3.2.7. Urea

There was no difference in the urea blood levels between the knotweed-fed and control horses at the end of either of the two experiments. However, urea measured before the start of Experiment 2 was significantly higher (5.96 mmol <sup>L</sup>−1) in the 2- and 3-year-old horses, i.e., those who had been receiving knotweed in the previous winter and spring in Experiment 1, compared with the respective control horses (5.51 mmol <sup>L</sup>−1).

#### *3.3. Sports Carrier of the Experimental Horses*

Owing to a delay between the experiments and this report, it was possible to find out which warm-blooded horses were already in use in sports and what their first sport results were. By 20 October 2021, roughly equal numbers of control (14) and knotweedfed (13) horses out of 26 in each category had already been registered for horse jumping and dressage competitions, and the control and knotweed-fed horses jumped over 104 and 109 cm high obstacles (in average; *p* = 0.3) and had been involved in 7 and 13 competitions (*p* = 0.15), respectively. These data are only of limited informative value as many other factors are involved, including socioeconomic ones. However, it is obvious that knotweed intake in feed restricted neither the fitness nor the performance of horses but rather supported it.
