M. Englmaierová

Do rearing system and free-range stocking density affect meat quality of chickens fed feed mixture with rapeseed oil?

Skřivanová V., Tůmová E., Englmaierová M., Chodová D., Skřivan M. (2017): Do rearing system and freerange stocking density affect meat quality of chickens fed feed mixture with rapeseed oil? Czech J. Anim. Sci., 62, 141−149. 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. Results 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.

Effect of the source and level of carotenoids in diets on their retention in eggs

Skřivanová V., Englmaierová M., Bendová M., Skřivan M. (2017): Effect of the source and level of carotenoids in diets on their retention in eggs. Czech J. Anim. Sci., 62, 323–330. The lutein and zeaxanthin deposition in egg yolks of hens was evaluated. The effects of various levels of extracts from Mexican marigold flowers in hen diets were compared in Experiments 1 (from 0 to 350 mg/kg) and 2 (from 0 to 950 mg/kg). In Experiment 3, the sources of carotenoids such as lutein (250 mg/kg) and Chlorella (12.5 g/kg) were examined. All three experiments were conducted using brown egg layers housed in enriched cages. The lutein concentrations in yolks were increased (P < 0.05) from 0.141 to 0.232 mg/60 g of egg (Experiment 1) and from 0.096 to 0.283 mg/60 g of egg (Experiment 2). A similar trend was observed for zeaxanthin. In Experiments 1 and 2, the zeaxanthin content increased from 0.096 to 0.150 mg/60 g of egg and from 0.046 to 0.200 mg/60 g of egg, respectively. However, the retention of lutein and zeaxanthin decreased in a dose-dependent manner from 55.8 to 33.0% and 49.1 to 29.3%, respectively, in Experiment 1 and from 81.2 to 23.3% and 57.0 to 21.6%, respectively, in Experiment 2. In Experiment 3, both the treated groups had greater lutein and zeaxanthin contents in the yolks. The ratio of lutein in the yolks from hens fed lutein to those from hens fed algae was 2.7 : 1 (1.044 and 0.382 mg/60 g of egg). Overall, 14.0 and 16.4% of lutein and 13.7 and 15.3% of zeaxanthin was retained in the eggs of hens fed lutein and algae, respectively. The concentrations of carotenoids in hen egg yolks depend on dietary intake, and the retention of carotenoids decreases with increasing dose. A higher carotenoid retention in the yolks was found when the hen diets were supplemented with the Mexican marigold extract than when Chlorella or pure lutein were used as supplements.