Short-term exposure of dairy cows to pyrrolizidine alkaloids from tansy ragwort (Jacobaea vulgaris Gaertn.): effects on organs and indicators of energy metabolism

Figures & data

Figure 1. Concentration of glucose [a], β-hydroxybutyrate (BHB) [b] and non-esterified fatty acids (NEFA) [c] in blood serum of dairy cows exposed to increasing concentrations of pyrrolizidine alkaloid (PA) over the course of the trial.

CONMolasses

(<0.01 mg PA/kg BW/d), PA1

(0.47 mg PA/kg BW/d), PA2

(0.95 mg PA/kg BW/d), PA3

(1.91 mg PA/kg BW/d). Symbols represent LS means (n = 4) with whiskers as standard error.

p-Values: Glucose: p_Group = 0.849; p_Day = 0.031; p_Groupxday = 0.860;

BHB: p_Group = 0.816; p_Day <0.001; p_Groupxday = 0.202; NEFA: p_Group = 0.172; p_Day <0.001; p_Groupxday = 0.777.

Figure 2. Composition of abdominal adipose tissues (AAT) containing retroperitoneal at (RAT), omental at (OAT), mesenteric at (MAT) before the start of the trial and at the end of the trial (d28) (left ordinate) and the resulting AAT in absolute masses (right ordinate) of the treatment groups determined by ultrasonic measurement method.

CON_Molasses (<0.01 mg PA/kg BW/d) and PA3 (1.91 mg PA/kg BW/d).

Values are presented as LS means (n = 4) with standard error (whiskers).

p-Values: AAT: p_group = 0.440; p_day = 0.254; p_Groupxday = 0.428; RAT: p_group = 0.348; p_day = 0.210; p_Groupxday = 0.330; OAT: p_group = 0.558; p_day: 0.366; p_Groupxday = 0.518;

MAT: p_group = 0.580; p_day = 0.286; p_Groupxday = 0.472

Table 1. Mean relative organ weights of dairy cows after a short-term PA exposure scenario on exposure day 28 with corresponding p-Values.

Relative weight [g/kg BW]:	Mean* ± SD	p-Value (group)
Heart	5.16 ± 0.13	0.767
Liver	16.65 ± 0.81	0.793
Lungs	6.78 ± 0.89	0.296
Spleen	1.55 ± 0.11	0.554
Kidneys	2.42 ± 0.16	0.491
Pancreas	0.91 ± 0.10	0.597
Thymus	0.24 ± 0.02	0.882
Thyroid gland	0.12 ± 0.01	0.819
Udder	41.52 ± 2.53	0.520
Rumen	23.02 ± 1.18	0.134
Omasum	11.70 ± 0.96	0.311
Abomasum	5.48 ± 0.70	0.258
Small intestines	13.89 ± 0.83	0.477
Large intestines	12.25 ± 1.02	0.211
Urinary bladder (empty)	0.41 ± 0.06	0.189
Gallbladder (filled)	0.80 ± 0.28	0.062
Gallbladder (empty)	0.11 ± 0.01	0.362
Uterus	1.40 ± 0.11	0.662
Ovaries	0.05 ± 0.03	0.160

BW = body weight.

*calculated from LS means with corresponding standard deviation (SD).

Figure 3. Liver histopathology scores for the different PA exposure groups on day 28.

CON_Molasses

(<0.01 mg PA/kg BW/d), PA1

(0.47 mg PA/kg BW/d), PA2

(0.95 mg PA/kg BW/d), PA3

(1.91 mg PA/kg BW/d)

Filled bars (n = 4) represent the enlarged hepatocyte nuclei leading to the hepatocyte nucleus enlargement score, while striped bars (n = 4) correspond to the liver immunological activity score, classified by focal infiltration of macrophages with multinucleated giant cells (granulomatous inflammation) and eosinophilic granulocytes, multifocal lymphohistiocytic portal infiltration with eosinophilic granulocytes or focal lymphohistiocytic infiltration. Both areas were summarised to the total liver score, each with standard error (whiskers).

p-Values: Total liver score: p = 0.029; hepatocyte nucleus enlargement score: p = 0.037; liver immunological activity score: p = 0.217

Significant differences between the values in the total liver score and the hepatocyte nucleus enlargement score were calculated using a Tukey adjusted t-test and presented as different letters (a,b).

BW = body weight; CON = control; PA = pyrrolizidine alkaloid

Figure 4. Liver histology of the control group. CON_Molasses (<0.01 mg PA/kg BW/d, left pictures) and group PA3 (1.91 mg PA/kg BW, right pictures) at 200 and 400 times magnification at day 28 of the experiment.

pyknotic cells;

enlarged nuclei; BW = body weight; CON = control; d = day; PA = pyrrolizidine alkaloid

Table 2. Histopathological findings in the liver of dairy cows on days 0, 7 and 28 of the PA exposure with regard to enlargement of the hepatocyte nuclei (_*) and immunological activity (+), characterised by focal infiltration of macrophages with multinucleated giant cells (granulomatous inflammation) and eosinophilic granulocytes, multifocal lymphohistiocytic portal infiltration with eosinophilic granulocytes or focal lymphohistiocytic infiltration. A symbol within a category represents an individual animal (n = 4 per group).

	Day
Group	0		7		28
CONMolasses		+			****
PA1		+		+	***
PA2				+	*** *^2	+
PA3		++	*	++	* *^2*^2*^2	+ +^2

*/+ indicates low-degree occurrence.

*²/+² indicates medium-degree occurrence.

Exposure [mg PA/kg BW/d]: CON_Molasses: <0.01; PA1: 0.47; PA2: 0.95; PA3: 1.91.

BW = body weight; CON = control; d = day; PA = pyrrolizidine alkaloids.

Figure 5. Hepatocyte nucleus area [a] and total liver lipid concentration [b] over the course of the experiment, with day 0 indicating the value before the start of PA exposure.

CONMolasses

(<0.01 mg PA/kg BW/d), PA1

(0.47 mg PA/kg BW/d), PA2

(0.95 mg PA/kg BW/d), PA3

(1.91 mg PA/kg BW/d). Symbols represent LS means (n = 4) and half-whiskers as standard error. The LS means for total liver lipid were calculated without covariate.

p-Values: Liver nucleus area: p_Group: p = 0.285; p_Day: p < 0.001; p_Groupxday: p = 0.089

Total liver lipid concentration: p_Group: p = 0.466; p_Day: p = 0.600; p_Groupxday: p = 0.513

BW = body weight, CON = control; d = day; PA = pyrrolizidine alkaloids

* Significant differences between day 0 and day 28 calculated using a Tukey adjusted t-test

Figure 6. Relative organ weight of the filled gallbladder after 28 days of PA exposure of the different exposure groups.

CONMolasses

(<0.01 mg PA/kg BW/d), PA1

(0.47 mg PA/kg BW/d), PA2

(0.95 mg PA/kg BW/d), PA3

(1.9 mg PA/kg BW/d). Values are displayed as LS means±standard error (n = 4).

p-Value: p_Group = 0.062

BW = body weight; CON = control; d = day; PA = pyrrolizidine alkaloids

Table 3. Histopathological findings in organs of dairy cows on day 28 concerning immunological activity (+), while a symbol within a category represents an individual animal (n = 4 per group).

					Rumen-
Group	Gallbladder	Lungs	Spleen	Kidneys	caudal	medial	cranial
CONMolasses	+++			+		+	+
PA1	++++	++		+		+	+ +^2
PA2	++++	++		+
PA3	++++	+		++

+ indicates low occurrence.

+² indicates medium occurrence.

Exposure [mg PA/kg BW/d]: CON_Molasses: <0.01; PA1: 0.47; PA2: 0.95; PA3: 1.91.

BW = body weight; CON = control; d = day; PA = pyrrolizidine alkaloids.