Commercial high-yielding corn hybrids have not been evaluated for their ability to pigment egg yolk. Therefore, the objective of this research was to investigate the effects of commercial hybrids with different carotenoid profiles as the only source of pigments in the diets of hens on yolk color and carotenoid content, as well as the carotenoid deposition efficiency into the yolk. Treatment diets, differing only in one of five corn hybrids, were offered in a completely randomized design in six cages per treatment, each with three hens. Treatment diets and yolks differed in carotenoid profile (contents of lutein, zeaxanthin, β-cryptoxanthin and β-carotene, p < 0.001), with total carotenoid contents ranging from 17.13–13.45 µg/g in diet and 25.99–21.97 µg/g in yolk. The treatments differed (p < 0.001) in yolk color, which was determined by yolk color fan (10.8–9.83) and CIE Lab (redness; range 12.47–10.05). The highest yolk color intensity was achieved by a diet with the highest content of zeaxanthin, β-cryptoxanthin and β-carotene. The deposition efficiency of lutein and zeaxanthin (25.52 and 26.05%, respectively) was higher than that of β-cryptoxanthin and β-carotene (8.30 and 5.65%, respectively), and the deposition efficiency of all carotenoids decreased with increasing dietary content. Commercial corn hybrids provided adequate yolk color and could be the only source of carotenoids in the diets of hens, which could reduce the cost of egg production and increase farmers’ income.

Understanding the importance of grassland management is crucial for predicting the effects on forage production, pasture and ecosystem stability. Studies about the impact of grassland management in temperate humid environments on soil, erosion and aboveground biomass properties are lacking. This study investigates the effect of different grassland managements—no grazing, moderate grazing and heavy grazing—on soil properties, hydrological responses and herbage quality in an organic farm located in Croatia. The results showed that heavy grazing significantly increased soil compaction, structural deterioration, erosion and nutrient transport compared with no grazing. Heavily grazed plots had significantly higher soil organic matter and nutrient concentrations compared with no-grazing plots. Moderately grazed plots had the highest biomass production and the herbage with higher quality compared with other treatments. Significantly higher ash contents on heavily and moderately grazed plots were due to cow trampling. Cow grazing behaviour was a more important factor for plant regrowth and herbage quality than soil properties. Moderate grazing did not induce serious soil erosion problems or reduce soil productivity. Soil conservation measures should focus only on the heavily grazed areas and include the introduction of rotational grazing in combination with various strategies: excluding grazing, reseeding and increasing the diversity of resting areas.

The objective of the present study was to determine the content and bioaccessibility of carotenoids in 104 maize hybrids available at the market. Lutein, zeaxanthin, α- and β-cryptoxanthin, and β-carotene were determined in whole grains and micelles produced during standardized INFOGEST digestibility analysis, and their bioaccessibility was calculated as the ratio of micellar and grain carotenoids. Tested hybrids varied in total carotenoid content, with 34% having total carotenoid content in the range of 15–20 µg/g dry matter (DM) and 41% in the range of 20–25 µg/g DM. The amount of bioaccessible carotenoids increased linearly (p < 0.05) with increasing content in the grain, and decreased among determined carotenoidsd in the order: lutein (52%) > zeaxanthin (43%) > β-carotene (43%) > α-cryptoxanthin (27%) > β-cryptoxanthin (26%). Bioaccessibility of lutein, zeaxanthin, and β-carotene decreased with increasing content in the grain (p < 0.05). On average, only 43% of the total carotenoids were bioaccessible in commercial maize hybrids tested, which should be considered when formulating an animal diet.

Yolk carotenoid profile reflects the hen diet when corn grain is the only source of carotenoids, but corn origin and processing may affect carotenoid utilization. In the present study, 2 commercial dent corn hybrids differing in grain hardness (soft- and hard-type) were dried at low (40°C) and high (85°C) temperature and ground through a 5- and 9-mm sieve to investigate their effects on carotenoid bioavailability in laying hens. With 3 hens per cage, 168 Lohmann Brown laying hens were allocated to 8 dietary treatments (2 hybrids × 2 drying temperatures × 2 grinding sieves) in a completely randomized design (8 treatments × 7 cages). The trial lasted 8 wk, during which eggs were collected for analysis every 3 d until carotenoid content stabilized, and then once a week until the end of the experiment. The carotenoid profile of the experimental diets and yolks was analyzed using an HPLC method and deposition efficiency was calculated based on carotenoid contents, yolk weight, egg production and diet intake. The deposition efficiency for lutein, zeaxanthin, α- and β-cryptoxanthin, and β-carotene averaged 27.37, 18.67, 6.29, 3,32, and 0.94%, respectively. As expected, the tested hybrids highly affected the carotenoid content in egg yolk due to their differences in carotenoid profile. Interestingly, hard- and soft-type hybrids differed in the deposition efficiency for all individual carotenoids but not for the total carotenoids. High grain drying temperature tended to increase the bioavailability of lutein and zeaxanthin in both hybrids. For the hard-type hybrid, the content of β-carotene in egg yolk was higher when grains were dried at a high temperature, while the opposite response was found in the soft-type hybrid. The effect of grinding sieve size was important for the zeaxanthin bioavailability in the soft-type hybrid only. In conclusion, our findings showed that corn hybrid had a primary influence on the carotenoid content in the yolks of laying hens, but grain processing may change the bioavailability of carotenoids.

Despite the high proportion of maize grain in animal diets, the contribution made by maize phytochemicals is neglected. Tocols and their contribution to the vitamin E content of animal diets are one example, exacerbated by sparse information on the tocol bioaccessibility of commercial hybrids. In this study, the contents of individual and total tocols and their bioaccessibility were determined in the grain samples of 103 commercial hybrids using a standardized INFOGEST digestion procedure. In the studied hybrids, total tocol content ranged from 19.24 to 54.44 µg/g of dry matter. The contents of micellar α-, γ-, δ-tocopherols, γ-tocotrienol, and total tocols correlated positively with the corresponding contents in the grain samples of the studied hybrids. In contrast, a negative correlation was observed between the bioaccessibility of γ- tocopherol, α- and γ-tocotrienol, and total tocols, along with the corresponding contents in the grain of studied hybrids. The highest bioaccessibility was exhibited by γ-tocotrienol (532.77 g/kg), followed by δ-tocopherol (529.88 g/kg), γ-tocopherol (461.76 g/kg), α-tocopherol (406.49 g/kg), and α-tocotrienol (359.07 g/kg). Overall, there are significant differences in the content and bioaccessibility of total and individual tocols among commercial maize hybrids, allowing the selection of hybrids for animal production based not only on crude chemical composition but also on the content of phytochemicals.