Genetic changes in layer breeding: Historical trends and future prospects

2000 ◽  
Vol 27 ◽  
pp. 20-28 ◽  
Author(s):  
Rudolf Preisinger ◽  
Dietmar K. Flock
Keyword(s):  
Genetic Variation ◽  
Egg Production ◽  
World Wide ◽  
Egg Quality ◽  
Selection Index ◽  
Pure Line ◽  
Genetic Progress ◽  
Housing Systems ◽  
Wide Range ◽  
Breeding Programmes

SummaryIn commercial egg type chicken breeding three and four way crosses are used to produce commercial layers. The primary breeders are using closed nucleus breeding programmes, with birds kept under maximum biosecurity. All grand parents and parents are produced from a closed nucleus for the world wide demand of commercial layers. The breeding goals have been focused for several decades on increasing number of eggs per hen housed. Additional traits have become more important during the last decade, i.e. feed efficiency, internal and external egg quality and general adaptability. Prior to each selection, weights for individual traits within the selection index are adjusted to meet market demands. Breeding stock and commercial layers have to be bred to perform adequately in a variety of systems ranging from large intensive cage units to free range management under different environmental conditions world-wide.Despite intensive selection for egg production the decrease in genetic variation observed in closed commercial lines is not yet critical. Peak production is approaching the biological limit of one egg a day. During this period genetic and phenotypic variation have been significantly reduced. But for early production (sexual maturity) and late production (persistency) genetic variation is still high. In a mating scheme avoiding full and half sib matings no serious inbreeding depression is observed. To achieve continued future genetic progress, selection pressure will shift to other traits like internal and external egg quality and perhaps behaviour traits which still respond to selection.Primary breeders are responding to this challenge by testing pedigreed cross-line hens in a wide range of environments and housing systems while the pure-line elite stock is kept under conditions of maximum biosecurity. Marker assisted selection is already part of commercial breeding programmes. In the past, blood typing has been used to improve Marek's resistance, whereas today anonymous microsatellites which are linked to traits of economic interest are used for selection. In particular, selection between full sib males can give a major improvement.The whole industry is getting more specialised. While the genetic potential of the birds is improved management and nutrition have also to be adapted to changing demands. The general goal for the future is to breed chickens with the ability to function well within a wider range of production conditions and do not respond to the slightest stress.

Genetic variation for egg production, egg quality and bone strength in selected and traditional breeds of laying fowl

2003 ◽  
Vol 44 (3) ◽  
pp. 365-373 ◽  
Author(s):  
P.M. Hocking ◽  
M. Bain ◽  
C.E. Channing ◽  
R. Fleming ◽  
S. Wilson
Keyword(s):  
Genetic Variation ◽  
Bone Strength ◽  
Egg Production ◽  
Egg Quality

scholarly journals Pathogenesis and Diagnostic Approaches of Avian Infectious Bronchitis

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Faruku Bande ◽  
Siti Suri Arshad ◽  
Abdul Rahman Omar ◽  
Mohd Hair Bejo ◽  
Muhammad Salisu Abubakar ◽  
...  
Keyword(s):  
Broiler Chickens ◽  
Egg Production ◽  
Egg Quality ◽  
Diagnostic Methods ◽  
Stunted Growth ◽  
Infectious Bronchitis ◽  
Highly Sensitive ◽  
Wide Range ◽  
Diagnostic Approaches ◽  
Polymerase Chain

Infectious bronchitis (IB) is one of the major economically important poultry diseases distributed worldwide. It is caused by infectious bronchitis virus (IBV) and affects both galliform and nongalliform birds. Its economic impact includes decreased egg production and poor egg quality in layers, stunted growth, poor carcass weight, and mortality in broiler chickens. Although primarily affecting the respiratory tract, IBV demonstrates a wide range of tissues tropism, including the renal and reproductive systems. Thus, disease outcome may be influenced by the organ or tissue involved as well as pathotypes or strain of the infecting virus. Knowledge on the epidemiology of the prevalent IBV strains in a particular region is therefore important to guide control and preventions. Meanwhile previous diagnostic methods such as serology and virus isolations are less sensitive and time consuming, respectively; current methods, such as reverse transcription polymerase chain reaction (RT-PCR), Restriction Fragment Length Polymorphism (RFLP), and sequencing, offer highly sensitive, rapid, and accurate diagnostic results, thus enabling the genotyping of new viral strains within the shortest possible time. This review discusses aspects on pathogenesis and diagnostic methods for IBV infection.

New advances in cloning and their potential impact on genetic variation in livestock

1999 ◽  
Vol 68 (2) ◽  
pp. 245-256 ◽  
Author(s):  
J. A. Woolliams ◽  
I. Wilmut
Keyword(s):  
Genetic Variation ◽  
Allelic Variation ◽  
Donor Cell ◽  
Genetic Progress ◽  
Livestock Breeding ◽  
Local Diversity ◽  
The Face ◽  
Breeding Programmes ◽  
The Impact ◽  
Number Of Individuals

AbstractCloning has advanced through the recent demonstrations that it is feasible to produce, in principle and with significant effort, an unlimited number of individuals of identical genotype from differentiated cell lines that have been frozen and thawed. These advances have been based upon understanding the importance of interactions between the stage of the cell cycle of both the oocyte and donor cell for the success of the nuclear transfer. Whilst the impact of the biological advance is immense for biomedicai applications, the significance is less clear for livestock breeding. In our view the scientific issues for breeding programmes lie in whether clones can increase genetic progress without a cost to biodiversity. Biodiversity within a species may be categorized as: (i) betvjeen-breed variation; (ix) genetic variation among parents within breeds; (iii) genetic variation among individuals within a farm; and (iv) allelic variation within an individual. In the face of a rapid global decline in breed diversity, cloning, in particular cloning of adults, may be an important route to protect biodiversity since it may allow far more genetic variation to be made available for new breed development in the future than is practicable at present. For variation among parents, the judicious use of clones may give significantly faster rates of progress without increasing the rate of loss of genetic variation and furthermore can help improve traits associated with health and welfare which are at present less tractable than, say, milk yield. Local diversity within a farm may be greatly affected if cloning is utilized to disseminate genetic progress widely and more answers are required on the importance of genetic variation within any one locality either in buffering diseases or ameliorating other management problems. Experience from clonal forestry can provide some indications but now there are models capable of answering this question directly in livestock. Allelic variation within individuals per se is not generally advantageous but at loci where it is identified to he beneficial, the use of cloning may exploit it more widely.

scholarly journals Effect of Housing System and Rosemary and Cinnamon Essential Oils on Layers Performance, Egg Quality, Haematological Traits, Blood Chemistry, Immunity, and Antioxidant

Animals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 245 ◽  
Author(s):  
Mahmoud M. Abo Ghanima ◽  
Mohamed F. Elsadek ◽  
Ayman E. Taha ◽  
Mohamed E. Abd El-Hack ◽  
Mahmoud Alagawany ◽  
...  
Keyword(s):  
Essential Oil ◽  
Essential Oils ◽  
Feed Intake ◽  
Egg Production ◽  
Egg Quality ◽  
Dietary Supplementation ◽  
Housing System ◽  
Control Group ◽  
Housing Systems ◽  
Antioxidant Parameters

Housing system and nutrition are non-genetic factors that can improve the well-being of animals to obtain higher quality products. A better understanding of how different housing systems and essential oils can influence the performance of layers is very important at the research and commercial levels. The current study aimed to investigate the effects of a housing system and dietary supplementation of rosemary and cinnamon essential oils on layers’ performance and egg quality. A factorial arrangement (2 × 3) was performed include two housing systems (floor and cage) and three different types of essential oils (0, 300 mg/kg diet of rosemary and 300 mg/kg diet of cinnamon essential oils) to study their effects on the productive performance, egg quality, immunity, oxidative stress and haematology of ISA brown laying hens during the production stages (from 28 to 76 weeks of age). Birds were randomly divided into two groups each comprising of 1500 birds; the first group was moved from the litter to reared laying cages while the second group was floor reared. Each group was randomly divided into three groups, the first was considered as a control group, the second treated with rosemary essential oil, and the third with cinnamon essential oil. The differences in egg production and weight, egg quality, feed intake and conversion, blood picture and chemistry, immunity, and antioxidant parameters between the different housing systems (floor and cage) were not significant at (p < 0.05 or 0.01). On the other hand, the egg production and weight, Haugh unit, feed intake and conversion, blood cholesterol, Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), urea, Ca, P, immunity, and antioxidant parameters were significantly (p < 0.05 or 0.01) better in rosemary and cinnamon groups than in the control group. Furthermore, the results of dietary supplementation with rosemary and cinnamon were very close. Regarding egg production and weight, there were no significant differences due to the interactions. The differences in egg mass among the interactions were also not significant except at 68–76 weeks, where the cage × cinnamon group was the highest. Under the floor rearing system, birds that were fed a diet supplemented with or without essential oils (EOs) consumed more feed than those raised under the cage system. Regarding feed conversion rate (FCR), the differences among the interactions were not significant except at 44–52, 52–60 and 68–76 weeks, where the cage × cinnamon group was the lowest. Excluding glutathione peroxidase (GPx) activity (p < 0.001), all immunity and antioxidant indices were not statistically different as a consequence of the interaction among EOs and housing systems. Additionally, the highest levels of phosphorus were observed for layers fed diets enriched with cinnamon oil with the cage or floor system. In conclusion, the data suggested that supplementation of rosemary and cinnamon essential oils in laying hen diet showed significantly positive effects on hen performance and egg production. Cholesterol, liver and kidney functions, immunity, and antioxidant parameters improved with rosemary and cinnamon supplementation when compared to the control. Additionally, the different housing systems did not result in any positive or negative impact on these traits.

scholarly journals Laying performance of 5th generation of BLRI improved native duck

2021 ◽  
pp. 15-23
Author(s):  
H Khatun ◽  
S Sultana ◽  
S Faruque ◽  
MRA Sumon ◽  
MSK Sarker ◽  
...  
Keyword(s):  
Egg Production ◽  
Egg Quality ◽  
Selection Index ◽  
Shape Index ◽  
Selection Response ◽  
Egg Mass ◽  
Egg Weight ◽  
Fifth Generation ◽  
Laying Performance ◽  
Duck Egg

This research was aimed to improve the egg production performances and to estimate the selection response of fifth generation (G5) of deshi white (Rupali) and white breasted black (Nageswari) duck genotypes through an individual selection program. All the ducks were reared in an open sided duck house. Diet containing 17.5% CP and 2750 Kcal ME/kg and fresh water provided twice daily in the morning and evening. Individual egg production was recorded from each duck. After 40 weeks of age, female ducks were selected on the basis of selection index and selection differences, selection intensity and responses were also measured. Egg weight, egg production and feed intake were recorded and FCR, egg mass was calculated. All recorded data were analyzed by SAS and differences were determined by DMRT. The selection criteria of fifth generation (G5) of both duck genotypes were studied. As a result of selection, age at sexual maturity (day), egg weight (g) and egg production % were expected to improve by -1.63d, 0.60g, 1.01% and -0.85day, 0.39g, 0.47% for Rupali and Nageswari ducks, respectively. Egg mass was significantly (p<0.05) higher in Rupali (40.24g) than Nageswari (37.55g) duck whereas, egg weight was not significantly differ in both genotypes. Egg production in Rupali and Nageswari duck was 65.41% and 62.74%, respectively. Rupali ducks were significantly (p<0.05) consumed more feed (134.54 g) than Nagesswari ducks (126.23 g). The FCR was significantly (p<0.05) better in Rupali (3.34) than Nageswari (3.61) ducks. The egg quality results showed that egg shell thickness of Rupali duck was significantly (p<0.05) higher than Nageswari. Higher values for albumen width (p<0.05) was also found in Rupali (65.03mm) than Nageswari (59.11mm) duck egg. On the other hand shape index, albumen index, yolk index and haugh unit were not found significantly different in both genotypes but the yolk color score of Nageswari found highest score than Rupali duck egg. Proximate composition of eggs was not significantly different of both duck genotypes. Based on the results it is revealed that Rupali duck was better in terms of egg weight, egg mass and egg production, but starting lay egg is earlier in Nageswari than Rupali duck. Bang. J. Livs. Res. Vol. 27 (1&2), 2020: P. 15-23

scholarly journals Effects of laying hens housing system on laying performance, egg quality characteristics, and egg microbial contamination

2014 ◽  
Vol 59 (No. 8) ◽  
pp. 345-352 ◽  
Author(s):  
M. Englmaierová ◽  
E. Tůmová ◽  
V. Charvátová ◽  
M. Skřivan
Keyword(s):  
Egg Production ◽  
Microbial Contamination ◽  
Egg Quality ◽  
Housing System ◽  
Feed Consumption ◽  
Total Count ◽  
Feed Conversion ◽  
Housing Systems ◽  
Laying Performance ◽  
Egg Shells

The objective of this study was to compare the performance, egg quality, and microbial contamination of egg shells from hens maintained in different housing systems, such as conventional and enriched cages, litter, and aviaries. The housing system significantly (P &lt; 0.001) influenced the performance characteristics. The highest egg production, lowest daily feed consumption, and feed conversion ratio were measured in conventional cages compared to litter and aviaries. Higher egg shell and albumen qualities were observed in conventional cages, whereas hens housed in enriched cages and aviaries laid eggs with a higher yolk index (P&nbsp;&lt;&nbsp;0.001). The housing system significantly (P &lt; 0.001) influenced the total count of bacteria on the egg surface and the microbial contamination of Enterococcus and Escherichia coli. The lowest values for the total count of bacterial contamination (P &lt; 0.001) were found in eggs from conventional cages (4.05 log colony-forming units (CFU)/egg) and enriched cages (3.98 log CFU/egg). Eggs from aviaries had 5.49 log CFU per egg, and the highest level of contamination was observed in eggs that were laid on litter (6.24 log CFU/egg). The level of the microbial contamination of egg shells from litter and aviaries was by 2 log CFU higher than in eggs from cages. It could be concluded, from the viewpoint of egg safety, a more suitable substitute for conventional cages are enriched cages and aviaries than litter. &nbsp;

Japon Bıldırcını Rasyonlarında Soya Küspesi Yerine Pamuk Tohumu Küspesi İkamesinin Yumurta Verim ve Kalite Özelliklerine Etkisi

2013 ◽  
Vol 1 (1) ◽  
pp. 44 ◽  
Author(s):  
Arda Yıldırım ◽  
Ergin Öztürk
Keyword(s):  
Protein Content ◽  
Cottonseed Meal ◽  
Soybean Meal ◽  
Shell Thickness ◽  
Egg Production ◽  
Egg Quality ◽  
Yield Traits

This study was conducted to determine the effect of cottonseed meal (CSM) incorporated into laying rations in place of soybean meal (SBM) at different ratios on yield traits. The birds began to lay at 6th week, 180 female and 45 male quails were used in laying period experiment. Birds were fed with rations containing 20% CP and 3000 Kcal/kg ME up to 20-week age (Laying period). CSM as a substitute, five different rations of the protein content (0, 30, 58, 86 and 100%) for SBM to basal diets based on corn-soybean meal were used. The results showed that there were no differences in terms of egg yield traits, cumulative feed consumptions and viabilities during the laying period. The highest dry shell rate and shell thickness were obtained from 5th group and 1st group, respectively. As a result, adding CSM instead of SBM in laying period were no significantly differences in terms of egg production and egg quality in laying period.

Effect of Supplementation of Multi Enzymes on Production Performance and Egg Quality Traits in White Leghorn Layers

2016 ◽  
Vol 12 (2) ◽  
Author(s):  
C. Pandian ◽  
A. Sundaresan ◽  
A. V. Omprakash
Keyword(s):  
Egg Production ◽  
Egg Quality ◽  
Live Weight ◽  
Economic Benefits ◽  
Production Performance ◽  
Feed Consumption ◽  
Quality Traits ◽  
White Leghorn ◽  
Significant Difference ◽  
Enzyme Supplementation

The present study was conducted to assess the effect of supplementation of Multi-enzymes with lysophospholipids on production performance of pure line White Leghorn layers. Body weights before and after the experiment did not differ significantly across the experimental diets. Irrespective of the dietary treatments, the birds gained 3.83 per cent of live weight relative to its initial body weight. Mean per cent Hen housed egg production was significantly (Pis less than 0.05) higher in diet supplemented with 0.10 MEC-L than other groups. Mean egg weight and average daily feed consumption during 25 to 35 weeks of age indicated no significant effect of enzyme supplementation. Average daily feed consumption per bird in control, 0.05 % and 0.1% multi-enzyme supplemented groups was 108.13, 105.66 and 107.67 g respectively and birds offered control diet recorded numerically more feed intake than enzyme supplemented groups. Comparatively low feed per egg was observed in 0.10 per cent group followed by 0.05 per cent group which offers economic benefits than control diets. However, the egg quality traits between different dietary enzyme supplementation groups showed no significant difference.

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