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Quality, content and properties of colostrum are crucial for the neonate and its further development. Due to essential differences between intrauterine and extrauterine environment, the neonate is exposed to oxidative stress conditions. Colostrum apart from nutrient and immunological components should contain antioxidative systems necessary for the protection against reactive oxygen species. This review describes available data on enzymatic and non-enzymatic antioxidants in colostrum. Due to the fact that the literature concerning bovine colostrum is scanty, the information based on bovine mature milk determinations as well as other species is provided. Bovine colostrum is used not only by calves, but also for the production of hyperimmunized colostrum, medicines or feed supplements. Quality of colostrum influences quality of mature milk. This is another reason, except from health of neonate, why antioxidative properties of bovine colostrum are of special importance and require further detailed elucidation.

The aim of this study was to characterize the stress level in sport horses subjected to exercise by measuring the cortisol concentration in their saliva. The experiment was conducted on 5 groups of horses (49 animals): one control and four groups undergoing different types of exercises. The saliva samples were collected 3 × a day: late at night (between 20:00 and 23:00 h), early in the morning (between 5:00 and 8:00 h) and directly after the exercise. The concentration of cortisol was measured by the enzyme-immunoassay programme. The highest cortisol concentration was observed for the horses participating in 3-day events (8.93 nmol/dm 3 ), whereas in the control group it was only 0.28 nmol/dm 3 . When compared to the cortisol concentration of other horse groups, this suggests that the stress level as measured by the cortisol concentration in saliva increases with increasing exercise intensity and its duration. The obtained results do not confirm the existence of a day rhythm of the cortisol concentration in horses. Moreover, the results may help in choosing the appropriate system of training and in improving horse welfare during competitions.

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