WELCOME TO THE PRESENTATION
Presenters Santosh Dhakal (25) Santosh Lamichhane (26) Shailesh Gurung (27) Subash Acharya (28) Suraj Subedi (29) Utsav Prakash Tiwari (30) Yanamani Nepal (31)
TRAITS OF ECONOMIC IMPORTANCE IN POULTRY AND ITS IMPLICATION IN GENETIC IMPROVEMENT PROGRAMME
Look at the history of poultry development Past and Present
Is it a MIRACLE????????????????? Probably not. Its due to genetic improvements ± th the e judic judicio ious us use use of of selection and mating m ating techniques.
What about the future??????? It depends upon you and me.
Economic traits Economic traits are those which have monetary m onetary value in the livestock and poultry production. Most of the economic traits are governed by many pairs of genes so known as quantitative traits or polygenic traits.
Quantitative traits have much more environmental influence.
In future certainly emphasis will be given to the welfare of poultry as well as poultry product consumers.
Traits for pedigree selection in broilers Growth Rate
Feed Conversion Livability Ascites Resistance Heat Resistance Eviscerated Yield Part and Meat Yield Carcass Fat Leg and Skeletal Strength Breast Conformation Degree of Feathering Feather and Skin Color
Heritability of Economic traits of Broiler Traits h2 level Growth and body composition Body B ody w weight eight a att 6 wk wk 0.49 High High Wt gain from 44 -6 -6 w wk k 0.30 Medium Medium Pectoralis P ectoralis m major ajor m/s m/s wt. wt. 0.38 High High Breast B reast m/s m/s yield yield 0.30 Medium Medium A Abdominal bdominal fafat t 00 .4.4 88 High High Muscle characteristics Fiber F iber cross cross section section 0.41 High High Lactate Lactate 0.27 Medium Medium pH p H at at 15 15 min. min. p post ost mortem mortem 0.30 Medium Medium Glycolytic G lycolytic potential potential 0.43 High High
Traits Traits
h2
Level
Ultimate U ltimate pH pH
0.34
High High
Lightness Lightness
0.35
High High
Redness Redness
0.25
Medium Medium
0.31
High High
Drip D rip lloss oss
0.26
Medium Medium
Thawing--cooking Thawing -cooking cooking loss loss
0.35
High High
Sheer S heer force force
0.34
High High
Meat quality traits
Yellowness Yellowness
Economic traits of layers
The trait egg production is polygenic in nature. It is a low heritable trait, while egg weight is moderately heritable and influenced by the environment in which they were grown. The components of egg production are as follows.
Age at Sexual Maturity: It is the age of the bird at which it lays the first egg. Early maturing hens lay more number of eggs, but smaller in size compared to late maturing ones. In order to prevent this problem lighting and feeding are monitored during growing period to delay sexual maturity. Age at sexual maturity is determined by both autosomal and sex linked genes. Sexual maturity of the pullets is highly correlated with the sexual maturity of dams. Males and females differ in transmitting the trait to their daughters. Hence males selected for breeding purposes should be the progeny from early maturing females.
Rate
of Lay: Rate of lay is defined as the number of eggs produced in a given period of time. If the bird lays more eggs in a given time higher is its rate of lay. Clutch size determines the rate of lay. If the bird lays more number of eggs per clutch it is usually a better layer than the bird which lays fewer numbers of eggs. It is a lowly heritable trait. Family selection for this trait can bring about improvement.
Broodiness:
Two dominant complementary autosomal genes A and C are responsible for broodiness. This behavior is seen in heavy breeds like Asiatic class. While Mediterranean breeds like Leghorn and Ancona are non broody. American class and English class are usually intermediate intermediat e in broodiness. The most effective way in reducing broodiness broodiness in a strain is, to avoid breeding of daughters and/or sisters of brooding hen, even though they are the progeny of non broody dams. The sires whose dams or sisters show broodiness should also be avoided.
Persistency:
It is the measure of the length of lying cycle. This factor is associated with egg production. The laying cycle of a hen is terminated by molting. The longer the laying cycle before the hen enters her molting period, the better she is for egg production. The laying cycle should be about 300 days.
Pauses:
Pause is defined as the time between two clutches in which the hen is out of production. If the pause is more than 3 to to 4 days, then the hen is considered c onsidered as a low producer. Pause may be due to environmental and genetic factors. In winter months it is more common, and it is called as the winter pause.
Other than the components of egg production, the associated economic traits related to egg production are ; Egg Weight: This is a highly heritable trait. It can be improved by selection. Birds which mature early tend to lay smaller eggs than those that mature late. The mature egg weight in layers should be approximately 5555-58 -58 gms. Egg weight is influenced by breed, nutrition, season and disease condition. It is also influenced by the type of housing.
Quality: The quality of egg is measured by 1) Haugh Unit Score; 2) Albumin Index; 3) Yolk Index; 4) Shell Thickness, and 5) Presence or absence of blood and meat spots. These traits are low to moderately m oderately heritable. It can be improved by using various selection methods.
Egg
Shell Color: White and brown are most commonly preferred egg colors. Shell color is not having any nutritive value. It is characteristic of breed. Indigenous chickens lay tinted eggs and they are preferred in the market because of aesthetic value.
Shell Texture: The soundness of an egg is judged from its texture. This is important from a commercial point of view, because eggs are transported for marketing purpose. This trait is influenced by genetic, nutritional and environmental factors.
Body
Size: Optimum body size of a hen at laying is an important factor to be considered for satisfactory egg size and persistency. Hence body weights at maturity. 20 weeks and 40 weeks are monitored to maintain good egg production and egg weight.
Feed Efficiency:
It is measured as amount of feed consumed in Kg/dozen of eggs or as amount of feed consumed in Kg/ Kg of egg mass. Small sized layers with high production are more efficient than those heavy layers with high production. So this trait may be included in selection to develop feed efficient stocks, economical in production than normal sized ones in pure line stocks.
Fertility
and Hatchability: Fertility and hatchability are low heritable traits, but can be improved by appropriate breeding methods. These traits can be improved by test mating the males before using them for breeding purpose. purpose. Fertility is defined as the percentage of eggs that are fertile out of total number of eggs set. Hatchability is defined in percentage that is total number of chicks obtained from the fertile eggs set and also expressed in percentage percentage that is total number of chicks obtained from the total number of eggs set. Factors influencing fertility and hatchability are breed, strain, family and individuals within a family. Inbreeding decreases, while out breeding increases these traits. Age of the bird, nutrition, disease, disease, management and environmental factors affect both fertility and hatchability
Heritability
of Economic traits of Layers
Traits Traits
H Heritability eritability %
Level
Egg E gg weight weight
55
High High
5555
High High
8-week 8-week week broiler broiler weight weight
45
High High
Egg E gg sshape h ap e
40
High High
Breast B reast fleshing fleshing
30
Medium Medium
Egg E gg production production
25
Medium Medium
2255
Medium Medium
25
Medium Medium
Adult Adult bbody ody w weight eight
Age Age aatt ssexual exual m maturity aturity Body B ody depth depth
Traits Traits
Heritability %
LLevel evel
Shell S hell thickness thickness
25
Medium Medium
Fertility Fertility
25
Medium Medium
Albumen Albumen quality quality 40
High High
Keel K eel length length
15
Low Low
Hatchability of fertile eggs Blood B lood spots spots
15 15
Low Low
10
Low Low
Adult Adult llivability ivability
55
Low Low
Chick C hick livability livability
5
Low Low
Breeding approach It is necessary to fix superior genes in inbred lines (for additive gene action) and then cross them to get combinations of genes ( for nonnon-additivity) -additivity) that will give hybrid vigor or heterosis.
Most of economic traits of poultry are low to medium in heritability. So, improvement is achieved by pure line selection and then crossbreeding of the inbred line. Remember, recurrent and reciprocal recurrent selection approach. Some polygenic trait is limited to only one sex e.g. roosters do not lay eggs. For such suc h traits selection of males is done on the basis of performance of close female relatives.
Breed A superior growth rate Inferior carcass quality
X
AB ( Back cross)
AB X A Continuous selection And inbreeding Inbred line 1
Breed B Inferior growth rate Superior carcass quality AB X B
Continuous selection And inbreeding
X
Inbred line 2 ( Cross breeding) Commercial Commerci al chicken
Economics traits of indigenous breed Disease resistant Broodiness Mothering ability Hatchability Hardiness Adaptability to local climate Meat quality
For indigenous breed Sakini 1. Under scavenging system it produced 60 eggs/hen/year. However great variation was existing among the individuals indicating chance of selection and mating of best to best for genetic improvements. 2. Under semisemi-intensive -intensive management system NH X Sakini was found better in terms of productivity. 3. Under intensive system it was very poor in performance compared to NH.
Thank you for your patience.
