The objective of the study was to determine the effect of caponizing Greenleg Partridge cockerels on slaughter parameters and meat quality. In total 80 Greenleg Partridge cockerels were assigned to two groups with 40 birds per group. Group I (control) consisted of uncastrated cockerels and group II contained birds that were castrated at 8 weeks of age. Birds were kept until 24 weeks of age and fed the same diet ad libitum. Body weight was recorded at 1, 8, 16 and 24 weeks of age. Dressing percentage, proportion of breast and leg muscles, giblets and abdominal fat, and microstructure of the pectoralis superficialis muscle were determined postmortem. Physicochemical characteristics of meat (pH, CIE L*a*b* colour, water holding capacity, drip loss, thawing loss, cooking loss, shear force, texture parameters and chemical composition) were determined and sensory evaluation was performed. The castration of Greenleg Partridge cockerels contributed to increases in body weight, dressing percentage, and carcass muscle and fat content, and changed the colour of bird skin and muscles. The leg muscles of capons were characterized by higher pH24h, better water holding capacity, a tendency for higher fat concentration, and better sensory quality. The breast muscles of castrated cockerels lost more water and were tougher than the same muscles from uncastrated cockerels, but received better scores for flavour. In conclusion, the results of this study indicate that the caponized Greenleg Partridge cockerels can be used as a valuable material for production of high quality meat.

The aim of the present study was to determine the effect of amaranth seeds, dried sea buckthorn pomace and dried chokeberry pomace on the growth performance of broiler chickens and on the fatty acid profile and oxidative stability of meat lipids. The study was conducted on 480 Ross 308 chickens assigned in the second production phase to 4 experimental groups. The birds from the control group received 3% flax oil, while the chickens from the experimental groups were fed with mixtures containing: 3% flax oil and 8% amaranth seeds (group II), 3% flax oil and 3% dried sea buckthorn pomace (group III), and 3% flax oil and 3% dried chokeberry pomace (group IV). Basic production parameters were evaluated for each feeding period. At 42 days of age, 8 birds with body weight close to the average from each group were slaughtered. A simplified analysis of the chicken carcasses was conducted and samples of the breast muscles were collected for further analysis. The addition of 8% amaranth seeds into the feed mixtures in the second feeding phase decreased body weight gains (P<0.05) and increased the feed conversion ratio compared with groups receiving sea buckthorn or chokeberry pomace. However, the addition of amaranth seeds into the feed mixtures increased breast muscle yield (P<0.05) and decreased fat content in comparison to the other experimental groups. Moreover, sensory analysis of the breast muscles from chickens fed the diet with amaranth seeds revealed that they were characterised by a better aroma (P<0.05) and flavour. The studied feed additives did not significantly affect the physicochemical properties of the breast muscles. Sea buckthorn pomace efficiently slowed down lipid oxidation in the breast muscles. The obtained results indicate that using tested plant additives in feed mixture may be an effective way to improved production parameters of broiler chicken and effectively enriched meat in n-3 fatty acid and protect against excessive oxidation of lipids.

Background: Intensive selection for growth rate (GR) in broiler chickens carries negative after-effects, such as aberrations in skeletal development and the immune system, heart failure, and deterioration of meat quality. In Poland, fast-growing chicken populations are highly non-uniform in term of growth rate, which is highly unprofitable for poultry producers. Therefore, the identification of genetic markers for boiler GR that could support the selection process is needed. The hypothalamus is strongly associated with growth regulation by inducing important pituitary hormones. Therefore, the present study used this tissue to pinpoint genes involved in chicken growth control. Results: The experiment included male broilers of Ross 308 strain in two developmental stages, after 3rd and 6th week of age, which were maintained in the same housing and feeding conditions. The obtained results show for the overexpression of genes related to orexigenic molecules, such as neuropeptide Y (NPY), aldehyde dehydrogenase 1 family, member A1 (ALDH1A1), galanin (GAL), and pro-melanin concentrating hormone (PMCH) in low GR cockerels. Conclusion: The results reveal strong associations between satiety centre and the growth process. The present study delivers new insights into hypothalamic regulation in broiler chickens and narrows the area for the searching of genetic markers for GR. Graphical

The aim of this study was to evaluate the effect of feed restriction on carcass composition, breast meat quality and microstructure of the m. pectoralis superficialis of broiler chickens. A total of 315 day-old female broilers (Ross 308) were randomly assigned to 3 groups of 105 birds each in 3 pen replicates. They were fed ad libitum as the control (I), and restricted for 6 h/day (from 08:00 to 14:00 h) as group II (3 and 4 weeks of age) and group III from 4 to 5 weeks of age. On day 42 of growth, 6 broilers with average body weight were chosen from each group for slaughter to analyse dressing percentage, carcass quality, physicochemical properties of breast muscles, including pH, colour (CIE L*a*b*), expressible juice, drip loss, thawing loss, cooking loss, Warner-Bratzler shear force, texture (TPA) and chemical composition, as well as histochemical profile of the m. pectoralis superficialis. Temporary feed restriction did not significantly alter the final body weight, dressing percentage and the proportion of breast and leg muscles, but increased the proportion of abdominal fat. No differences were found in the microstructure of the m. pectoralis superficialis of restricted and ad libitum fed chickens. Restricted feeding had an effect on water holding capacity and tenderness of breast muscles, and a non-significant effect on texture parameters and chemical composition. Restricted feeding of chickens changed their meat quality to a greater extent when applied from 3 to 4 weeks compared to analogous procedures introduced from 4 to 5 weeks of age.

The quality of chicken meat, which is one of the most widely consumed meats in the world, has been the subject of research and studies for many years. There are several ways to improve the quality of this type of meat, including changing the concentrations of individual molecular components. Such important components of meat are inter alia, cholesterol, vitamin E, and some fatty acids such as ω-3 and ω-6. Manipulation of ingredient levels may be achieved by enriching chicken feed with elements of different types such as vegetable oils, garlic, or selenium. Thus far, various biochemical and biophysical methods have been used to study quality of different meat types, especially broiler meat. Here, the authors demonstrate the use of high-resolution time-of-flight secondary ion mass spectrometry (TOF-SIMS) mass spectrometry to assess how variations in animal nutrition affect concentrations of specific lipids in the meat, such as cholesterol and vitamin E. In the presented experiment, there were four different dietary treatments. Feed for animals in the first group was supplemented with soy oil in 50%, the second group's feed was supplemented with linseed oil in 50%, a combination of these two oils in the proportion of 44%:56% was used for the third group, and in the reference group, animals were fed with beef tallow. From each group, four individuals were selected for further analysis. Positive and negative ion mass spectra were generated from the pectoralis superficialis muscle tissue of the left carcass side of each one animal. Using TOF-SIMS with a bismuth cluster ion source (Bi3+), and based on characteristic peaks for cholesterol in the positive mode and vitamin E in the negative mode, the authors have illustrated the relationship of these lipids levels to the various feeding regimens. Simultaneously, the authors characterized the varying dependences on the concentrations of measured lipids in fat and muscle fibers. The cholesterol concentration in muscle fibers was the lowest in the group fed with soybean oil and the highest in reference group IV (tallow feed). In the fatty region, the highest level of cholesterol was found in the third group. The highest concentrations of vitamin E were found in the fibers of the first group and the fat region of the second group. The obtained results show that SIMS imaging is a useful approach for assessing changes in lipid concentrations in the meat tissue from animals on different diets and provides a foundation for future research.