Hybrid Chickens Research Articles

Effects of Tinospora crispa on production performances and nutrient utilizability in hybrid chickens

Effects of Tinospora crispa on production performances and nutrient utilizability in hybrid chickens

Novel insights into heat tolerance: the impact of dwarf and frizzled feather traits on crossbreed chicken performance under thermal stress

Heat stress (HS) poses significant challenges to broiler production, negatively influencing growth performance and meat quality. This study explores the resilience and the meat quality of hybrid chickens with dwarf size and frizzled feather traits to HS. We investigated F1 progeny derived from a crossbreed of dwarf yellow chickens (DYCs) with Yuexi frizzled feather chickens. Following a rearing period of 12 weeks, we randomly assigned 72 chickens into two distinct environmental conditions: a HS group subjected to 35 ± 1 °C for 8 h per day, and a control group (CN) maintained at 26 ± 1 °C. Seven days post-HS, multiple tissue samples were collected to assess meat quality attributes and measure expression levels of heat shock proteins (HSPs), muscle growth-related genes and cytokines. The results demonstrated a substantial reduction in weight gain of the F1 chickens exposed to HS, along with decreased expression of insulin-like growth factor-1 (IGF-1) and its receptor (IGF-1R) in the liver. Furthermore, HS exposure significantly increased muscle shear force and the expression of HSP70 in both liver and pectoral muscle tissues (p < .05). Despite these changes, there were no significant alterations in the other meat quality indices, or indicators of splenic and hepatic tissue injury. Likewise, expression levels of growth hormone receptor (GHR) and cytokines remained stable, implying a lack of heightened inflammation. These observations suggest an inherent thermotolerance in the chickens possessing dwarf size and frizzled feather traits, warranting further exploration for their potential in heat-stress-prone poultry production environments. Highlights Dwarf and frizzled feather traits in crossbreed chickens show potential for improved heat tolerance in poultry production. Heat stress had limited impact on meat quality parameters, suggesting resilience of these local chicken traits. Understanding the genetic basis of thermotolerance can inform breeding strategies for climate-resilient chickens.

The use of fermented feed containing black soldier fly (Hermetia illucens) and azolla sp on egg production and egg clutch in hybrid chickens

The purpose of the study is to investigate the effect of fermented feed containing black soldier fly and azolla meal on egg production and egg clutch. The research material used 20 female hybrid chickens and local feed ingredients. The research method was conducted experimentally using a Complete Randomized (RAL) with five (5) treatments and four (4) replications respectively. The feed treatments were P0 (100% feed control), P1 (90% basal feed + 5% black soldier fly + 5% azolla), P2 (85% basal feed + 5% black soldier fly + 10% azolla), P3 (85% basal feed + 10% black soldier fly + 5% azolla), P4 (80% basal feed + 10% black soldier fly + 10% azolla). The observed parameters included egg production, egg clutch, eggshell color, and thickness. The data obtained were analyzed using Analysis of Variance (ANOVA). The study found no significant effect on egg production, egg clutch, shell color, and thickness when feeding fermented black soldier fly and azolla at different levels. It was concluded that fermented feed containing 5-10% black soldier fly and 5-10% azolla did not negatively affect egg production and egg clutch in hybrid chickens.

Performance of broiler chickens fed compound feeds with various of cereal grains

Maize and wheat are the main cereal forage crops cultivated at a global scale. They are among preferred forage grains for poultry nutrition. The aim of this study was to evaluate the productive performance of broiler chickens, whose compound feeds contained either maize, or wheat alone and maize +wheat combination. The experiment was performed with 120 day-old male ROSS hybrid chicks reared on the floor for 49 days. The birds were divided into three groups, each one consisting of two subgroups, as follows: group Е1 – fed forage with maize and wheat; group Е2 – fed forage with wheat and group Е3 – forage with maize. The live weight, feed intake, feed conversion and slaughter traits were investigated. By the 49th day of age, the live weight of chickens from groups Е1 and Е2 fed diet with maize and wheat (35.99%+28%), and only wheat without maize (66%) were the heaviest, 3147.18 g and 3361.32 g, respectively. Chicks from group E3 fed the diet containing only maize (64.12%) without wheat had the lowest average live weight (2587.75 g at Р&lt;0.0001). Wheat, as a single cereal in broiler compound feeds, and its combination with maize had the most beneficial effect on weight gain and feed conversion over the entire fattening period (P&lt;0.001). The improved weight gain of birds fed these diets was accompanied with higher feed intake (P&lt;0.001) compared to birds fed forage with maize only. The slaughter yield and the breast with bone cut increased statistically significantly in the wheat-fed groups (P&lt;0.001).

Effect of wet fermented diet containing a combination of maggot flour (Hermetia ilucen) and active digestive enzymes on growth and protein retention of hybrid chickens in the early phase of growth

The aim of this study was to determine the effect and level of wet fermented feed containing a combination of maggot flour (Hermetia illucen) and active digestive enzymes on the growth and protein retention of early-phase on hybrid chickens. The experimental design used was Completely Randomized Design consisting of 4 ration treatments and 4 replications. The treatment rations used were: P0 (100% commercial/control feed), P1 (wet fermented feed + 9% maggot flour and 0.5 %), P2 (wet fermented feed + 12% maggot flour and 1% bioresic), P3 (Wet fermented feed). The parameters: ration consumption, weight gain, final body weight, ration conversion and protein retention. The results showed that fermented diet contained maggot flour with different feeding levels and active digestive enzymes had no significant effect (P>0.05) on final body weight, weight gain feed consumption, feed conversion and protein retention of hybrid chickens on 12 weeks of age. However, it had a significant effect (P<0.05) on the weight gain of hybrid chickens on 6 weeks of week. It was concluded that the use of 9-12% maggot flour and 1% active digestive enzymes did not have a negative effect on the growth and protein retention of 12-week-old hybrid chickens and could compensate and replace the role of commercial diet in stimulating the growth in early phase of hybrid chickens.

Differences in morphometric characterization of female BSA hybrid chickens fed on wet fermented diet containing a combination of maggot flour (Hermetia illucens) and active digestive enzymes in ration

The present study was aimed to examine the effect of feeding fermented diet containing a combination of maggot flour and active digestive enzymes in the ration on feed consumption, weight gain and exterior appearance or morphometric parameters of female BSA hybrid chickens (BSA-HC). The present study was carried out at Field Laboratory of Animal Sciences, Department of Animal Science, University of Syiah Kuala-Banda Aceh for 90 days, starting from December 1, 2021 to March 1, 2022. The study used a completely randomized design consisting of 4 treatments which were: P0 (control: chicken fed on commercial diet), P1 (chicken fed on a wet fermented diet, 9% maggot flour and 0.5% enzyme), P2 (chicken fed on a wet fermented diet, 12% maggot flour and 1 % enzyme), and P3 (chicken fed on a wet fermented diet without maggot flour and without digestive enzymes). Each treatment was repeated 4 times and total number of chickens used in the study was 80 female hybrid chickens. The data obtained were analyzed by Analysis of Variance and it was continued with Duncan’s Multiple Test by SPSS program. The results showed that difference in a combination of maggot flour and active digestive enzymes percentage in wet fermented diet had an effect on the increased in morphometric parameters such us: thigh circumference, height, and head width of chicken until 9 weeks of chicken age. However, feeding of wet fermented diet containing maggot flour and digestive enzymes resulted the same effect on morphometric parameters as commercial diet on BSA-HC hens resulted a high efficiency feed. It was presumably due to the nutritional value contained in wet fermented diet was absorbed by part of chicken body which was supported by the development of body and digestive organs. Although a combination of maggot flour and active digestive enzymes percentage in wet fermented diet does not significantly affect the morphometric parameters, the nutritional content such as protein and energy contained in the feed increased the process of performance and growth process of female hybrid chicken which was comparable to commercial diet.

The Impact of Thyme and Oregano Essential Oils Dietary Supplementation on Broiler Health, Growth Performance, and Prevalence of Growth-Related Breast Muscle Abnormalities.

The objective of this study was to investigate the effects of thyme and oregano essential oils (as growth promotors), individually and in combination, on the health, growth performance, and prevalence of muscle abnormalities in broiler chickens. Six hundred day-old Cobb 500 hybrid chickens were randomized into four dietary treatment groups with three replicates each. Chicks in the control group (C) received a basal diet, while the experimental treatment groups received basal diets containing 350 mg/kg of thyme oil (T1), 350 mg/kg of oregano oil (T2), and 350 mg/kg of thyme and oregano oil (T3). Growth performance parameters were evaluated at 14, 28, and 42 days. The broilers in treatments T1 and T2 had significantly higher body weights than the control group. The feed conversion ratio was the lowest in chicks who received oregano oil, followed by those fed thyme oil. The overall prevalence of growth-related breast muscle abnormalities (including white striping and white striping combined with wooden breast) in groups receiving essential oils (T1, T2, and T3) was significantly higher than in the control group (C). The thyme and oregano oil diets showed no significant differences in antibody titers against Newcastle disease or interferon-γ (INF-γ) serum levels. In conclusion, thyme and oregano oils had a positive impact on the growth performance of broiler chickens but increased the incidence of growth-related breast muscle abnormalities.

Multilocus genetic analysis of two-breed chicken hybrids

Abstract. Background. Due to the fact that now many new forms of poultry are created by crossing existing breeds and populations, a comprehensive genetic analysis of hybrid chickens as a ground for further breeding work is of particular importance. Aim. To study the features of the population and genetic organization of the genomes of inter-breed chicken hybrids. Materials and methodology. The experimental work was based on the use of an oligonucleotide probe (GTG)5, which was labeled with digoxygenin. The probe was hybridized with genomic DNA on a nylon filter, and then labeled DNA fragments were visualized using a streptavidin-alkaline phosphatase conjugate chemistry. The number and distribution of DNA fragments was highly specific for each individual. These parameters under study include similarity coefficient (BS), genetic distances between groups (D) and average heterozygosity levels (H). Scientific novelty. For the first time, marker DNA fragments characterizing individual groups of birds have been identified; these fragments can be used in the certification of populations. The novelty of the work also lies in the determination of the main genetic characteristics in new groups of hybrid chickens, which will be used to consolidate the desired breeding traits. Results. Based on the data obtained, it can be concluded that there are relatively small genetic differences between various hybrid forms, which is the result of using the same source breeds. Brahma × Sussex Light and Uzbek Game × Amrock hybrids were relatively distant from each other (D = 0.070). Sussex Light× Amrock hybrids were the most genetically diverse according to the criterion of average heterozygosity (P = 0.66).

The Production of Superior Hybrid Jawa Super Chicken as a Food Security Strategy During COVID-19 Pandemic in Ngoro-Oro Village, Patuk, Gunung Kidul, Yogyakarta

During the COVID-19 outbreak, economic sectors slowed down and caused a significant impact on almost any level of society, especially the middle to lower class income. Thus, a strategy needs to be developed to overcome this situation. The Ngoro-Oro Village has potency in the livestock sector, especially in the development of superior hybrid Jawa super chicken. Therefore, the purposes of our community service in the Ngoro-Oro Village were to develop superior hybrid Jawa super chicken and use black soldier fly larvae as an alternative feed for chicken. We distributed 105 Jawa super hens aged ± three months and 21 superior free-range roosters. Furthermore, the hens and rooster were mated at the age of ± six months with a ratio of 5:1.The hybrid chickens were evaluated for their body weight and morphometric measurements until the age of four months. We also monitored the farmer community’s use of black soldier fly larvae as an alternativ e feed for chickens. The hybrid chicken at the age of 4 months old has a body weight of about 971.64 ± 271.06 grams with a height of about 41.73 ± 5.87 cm, head’s length of 5.01 ± 0.44 cm, body length of 22.82 ± 3.14 cm, body width of 10.68 ± 1.49 cm, wing’s length 19.14 ± 2.67 cm, thigh’s length 11.95 ± 1.71 cm, and leg’s length is about 7.91 ± 1.41 cm. Moreover, Ngoro-Oro farmers can improve the community’s economy by selling superior hybrid Jawa super chicken at a price 75,000 – 85,000 rupiahs per head. Through all of this community service program, it could be concluded that superior hybrid Jawa super chicken is potential to be developed as broiler, and the farmer community could develop black soldier fly larvae as an alternative feed for chicken.

English

This study was undertaken to contribute to the search for alternative ways to improve poultry feed. The objective was to evaluate the effects of incorporating roasted cowpea seed meal as a protein source in broiler feed. The experiment was conducted for 56 days with 120 Dutch Blue hybrid chicks divided into three batches of 40 chicks. These batches were each subdivided into two sub-batches of 20 chicks corresponding to two replicates. These batches received three feed treatments consisting of a control (R0) containing roasted soybeans and two rations (R1, R2) containing roasted cowpea seeds incorporated at 7 and 14%. The results showed that these three feeds resulted in good weight gain, better feed conversion and low mortality. The chicks showed better growth performance with (R0). Roasted soybeans and roasted cowpea seeds appear to be interesting feedstuffs for broilers since the 7 and 14% rates gave good weight growth performance comparable to that of roasted soybeans. We suggest the use of roasted cowpea at rates between 7 and 14% since they are locally available and significantly cheaper than soybean. The continuation of this study on the blood profile, a very important aspect of feeding, should be considered. Key words: Parkia biglobosa, chicken, food, growth performance.

Quality Characterization of Different Parts of Broiler and Ligor Hybrid Chickens.

The quality characterization of different parts of male and female Ligor hybrid chickens was investigated and compared with those of commercial broiler. Genotypes, muscle types, and sex had effects on the composition, physicochemical, and textural properties of chicken samples. Ligor hybrid chicken contained higher percentages of protein, moisture, ash, and collagen content but lower fat content than those of commercial broiler (p < 0.05), except in the case of breast, where no significant difference in moisture and ash was observed (p ≥ 0.05). The pH in breast meat of both chickens was lower than that of thigh meat. The color (L*, a*, and b*) values of male and female chickens were not significantly different, except for the L* value of broiler chicken, which was higher in female chickens than in male chickens. Higher cooking loss and shear force were found in male Ligor hybrid chicken. A similar protein pattern was observed for the protein from the same muscle type, irrespective of sex and genotype tested. It was observed that Ligor hybrid chicken contained higher glutamic acid and aspartic acid than commercial broilers. Therefore, Ligor hybrid chicken is a promising new source of nutrition, which can be beneficial for consumers.

Genetic effects on growth and egg production traits in two-way crosses of Egyptian and commercial layer chickens

A crossbreeding experiment was conducted between the Sinai (SI), an indigenous Egyptian strain, and the exotic Lohmann Brown (LB) breeds of chickens. A total of 790 chicks were produced in four genetic groups, namely SI x SI, LB x LB, SI x LB, and LB x SI. The objective was to estimate the direct additive effect (gi), individual heterosis (hi), and maternal additive effect (gm) for growth and reproduction traits. Direct additive effects were positive (P ≤0.01) for bodyweight (BW) at 4, 8, and 12 weeks old in favour of SI. For egg production traits, gi was positive for age at sexual maturity (ASM) and age at which the first 10 eggs were produced (P10), but negative for mean 10 egg production (MP10), egg number at 90 days (EN90),mean egg number at 90 days (MEN90), and egg mass (EM). The estimates of heterosis (%) were high for BW and daily gain except for BW0. Maternal effect estimates of BW and daily weight gain were significant (P &lt;0.05) only for bodyweight at hatching (BW0), bodyweight at 4 weeks old (BW4) and daily weight gain from four to eight weeks old (DWG4-8). Thus, the Sinai and Lohmann Brown crossbreed produced favourable heterosis on the growth of the chicks. As an adapted indigenous strain, SI should be regarded as a dam line in crossing with LB, which has greater genetic potential for growth. Use of LB as a sire strain in conjunction with Sinai would increase egg production from the resulting hybrid chickens.

Body Weight Gain and Carcass Quality of the Hybrid Chicken Derived from the Crossing between Female F1 Kampung Super and Male F1 Kampung-Broiler

This research was conducted to observe the body weight gain and carcass quality of the hybrid chicken derived from the crossing between female F1 Kampung Super and male F1 Kampung-Broiler. The weekly weight gain for seven weeks and carcass quality, including breast yield, protein content, lipid content, moisture, and pH were measured with each group consists of six individuals. The chickens were slaughtered for meat quality measurements on the 7th week. The results showed that the hybrid chickens’ weight at the 7th week (888.22±139.63) was higher than layer (467.06±85.7) and pelung (436.39±42.33). The hybrid chicken’s breast yield (3.20%) was significantly higher than pelung’s (1.66%). These characteristics of hybrid chicken breast muscle lead to the conclusion that hybrid chicken is a potential alternative meat-type chicken with local chicken meat characteristics and has relatively fast growth.

Assessment of production capacity of three combinations of hybrid chickens

The research was conducted at the Pho Yen Chicken Research Station, Thuy Phuong Poultry Research Center, from January 2019 to August 2020 to evaluate the productive ability of the combinations of hybrid parent hens (♂TN1 x ♀TN2, ♂TN1 x ♀TN3, ♂TN1 x ♀TN32) and commercial chicken TN12, TN13, TN132. The results achieved: 3 parent hen hybrid combinations (♂TN1 x ♀TN2, ♂TN1 x ♀TN3, ♂TN1 x ♀TN32) have the egg yield/hen/68 weeks of age and feed consumption/10 eggs are 191.74 eggs and 2.30 kg; 196.32 eggs and 2.27 kg; 198.78 eggs and 2.25 kg respectively. The rate of embryo reaches 97.43, 97.07, and 97.67%. The commercial chickens TN12, TN13, TN132 have the body weight at 8 weeks of age and feed consumption/kg body weight gain are 2440.07 and 2.29 kg; 2360.12 and 2.26 kg; and 2407.15 g and 2.22 kg respectively.

The effectiveness of an SNP marker in the cholecystokinin type A receptor gene for improving growth traits in Amakusa Daioh cross chickens

Amakusa Daioh cross chickens from Kumamoto Prefecture, Kyushu Island, Japan, are F 1 hybrid chickens resulting from a cross between the Amakusa Daioh and Kyushu Rhode breeds. A significant association has been reported between a SNP (AB604331, g.420 C>A) in the cholecystokinin type A receptor gene and growth traits in some Japanese slow-growing chickens. This genetic improvement effect was examined in Amakusa Daioh cross chickens by comparing superior A allele-fixed chickens with conventional ones. Fattening experiments using 436 conventional and 297 improved (A allele-fixed) Amakusa Daioh cross birds were performed over two seasons. In each season, experimental birds of both sexes were hatched on the same day, raised in the same chicken house, and fed the same diet ad libitum for 15 wk for cockerels and 19 wk for pullets, after which they were slaughtered. Body weight (BW), average daily gain ( ADG ), and carcass weights were measured. SNP genotypes were determined using mismatch amplification mutation assay. Association between the SNP and growth traits was analyzed using GLM, taking into account gender, season, genetic additive and dominance, and test group effects. The improved pullets were significantly heavier than the conventional pullets at slaughter age. Boneless carcasses of the improved pullets were significantly heavier than those of the conventional pullets as well. In the conventional cockerels, significantly positive additive effects of the A allele on BW were detected during the entire experimental period, except at 10 and 11 wk. Significantly positive additive effects of the A allele on thigh weight were detected. We concluded that g.420 C>A is a good selective marker for increased slaughter live weight and meat weight in Amakusa Daioh cross chickens.

Growth rates of main and reciprocal crosses of Isa Brown and local chickens

The absolute and relative instantaneous growth rates of F1 hybrid chickens were determined at 2- 10 and 12-20 week periods of growth. The hybrids were hatched from eggs laid by 69 Isa Brown and local chicken parents. A total of 123, 49 and 116 chicks of Isa Brown x frizzle feathered (IBxF), Isa Brown x naked neck (IBxNa) and Isa Brown x normal feathered IBxN) main crosses and 137, 42 and 64 chicks of frizzle feathered x Isa Brown (FxIB), naked neck x Isa Brown (Na x IB) and normal feathered x Isa Brown (NxIB) reciprocal crosses, respectively were produced at day-old. The greatest absolute growth rates of 49.44g/week at 2-10 weeks and 71.11 g/week at 12-20 weeks were obtained from IBxN and FxIB genotypes, respectively. Instantaneously, IBxNa had the greatest rate of 0.28 g/time at 2-10 weeks, while IB x F and Na x IB each at 12-20 weeks were found to grow at the greatest rate of 0.091 g/time, respectively. It was concluded that normal and naked neck genes could be utilised in main crosses to develop fast growing broiler chicks while frizzle and naked neck genes could be used in reciprocal crosses to improve good laying pullets without precocious maturity.

Phenotypic Characteristics and Growth Performance of Hybrids Chicken BC1 Kamper

Indonesia is currently in the top 10 of the world's poultry meat and egg producers. Poultry house in Indonesia is the main key in fulfilling the need for consumption of animal protein. Broiler and Layer types are the type of chicken that dominates the poultry farm sector in Indonesia, this is a serious threat to food sovereignty in Indonesia because Indonesia has not been able to provide Broiler and Layer grand parent stock as breed on several neighboring countries by doing import grand parent stock (GPS). So the objective of this research is to obtain the hybrid chickens with high egg and meat productivity yet still had the superiority of meat taste and strong body resistance like local chicken or native chicken. This Research conducted in Pusat Informasi Agroteknologi (PIAT) UGM di Kalitirto, Berbah, Sleman, D.I.Yogyakarta. In this study Back Crossess were conducted between F1 Kamper roosters and Layer hens. The growth rate of BC1 Kamper is lower than Layer and F1 Kamper and based on the statistical analyses, there are no differences of growth rate between BC1 Kamper and parental. Hybrid Chicken BC1 Kamper resulted from ♀ F1 Layer And ♂ F1 Kamper crosses has diverse phenotypic variations quantitative and qualitative data, the phenotype characters of BC1 Kamper such as ♂ F1 Kamper and the growth rate such as ♀ F1 Layer.

Morphological Traits, Productive Performance and Genotyping Fat Deposition PPAR Gene in Gama Ayam Crossbreeds of Female F1 Kamper and Male BC1 Kambro

On the recent classification of native Indonesian chicken, there are 31 breeds of chicken. Highly circulated chicken breed in Indonesia is fast-growing broiler that includes several strains such as Cobb 500, Hubbard, Hybro, Isa Hyline, and Hisex. Fast-growing broiler chickens have rapid growth, with excessive fat deposition on chicken carcass which implicates a health problem and unfavorable meat quality. Gama Ayam Research Team conducted selective breeding which produces two new chicken breed Kamper and Kambro. Further selective breeding then crossbred female F1 Kamper and male BC1 (backcross I) Kambro. In this research morphological traits, productive performance and genotyping of PPAR gene related to fat deposition gene and blood lipid content in Gama Ayam were identified. Based on data analysis hybrid chickens morphological traits it concluded that Gama Ayam has a significant variation based on feather color. The productive performance was determined with the feed-conversion ratio (FCR) value which was 3.17. Genotyping of PPAR gene resulted in four polymorphisms that formed 14 haplotypes groups. Based on blood lipid content analysis of cholesterol content, triglycerides content, HDL and LDL, Gama Ayam have significantly lower content of cholesterol (107.05 mg/dl), LDL (44.71 mg/dl) and triglycerides (22.41 mg/dl). PPAR gene polymorphisms are not correlated with blood lipid content in Gama Ayam. A significantly strong correlation between PPAR gene polymorphism on the bodyweight of Gama Ayam at 49-days-old. Triglyceride level, cholesterol level and LDL level in Gama Ayam were lower than broiler chicken. Further research with a larger population size and sex classification of hybrid chicken must be conducted to validate the results.

Histological Analysis of Breast Muscle Growth in Young Hybrid Chickens in Response to Different Dietary Energy-Protein Ratios

Histological Analysis of Breast Muscle Growth in Young Hybrid Chickens in Response to Different Dietary Energy-Protein Ratios

Are dual-purpose and male layer chickens more resilient against a low-protein-low-soybean diet than slow-growing broilers?

ABSTRACT1. Although fattening dual-purpose types or male layer hybrid chickens appears more ethical than the common practice of culling day-old male layer chicks, the lower feed efficiency of these birds raises concerns. Replacing feed ingredients that compete with food production by those of lower value for human nutrition would be beneficial.2. Lohmann Dual (LD), a modern dual-purpose type, Lohmann Brown (LB), a male layer hybrid, and Hubbard JA 957 (HU), a slow-growing broiler type, were fattened for nine weeks on two diets (control or −20% crude protein; n = 6 × 12 birds). Growth, carcass and meat quality were analysed.3. Growth performance of HU exceeded that of LD and especially of LB. The growth depression caused by the low-protein diet fed to LD (−7%) was only half of that found in HU (−13%). The LD fed the control diet had the same feed efficiency as the HU fed the low-protein diet. Even the LB had a lower performance and feed efficiency with the low-protein diet in growth. There was a gradient in carcass properties (weight, dressing percentage, breast meat yield, breast proportion and breast angle) from HU to LD to LB, with some additional adverse effects of the low-protein diet especially in HU. There were some breed differences in fatty acid profile in the intramuscular fat.4. In conclusion, the dual-purpose type used complied with regulations for Swiss organic poultry systems in terms of growth rate and was found to respond less when fed a low-protein diet than the slow-growing broiler type. The LB males were inferior in all growth and carcass quality traits. Future studies need to determine the exact protein and amino acid requirements of dual-purpose and layer hybrid chickens and the economic feasibility of the systems, especially for organic farming.