest glandular organ of the bird and has different important functions like synthesis of different substances and maintaining the homeostasis of nutrients in the body. The spleen is a lymph organ and part of the blood filtering system and contributes to the immune system.
The length of the intestines and the bursa of Fabricius was in this trial not related to chick length. The size of the bursa of Fabricius might not be related to the development of the chick. The length of the intestine showed a lot of variation and was difficult to measure precisely, which might be the cause that no difference was found.
It can be concluded that chick length is positive related to the chick weight and the development of important organs like heart, liver and spleen. Chick length is, therefore, an important aim for hatcheries and broiler farmers. Chicks with a large chick length have better developed organs and may have a better potential for growth.
Note:
The Bursa of Fabricius
The bursa of Fabricius is a round sac and is located just above the cloaca in birds. Mammals generally have no bursa. The chicks’ bursa reaches its largest size a few weeks after hatching and then gradually decreases. B-cells, which are part of the immune system, develop, mature and migrate from the bursa to other part of the body.
We have evaluated the relationship between hatchling length or weight and slaughter weight, breast meat yield and feed conversion ratio (FCR) in both male and female broilers in two experiments.
Results showed that in male broilers a positive relationship was found between hatchling length and slaughter weight or breast meat yield, but no relationship was found with hatchling weight. In female broilers, a negative relationship between hatchling weight and breast meat yield was found. The relation between chick length and performance was not found in the first experiment, but in the second experiment we found a positive relation. No relationship between hatchling length and FCR in both male and female broilers was found.
We concluded that hatchling length rather than hatchling weight seems to have a predictive value in males for slaughter weight and breast meat yield. In females, this is less clear. Additionally, FCR seems not to be related with hatchling length.
Results of this experiment are published in World’s Poultry Science Journal, 2008, Volume 64, p. 599-604
Dear Mister,
Your question was how you can produce longer chicks. First of all there are a lot of factors influencing chick length and therefore chick quality. Two of them are breeder strain and age of the breeder flock.
Another factor influencing chick length is the incubation process, which needs to fit to the requirements of the embryo. Our recommendation is to incubate chicken embryos at an eggshell temperature of 37.8ºC (=100F). The eggshell temperature differs from the environmental temperature in the incubator. The environmental temperature needs to decrease in time to incubate at an eggshell temperature of 37.8C (=100ºF), especially after 10 days of incubation when the embryos start to produce more and more heat.
An easy method to measure this eggshell temperature is by using an infrared thermometer and measure the temperature of the eggshell. Such an thermometer is available at HatchTech Incubation Technology.
Regards,
Inge Reijrink & Roos Molenaar
It's a nice work. I believe early mortality was much less in large chick length group. Do you have data on mortality by time, early, middle and late? As someone mentioned already, we need to find out relation between egg size and chick length because it may give us more opportunity to improve incubation technology.
.jpg&w=3840&q=75)