The aim of the study is to determine the effect of hemp seed (HS) of the nonpsychotropic variety Futura and extruded flaxseed (EF) in the diet of cockerels on cockerel growth performance, breast muscle and liver α- and γ-tocopherol concentrations, breast muscle fatty acid concentrations and tibia strength. Five hundred and forty one-day-old male Ross 308 cockerels are equally allocated into six groups. Each group has three replicates of 30 cockerels in pens with litter. The formulated diets are isoenergetic (the metabolisable energy ranged from 12.4 to 12.8 MJ/kg) and isonitrogenic (the protein concentration ranged from 209.7 to 210.9 g/kg) and provided ad libitum. During the experiment, which lasts 35 days, the control group is fed a diet without EF or HS. Rapeseed oil was the lipid source in the control diet. The diet for the second group contains EF at 60 g/kg, the diet for the third group contains HS at 40 g/kg, and the diets for the fourth to sixth groups contain HS and EF at 30 and 60 g/kg, 40 and 60 g/kg and 50 and 60 g/kg, respectively. At the end of the experiment, 15 cockerels of average weight are slaughtered per group, and the breast muscle, liver and tibia bone are dissected for chemical analyses. The all dietary combination of HS and EF increases (p < 0.001) cockerel body weight (2375–2493 g) more than HS alone (2174 g) or EF alone (2254 g). A similar finding is observed for the diet composition and tocopherol content in the liver, but the doses of HS required to achieve this effect are higher (40 and 50 g/kg). The tocopherol content in the breast muscle is not influenced by the diet. The dietary combination of 60 g/kg EF and 40 g/kg HS results in the most promising findings of the experiment, since it leads to the lowest n-6/n-3 polyunsaturated fatty acids ratio (p < 0.001; 1.75). Incorporation of HS into the diet increases cockerel tibia strength (p < 0.001), which is of great practical importance due to the frequent occurrence of limb fractures. To conclude, the dietary supplementation with 40 g/kg HS and 60 g/kg EF improves cockerel performance, meat and bone quality and deposition of α-tocopherol in the liver.

The activity of enzymes in the digestive tract is an important parameter for appropriate digestive tract function. Feed mixtures can be adjusted to support enzymatic activity in different parts of the digestive tract. Flaxseed and hemp seed are commodities and significant sources of nutrition, and their addition to feed could change enzymatic activity in the digestive tract and improve nutritional intake. The aim of this study was to determine the effects of flaxseed, hemp seed and a combination of both on basic enzymes in the polysaccharidase group, such as amylase, cellulase, pectinase, xylanase and inulinase; basic enzymes in the disaccharidase group, including maltase, invertase and lactase; proteinases and lipases in the digestive tract of broiler chickens. During the experiment, the control group was fed a diet without flaxseed or hemp seed. The diet of the second group contained 80 g/kg flaxseed, the diet of the third group contained 40 g/kg hemp seed, and the diets of the fourth to sixth groups contained 80 and 30 g/kg, 80 and 40 g/kg and 80 and 50 g/kg flaxseed and hemp seed, respectively. Enzyme activity was found to depend on the location in the digestive tract and the composition of the feed mixture (P < 0.05). Most enzymatic conversion occurs in the ileum, where the addition of flaxseed and hemp seed to the diet increased most enzyme activities, namely, amylase, cellulase, pectinase, xylanase, maltase, invertase, proteinase and lipase activities. The highest values of enzyme activity were found in groups IV-VI fed a combination of flaxseed and hempseed, especially in chickens fed diet VI (flaxseed and hemp seed at 80 and 50 g/kg). Growth performance results confirmed the enzyme activity results, as the weights of the chickens increased after the addition of flaxseed and/or hemp seed. The findings have economic implications, suggesting that feeding a diet with a combination of flaxseed and hemp seed is beneficial.

The culling of layer cockerels due to economic inefficiency is an ethical problem. Organic or free-range fattening of these cockerels or dual-purpose genotypes breeding is a possible solution to this problem. The aim of the study was to assess the differences in performance and meat quality characteristics in dual-purpose cockerels Dominant of three genotypes (Dominant Sussex D 104, Dominant Brown D 102 and Dominant Tinted D 723, 100 cockerels per genotype) with access to pasture. The cockerels were housed in mobile boxes on the pasture herbage from the 50th to 77th day of age (stocking density: 0.108 m²/bird). The highest body weight on the 77th day of age (p < 0.001) and the nonsignificantly lowest feed conversion was achieved by Dominant Brown D 102 cockerels (1842 g and 2.79, respectively). Non-significantly higher pasture herbage intake on the 70th day of age was recorded in genotype Dominant Brown D 102 (7.41 g dry matter (DM)/bird/day) and Dominant Tinted D 723 (7.52 g DM/bird/day). The pasture herbage contained 56.9 mg/kg DM α-tocopherol, 170.3 mg/kg DM zeaxanthin and 175.0 mg/kg DM lutein and had a favourable n6/n3 ratio (0.26). The boiled meat of cockerels Dominant Tinted D723 showed the highest tenderness based on both the sensory evaluation (p = 0.022) and the value of shear force (p = 0.049). This corresponds with a higher (p < 0.001) cross-sectional area and muscle fibre diameter in these chickens. The highest content of n3 fatty acids (eicosapentaenoic, clupanodonic and docosahexaenoic acids) in breast meat were found in Dominant Sussex D104 chickens (p < 0.001). In contrast, a significantly higher α-tocopherol content (p < 0.001) and higher oxidative stability (p = 0.012) were found in Dominant Brown D102 (4.52 mg/kg and 0.282 mg/kg) and Dominant Tinted D 723 chickens (4.64 mg/kg and 0.273 mg/kg) in comparison with the Dominant Sussex D104 genotype (3.44 mg/kg and 0.313 mg/kg). The values of the atherogenic and thrombogenic indexes were the lowest (p < 0.001) in meat from Dominant Brown D102 chickens. Moreover, a lower cholesterol content (p < 0.001) was recorded from the genotypes Dominant Brown D102 (396 mg/kg) and Dominant Tinted D723 (306 mg/kg) chickens, contrary to the Dominant Sussex D104 cockerels (441 mg/kg). It can be concluded that cockerels Dominant Brown D102 are a suitable genotype for free-range rearing due to higher performance and higher pasture herbage intake, which positively influences meat quality, whereas the meat of Dominant Sussex D104 cockerels shows higher amounts of n3 fatty acids and lower n6/n3 ratios.