The aim of the investigation was to determine influence of L-histidine dietary supplementation (P1 0.0%, P2 0.1%, P3 0.2% and P4 0.3%), hybrid line (Cobb 500 and Hubbard Classic) and gender on meat quality and carnosine concentration in chicken breast and thigh muscles. The research was carried out on 184 one day old broiler chickens as 4×2×2 factorial design. Chicken live weight, carcass weight, dressing percentage, absolute and relative shares of main body parts in the carcass, pHi, pHu, colour, drip loss, cooking loss and share force of breast muscle, and carnosine concentration in breast and thigh muscles were determined. L-histidine dietary supplementation significantly affected live weight, carcass weight, weight of drumsticks and thighs, backs and wings, share of back and the CIE a* value (P＜0.05), as well as the content of carnosine in breast muscle (P＝0.003). Hybrid line influenced relative shares of main body parts in the carcasses, except for wings, and the CIE a* value of breast muscle (P＜0.001). Chicken gender affected live weight of chickens, carcass weight, as well as weight of main parts (P＜0.001), except for breast. The results of the investigation showed that dietary L-histidine significantly increased carnosine content in broiler breast muscle. Cobb 500 female chickens of the P4 group had higher carnosine concentrations in breast muscle by 156.61 and male chickens by 150.49 μg/g of tissue than the control group. Cobb 500 broiler chickens deposited more carnosine in meat than Hubbard Classic broilers.

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The research focused on the effects of dietary replacement of 3% sunflower oil (SO group) with 3% milk thistle oil (MTO group) on the technological quality of meat, such as pH value, colour (CIE L*, CIE a*, CIE b*), drip loss (%), shear force (N), and cooking loss (%), as well as on the content of fatty acid lipids in broiler breast and thigh muscles. Significant difference (P < 0.05) was determined for pH i, pH u , CIE a*, CIE b* values between groups, although the values for the stated indicators were within the standard range. Lipids of breast meat of the MTO group contained more arachidic acid (P < 0.001), octadecenoic acid isomer B (P = 0.047) and eicosatrienoic acid (P = 0.041), and less α-linolenic acid (P < 0.001) and Σn-3PUFA. Lipids of thigh meat of the MTO group contained more ΣSFA, myristoleic acid, eicosatrienoic acid (P < 0.05) and eicosenoic acid (P < 0.001), and less α-linolenic acid, and had narrower Σn-3/n-6 PUFA ratio than the SO group. According to the antioxidant status of broiler liver, there was significantly higher catalase activity determined in the MTO group.

The research was conducted on 120 laying hens of Tetra SL provenience, which were divided into two experimental groups (K and P), with 60 laying hens in each group (12 replications, 5 hens per replication). The control group was fed standard diet, while laying hens of experimental groups were given modified diet supplemented with 5% of oil mixture, 0.5 mg/kg organic selenium, 200 mg/kg lutein and 200 mg/kg vitamin E. Portion of n-3 PUFA was significantly better in designed eggs than in conventional eggs (3.76% and 1.69%, P<0.001). Ratio of n-6/n-3 PUFA in experimental group was more than twice as favorable as in the control group (5.91 vs. 13.34; P<0.001). Content of selenium, lutein and vitamin E in designed eggs was statistically significantly higher than in conventional eggs (P<0.001). The content of selenium in egg yolks in conventional eggs was 0.053 μg/g and in designed eggs 0.143 μg/g, and in egg whites 0.387 μg/g and 0.662 μg/g, respectively (P<0.001). Lutein content increased from 12.44 μg/g inconventional eggs to 104.95 μg/g in designed eggs, while vitamin E increased from 12.5 μg/g to 19.82 μg/g egg yolk.

The objective of this study was to compare the internal and external quality of conventional and designer eggs. In total, 120 Tetra SL laying hens were randomly allotted to two treatments (K and P groups), with 12 replicates of five hens each. The control group (K) was fed a standard layer diet, producing conventional eggs, and the P group was fed a modified diet supplemented with 5% of an oil mixture, 0.5 mg organic selenium/kg, 200 mg lutein/kg and 200 mg vitamin E/kg, producing designer eggs. Treatments did not influence (p>0.05) egg weight or egg component weights. Designer eggs presented higher albumen proportion and lower eggshell proportion than conventional eggs (p<0.01). Relative to egg quality parameters, designer eggs presented higher HU values (83.99 vs. 80.81; p=0.042), more intense yolk color (14.38 vs. 8.70; p<0.01), and lower albumen pH (8.39 vs. 8.67; p=0.007). Feeding treatments and duration of egg storage did not significantly influence egg yolk lipid oxidation (p>0.05).