Evgeni Petkov - Academia.edu (original) (raw)
Papers by Evgeni Petkov
Journal of insects as food and feed, Apr 13, 2021
The aim of the work was to assess the effect of dietary inclusion of meals derived from black sol... more The aim of the work was to assess the effect of dietary inclusion of meals derived from black soldier fly (BSF) larvae on the performance and carcass composition in broilers. The trial was carried out with Ross 308 broilers divided in three groups according to the formulated diets: control, receiving standard diet, DFBSFM (receiving 5% partially defatted BSF meal), and FFBSFM (receiving 5% full fat BSF meal during the growing-finishing period, 14 to 35 days of age). The performance parameters controlled included body weight, weight gain, feed intake, feed conversion ratio, as well as the growth rate for each week of the trial. At 35 days of age, 10 broilers from each group were slaughtered and subjected to carcass analysis. The inclusion of 5% DFBSFM and FFBSFM in the diet improved performance of the broilers at the age of 21 and 35 days. The carcass weight and dressing percentage were higher in the groups receiving the insect meals. The results indicate potential of the DFBSFM and FFBSFM to alter the carcass composition of the broilers. Their inclusion in the diet of the birds tended to increase the percentage of the breast cuts, whereas the thigh muscles significantly decreased. The results of the study suggest good prospective for further research with the examined BSF meals, for their application as feed components in broiler nutrition that will not have adverse effect on the carcass composition and quality.
Journal of Insects as Food and Feed
The aim of the study was to compare the effect of the inclusion of 5% partially defatted or full ... more The aim of the study was to compare the effect of the inclusion of 5% partially defatted or full fat meal made of black soldier fly larvae (BSF) as replacement of the soybean meal in the diet of laying hens on their performance and hatchability of the eggs. The trial was carried out with 150 Lohmann Brown Classic layers at 54 weeks of age, mixed with 15 cocks all divided into three treatments. The treatments consisted of a basal diet (CON), and diets containing 5% partially defatted BSF meal (T1) and 5% full fat BSF meal (T2). After 3 weeks of adaptation, the birds started receiving the experimental diets for a period of 6 weeks. During the trial period, the feed consumed and the eggs for each replicate were daily controlled. These parameters were used to calculate the egg production, eggs per hen and feed efficiency (g feed/egg). The hatching traits were measured at the end of the trial in a total of 1,430 eggs, stored for 5, 10 and 15 days prior incubation, and included fertility,...
Brazilian Journal of Poultry Science
Male layer-type chickens, carcass quality, meat characteristics.
Dokladi na Bʺlgarskata akademiâ na naukite, Jan 30, 2023
An experiment with male layer-type chickens was carried out in the Institute of Animal Science-Ko... more An experiment with male layer-type chickens was carried out in the Institute of Animal Science-Kostinbrod, aiming to investigate their growth performance and carcass composition, as well as the cooking loss and tenderness of the meat at the age of 5 and 9 weeks. The birds were reared in controlled microclimate, with initial stocking density of 22 birds/m 2. After 5 weeks of age, fragmentation of the stocking density was applied and it was diminished to 7 birds/m 2. Chickens were slaughtered at 5 and 9 weeks of age, and 10 chickens of each age group were subjected to carcass analysis. The average live weight of the birds at 5 weeks was 329 g, while the 9 weeks old chickens reached 1096 g. In order to attain the weight of the first age of slaughter (5 weeks) the chickens gained 294.03 g with a feed conversion ratio of 2.97, whereas for the whole period the feed conversion ratio was 2.91. The dressing percentage of the 5 weeks old chicks was 51.26%. For the 9 weeks old it was 77.62%. The age affected the yield of the main carcass components and the older birds had higher yield of breast (P = 0.0035) and thighs (P < 0.0001). The cooking loss for both breast and thigh meat was higher in younger chickens (P < 0.0001).
Agriculture
An experiment with male layer-type chickens of the Lohmann Brown Classic breed was carried out at... more An experiment with male layer-type chickens of the Lohmann Brown Classic breed was carried out at the Institute of Animal Science-Kostinbrod, Bulgaria, aiming to investigate the effect of age at slaughter on the meat quality. The birds were reared in a controlled microclimate, with an initial stocking density of 22 birds/m2. At five weeks of age, fragmentation of the stocking density was applied, decreasing the number to seven birds/m2. Chickens were slaughtered at five and nine weeks of age at an average live weight of 329 g and 1096 g, respectively. After slaughter, 10 chickens from each age group were subjected to analysis to determine the quality of breast and thigh meat. The results of the study showed that the age affected the meat quality parameters of the male layer-type chickens and its effect differed between the breast and thigh. The chickens slaughtered at nine weeks of age displayed a lower pH but darker meat color (p < 0.001) than those slaughtered at five weeks. Fu...
Macedonian Journal of Animal Science, 2019
The antioxidant, antibacterial and antifungal effects of the natural plant additives such as turm... more The antioxidant, antibacterial and antifungal effects of the natural plant additives such as turmeric powder, dry extract of geranium (Geranium sanguineum) and oregano oil on the contents of bacteria and moulds as well as the changes of pH and peroxide values in maize, wheat, barley and triticale during storage were studied. These additives have in a different extent, an inhibitory influence on the bacteria and moulds in the cereals chosen for the study, which depends on their composition and micro-organisms' strain activity. Their influence is directed mainly to the representatives of Aspergillus and Penicillinum species, whereas they have almost no influence on those of the genus Fusarium. Oregano oil achieved the highest antibacterial and antifungal effect. Turmeric powder showed a pronounced antifungal effect in wheat, barley and triticale. Geranium's dry extract had a strong antibacterial effect, at the same time achieving only a weak antifungal effect. On 58 th day and 136 th day after the addition of these herbal additives, pH values were higher than those in untreated grains. The highest pH value was measured in the grains treated with oregano oil. All the pH values measured are within the normal range for maize and cereals, showing values between 5.41 and 6.44. Peroxide values obtained in the whole period of the trial don't exceed 8 mEq O2/kg. These values are lower in the treated cultures than in the untreated ones.
Effect of betaine on egg performance and some blood constituents in laying hens reared indoor und... more Effect of betaine on egg performance and some blood constituents in laying hens reared indoor under natural summer temperatures and varying levels of air ammonia .Bulg.
ABSTRACT This study was carried out with 80 White Cornish males from strain A and 80 White Plymou... more ABSTRACT This study was carried out with 80 White Cornish males from strain A and 80 White Plymouth Rock males from strain C (40 F0 males of unknown origin and their offspring 40 F1 males in each strain) in the Department of Poultry Science at the Institute of Animal Science - Kostinbrod. Broiler breeder males from both generations were first tested for response to abdominal massage at 18 and then at 19 and 20 weeks of age. The sperm assessment carried out from 24 to 56 weeks of age in the F0 males of unknown origin and their F1 progeny. For establishment of the relationship between the main semen traits and cockerel response to massage it was allocated two groups for each generation (F0 and F1) and from each strain - first group cockerels responded positively to the first massage for receiving of semen and second group cockerels responded to the second and third massage. It was found that the response to massage at 18 weeks of age and the size of development of the secondary sexual characters at 7 weeks of age can be used as predictive criteria for sperm characteristic in broiler breeder males from the A and C strains. The males of both strains that responded to the first massage had better developed combs and wattles and better semen traits. Also, they had higher sexual activity demonstrated by the higher rate of ejaculation in response to abdominal massage. There were pronounced genotype differences regarding ejaculate volume and less pronounced differences with respect to sperm motility and concentration that were in favor of strain C relative to strain A. The response of cockerels to massage at early age and the size of development of their secondary sexual characters can be used as criteria for prediction the quantity and quality of sperm production in broiler breeder males. Keywords: broiler breeder male, cockerel, semen, secondary sexual characters
Archiva Zootechnica
The aim of the study was to develop a dual-purpose cross suitable for rearing in alternative syst... more The aim of the study was to develop a dual-purpose cross suitable for rearing in alternative systems and to examine its growth performance and carcass composition in comparison to the parent lines. The experiment was carried out in the experimental poultry farm in the Institute of Animal Science - Kostinbrod. The cross was developed using females of a layer type line L and cocks from line BB. The latter was based on Bresse Gauloise that is also dual purpose but mainly used for meat. The chickens from the lines and the cross were reared in mixed-sex groups on deep litter, at stocking density of 25 birds/m2, and fed with standard broiler feed until the age of 9 weeks. Then the males were separated and sent to slaughter while the females were left for layers. Crossing hens from layer type line L with BB cocks resulted in dual-purpose chickens with a live weight and feed efficiency that were better in comparison to L line, but lower when compared to the BB line. These parameters were ho...
International Journal of Innovative Approaches in Agricultural Research
The study was carried out to examine the effect of the pasture access vs. conventional rearing on... more The study was carried out to examine the effect of the pasture access vs. conventional rearing on the fatty acid composition an of the thigh meat in two lines of slow growing chickens - La Belle (LB) and Bresse Gauloise (BB). Additionally differences between the lines were also examined. The influence of both factors on the lipid profile were assessed through two-way ANOVA. The effect of pasture was more pronounced than the line and was associated with lower contents of the saturated (SFA) (P<0.001), and significant increase (P<0.001) of the polyunsaturated fatty acids (PUFA). Such changes in the fatty acids of the thigh meat in the chickens having access to pasture induced considerably lower atherogenic (AI) and thrombogenic (TI) indices. Furthermore, the n-6/n-3 ratio was reduced (P<0.001), while the ratios between the poly- and saturated fatty acids (P/S), as well as the hypo- and hypercholesterolemic (h/H) (P<0.001) were increased in the pastured lines. Differences in the fatty acid composition of the thigh meat due to the line of the birds, were not observed, however the BB birds reared conventionally tended to have higher content of C18:2n-6 and C18:3n-3.
Archiva Zootechnica, 2021
The aim of the study was to assess the effect of the storage time on the hatching traits of eggs ... more The aim of the study was to assess the effect of the storage time on the hatching traits of eggs obtained from a two-line dual-purpose combination for production of male chickens that will be utilized for meat. The trial was carried out in the experimental poultry farm of the Institute of Animal Science-Kostinbrod, with a total of 150 Lohmann Brown Classic layers, at the age of 54 weeks. Hatching eggs were gathered for three weeks and were stored for 5, 10 and 15 days at 15-18°C ambient temperature prior incubation. The storage time had no effect on the fertility of the set eggs, however, it adversely affected the hatchability. Prolonged storage led to significant decline in the total hatchability (P=0.0027) and the hatchability of the fertile eggs (P<0.0001) which was lowest after 15 days of storage prior incubation. The viability of the chickens was influenced by the storage of the eggs prior incubation (P<0.0001), and decreased considerably when the chicks were hatched from...
Iranian Journal of Applied Animal Science, 2020
The quality of eggs and the hatching traits of two slow-growing lines – La Belle (LB) and Bresse ... more The quality of eggs and the hatching traits of two slow-growing lines – La Belle (LB) and Bresse Gauloise (BB) reared under conventional or alternative system with pasture access were compared. The birds of both lines in the study were at the age of 27-37 weeks. Two-way ANOVA was used to assess the effect of the rearing system as well as the line on the quality characteristics of the eggs and hatching traits of the LB and BB lines. Both factors affected to a different extent the examined traits. The effect of the rearing system was much stronger than that of the line in regard to the quality of the eggs. The birds reared on pasture had increased weight (P<0.001) of the eggs and its components-yolk, albumen and shell (P<0.001), however the alternative system decreased significantly the colour (P<0.001) of the yolk. The influence of the line was more pronounced in terms of the hatching traits, however it often interacted with the rearing system. Generally, the fertility of th...
Bulgarian Journal of Agricultural Science, 2020
Petkov, E., Ignatova, M. & Popova, T. (2020). Effect of the sex separate and straight-run type of... more Petkov, E., Ignatova, M. & Popova, T. (2020). Effect of the sex separate and straight-run type of rearing on the performance, carcass and meat chemical composition in fast growing broilers. Bulg. J. Agric. Sci., 26 (3), 652–658 The aim of the study was to assess the effect of the type of rearing (sex separate vs. straight-run) in broiler chicks on their performance, carcass and meat quality. The trial was carried out in the experimental poultry farm of the Institute of Animal Science – Kostinbrod with the fast growing hybrid Cobb-500. The one day old chickens were sexed, marked and separated into three groups (n = 100): two sex separate groups containing male and female chickens respectively and one straight-run reared into deep litter. The chickens were fed ad libitum starter, grower and finisher diet and the major zootechnical parameters were controlled. The carcass quality and meat chemical composition were analyzed at 35 d of age. The effect of the rearing system was slight in t...
Agricultural and Food Science, 2020
The experiment aimed to assess the effect of dietary inclusion of meals derived from Black soldie... more The experiment aimed to assess the effect of dietary inclusion of meals derived from Black soldier fly (BSF) larvae on the meat quality in broilers. The birds were divided into three groups according to the formulated diets: control (CON)– receiving standard diet, Т1 – receiving 5% partially defatted and Т2 – receiving 5% full fat BSF meal during the finishing period (14–35 d). At the age of 35 days, 10 broilers from each group were slaughtered for meat quality evaluation. The dietary inclusion of the BSF meals was associated with decrease of pH and lighter colour of the meat. The total amount of the saturated fatty acids (SFA) and atherogenic index (AI) were increased, while polyunsaturated fatty acids (PUFA), the ratios between PUFA and SFA (P/S), n-6/n-3 PUFA and hypo/hypercholesterolemic fatty acids (h/H) were decreased in the meat of the broilers consuming insect meals. The results of the study suggest good prospective for further research with the examined BSF meals for broile...
International Journal of Innovative Approaches in Agricultural Research, 2018
The study was carried out to compare the fatty acid profile and related lipid nutritional indices... more The study was carried out to compare the fatty acid profile and related lipid nutritional indices in the breast and thigh meat of two slow-growing lines of chickens La Belle (LB) and Bresse Gauloise (BB) and their crosses (♂LBx♀BB, ♂BBx♀LB). The birds were reared indoors in the experimental poultry farm of the Institute of Animal Science –Kostinbrod, Bulgaria. At the age of 12 weeks, 6 male chickens of each line were slaughtered and lipid analysis of the breast and thigh meat was done. The differences in the fatty acid profile and related nutritional indices of the meat between the lines were assessed by one-way ANOVA. The fatty acid composition was affected by the crossing of the lines but to a different extent in breast and thigh meat. The highest amount of monounsaturated fatty acids (MUFA) was observed in the meat of ♂BBx♀LB chickens due to the significant increase of C16:1n-7 in breast and C18:1n-9 in the thigh of these birds. On the other hand, this crossbred line exhibited the lowest levels of polyunsaturated fatty acids (PUFA). Furthermore, the lowest content of MUFA was observed in the breast of the pure lines and thigh in BB and ♂LBx♀BB, while the highest PUFA level was determined in the breast of LB and thigh of ♂LBx♀BB. The differences in the meat dietetic quality described by the lipid indices showed no consistent patterns in the pure and crossbred lines depending on the type of meat. When compared with the rest, the breast meat of the LB male chickens showed significantly higher polyunsaturated/saturated fatty acids (P/S) ratio, while lowest n-6/n-3 PUFA and thrombogenic index (TI). The values of the atherogenic index (AI) and the ration between the hypo-and hypercholesterolemic fatty acids (h/H) were also improved in this line. Thigh meat however, showed best characteristics in terms of P/S and n-6/n-3 in the ♂LBx♀BB cross.
Food Science and Applied Biotechnology, 2018
The study was carried out to compare the fatty acid composition of the breast meat in two lines o... more The study was carried out to compare the fatty acid composition of the breast meat in two lines of slow growing chickens - La Belle (LB) and Bresse (BB), reared conventionally or having access to pasture. The differences in the lipid profile due to the lines and rearing strategies were assessed through two-way ANOVA. Both factors influenced the lipid composition in the breast meat, however the effect of pasture was more pronounced. It was associated with lower contents of C14:0, C16:0 and C16:1Δ7 (P<0.001), C18:1 (P<0.05), total saturated (SFA) and monounsaturated fatty acids (MUFA) (P<0.01), and significant increase (P<0.001) of the long chain polyunsaturated fatty acids (PUFA). These changes in the lipid profile of the breast meat in the chickens reared outdoors led to considerably lower atherogenic and thrombogenic indices, reduced n-6/n-3 ratio (P<0.001), as well as higher P/S and h/H values (P<0.001). Differences in the fatty acid composition of the breast mea...
International Journal of Innovative Approaches in Agricultural Research, 2018
The study was carried out to compare the carcass quality, meat chemical composition and its fatty... more The study was carried out to compare the carcass quality, meat chemical composition and its fatty acid profile in two slow-growing crosses obtained from La Belle (LB) and Bresse Gauloise (BB) parents, reared in conventional or alternative system with pasture access. At the age 12 weeks, male chickens (n=6) of each cross were slaughtered. Two-way ANOVA was used to assess the effect of the rearing strategies as well as the crossbreed on the carcass quality and meat chemical and fatty acid composition. The live and carcass weight of both crosses, as well as the dressing percentage were influenced mostly by the rearing system, showing advantage of the indoors grown birds. Despite the reduced values of these parameters, no deposition of abdominal fat was detected in the pastured birds from both crosses, which is a positive influence of the outdoors system observed in the particular crosses. In regard to the chemical composition of the meat, the pasture access decreased the protein content in both breast and thigh meat (P<0.001) but increased the moisture (P<0.001). The cross and the rearing system had different effect on the fatty acid composition of the meat and the related lipid indices, associated with its dietetic quality. While the thigh meat was mostly affected by the cross of the chickens, showing higher content of monounsaturated fatty acids (MUFA) (P<0.01) but lower in polyunsaturated fatty acids (PUFA) (P<0.05) in the ♂BBx♀LB birds, the fatty acid of the breast meat, showed different response according to the crossbreed and the rearing system. The differences were more pronounced in the ♂LBx♀BB, indicating certain advantage of the pastured chickens from this cross with lower content of saturated fatty acids (SFA) but higher of PUFA and improved values of the polyunsaturated/saturated fatty acids (P/S) and n-6/n-3 PUFA ratios.
AGROFOR, 2019
The study was carried out to compare the carcass quality and the chemicalcomposition of breast an... more The study was carried out to compare the carcass quality and the chemicalcomposition of breast and thigh meat in two lines of slow-growing male chickens -La Belle (LB) and Bresse Gauloise (BB) reared conventionally or outdoors, havingaccess to pasture. The birds were slaughtered at 12 weeks of age. Two-wayANOVA was used to assess the effect of the rearing strategies as well as the line onthe carcass quality and meat chemical composition. Rearing system affectedsignificantly the carcass traits of the birds. The lines reared on pasture had lowerlive and carcass weight as well as lower dressing percentage (P<0.001). On theother hand they had higher percent (P<0.001) of the edible by-products (neck andgiblets). The percentage of the breast meat was significantly reduced in the birdsthat had access to pasture (P<0.001), while thigh remained unaffected. Thepastured chickens displayed higher part of the wings (P<0.01). Outdoors rearinginfluenced the chemical composition in the ...
Journal of insects as food and feed, Apr 13, 2021
The aim of the work was to assess the effect of dietary inclusion of meals derived from black sol... more The aim of the work was to assess the effect of dietary inclusion of meals derived from black soldier fly (BSF) larvae on the performance and carcass composition in broilers. The trial was carried out with Ross 308 broilers divided in three groups according to the formulated diets: control, receiving standard diet, DFBSFM (receiving 5% partially defatted BSF meal), and FFBSFM (receiving 5% full fat BSF meal during the growing-finishing period, 14 to 35 days of age). The performance parameters controlled included body weight, weight gain, feed intake, feed conversion ratio, as well as the growth rate for each week of the trial. At 35 days of age, 10 broilers from each group were slaughtered and subjected to carcass analysis. The inclusion of 5% DFBSFM and FFBSFM in the diet improved performance of the broilers at the age of 21 and 35 days. The carcass weight and dressing percentage were higher in the groups receiving the insect meals. The results indicate potential of the DFBSFM and FFBSFM to alter the carcass composition of the broilers. Their inclusion in the diet of the birds tended to increase the percentage of the breast cuts, whereas the thigh muscles significantly decreased. The results of the study suggest good prospective for further research with the examined BSF meals, for their application as feed components in broiler nutrition that will not have adverse effect on the carcass composition and quality.
Journal of Insects as Food and Feed
The aim of the study was to compare the effect of the inclusion of 5% partially defatted or full ... more The aim of the study was to compare the effect of the inclusion of 5% partially defatted or full fat meal made of black soldier fly larvae (BSF) as replacement of the soybean meal in the diet of laying hens on their performance and hatchability of the eggs. The trial was carried out with 150 Lohmann Brown Classic layers at 54 weeks of age, mixed with 15 cocks all divided into three treatments. The treatments consisted of a basal diet (CON), and diets containing 5% partially defatted BSF meal (T1) and 5% full fat BSF meal (T2). After 3 weeks of adaptation, the birds started receiving the experimental diets for a period of 6 weeks. During the trial period, the feed consumed and the eggs for each replicate were daily controlled. These parameters were used to calculate the egg production, eggs per hen and feed efficiency (g feed/egg). The hatching traits were measured at the end of the trial in a total of 1,430 eggs, stored for 5, 10 and 15 days prior incubation, and included fertility,...
Brazilian Journal of Poultry Science
Male layer-type chickens, carcass quality, meat characteristics.
Dokladi na Bʺlgarskata akademiâ na naukite, Jan 30, 2023
An experiment with male layer-type chickens was carried out in the Institute of Animal Science-Ko... more An experiment with male layer-type chickens was carried out in the Institute of Animal Science-Kostinbrod, aiming to investigate their growth performance and carcass composition, as well as the cooking loss and tenderness of the meat at the age of 5 and 9 weeks. The birds were reared in controlled microclimate, with initial stocking density of 22 birds/m 2. After 5 weeks of age, fragmentation of the stocking density was applied and it was diminished to 7 birds/m 2. Chickens were slaughtered at 5 and 9 weeks of age, and 10 chickens of each age group were subjected to carcass analysis. The average live weight of the birds at 5 weeks was 329 g, while the 9 weeks old chickens reached 1096 g. In order to attain the weight of the first age of slaughter (5 weeks) the chickens gained 294.03 g with a feed conversion ratio of 2.97, whereas for the whole period the feed conversion ratio was 2.91. The dressing percentage of the 5 weeks old chicks was 51.26%. For the 9 weeks old it was 77.62%. The age affected the yield of the main carcass components and the older birds had higher yield of breast (P = 0.0035) and thighs (P < 0.0001). The cooking loss for both breast and thigh meat was higher in younger chickens (P < 0.0001).
Agriculture
An experiment with male layer-type chickens of the Lohmann Brown Classic breed was carried out at... more An experiment with male layer-type chickens of the Lohmann Brown Classic breed was carried out at the Institute of Animal Science-Kostinbrod, Bulgaria, aiming to investigate the effect of age at slaughter on the meat quality. The birds were reared in a controlled microclimate, with an initial stocking density of 22 birds/m2. At five weeks of age, fragmentation of the stocking density was applied, decreasing the number to seven birds/m2. Chickens were slaughtered at five and nine weeks of age at an average live weight of 329 g and 1096 g, respectively. After slaughter, 10 chickens from each age group were subjected to analysis to determine the quality of breast and thigh meat. The results of the study showed that the age affected the meat quality parameters of the male layer-type chickens and its effect differed between the breast and thigh. The chickens slaughtered at nine weeks of age displayed a lower pH but darker meat color (p < 0.001) than those slaughtered at five weeks. Fu...
Macedonian Journal of Animal Science, 2019
The antioxidant, antibacterial and antifungal effects of the natural plant additives such as turm... more The antioxidant, antibacterial and antifungal effects of the natural plant additives such as turmeric powder, dry extract of geranium (Geranium sanguineum) and oregano oil on the contents of bacteria and moulds as well as the changes of pH and peroxide values in maize, wheat, barley and triticale during storage were studied. These additives have in a different extent, an inhibitory influence on the bacteria and moulds in the cereals chosen for the study, which depends on their composition and micro-organisms' strain activity. Their influence is directed mainly to the representatives of Aspergillus and Penicillinum species, whereas they have almost no influence on those of the genus Fusarium. Oregano oil achieved the highest antibacterial and antifungal effect. Turmeric powder showed a pronounced antifungal effect in wheat, barley and triticale. Geranium's dry extract had a strong antibacterial effect, at the same time achieving only a weak antifungal effect. On 58 th day and 136 th day after the addition of these herbal additives, pH values were higher than those in untreated grains. The highest pH value was measured in the grains treated with oregano oil. All the pH values measured are within the normal range for maize and cereals, showing values between 5.41 and 6.44. Peroxide values obtained in the whole period of the trial don't exceed 8 mEq O2/kg. These values are lower in the treated cultures than in the untreated ones.
Effect of betaine on egg performance and some blood constituents in laying hens reared indoor und... more Effect of betaine on egg performance and some blood constituents in laying hens reared indoor under natural summer temperatures and varying levels of air ammonia .Bulg.
ABSTRACT This study was carried out with 80 White Cornish males from strain A and 80 White Plymou... more ABSTRACT This study was carried out with 80 White Cornish males from strain A and 80 White Plymouth Rock males from strain C (40 F0 males of unknown origin and their offspring 40 F1 males in each strain) in the Department of Poultry Science at the Institute of Animal Science - Kostinbrod. Broiler breeder males from both generations were first tested for response to abdominal massage at 18 and then at 19 and 20 weeks of age. The sperm assessment carried out from 24 to 56 weeks of age in the F0 males of unknown origin and their F1 progeny. For establishment of the relationship between the main semen traits and cockerel response to massage it was allocated two groups for each generation (F0 and F1) and from each strain - first group cockerels responded positively to the first massage for receiving of semen and second group cockerels responded to the second and third massage. It was found that the response to massage at 18 weeks of age and the size of development of the secondary sexual characters at 7 weeks of age can be used as predictive criteria for sperm characteristic in broiler breeder males from the A and C strains. The males of both strains that responded to the first massage had better developed combs and wattles and better semen traits. Also, they had higher sexual activity demonstrated by the higher rate of ejaculation in response to abdominal massage. There were pronounced genotype differences regarding ejaculate volume and less pronounced differences with respect to sperm motility and concentration that were in favor of strain C relative to strain A. The response of cockerels to massage at early age and the size of development of their secondary sexual characters can be used as criteria for prediction the quantity and quality of sperm production in broiler breeder males. Keywords: broiler breeder male, cockerel, semen, secondary sexual characters
Archiva Zootechnica
The aim of the study was to develop a dual-purpose cross suitable for rearing in alternative syst... more The aim of the study was to develop a dual-purpose cross suitable for rearing in alternative systems and to examine its growth performance and carcass composition in comparison to the parent lines. The experiment was carried out in the experimental poultry farm in the Institute of Animal Science - Kostinbrod. The cross was developed using females of a layer type line L and cocks from line BB. The latter was based on Bresse Gauloise that is also dual purpose but mainly used for meat. The chickens from the lines and the cross were reared in mixed-sex groups on deep litter, at stocking density of 25 birds/m2, and fed with standard broiler feed until the age of 9 weeks. Then the males were separated and sent to slaughter while the females were left for layers. Crossing hens from layer type line L with BB cocks resulted in dual-purpose chickens with a live weight and feed efficiency that were better in comparison to L line, but lower when compared to the BB line. These parameters were ho...
International Journal of Innovative Approaches in Agricultural Research
The study was carried out to examine the effect of the pasture access vs. conventional rearing on... more The study was carried out to examine the effect of the pasture access vs. conventional rearing on the fatty acid composition an of the thigh meat in two lines of slow growing chickens - La Belle (LB) and Bresse Gauloise (BB). Additionally differences between the lines were also examined. The influence of both factors on the lipid profile were assessed through two-way ANOVA. The effect of pasture was more pronounced than the line and was associated with lower contents of the saturated (SFA) (P<0.001), and significant increase (P<0.001) of the polyunsaturated fatty acids (PUFA). Such changes in the fatty acids of the thigh meat in the chickens having access to pasture induced considerably lower atherogenic (AI) and thrombogenic (TI) indices. Furthermore, the n-6/n-3 ratio was reduced (P<0.001), while the ratios between the poly- and saturated fatty acids (P/S), as well as the hypo- and hypercholesterolemic (h/H) (P<0.001) were increased in the pastured lines. Differences in the fatty acid composition of the thigh meat due to the line of the birds, were not observed, however the BB birds reared conventionally tended to have higher content of C18:2n-6 and C18:3n-3.
Archiva Zootechnica, 2021
The aim of the study was to assess the effect of the storage time on the hatching traits of eggs ... more The aim of the study was to assess the effect of the storage time on the hatching traits of eggs obtained from a two-line dual-purpose combination for production of male chickens that will be utilized for meat. The trial was carried out in the experimental poultry farm of the Institute of Animal Science-Kostinbrod, with a total of 150 Lohmann Brown Classic layers, at the age of 54 weeks. Hatching eggs were gathered for three weeks and were stored for 5, 10 and 15 days at 15-18°C ambient temperature prior incubation. The storage time had no effect on the fertility of the set eggs, however, it adversely affected the hatchability. Prolonged storage led to significant decline in the total hatchability (P=0.0027) and the hatchability of the fertile eggs (P<0.0001) which was lowest after 15 days of storage prior incubation. The viability of the chickens was influenced by the storage of the eggs prior incubation (P<0.0001), and decreased considerably when the chicks were hatched from...
Iranian Journal of Applied Animal Science, 2020
The quality of eggs and the hatching traits of two slow-growing lines – La Belle (LB) and Bresse ... more The quality of eggs and the hatching traits of two slow-growing lines – La Belle (LB) and Bresse Gauloise (BB) reared under conventional or alternative system with pasture access were compared. The birds of both lines in the study were at the age of 27-37 weeks. Two-way ANOVA was used to assess the effect of the rearing system as well as the line on the quality characteristics of the eggs and hatching traits of the LB and BB lines. Both factors affected to a different extent the examined traits. The effect of the rearing system was much stronger than that of the line in regard to the quality of the eggs. The birds reared on pasture had increased weight (P<0.001) of the eggs and its components-yolk, albumen and shell (P<0.001), however the alternative system decreased significantly the colour (P<0.001) of the yolk. The influence of the line was more pronounced in terms of the hatching traits, however it often interacted with the rearing system. Generally, the fertility of th...
Bulgarian Journal of Agricultural Science, 2020
Petkov, E., Ignatova, M. & Popova, T. (2020). Effect of the sex separate and straight-run type of... more Petkov, E., Ignatova, M. & Popova, T. (2020). Effect of the sex separate and straight-run type of rearing on the performance, carcass and meat chemical composition in fast growing broilers. Bulg. J. Agric. Sci., 26 (3), 652–658 The aim of the study was to assess the effect of the type of rearing (sex separate vs. straight-run) in broiler chicks on their performance, carcass and meat quality. The trial was carried out in the experimental poultry farm of the Institute of Animal Science – Kostinbrod with the fast growing hybrid Cobb-500. The one day old chickens were sexed, marked and separated into three groups (n = 100): two sex separate groups containing male and female chickens respectively and one straight-run reared into deep litter. The chickens were fed ad libitum starter, grower and finisher diet and the major zootechnical parameters were controlled. The carcass quality and meat chemical composition were analyzed at 35 d of age. The effect of the rearing system was slight in t...
Agricultural and Food Science, 2020
The experiment aimed to assess the effect of dietary inclusion of meals derived from Black soldie... more The experiment aimed to assess the effect of dietary inclusion of meals derived from Black soldier fly (BSF) larvae on the meat quality in broilers. The birds were divided into three groups according to the formulated diets: control (CON)– receiving standard diet, Т1 – receiving 5% partially defatted and Т2 – receiving 5% full fat BSF meal during the finishing period (14–35 d). At the age of 35 days, 10 broilers from each group were slaughtered for meat quality evaluation. The dietary inclusion of the BSF meals was associated with decrease of pH and lighter colour of the meat. The total amount of the saturated fatty acids (SFA) and atherogenic index (AI) were increased, while polyunsaturated fatty acids (PUFA), the ratios between PUFA and SFA (P/S), n-6/n-3 PUFA and hypo/hypercholesterolemic fatty acids (h/H) were decreased in the meat of the broilers consuming insect meals. The results of the study suggest good prospective for further research with the examined BSF meals for broile...
International Journal of Innovative Approaches in Agricultural Research, 2018
The study was carried out to compare the fatty acid profile and related lipid nutritional indices... more The study was carried out to compare the fatty acid profile and related lipid nutritional indices in the breast and thigh meat of two slow-growing lines of chickens La Belle (LB) and Bresse Gauloise (BB) and their crosses (♂LBx♀BB, ♂BBx♀LB). The birds were reared indoors in the experimental poultry farm of the Institute of Animal Science –Kostinbrod, Bulgaria. At the age of 12 weeks, 6 male chickens of each line were slaughtered and lipid analysis of the breast and thigh meat was done. The differences in the fatty acid profile and related nutritional indices of the meat between the lines were assessed by one-way ANOVA. The fatty acid composition was affected by the crossing of the lines but to a different extent in breast and thigh meat. The highest amount of monounsaturated fatty acids (MUFA) was observed in the meat of ♂BBx♀LB chickens due to the significant increase of C16:1n-7 in breast and C18:1n-9 in the thigh of these birds. On the other hand, this crossbred line exhibited the lowest levels of polyunsaturated fatty acids (PUFA). Furthermore, the lowest content of MUFA was observed in the breast of the pure lines and thigh in BB and ♂LBx♀BB, while the highest PUFA level was determined in the breast of LB and thigh of ♂LBx♀BB. The differences in the meat dietetic quality described by the lipid indices showed no consistent patterns in the pure and crossbred lines depending on the type of meat. When compared with the rest, the breast meat of the LB male chickens showed significantly higher polyunsaturated/saturated fatty acids (P/S) ratio, while lowest n-6/n-3 PUFA and thrombogenic index (TI). The values of the atherogenic index (AI) and the ration between the hypo-and hypercholesterolemic fatty acids (h/H) were also improved in this line. Thigh meat however, showed best characteristics in terms of P/S and n-6/n-3 in the ♂LBx♀BB cross.
Food Science and Applied Biotechnology, 2018
The study was carried out to compare the fatty acid composition of the breast meat in two lines o... more The study was carried out to compare the fatty acid composition of the breast meat in two lines of slow growing chickens - La Belle (LB) and Bresse (BB), reared conventionally or having access to pasture. The differences in the lipid profile due to the lines and rearing strategies were assessed through two-way ANOVA. Both factors influenced the lipid composition in the breast meat, however the effect of pasture was more pronounced. It was associated with lower contents of C14:0, C16:0 and C16:1Δ7 (P<0.001), C18:1 (P<0.05), total saturated (SFA) and monounsaturated fatty acids (MUFA) (P<0.01), and significant increase (P<0.001) of the long chain polyunsaturated fatty acids (PUFA). These changes in the lipid profile of the breast meat in the chickens reared outdoors led to considerably lower atherogenic and thrombogenic indices, reduced n-6/n-3 ratio (P<0.001), as well as higher P/S and h/H values (P<0.001). Differences in the fatty acid composition of the breast mea...
International Journal of Innovative Approaches in Agricultural Research, 2018
The study was carried out to compare the carcass quality, meat chemical composition and its fatty... more The study was carried out to compare the carcass quality, meat chemical composition and its fatty acid profile in two slow-growing crosses obtained from La Belle (LB) and Bresse Gauloise (BB) parents, reared in conventional or alternative system with pasture access. At the age 12 weeks, male chickens (n=6) of each cross were slaughtered. Two-way ANOVA was used to assess the effect of the rearing strategies as well as the crossbreed on the carcass quality and meat chemical and fatty acid composition. The live and carcass weight of both crosses, as well as the dressing percentage were influenced mostly by the rearing system, showing advantage of the indoors grown birds. Despite the reduced values of these parameters, no deposition of abdominal fat was detected in the pastured birds from both crosses, which is a positive influence of the outdoors system observed in the particular crosses. In regard to the chemical composition of the meat, the pasture access decreased the protein content in both breast and thigh meat (P<0.001) but increased the moisture (P<0.001). The cross and the rearing system had different effect on the fatty acid composition of the meat and the related lipid indices, associated with its dietetic quality. While the thigh meat was mostly affected by the cross of the chickens, showing higher content of monounsaturated fatty acids (MUFA) (P<0.01) but lower in polyunsaturated fatty acids (PUFA) (P<0.05) in the ♂BBx♀LB birds, the fatty acid of the breast meat, showed different response according to the crossbreed and the rearing system. The differences were more pronounced in the ♂LBx♀BB, indicating certain advantage of the pastured chickens from this cross with lower content of saturated fatty acids (SFA) but higher of PUFA and improved values of the polyunsaturated/saturated fatty acids (P/S) and n-6/n-3 PUFA ratios.
AGROFOR, 2019
The study was carried out to compare the carcass quality and the chemicalcomposition of breast an... more The study was carried out to compare the carcass quality and the chemicalcomposition of breast and thigh meat in two lines of slow-growing male chickens -La Belle (LB) and Bresse Gauloise (BB) reared conventionally or outdoors, havingaccess to pasture. The birds were slaughtered at 12 weeks of age. Two-wayANOVA was used to assess the effect of the rearing strategies as well as the line onthe carcass quality and meat chemical composition. Rearing system affectedsignificantly the carcass traits of the birds. The lines reared on pasture had lowerlive and carcass weight as well as lower dressing percentage (P<0.001). On theother hand they had higher percent (P<0.001) of the edible by-products (neck andgiblets). The percentage of the breast meat was significantly reduced in the birdsthat had access to pasture (P<0.001), while thigh remained unaffected. Thepastured chickens displayed higher part of the wings (P<0.01). Outdoors rearinginfluenced the chemical composition in the ...