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The aim of the study was to evaluate the effect of feeding regime (FR) and the combination of FR with pasture on the carcass composition and meat quality parameters of fast-growing chickens. Ross 308 chickens were split into three groups: Group 1 was fed ad libitum, and Groups 2 and 3 had a restricted diet. The chickens were feed-restricted at a rate of 70% ad libitum from 8 to 14 days of age. In Group 3, after restriction at the age of 21 days, chickens were kept on a pasture until the end of the experiment at 35 days of age. The chickens were fed ad libitum prior to and following restriction. Feed restriction and the combination of feed restriction and pasture significantly reduced final body weight, but the dressing out percentage was not affected. The breast percentage was the highest (P = 0.005) in the ad libitum group (30.5%), followed by the restricted group (28.2%) and the lowest in the group with a combination of feed restriction and pasture (27.4%). Breast pH and colour measured 24 h post mortem were not affected, whereas texture expressed as Fmax was the lowest in the group with the combination of feed restriction and pasture (P = 0.05). There was no effect of the group on meat dry matter, crude protein, cholesterol, and fatty acid content, but ether extract was the highest, and significantly so, in the ad libitum-fed group. In summary, feed restriction and the combination of feed restriction and pasture negatively affected final body weight and breast and abdominal fat percentages, which might be related to a short realimentation period for compensatory growth. However, these conditions negligibly affected carcass composition and the physical and chemical parameters of the meat.

The aim of this study was to monitor the occurrence of abnormal eggs in five initial laying lines of the domestic chicken (Gallus domesticus) between 2017 and 2021. The incidence of abnormal eggs, cracks, shell-less eggs, and double-yolk eggs were examined as part of the monitoring. Also assessed was the laying intensity, which ranged from 83.7% for the Barred Plymouth Rock (BPR) B line to 96.8% for the Rhode Island Red (RIR) A line. A statistically significant relationship between the line and control year was discovered for all varieties of abnormal eggs. The highest occurrence of cracks was in the RIR B line (2.2%). The BPR A line of hens had the highest concentration of shell-less eggs (1.7%), while the RIR A line, which also had the highest laying intensity (96.8%), had the highest frequency of double-yolk eggs (1.5%). A positive trend between the intensity and the occurrence of abnormal eggs was also confirmed. The BPR B (3.4%) and BPR C (3.0%) lines, which belonged to the lines with the lowest laying intensity, had the lowest percentage of abnormal eggs. For the BPR C line, cracks (1.2%), shell-less eggs (0.9%), and double-yolk eggs (0.9%) had the lowest occurrence rates. The correlation between laying intensity and double-yolk eggs reached 0.67, and a significant positive relationship was seen. On the other hand, no association was found between the laying intensity and the prevalence of cracked or shell-less eggs. There was also a strong correlation between abnormal eggs and double-yolk eggs (0.80) and between abnormal eggs and cracks (0.73). The correlation between the total occurrence of abnormal eggs and the intensity of laying reaches a mean value of 0.41. An increase in the intensity of laying from 80% to almost 100% leads to an increase in the occurrence of abnormal eggs from 2.6% to 6.3%.

Camelina sativa can be identified as a promising oilseed crop due to its short growth cycle, tolerance to drought and frost, low-input requirements, resistance to pests and diseases, feed, and non-feed applications. Compared to other Brassicaceae family plants, camelina is mainly distinguished by high levels of n-3 polyunsaturated fatty acids and antioxidant content. However, camelina contains secondary plant metabolites, such as glucosinolates, phytic acid, sinapine, etc., and their presence limits the use of camelina by-products (oil, seed or cake) in poultry feeding. The breakdown of these compounds forms complexes that can inhibit digestive enzymes, reduce the absorption of nutrients, and ultimately modify product quality. The content of these anti-nutritional compounds and plant seed quality can be modified by various techniques: hybridisation, mutation induction, gene engineering, etc. Moreover, methods such as infrared irradiation, multi-enzyme and copper supplementation, etc., can counter or mitigate the effect of plant secondary metabolites present in camelina seed or cake. In general, dietary inclusion of camelina seed or cake at high inclusion levels (> 10%) worsened the nutrient digestibility and thus reduced growth performances. However, carcass traits and meat proximate composition were comparable in birds-fed diets containing camelina by-products. The fatty acid profile of meat cuts and abdominal fat was significantly higher in alpha-linolenic acid and lower n-6/n-3 ratio, thus promoting the healthiness of products for human consumption. Also, the dietary inclusion of camelina did not modify the sensory profile of the products. The present article is a comprehensive and critical review of research carried out to improve the quality of camelina and its by-products to be used in broiler poultry feeding. This review gives information on the feeding value of camelina by-products, as well as a survey of the literature on their use in poultry diets to evaluate digestibility, performance, carcass traits, and meat quality.

The present study aimed to determine the incidence and coincidence of white striping (WS), woody breast (WB) and spaghetti meat (SM) in raw chicken breast meat (n = 300) collected 3-3.5 h post mortem from commercial broiler flocks (Ross 708 males, 56 days of age). The fillets were scored for the occurrence and severity of WS, WB and SM using visual and tactile methods, and the relationship between myopathies and breast weight was evaluated. A total of 88% of samples (out of 300) had either one or a combination of three myopathies, leaving only 12% without any myopathies. Approximately 29% of the fillets had only one myopathy present, with 59% of the samples demonstrating the cooccurrence of breast myopathies. In the present study, 47.7% of WB samples also exhibited WS, while the cooccurrence of WB and SM was exhibited in 14.7%. Based on binomial logistic regression, an increase in WB scores decreases the odds that the fillet may be affected by SM myopathy. No association was found between SM and fillet weight. Multinomial logistic regression showed that the weight of breast fillets was positively associated with WB1 (P = 0.011), WB2 (P < 0.001), and WB3 (P < 0.001). Furthermore, positive associations were found between WS1 and WB3 (P = 0.004) as well as between WS2 and WB3 (P < 0.001). The percentage distribution changes of each WB and WS myopathy score were used in relation to the 10 weight groups. The percentages of WB3 increased and WB0 decreased as the average fillet weight increased. Regarding linear regression, these results exhibited a positive linear relationship for both WB (R2 = 0.91, P < 0.001) and WS (R2 = 0.71, P = 0.002) myopathy with fillet weight. A high prevalence of myopathies was observed. The incidence of severe WB categories and the overall high cooccurrence rate are alarming.

The aim of the present study was to compare carcass characteristics and meat quality of fast- (Ross 308), medium- (Hubbard JA757) and slow-growing (ISA Dual) chickens (n = 1 980). When the chickens reached an average live weight of 2 kg, 40 birds (males to females, 1 : 1) of each genotype were randomly selected and slaughtered for carcass analysis. Pectoralis major (PM) muscle samples were taken to determine the physical and chemical parameters of the meat quality. The fast- and medium-growing genotypes had higher (+3.24% and +3.84%, respectively) dressing out percentages than the slow-growing chickens. As expected, the breast percentage significantly decreased in the order of fast growth > medium growth > slow growth. The abdominal fat percentage was the lowest in Ross 308 chickens, but the abdominal fat percentage in JA757 and ISA Dual chickens did not differ. For edible organs, fast- and medium-growing chickens had heavier hearts and livers than slow-growing chickens. In contrast, ISA Dual chickens showed heavier gizzards. Genotype dramatically affected the chemical composition of PM muscle. The ISA Dual chickens exhibited a significantly higher proportion of dry matter and protein and lower ether extract and cholesterol content than Ross 308 chickens, with intermediate values for JA757 chickens. The ISA Dual group had a lower ash content than Ross 308 and JA757 groups. In terms of physical parameters, the ISA Dual chickens had higher lightness and yellowness and lower redness, pH 24, and cooking loss than those of the other genotypes. Concerning all genotypes, the shear force values increased from fast- to slow-growing chickens. In conclusion, this study found a difference between the genotypes. Although the slow-growing chickens showed the lowest dressing out and breast percentages compared with the other genotypes, the breast meat of the slow-growing chickens had more favourable nutritional properties.

The objective of the study was to evaluate the effects of feed restriction and sex on the physical, chemical and histochemical parameters of meat quality in chickens, rabbits and nutrias. Feed restriction was applied at a rate of 70% ad libitum from 14 to 21 days of age in chickens, 70% ad libitum from 42 to 49 days of age in rabbits, and 70% ad libitum from 12 to 15 weeks of age in nutrias. Animals were fed ad libitum prior to and following restriction. The results showed stronger effects of feed restriction, sex, and their interaction on the meat quality of broiler chickens than in rabbits and nutrias. The effect of feed restriction, sex and their interaction were mainly observed in the nutritional value of meat, while physical measurements of meat were negligibly affected. The interaction between feed restriction and sex affected the cross-sectional area of muscle fibre only in rabbits and nutrias. The data indicated the relationships between compensatory growth, muscle fibre distribution, and nutritional value of meat.

The aim of the study was to compare the effects of feed restriction on the growth performance and carcass composition of chicken, rabbit and nutria males and females. Feed restriction was applied at a rate of 70% ad libitum from 14 to 21 days of age in chickens, 70% ad libitum from 42 to 49 days of age in rabbits, and 70% ad libitum from 12 to 15 weeks of age in nutrias. Animals were fed ad libitum prior to and following restriction. Carcass composition was evaluated at common slaughter ages, i.e., 31 days in chickens, 70 days in rabbits, and eight months in nutrias. The results showed stronger effects of feed restriction, sex, and their interaction in broiler chickens than in rabbits and nutrias. In chickens, feed restriction increased the sex differences in final body weight, which were associated with interaction of feed restriction and sex (P = 0.009). Feed restriction as a fixed factor significantly affected growth and feed conversion in chickens and it was with no effect in rabbits and nutrias. The effect of feed restriction on carcass composition was negligible in all selected species. With respect to sex, significant differences were observed in chickens in final body weight, daily weight gain, dressing out percentage and breast percentage, in rabbits in loin percentage, and in nutrias in growth and perirenal fat percentage. Results of the study indicated that interactions of feed restriction and sex in growth might be associated with a short realimentation period.

Cadmium (Cd) is a toxic heavy metal, discharged into environments naturally or anthropogenically, where industrial and agricultural revolutions have led to serious Cd pollution into the environment. Poultry feed may be contaminated by Cd due to its presence in concentrates and supplements, and also in the machinery and equipment used in feed production and processing. After absorption in the digestive system, Cd largely accumulates in kidneys, liver, bones and other organs and causes irreversible damage to these organs. Higher doses of Cd in the poultry diet reduced feed intake, body weight, bone mineral density, egg production and eggshell quality. Selenium (Se) is an essential micronutrient and important component of a variety of antioxidant enzymes, with the ability to antagonize metal toxicity including Cd. Hence, in the current review, we try to summarize recent information about the toxicological effects of Cd and provide updated information about the role of Se as an effective strategy in reducing Cd toxicity in poultry.

The aim of the present study was to evaluate the effect of two dietary protein levels on performance, carcass characteristics, and meat quality parameters in fast- (Ross 308), medium- (JA757), and slow-growing (ISA Dual) chickens to assess the interaction of the two factors. Each genotype was divided into a control group fed a commercial type of feed mixture and an experimental group fed a low-protein diet (LP). The trial was terminated after a common period of fattening of each genotype, and 20 chickens per group (sex ratio 1 : 1) were selected for the carcass and meat analysis. The results indicated that the LP diet decreased growth (P < 0.001) and increased feed consumption (P < 0.001) more in the fast-growing than in the slow-growing genotypes; however, reduced mortality was detected in fast-growing chickens. The LP diet had a negative effect on the European performance efficiency factor (P < 0.001) in fast- (-10%) and medium-growing (-6%) but not in slow-growing chickens. The main effect of the genotype on the carcass characteristics included the highest (P < 0.001) dressing out and breast percentage in fast-growing chickens and the highest (P < 0.001) percentage of thigh and abdominal fat in the slow-growing genotype. The LP diet had only a minor effect on the carcass traits. Regarding meat quality characteristics, slow-growing chickens were characterized by higher contents of dry matter (P < 0.001) and crude protein (P < 0.001) and lower contents of ether extract (P < 0.001) and cholesterol (P < 0.001) compared to medium- and fast-growing chickens. The individual effects of the genotypes were manifested by the largest cross-sectional area of the muscle fibres of pectoralis major in fast-growing chickens (P < 0.001). The results of the present study indicate a significant interaction of the dietary protein levels and genotypes in growth performance and a negligible effect on the carcass composition and physical and chemical quality of meat

An experiment was conducted with 1 680 one-day-old turkey poults (720 males and 960 females) of the Hybrid ConverterTM genotype to compare the growth performance of male and female turkeys. The experiment lasted until 119 days of age for males and 126 days for females, during which 6 commercial-type feeds were administered, with changes occurring at 21, 42, 63, 84 and 102 days of age. Performance was evaluated by weekly weighing and measuring feed consumption in each pen at weekly intervals. At 1, 7, 14, 21, 35, 56, 77, 119 (males) and 126 (female) days, 12 birds from each sex were sampled for weights of carcass, liver, gizzard, heart, thighs and breast. The Gompertz equation fitted separately to male and female growth data suggested that the mature weight of males would be by 16 kg heavier than in females (34.6 vs 18.7 kg) and that the females would mature 36% faster than males (0.023 2 vs 0.017 0/day). The weights of liver, gizzard and heart were similar in males and females in the early part of the growth period but they diverged from 35 days for the gizzard, 56 days for the liver and 77 days for the heart. However, the allometric coefficients describing the growth of each of these internal organs in relation to body weight were the same for males and females. Thigh weight was allometrically related to body weight, with males and females sharing the same relationship, but although the slope of the allometric relationship for breast weight in males and females was the same, breast weights in females were heavier than in males at any given body weight. Female turkeys became fatter than males from 56 days onwards.

Sex differences in growth, blood indicators, carcass values and meat quality in nutrias were evaluated. In the fattening experiment, 136 nutrias of both sexes (1 : 1 ratio) were fattened until 8 months of age. At the end of the experiment, 18 males and 18 females with average weights were selected for the determination of biochemical indicators, carcass value and meat quality. The growth of males was significantly higher than in females; the differences were 12% at three months of age and increased to 24% at eight months of age. The effect of sex on the biochemical indicators of blood was observed in total protein (P ≤ 0.029), albumin (P ≤ 0.012), urea (P ≤ 0.019) and cholesterol (P ≤ 0.026), with higher values in males. In the case of haematology examination, the significantly higher values in males were in the number of erythrocytes (5.10 × 1012/l) and in the haematocrit value (55.8%). Dressing out percentage was higher in males (P ≤ 0.039), and other parameters of carcass value were not affected by sex. For the meat physical properties, only lightness (P ≤ 0.019) was higher in males. In the case of the chemical composition of meat, ether extract (P ≤ 0.033) and energetic value (P ≤ 0.024) were lower in females. The results of this study show high differences in the growth of male and female nutrias, whereas carcass composition, physical meat quality and meat chemical composition are less affected by nutria sex.

Objective The aim of this study was to compare male and female geese of two contrasting genotypes in terms of fatty acid composition, indexes related to human health, lipid metabolism and oxidative stability of the meat. Methods The experiment was carried out on total of 120 geese of two different genotypes; the native breed Czech goose (CG) and commercial hybrid Novohradska goose (NG). One-d-old goslings were divided into 4 groups according to genotype and sex, and 8 birds from each group were slaughtered at 8 weeks of age. Results The effects of the interactions between genotype and sex were observed on growth performance and carcass traits. Final body weight (p

The aim of this study was to evaluate the effect of one week of intensive feed restriction (50 g and 65 g per rabbit per day for R50 and R65, respectively) on carcase traits, meat quality characteristics and muscle fibre parameters in early weaned growing rabbits. Rabbits were restricted between 32 and 39 days of age but fed ad libitum before and following feed restriction. The live weight at 81 days of age was not affected by the feeding regime. At the time of feed restriction, the daily weight gain decreased (p = .001) to 61% in R50 and 67% in R65 compared with rabbits fed ad libitum. However, the average daily weight gain and feed intake or feed conversion ratio were not significantly affected by feeding regime over the entire experimental period. Feed restriction had no effect on dressing out a percentage or the percentages of the hind and foreparts. No effect of feeding regime was observed in meat tenderness and cooking loss, but significant interactions between feeding regime and age were detected in the cross-sectional area and diameter of βR and αW muscle fibres. Smaller type βR cross-sectional area and diameter were observed in group R50 under more intensive feed restriction. The distribution of fibre type was not significantly affected by the treatment and age interaction or by feeding regime alone. It could be concluded that one week of intensive feed restriction in early weaned rabbits affects some morphological muscle fibre characteristics but has no effect on performance, carcase traits and meat quality.Highlights No effect on performance and meat quality. Smaller area of βR muscle fibres in restricted rabbits. Distribution of fibre type was not affected.

The differences in the performance, carcass parts, and internal organs of broiler chicken females and males fed ad libitum or restricted by 80 and 65% ad libitum were evaluated. Ross 308 males and females (2430 chickens) were fed ad libitum (ADL) or were restricted in days 8-14 of age by 80% ADL (R1) and 65% ADL (R2), respectively. Feed restriction depressed the live weight (P ≤ 0.001) in both sexes. Both sexes compensated for growth, and at the end of the fattening at 35 days, the restricted males (-3% R1 and -6% R2) and females (-3% R1 and -4% R2) were not significantly lighter than the ADL chickens. Feed intake was lower (P ≤ 0.001) in females than in males, and feed restriction and sex did not affect the feed conversion ratio. The growth of internal organs as early-developing tissues (heart, gizzard, liver) was less affected than the growth of late-developing tissues (breast, thigh, abdominal fat). Restricted males and females had more abdominal fat than the ad libitum chickens (P ≤ 0.05). Differences in allometric growth between males and females were in the liver, breast, and thigh. At the end of the experiment, restricted males had a higher weight of breast and thigh, whereas in females, the weights of both parts were similar to those of the ADL group. During the restriction period, the growth of internal organs is given priority compared to muscles, which was confirmed by allometric growth. Males showed a higher compensatory growth, including the growth of breasts and thighs.

Objective The aim of this study was to compare carcass traits, meat quality and sensory attributes in two different genotypes of geese according to age and sex. Methods The experiment was carried out on 160 birds of two genotypes of geese: the Czech Goose (CG) breed and a Eskildsen Schwer (ES) hybrid. One-d-old goslings were divided into four groups according to genotype and sex. Two dates for slaughtering (at 8 and 16 wk of age of goslings) were undertaken. Results The slaughter weight, cold carcass weight and dressing percentage were affected by all the studied factors, and significant interactions between age, genotype and sex were detected in the slaughter weight (p

Hens of the laying hybrid ISA Brown were used in the study with the objective to evaluate eggshell quality, microbial contamination of eggshells, and penetration of microorganisms into the egg content in different housing systems (enriched cage: 60 hens, 10 hens per cage, 750 cm2 per hen vs free range: 60 hens, 9 hens per m2) and at different hen ages (26 vs 51 weeks) during storage time (0, 2, 7, 14, and 21 days). A significant interaction between the housing system and age was observed in egg weight and most of eggshell quality measurements. However, microbial contamination and penetration were affected mostly by the housing system and storage time. The numbers of Escherichia coli (P < 0.001, 4.51 vs 2.75 log cfu/eggshell) and Enterococcus (P < 0.001, 2.56 vs 1.11 log cfu/eggshell), and the total number of microorganisms (P < 0.001, 5.04 vs. 3.65 log cfu/eggshell) were higher in free range eggs compared to enriched cage eggs, respectively. The counts of Escherichia coli (P < 0.001, 4.23 vs 2.91 log cfu/eggshell) and Enterococcus (P < 0.001, 2.31 vs 1.27 log cfu/eggshell) decreased with storage time. A positive correlation between the total number of pores and penetration of Escherichia coli in both housing systems was observed in the albumen. It can be concluded that the housing system and age of laying hens significantly affected eggshell quality. Microbial contamination presumably affects the penetration of microorganisms. The correlation between the number of pores and penetration is assumed to be affected by the microbial species.

The aim of this study was to evaluate changes in the histological characteristics of the pectoralis major (PM) muscle in chickens as well as histological changes in the caecum after a low dose of Eimeria tenella (E. tenella). The chickens were inoculated orally with 5 × 102 E. tenella oocysts (Gr1) and 1 × 103 E. tenella oocysts (Gr2) at 16 days of age. Six chickens from each group were sacrificed for post mortem examination at 9 days post-infection (pi) and 16 days pi. Chicken growth was not affected by infection. On the 9th day of infection, caecal villus height was significantly greater in the non-infected control group. However, infected chickens from group Gr1 sacrificed seven days later had an even greater caecal villus height than those of the control (p =.001). Both infected groups had higher PM weights at 16 days pi than did the control group (p = .001). The fibre cross-sectional area was smaller in Gr2 at 9 days pi; however, this parameter was larger in these chickens at 16 days pi. The pH value of PM of group Gr2 was significantly higher than that of the control group or group Gr1 at 16 days pi (p = .020).

The objective of the present study was to determine the relationship between eggshell thickness and other eggshell characteristics in eggs produced in litter housing system and enriched cages. Eggs were collected from 200 birds of ISA Brown genotype at 40–42 weeks of age. Half of the birds were housed in enriched cages (750 cm2/hen, 10 hens/cage) and the other half were housed in littered pens (9 hens/m2, 10 hens/pen). Eggs in each housing system were split into three categories varying in shell thickness: the first category (thin shells 0.28–0.30 mm), the second category (medium shells 0.33–0.36 mm) and the third category (thick shells 0.39–0.41 mm). Results indicated that eggshell parameters differ significantly according to eggshell thickness. Significant interaction of shell category and housing system were observed in eggshell strength. As expected, the eggshell strength was increased with eggshells becoming thicker. Moreover, eggs with the thickest shells from enriched cages had significantly stronger shells than those from litter system. Eggshell weight was significantly increased in the thick eggshell category being higher in enriched cages (7.23 g) than in litter system (5.14 g). The Pearson’s correlation coefficients showed a positive correlation between eggshell parameters and eggshell thickness in both housing systems. Moreover, the correlation between eggshell thickness and eggshell strength was higher on litter (0.64, p

The differences in egg production traits in six laying hen genotypes (brown-egg hens Bovans Brown, Bovans Sperwer, ISA Sussex; white-egg hen Dekalb White; laying hens with tinted shells Moravia Barred and Moravia BSL) and the interactions of genotype and oviposition on egg quality were evaluated. The genotype affected the laying rate (P ≤ 0.003), mean sequence length (P ≤ 0.001), and time of oviposition (P ≤ 0.001). The brown-egg genotypes laid eggs approximately 1 h earlier than the white-egg genotypes and approximately 2 h earlier than the tinted-egg genotypes. Egg shell strength was the lowest in tinted-egg genotypes (P ≤ 0.001) and declined with the time of oviposition (P ≤ 0.002). Egg shell percentage (P ≤ 0.011) and thickness (P ≤ 0.011) were affected by the interaction of genotype and oviposition. None of the effects affected egg weight; however, the proportion of egg components was significantly influenced by the interaction of genotype and oviposition. The study confirmed that the differences in the egg production and egg quality of various genotypes are associated with the laying pattern.

Recently, consumers have paid an attention to animal-friendly meat. The aim of the study was to evaluate the meat quality of breast muscles in indoor and free-range chickens with respect to the stocking density of outdoor chickens (8.3 or 4.15 birds per m2) fed feed with rapeseed oil. The free-range chickens reached 96 and 97% of the final live weight of the indoor chickens and their feed : gain ratio was by 7 and 9% higher. The pasture intake had a small effect on the breast meat quality and was presumably associated with rapeseed oil in the basal diet which strongly influenced meat monounsaturated and polyunsaturated fatty acid content and reduced the effect of pasture. The free-range system and lower stocking density led to an increase in muscle fibre cross-sectional area and diameter and a higher meat shear force (P = 0.003). Concerning the meat sensory properties, the total acceptability of the meat of free-range chickens with a lower stocking density was found to be lower compared with the other groups.esults indicate a minor effect of the rearing system and free-range stocking density on chicken meat quality, and also that meat quality in experiments with free-range housing can be affected by a fat source in basal diet.

The objective of this study was to evaluate hen performance and eggshell quality response to genotype, housing system, and feed calcium (Ca) level. For this purpose, an experiment was conducted on 360 laying hens of ISA Brown, Bovans Brown (commercial hybrids), and Moravia BSL (traditional Czech hybrid). Laying hens were kept in enriched cages and on littered floor and fed similar feed mixtures with different Ca content (3.00% vs. 3.50%). In terms of hen performance, ISA Brown had the highest egg production (84.2%) compared to Moravia BSL (74.3%) and Bovans Brown (71.4%). Regarding eggshell quality, Bovans Brown showed the highest values of all eggshell quality parameters. Increasing feed Ca level augmented egg production (p ≤ 0.001) but had no effect on other performance parameters. Except eggshell thickness, all eggshell quality parameters were affected by the three-way interaction of genotype, housing, and Ca. Bovans Brown, which had the strongest eggshells (5089 g/cm2) when housed on a littered floor system and fed 3.00% Ca, while Moravia BSL housed on a littered floor had the weakest eggshells (4236 g/cm2) at 3.50% Ca. The study pointed out the importance of the interactions between studied factors on performance and eggshell quality compared to an individual factor effect.

The aims of this study were to describe selected performance characteristics of Czech local breeds and to compare these breeds with a commercial hybrid. Seven original Czech breeds were included in the study: the giant breed Moravian Blue (MB), the medium breeds Czech White (CW), Czech Spotted (CS), Czech Solver (CSo), Moravian White of Brown Eye (MW) and the small breeds Czech Black Guard Hair (CB) and Czech Gold (CG) and the Hyplus rabbits. Growth of the rabbits was significantly (P=0.001) affected by genotype; MB and CW breeds grew non-significantly faster than Hyplus. The highest daily weight gain was observed in MB (42.6 g/d) and the lowest was in CB (23.9 g/d). Digestibility of ether extract was significantly (P=0.001) affected by genotype, with the lowest value for MB (0.823). Slaughter characteristics mostly correlated with live weight; the highest dressing-out percentage was in the small breed CG (62.0%) and the lowest in the Hyplus rabbit (57.0%). Of the biochemical traits evaluated, only cholesterol concentration was significantly (P=0.041) affected by genotype, with the highest values observed in Hyplus rabbits (4.2 mmol/L).