*3.1. Blood Characteristics—Overview*

Since body weight was not affected by knotweed in either experiment, only blood characteristics are dealt with here. Biochemical and haematological characteristics measured at the end of the two experiments are presented in Table 2. Besides the blood characteristics of significance described below, there were also a higher number of monocytes in knotweed-fed horses but only in Experiment 1.

The parameters shown in Figure 1 are the biochemical (Figure 1a) and haematological (Figure 1b) characteristics measured in the blood samples drawn at the end of Experiment 1, explaining the variability due to treatment—the closer a vector of a certain characteristic towards "Fed knotweed", the more significantly would "feeding with knotweed" influence this characteristic. The similar direction of vectors indicates correlation among characteristics.

**Figure 1.** (**a**) Diagram showing the relationship of the biochemical data in Experiment 1. Treatment explained 1% of the variability in the biochemical data. Vectors pointing in the same direction show characteristics with positive correlations; arrows heading towards a type indicate that this type positively affects these characteristics. (**b**) Diagram showing the relatedness of the haematological data of Experiment 1. Treatment explained 1.5% of the variability in the haematological data. Vectors pointing in the same direction show characteristics with positive correlations; arrows heading towards a type indicate that this type positively affects these characteristics.


**Table 2.** Biochemical and haematological characteristics of horse blood from the end of Experiment 1 and of Experiment 2. Mean ± SEM. Significant differences between control and knotweed-fed horses are marked by different letters in superscript.

Additional variability is explained by the horse type and age, revealed in more detailed analyses of the individual characteristics described below. Only significantly different blood parameters are reported in the following section.

#### *3.2. Blood Characteristics of Significance*

## 3.2.1. Total Protein

The stallions fed knotweed had a significantly larger decrease in the amount of total protein in the oldest age group (born in 2016) than the control stallions (Experiment 2, Figure 2).

#### 3.2.2. Globulin and Albumin/Globulin Ratio

Blood tests also revealed a statistically significant effect of knotweed on the globulin level in Experiment 1. Stallions fed knotweed had a higher level of globulin than horses in the control group (*p* = 0.05), and the difference was more distinct among warm-blooded horses (Figure 3).

**Figure 2.** Differences in the total protein content in equine blood between the beginning and the end of Experiment 2, shown for stallions of the three age groups (born in 2016, 2017 and 2018) fed and not fed knotweed. Means ± SEM. Statistically different values at *p* ≤ 0.05 are marked with \*. N.S. = non-significant difference.

**Figure 3.** Globulin content in the blood of stallions of all ages. The comparison was between warmblooded and cold-blooded stallions fed with and without knotweed, Experiment 1. Means ± SEM. Statistically different values at *p* ≤ 0.05 are marked with \*; N.S. = non-significant difference.

Additionally, the albumin/globulin ratio was significantly affected by knotweed supplementation (*p* = 0.04); the effect of knotweed was significant in warm-blooded horses (Figure 4).

#### 3.2.3. Thrombocytes, Plateletcrit (PCT) and Mean Cell Hemoglobin (MCH)

In Experiment 2, the stallions fed knotweed also produced more thrombocytes (*p* = 0.006) and PCT (*p* = 0.002) than the control stallions. The MCH increase in the stallions in the control group during Experiment 2 was more pronounced than that in the stallions fed knotweed (*p* = 0.02).

## 3.2.4. Activity of ALP

ALP activity decreased more in the blood of knotweed-fed horses than in the blood of the control horses (*p* = 0.05). If the warm-blooded and cold-blooded breeds were compared, the decrease was significant only in cold-blooded stallions (Figure 5).

**Figure 5.** Differences in equine ALP activity between the beginning and the end of Experiment 1 among horses fed and not fed knotweed. The warm-blooded and cold-blooded breeds were compared. Statistically different values at *p* ≤ 0.05 are marked with \*. N.S. = non-significant difference.

This effect was significant in Experiment 1 but not in Experiment 2, in which a number of ALP values were missing.
