The Effect of Saponaria officinalis Root Supplementation During the Dry Period on Blood Biochemical Parameters in Cows and Calves and the Biological Quality of Colostrum and Milk

Abstract

The purpose of this study was to assess the effect of dietary Saponaria officinalis inclusion in the diet of dairy cows during the dry period on colostrum and milk quality, focusing specifically on the somatic cell count (SCC), the physicochemical composition and fatty acid (FA) profile. The effect of the addition on various biochemical parameters was evaluated in the serum of cows and their calves. This study was conducted on Ukrainian Black and White cattle. Twenty-four cows were selected from the herd twenty-one days prior to their expected calving date. They were allocated into three groups of eight cows each (n = 8) and began to be fed soapwort, as outlined below. Group C was fed a conventional TMR diet (0 g/cow per day); Group E1—TMR and 20 g of dry soapwort root powder per cow per day; and Group E2—50 g of dry soapwort root powder per cow per day. Blood samples were collected from the cows 21 d before labour and on the day of calving, and from calves on day 3, in week 2, and in week 6. Biochemical profiles of the liver, lipids, and kidneys were evaluated in the collected samples. Colostrum was collected from the cows two hours after calving during the initial complete milking, and milk was collected in the eighth week of lactation. The fundamental composition, SCC, and FA profiles were assessed in colostrum and milk. Higher protein levels were found in the serum of calves in the second week of life in groups E1 (p < 0.01) and E2 (p < 0.05) compared to group C. In calves, serum ALT levels were higher in group C than in groups E1 and E2 at 2 and 6 weeks of age (p < 0.05). The addition did not affect the biochemical profiles of lipids, liver, or kidneys in cows. The SCC in the colostrum was higher in group E2 than in group C (p < 0.05). A decrease (p < 0.01) in SCC was noted in the milk of groups E2 and E3 compared to the control group. In the colostrum of cows in group E2, an increase in UFA levels was observed, including beneficial acids, such as C18:2n6c, C22:6n3, and conjugated linoleic acid (CLA), while trans isomers decreased. The results suggest that Saponaria officinalis can be used as a supplement in the feeding of cows during the dry period to improve colostrum quality and also support the physiological development of calves and the health of the cows’ mammary glands.

1. Introduction

The dry period, especially the last 21 d before calving, plays a crucial role in the regeneration of the mammary gland and in preparing the cow for the next lactation. During this period, significant metabolic, hormonal, and immunological changes occur in the body [1,2]. Proper nutrition during this period aims to prevent metabolic disorders such as ketosis, acidosis, fatty liver disease, or hypocalcaemia, and to support the proper development of the foetus and placenta. The pre-calving nutrition of cows is also a key factor determining colostrum composition, which in turn affects the health and rearing of calves [3,4,5]. During this critical period, it is also particularly important to use appropriate supplementation of feed rations with feedstuffs rich in bioactive substances that have a beneficial effect on the cow’s health and future offspring [2].

Natural feed additives containing saponins have recently gained popularity in dairy cattle nutrition [6,7,8]. Saponins can reduce the production of fermentation gases, including methane, which is one of the main by-products of microbial fermentation in the rumen of cows [9]. Reducing methane emissions improves the efficiency of animals utilising energy from their feed. Additionally, reduced methane emissions have a positive impact on the environment [8]. Plant extracts containing saponins, used in ruminant nutrition, can lower blood serum levels of glucose, cholesterol, urea, creatinine, and liver enzymes, indicating improved liver and kidney function [10,11]. Saponins can also improve nitrogen transfer to milk by retaining ammonia from the rumen into the bloodstream [12]. Studies conducted by Holtshausen et al. [6] showed that supplementation with saponins from Yucca schidigera and Quillaja saponaria had no significant effect on milk yields or the basic chemical composition of cow’s milk. Szczechowiak-Piglas et al. [13] showed that the saponins from Saponaria officinalis affect milk composition, including protein and fat content. However, we have not found any studies describing the impact of saponin use in cow nutrition on the composition of cow colostrum.

In the available literature, research has primarily focused on the use of plants with high concentrations of saponins in ruminant nutrition, such as Yucca schidigera, Quillaja saponaria, Camellia sinensis, Agave americana and Biophytum petersianum [6,11,14]. To the best of our knowledge, only two studies described the effect of Saponaria officinalis on the fermentation profile in the rumen and changes in the fatty acid (FA) profile of cow milk in vivo [13,15]. Saponaria officinalis is a perennial plant of the Caryophyllaceae family that is easy to cultivate and is commonly found in America, Europe, Asia, Africa, and Australia [16,17]. The root of Saponaria officinalis is a rich source of triterpenoid saponins [17]. This type of saponin exhibits multifaceted biological activity, including anticancer, anti-inflammatory, antioxidant, antiviral, antibacterial, and immunomodulatory properties, and supports the wound granulation process [18,19]. The high saponin content in Saponaria officinalis root may indicate its potential as a natural supplement to support health and metabolism in both cows and calves during the peripartum period when included in their diet.

Therefore, this study aimed to evaluate the effect of adding Saponaria officinalis root to the feed ration during the dry period on the physicochemical properties of colostrum and milk, as well as selected biochemical parameters of cows and their calves.

2. Materials and Methods

2.1. Plant Material

Dried soapwort root was purchased from a commercial company (Eko Herba Hajnówka, Hajnówka, Poland). Representative samples of the plant material are stored for future reference at the Department of Biostructure and Animal Physiology, Wroclaw University of Environmental and Life Sciences, Norwida 31, 50-375 Wroclaw, Poland.

The soapwort root was chopped into small pieces, ground into a fine powder using a mechanical mixer grinder (IKA, Staufen, Germany), and sieved through a 0.25 mm mesh. The preparation was kept for future use in an airtight dark glass container to protect it from sunlight.

2.2. Animals, Diet, and Experimental Design

In this study, the Ukrainian Law on Animal Welfare and Protection was adhered to, and authorisation was obtained from the Ethics Commission for Experiments on Animals at the SE Medical Institute of Sumy State University with approval number 3/9. We provided comprehensive information to the animal’s owners about the purpose, procedures, potential risks, and benefits of the study. Informed consent was obtained from all owners.

The study was conducted in 2024 on a commercial dairy farm located in Yaseny, Sumy district, Sumy region, Ukraine (latitude: 50°51′23.2″ N, longitude: 34°40′49.1″ E). Cows of the Ukrainian Black and White (Holsteinised) dairy breed (650 ± 30 kg live body weight; BW) were housed in a free-stall system in accordance with welfare requirements [20,21,22]. The animals exhibited no signs of illness. All animals had unlimited access to water and were fed a total mixed ration (TMR) ad libitum throughout the experiment. The animals were fed to meet the recommended requirements of the NRC (

Table 1. TMR composition and nutritional content (g/kg DM).

Feed Ration Composition
Corn silage	573
Haylage	231
Straw	112
Barley ground	25
Rapeseed meal	25
Meadow hay	27
Premix 1	7.0
Ammonium chloride 57 g/kg DM TMR
DCAD mEq/kg DM	−116
Energy UFL/kg DM	0.79
Protein PDIN	82
Protein PDIE	79
Filling value (LFU/kg DM)	0.8

¹ Contained per kilogram: Calcium (Ca) 83 g; Phosphorus 134 g; Magnesium 50 g; Sodium 100 g; Vitamin A 700,000 IU; Vitamin D3 120,000 IU; Vitamin E, 3 g; Vitamin B1, 30 mg, B2, 30 mg, B6, 20 mg; Vitamin B12, 150 µg; Folic acid, 10 mg; Niacin, 1.5 g; Calcium pantothenate, 40 mg; Biotin, 1200 µg; Zinc, 4 g; Manganese, 3.2 g; Copper, 1.2 g; Iodine, 80 mg; Cobalt, 20 mg and Selenium, 40 mg. DCAD, Dietary Cation-Anion Difference; UFL, unit for lactation; PDIN, the sum of microbial protein that could be synthesised from available N and undegraded dietary protein in the rumen but is digestible in the small intestine; PDIE, the sum of microbial protein that could be synthesised from available energy and undegraded dietary protein in the rumen but is digestible in the small intestine.

) [23].

A total of 24 cows were selected from a herd of 286 cows, based on specific criteria: age between 2 and 3 lactations and an average milk yield ranging from 5300 to 6080 kg per year. An entirely random experimental design was used. 21 d before the estimated calving date, the cows were divided into three groups, each consisting of eight individuals (n = 8). Group C received a traditional TMR diet without supplementation (0 g/cattle per day). Group E1 was provided with TMR and 20 g of dry soapwort root powder per cow per day. Group E2 received 50 g of dry soapwort root powder per cow per day. Soapwort powder was mixed with 2 kg of TMR and fed to the animals individually. After completely eating the prepared feed, the cows were provided TMR ad libitum. On the day of calving, the use of feed additive in the form of soapwort root was discontinued. Figure 1 illustrates the timeline of the experiment.

Samples were collected from all cows that participated in the experiment during the research period. Colostrum was collected from the cows in all groups and stored in sterile containers during the first complete milking post-calving. Milk samples were collected during the eighth week of lactation. Colostrum and milk were transported to the laboratory at 4 °C, frozen at −20 °C, and stored for further analysis. Blood samples were collected from cows 21 d before calving and on the first day post-calving from the subcaudal vein in a volume of 10 mL, following established methods while adhering to aseptic and antiseptic protocols. Blood samples were collected from calves in both control and experimental groups on the 3rd day, 2nd week, and 6th week after birth. All blood samples were obtained from the jugular vein in a volume of 5–8 mL, following established methods and adhering to aseptic and antiseptic protocols.

In blood serum obtained from cows and calves, the following parameters were determined to check the health status of the liver and kidney: total protein, albumin, bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gammaglutamyltransferase (GGT) and alkaline phosphatase (ALP), urea, creatinine, uric acid and additionally, the lipid profile, which includes cholesterol, triglycerides, high-density lipoproteins (HDL), low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL). Furthermore, the basic composition and FA profiles of colostrum and milk were determined.

2.3. Sampling and Laboratory Analyses

2.3.1. Feed

The total mixed ration and soapwort root samples were analysed according to the Standards of the Association of Official Analytical Chemists (AOAC,

Table 2. Composition of used feed in rations [%DM].

Parameters	TMR	Soapwort Root
Dry matter (DM, % of fresh)	49.00	92.65
Ash	5.91	7.45
Crude protein (CP)	11.13	9.55
Fibre	31.56	8.77
Neutral detergent fibre (NDF)	50.01	23.50
Acid detergent fibre (ADF)	29.28	9.82
Ether extract	2.73	3.40

) [24] as follows: dry matter (DM; AOAC method 934.01), Kjeldahl N (984.13 of 143 AOAC) using a Kjeltec 2300 FOSS Tecator Analyser Unit (Häganäs, AB, Sweden) for the calculation of crude protein (CP) as Kjeldahl N × 6.25. Ether extracts (EE) were determined according to the AOAC 920.39 method [25]. The neutral detergent fibre (NDF) and acid detergent fibre (ADF) fractions were measured using a Fibertec Tecator apparatus (Häganäs, Sweden) according to Holst and the AOAC method 973.18, respectively (AOAC) [26].

2.3.2. Blood

Two hours after collection, the blood samples were centrifuged at 3000× g for 10 min at room temperature (RT) to separate serum from blood cells. After centrifugation, we recovered and transferred the serum samples into pre-labelled tubes and subsequently stored them at −20 °C until use (for up to 2 months and without freeze-thawing). Biochemical parameters were determined under laboratory conditions according to generally accepted methods using a Humalyzer Junior (HUMAN GMBH, Wiesbaden, Germany) and commercially available test kits (HUMAN Gesellschaft für Biochemica und Diagnostica mbH, Wiesbaden, Germany).

2.3.3. Colostrum and Milk

The basic composition of colostrum and milk, including levels of fat, total protein, lactose, and total solids, was determined using an Infrared Milk Analyser 150 (Bentley Instruments Inc., Chaska, MN, USA). The somatic cell content was determined using a Somacount 150 apparatus (Bentley Instruments Inc.).

Colostrum samples were collected within two hours after calving, during the first complete milking, into sterile containers and transported to the laboratory at 4 °C. To determine the FA profile in colostrum and milk, fat was extracted according to the Folch method [27] and analysed by gas chromatography. Briefly, a 10 mL sample was homogenised in a chloroform–methanol mixture (2:1) and then centrifuged at 3000× g for 10 min at 4 °C. The lower layer was transferred to a dry vial, after which the solvent was evaporated under a stream of nitrogen. Next, to produce fatty acid methyl esters (FAME), 0.1 mL of a 2 M potassium hydroxide (KOH) solution in methanol and 1 mL of hexane were added to the fat extract [28]. The vial was securely sealed, and the reaction mixture was maintained at RT for 150 min. Upon completion of the reaction, a biphasic solution was acquired. The supernatant was transferred into new vials and used for further analysis. The fatty acid profile was determined using an Agilent Technologies 7890A gas chromatograph (Santa Clara, CA, USA) equipped with an FID detector. The gas chromatography injection volume was 1 μL. The detection range for saturated fatty acids (SFA) was C4 to C18, and for unsaturated fatty acids (UFA) it ranged from C14 to C22.

The analyses were performed using an HP-88 capillary column (Agilent Technologies) with a length of 100 m, an internal diameter of 0.25 mm, and a film thickness of 0.20 μm. The initial furnace temperature was 50 °C, which was then increased by 3 °C/min to a final temperature of 220 °C. The injector and detector temperatures were maintained at −270 °C and 270 °C. Helium was used as the carrier gas, while hydrogen and synthetic air also flowed through the detector. Identification of FA was performed by comparing chromatograms with the retention times of Supelco^TM 37 FAME standards (Sigma Aldrich, St. Louis, MO, USA) and CLA cis-9, trans-11, trans-10, and cis-12 (Larodan, Malmö, Sweden) using ChemStation software (ver. no. B.03.02. Agilent Technologies). The concentration of each FA was expressed in g/100 g, with 100 g representing the sum of all the identified FAME peak areas.

2.4. Statistical Analysis

Before statistical analysis, data were evaluated for adherence to the assumptions of normal distribution (Shapiro–Wilk test) and homogeneity of variance (Levene test). In the absence of normality in the residuals, a nonparametric Kruskal–Wallis test was used. Statistical analysis was performed using one-way analysis of variance (ANOVA). Duncan’s test was used to determine significant differences among groups. In a subsequent analysis, we use ANOVA for repeated measures (rANOVA) to evaluate the effects of soapwort dose on blood, milk and colostrum parameters between and within groups over the timeline considered. We therefore applied a Duncan post hoc comparison test between time 0 (first sampling) and each subsequent time point. The differences were deemed significant with a p-value of < 0.05 and highly significant with p < 0.01. All analysis was performed using the Statistica 13.3 software (StatSoft Polska, Kraków, Poland).

3. Results

3.1. Effects of Soapwort on Serum Protein and Albumin Levels

The addition of soapwort root extract to cow feed during the peripartum period slightly affected total protein and albumin levels in the blood serum of both the cows and calves (

Table 3. Serum protein and albumin levels in cows and their calves.

Time	C	E1	E2	SEM	p-Value (Soapwort)	p-Value (Time)
	Total protein [g/L]
		Cows
21 d before calving	68.00 Bb	74.17 A	76.58 a	1.23	0.01	<0.01
Calving	58.17 B	63.17 A	62.83 A	0.66	<0.01
		Calves
3 day	43.33	47.17	47.33	0.80	0.07	<0.01
2 week	52.00 Ba	57.67 Aa	54.00 b	0.75	0.01
6 week	61.50	60.17	60.33	0.41	0.36
	Albumin [g/L]
		Cows
21 d before calving	26.33	28.00	27.83	0.32	0.06	0.99
Calving	27.83	27.00	27.33	0.32	0.58
		Calves
3 day	22.50	22.33	23.00	0.22	0.429	<0.01
2 week	24.33	25.00	24.67	0.19	0.36
6 week	26.67 a	26.17 a	24.83 b	0.22	<0.01

SEM—standard error of the mean; A two-superscript letter system indicates statistical significance among values within the same row (a, b for p < 0.05 and A, B for p < 0.01).

). Cows in groups E1 and E2 had higher serum total protein levels regardless of the sampling period. During the second week of life, the serum of calves in groups E1 (p < 0.01) and E2 (p < 0.05) showed elevated protein levels compared to the control group. A significantly higher (p < 0.05) total protein level (p < 0.05) was observed in group E1 than in group E2. At 6 weeks of age, the calves in group E2 had lower albumin levels than those in groups C and E1 (p < 0.05).

Our research showed a significantly higher (p < 0.01) total protein level in cows at 21 d prior to the expected calving date compared to the calving day, with no observed changes in albumin concentration. In calves, total protein and albumin levels demonstrated a significant increase with age (p < 0.01).

3.2. Impact of Soapwort on Hepatic Enzymes and Lipid Profiles

Cows in the experimental group E2 showed significantly higher serum ALT activity at the onset of the experiment than those in group E1 (p < 0.05) and on the day of calving relative to the other groups (p < 0.01) (

Table 4. Effects of soapwort on lipid profiles and hepatic enzymes in the serum of cows and their calves.

Time	C	E1	E2	SEM	p-Value (Soapwort)	p-Value (Time)
	ALT [U/L]
	Cows
21 d before calving	26.17	22.17 b	30.83 a	1.15	<0.01	0.92
calving	21.17 B	24.67 B	32.83 A	1.54	<0.01
	Calves
3 day	17.83	22.67	30.83	2.74	0.15	<0.01
2 week	18.50 a	15.33 b	15.50 b	0.50	0.01
6 week	9.00 a	7.50 b	7.83 b	0.19	<0.01
	AST [U/L]
	Cows
21 d before calving	53.17 b	53.67 b	61.50 a	1.59	0.05	0.01
calving	65.00	61.50	64.33	2.28	0.81
	Calves
3 day	62.83 a	79.83 a	56.00 b	3.70	0.02	<0.01
2 week	41.00	42.33	48.33	2.91	0.56
6 week	25.33 Bb	31.83 A	28.00 Ba	0.85	<0.01
	ALP [U/L]
	Cows
21 d before calving	63.00	72.50	74.83	2.51	0.13	<0.01
calving	71.17	80.17	79.67	1.92	<0.01
	Calves
3 day	263.25 Bb	338.50 a	381.67 A	14.32	<0.01	<0.01
2 week	173.17 Bb	278.00 A	225.33 a	10.15	<0.01
6 week	126.00 Bb	206.33 A	186.17 a	9.48	<0.01
	GGT [U/L]
	Cows
21 d before calving	22.83	22.83	24.83	0.86	0.56	<0.01
calving	26.83	28.33	30.17	1.62	0.71
	Calves
3 day	285.17	253.33	221.20	15.74	0.27	<0.01
2 week	139.67	139.33	117.00	8.24	0.44
6 week	50.33 a	39.00 b	48.67 a	1.52	<0.01
Cholesterol [mmol/L]
Cows
21 d before calving	2.80	2.61	2.87	0.07	0.28	<0.01
calving	2.07	1.83	1.88	0.05	0.12
Calves
3 day	0.87	0.92	0.93	0.03	0.70	<0.01
2 week	1.99	1.90	1.94	0.02	0.25
6 week	2.39	2.53 A	2.25 B	0.03	<0.01
LDL [mmol/L]
Cows
21 d before calving	0.78 a	0.72	0.65 b	0.02	0.04	<0.01
calving	0.81 Aa	0.62 b	0.44 B	0.04	<0.00
Calves
3 day	0.22	0.23	0.22	0.01	0.78	<0.01
2 week	0.31	0.32	0.33	0.01	0.19
6 week	0.41 A	0.40	0.39 B	0.00	0.01
HDL [mmol/L]
Cows
21 d before calving	0.95	0.90	0.79	0.03	0.09	<0.01
calving	0.68	0.70	0.69	0.01	0.60
Calves
3 day	0.37	1.30	1.57	0.02	0.09	0.80
2 week	0.35	1.39	1.55	0.02	0.07
6 week	0.43	1.31	1.51	0.02	0.18
VLDL [mmol/L]
Cows
21 d before calving	0.73	0.78	0.90	0.06	0.47	0.01
calving	0.67	0.69	0.48	0.04	0.02
Calves
3 day	0.21 B	0.28 b	0.36 Aa	0.02	<0.01	<0.01
2 week	0.31 B	0.33	0.35 A	0.01	<0.01
6 week	0.53 A	0.47 A	0.40 Bb	0.02	<0.01
Triglycerides [mmol/L]
	Cows
21 d before calving	0.28 b	0.35 a	0.39 a	1.25	0.01	0.17
calving	0.30 B	0.39 A	0.40 A	0.646	<0.01
Calves
3 day	0.40	0.57	0.55	0.80	0.07	<0.01
2 week	0.37	0.33	0.42	0.75	0.07
6 week	0.68	0.66	0.71	0.41	0.36

SEM—standard error of the mean; A two-superscript letter system indicates statistical significance among values within the same row (a, b for p < 0.05 and A, B for p < 0.01); ALT—alanine aminotransferase; AST—asparagine aminotransferase; ALP—alkaline phosphatase; GGTP—gammaglutamyltransferase; LDL—Low-Density Lipoprotein; HDL—High-Density Lipoproteins; VLDL—Very Low-Density Lipoproteins.

). In calves, serum ALT levels were significantly elevated in the control group in contrast to the E1 and E2 groups at both 2 and 6 weeks of age (p < 0.05). Group E2 showed higher AST activity in cows at the beginning of the experiment than the other groups (p < 0.05). No significant differences in AST levels were observed between the groups on the day of calving. The inclusion of soapwort root preparation in the cows’ diet did not result in a significant alteration in serum ALP activity. In calves, ALP activity was elevated in groups E1 and E2 relative to that in the control group, independent of the sampling time. At 6 weeks of age, a decrease in GGT activity was observed in calves from group E1 (p < 0.05). This was compared with groups C and E2.

Groups E1 (p < 0.05) and E2 (p < 0.01) showed lower levels of LDL on the calving day compared to group C. In calves, serum LDL levels in group C were significantly higher at 6 weeks (p < 0.01) compared to group E2. The addition of soapwort root to the cow’s diet during the peripartum period did not affect the HDL levels. The cows in groups E1 and E2 demonstrated increased serum triglyceride levels, regardless of the sampling time. VLDL levels were elevated in calves in group E2 on day 3 and week 2, whereas a reduction in this parameter was observed at week 6. Furthermore, in calves, a significant difference (p < 0.01) in cholesterol concentration was observed at 6 weeks between the E2 and E1 groups. Nonetheless, no alterations in cholesterol levels were observed in the cows.

Statistical analysis using repeated measures at multiple time points showed that sampling time did not affect ALT activity and triglyceride levels in cows, nor HDL levels in calves. In calves, blood parameters such as ALT, AST, ALP, and GGT significantly decreased with age (p < 0.01). Simultaneously, an increase (p < 0.01) in LDL, VLDL, triglyceride, and cholesterol concentrations was observed with the age of the calves. Furthermore, cows showed an increase (p < 0.01) in the blood activity of the enzymes AST, ALP, and GGT on the day of calving compared to 21 d before expected parturition. Simultaneously, on the day of delivery, a significant decrease (p < 0.01) in total cholesterol, LDL, and HDL levels was observed, as well as a decrease in VLDL (p < 0.05).

3.3. Impact on Kidney Function

The soapwort root preparation added to the diet of cows during the peripartum period did not affect their renal biochemical profile (

Table 5. Effects of soapwort on kidney function in cows and calves.

Time	C	E1	E2	SEM	p-Value (Soapwort)	p-Value (Time)
	Total bilirubin [µmol/L]
Cows
21 d before calving	1.58	1.66	1.77	0.07	0.54	<0.01
Calving	6.73	3.20	6.70	0.51	0.30
	Calves
3 day	21.97	23.37	23.33	0.72	0.67	<0.01
2 week	2.89 b	3.53 a	3.60 a	0.11	0.01
6 week	2.80 B	3.90 B	4.10 A	0.12	<0.01
	Urea [mmol/L]
	Cows
21 d before calving	2.29	1.95	2.42	0.11	0.20	<0.01
Calving	3.80	2.67	3.87	0.19	0.11
	Calves
3 day	4.25 A	2.74 Bb	3.54 a	0.17	<0.01	0.02
2 week	3.42 B	3.83	4.54 A	0.16	0.02
6 week	3.26	3.49	3.32	0.04	0.06
	Uric acid [µmol/L]
	Cows
21 d before calving	48.00	53.17	49.17	2.33	0.65	0.39
Calving	49.00	52.17	48.83	1.86	0.72
	Calves
3 day	58.67 B	95.00 A	63.17 B	0.99	<0.01	0.02
2 week	54.33 B	95.50 A	58.83 B	1.20	<0.01
6 week	62.50 B	100.83 A	72.17 B	1.69	<0.01
	Creatinine [µmol/L]
Cows
21 d before calving	111.33	119.33	109.00	2.21	0.13	0.34
Calving	116.33	113.00	118.17	2.39	0.68
	Calves
3 day	147.33	159.17	142.50	4.64	0.33	<0.01
2 week	109.67	108.67	104.50	1.40	0.29
6 week	85.17	83.67	88.33	0.96	0.13

SEM—standard error of the mean; A two-superscript letter system indicates statistical significance among values within the same row (a, b for p < 0.05 and A, B for p < 0.01).

). Higher levels of total bilirubin and urea were noted in calves in group E2 at 2 and 6 weeks of age. In group E1, a significantly higher level of uric acid was found than in the other groups (p < 0.01), regardless of the sampling time. Furthermore, no significant changes in creatinine levels were observed in calves. No influence of sampled time on blood creatinine and uric acid concentrations was noted in cows. On the day of calving, a significant elevation (p < 0.01) in urea and total bilirubin concentrations was observed. As calves aged decrease in total bilirubin levels (p < 0.01), creatinine (p < 0.01), and urea (p < 0.05) was observed. Blood uric acid levels decreased during the second week of birth and then increased in the sixth week (p < 0.05).

3.4. Analysis of the Composition of Milk and Colostrum

A significant effect of adding soapwort root during the dry-off period on colostrum collected after 2 h post-calving and milk composition collected in week eight was observed (

Table 6. Composition of milk and colostrum.

Parameter	C	E1	E2	SEM	p-Value
Colostrum
SCC × 1000/mL	1816.69 b	2118.5	3224.8 a	307.75	0.05
Fat [%]	5.06 B	8.31 A	4.79 B	0.50	<0.01
Protein [%]	12.03	13	11.22	0.54	0.41
Lactose [%]	2.72	2.3	2.95	0.13	0.12
Dry matter [%]	20.52	24.3	19.65	0.84	0.06
Milk
SCC × 1000/mL	348.0 A	242.0 B	36.0 B	62.62	<0.01
Fat [%]	1.64	1.77	1.61	0.08	0.65
Protein [%]	3.29 A	3.08 B	3.00 B	0.04	<0.01
Lactose [%]	4.76 b	4.82 a	4.78 a	0.04	0.02
Dry matter [%]	9.9	10.08	9.79	0.10	0.43

SEM—standard error of the mean; SCC—somatic cell count; A two-superscript letter system indicates statistical significance among values within the same row (a, b for p < 0.05 and A, B for p < 0.01).

). The somatic cell count in the colostrum was significantly higher (p < 0.05) in group E2 than in the control group. The fat content in the colostrum was significantly elevated (p < 0.01) in group E1 relative to that in the other groups. A significant reduction (p < 0.01) in SCC was observed in the milk of the E2 and E3 groups relative to that of the control group. In cows from groups E1 and E2, which were administered an extract of soapwort root, there was a significant increase in lactose content (p < 0.01) and a notable decrease in protein content (p < 0.05) in the milk relative to the control group.

3.5. Effects of Soapwort on the Fatty Acid Content in Milk and Colostrum

The use of soapwort root in cow nutrition affected the SFA profile of colostrum and milk (

Table 7. Saturated fatty acid content in colostrum and milk (g/100 g fat).

Parameter	C	E1	E2	SEM	p-Value
Colostrum
C4:0	0.45 a	0.40 b	0.32 b	0.02	0.02
C6:0	0.50	0.50	0.43	0.02	0.08
C8:0	0.37	0.38	0.34	0.01	0.23
C10:0	1.02 B	1.16 A	0.95 B	0.02	<0.01
C12:0	1.90 B	2.24 A	1.80 B	0.04	<0.01
C14:0	11.90 B	13.11 A	11.17 B	0.22	<0.01
C15:0	0.58 B	0.82 Aa	0.65 b	0.02	<0.01
C16:0	40.60 B	44.55 A	38.05 B	0.68	<0.01
C17:0	0.50	0.52	0.60	0.02	0.02
C18:0	8.12 A	6.38 Bb	7.42 a	0.22	<0.01
ΣSFA	65.94 C	70.11 A	61.73 B	0.75	<0.01
Milk
C4:0	0.38 B	0.41 b	0.48 Aa	0.01	<0.01
C6:0	0.71 B	0.71 B	0.80 A	0.01	0.01
C8:0	0.70	0.76	0.72	0.02	0.24
C10:0	2.12	2.23	2.09	0.05	0.36
C12:0	2.94	3.15	2.79	0.07	0.07
C14:0	11.17	11.27	10.87	0.16	0.55
C15:0	1.58 b	1.51 Bb	1.64 Aa	0.02	<0.01
C16:0	30.57	29.63	29.62	0.50	0.70
C17:0	0.90	0.91	0.91	0.01	0.97
C18:0	10.12	10.75	10.34	0.30	0.69
ΣSFA	61.44	61.46	60.51	0.46	0.64

SEM—standard error of the mean; A two-superscript letter system indicates statistical significance among values within the same row (a, b for p < 0.05 and A, B, C for p < 0.01).

). Group E1 had the highest levels of total SFA, including decanoic (C10:0), dodecanoic (C12:0), myristic (C14:0), and palmitic (C16:0) SFA, compared to the other groups (p < 0.001).

Colostrum from cows in group E1 also showed a higher level of pentadecanoic acid (C15:0) and a lower level of stearic acid (C18:0) compared to the control group (p < 0.01) and group E2 (p < 0.05). The control group was characterised by a higher level of total SFA in colostrum compared to group E2 (p < 0.01), as well as a higher level of butyric acid (C4:0) than the other groups (p < 0.05). The use of soapwort root during the dry period slightly affected the proportion of SFA in milk. Higher levels of butyric acid (C4:0), hexanoic acid (C6:0), and pentadecanoic acid (C15:0) were observed in the milk of cows in group E2 than in cows milk in groups C and E1.

The colostrum in group E1 was characterised by a significantly higher level of myristoleic acid (14:1) (p < 0.01) compared to the other groups (

Table 8. Unsaturated fatty acid content in colostrum and milk (g/100 g fat).

Parameter	C	E1	E2	SEM	p-Value
Colostrum
C14:1	0.74 B	1.26 A	0.78 B	0.04	<0.01
C15:1	0.09 B	0.09 B	0.12 A	<0.01	<0.01
C16:1	3.06	3.27	3.44	0.07	0.06
C17:1	0.31 B	0.28 B	0.38 A	0.01	<0.01
C18:1n9c	22.84 b	17.83 B	23.65 Aa	0.62	<0.01
C18:1n9t	0.23 A	0.16 B	0.18 B	0.01	<0.01
C18:1n7t	0.55	0.54	0.53	0.02	0.97
C18:2n6c	0.12 B	0.13 B	0.20 A	0.01	<0.01
C18:2n6t 1	3.41 A	3.38 A	2.44 B	0.08	<0.01
CLA	0.26 B	0.29	0.33 A	0.01	<0.01
C18:3n6	0.18 B	0.20 B	0.28 A	0.01	<0.01
C18:3n3	0.11	0.10	0.11	0.01	0.68
C20:4n6	0.38	0.39	0.37	0.01	0.79
C22:6n3	0.11 B	0.12 B	0.16 A	0.01	<0.01
ΣUFA	32.87 b	28.43 Ba	33.49 Aa	0.61	<0.01
Milk
C14:1	1.45	1.44	1.49	0.02	0.71
C15:1	0.33	0.36	0.35	0.01	0.27
C16:1	3.63 A	2.96 B	2.81 B	0.10	<0.01
C17:1	0.41	0.41	0.41	0.01	0.01
C18:1n9c	23.16	23.01	23.44	0.36	0.88
C18:1n9t	0.18	0.21	0.22	0.01	0.13
C18:1n7t	1.46	1.61	1.65	0.04	0.10
C18:2n6c	0.32	0.30	0.33	0.01	0.21
C18:2n6t	2.58	2.46 B	2.74 A	0.04	<0.01
CLA	0.69	0.70	0.78	0.02	0.17
C18:3n6	1.01 A	0.85 B	0.99	0.02	<0.01
C18:3n3	0.16	0.16	0.17	0.01	0.81
C20:4n6	0.17	0.17	0.14	0.01	0.10
C22:6n3	0.10	0.09	0.11	<0.01	0.23
ΣUFA	36.32	35.45	36.39	0.42	0.60

¹ trans-Methyl linolelaidate (linolelaidic acid); SEM—standard error of the mean; A two-superscript letter system indicates statistical significance among values within the same row (a, b for p < 0.05 and A, B for p < 0.01); UFA—unsaturated fatty acid; CLA—conjugated linoleic acid.

). In contrast, in group E2, a significantly higher proportion (p < 0.01) of the following acids were found: pentadec-8-enoic (C15:1), heptadec-8-enoic (C17:1), gamma-linolenic (C18:3n6), linoleic (C18:2n6c) and docosahexaenoic (C22:6n3). Simultaneously, the level of Δ9,12-octadecadienoic acid (C18:2n6t) was lower than that in the control and E1 groups (p < 0.01). A higher level of Δ9-octadecenoic acid (C18:1n9t) was observed in the control group than in the E1 and E2 groups (p < 0.01). Furthermore, cows in group E2 had an elevated level of conjugated linoleic acid (CLA) compared to the control group (p < 0.01).

Analysis of the sum of unsaturated fatty acids (UFA) revealed a higher proportion in the colostrum of cows in group E2 than in group E1 (p < 0.01) and the control group (p < 0.05). In contrast, in group E1, a lower proportion of UFA was observed than in the control group (p < 0.05). Moreover, a higher level of cis-9-hexadecenoic acid (C16:1) was observed in milk in the control group than in the experimental groups (p < 0.01). Additionally, milk from cows in group E2 was characterised by a higher (p < 0.01) level of Δ-9,12-octadecadienoic acid (C18: 2n6t) (p < 0.01) than that from group E1. A higher proportion (p < 0.01) of all-cis-6,9,12-octadecatrienoic acid (C18:3n6) was found in group C than in group E1.

4. Discussion

Approximately 30% of all diseases in dairy cows during lactation are estimated to occur within the first 21 d after calving, accounting for 66% of clinical cases diagnosed in cows during lactation [29]. Proper feeding of cows during the dry period reduces the risk of diseases occurring in early lactation but can also stimulate the immune system of cows and their calves [4]. Therefore, the objective of the nutritional management during this crucial period is to prevent health and ensure the physiological development of the foetus, as well as to prepare the cow for the upcoming lactation [30,31].

In this study, Ukrainian Black and White (Holsteinised) dairy breed cows received a supplement of Saponaria officinalis root powder 21 d before the expected calving date to the day of calving. The average calving time observed in the experiment, relative to the predicted calving date, was 21 days, with the range extending from 19 to 22 days. In detail, three cows calved on day 19, three on day 20, and four on day 22. Despite these slight differences in calving time, the experimental regime was maintained with respect to the measurement points, as schematically presented in Figure 1.

This research allowed for an assessment of the impact of the additive used on the quality of colostrum and cow’s milk, as well as on the biochemical profile of their blood serum and blood of newborn calves. The results of the analysis are significant indicators of the impact of the additive used on the health of cows and the physiological state of calves in the first weeks of life.

4.1. Blood Parameters in Cows and Calves

The present study provides new insights into the dynamics of protein and enzyme metabolism in cows during the periparturient period and in calves during early postnatal development. In cows, the significantly higher total protein concentrations observed at 21 d prior to calving compared with parturition suggest a mobilisation of protein reserves or altered protein metabolism around delivery. This pattern may reflect increased protein demand for colostrum synthesis and foetal development, processes known to intensify in late gestation. Interestingly, albumin concentrations remained stable, indicating that the decline in total protein is likely attributable to globulin fractions rather than albumin. This observation aligns with previous reports describing periparturient hypoproteinemia driven by colostrogenesis rather than systemic albumin depletion [32].

Total protein concentration in calf serum is a significant indicator of passive immunity. A positive correlation exists between total serum protein levels and immunoglobulin concentrations [33]. Passive immunoglobulin transfer was considered successful when the total protein concentration between days 1 and 7 of life was greater than 50 g/L, which corresponds to 10 mg/mL of IgG in the serum [34]. On the other hand, according to [35], failure of passive transfer (FPT) of IgG occurs at a serum protein level below 42 g/L. The level of globulins in the blood serum of calves should increase after the absorption of immunoglobulins and other globulins from the colostrum into the bloodstream of the newborn, without changes in albumin concentration. In contrast, an increase in serum albumin concentration may be associated with the body’s compensatory response to a decrease in osmotic pressure resulting from low globulin levels [36].

In our study, the serum total protein level in calves at 2 weeks of age in the experimental group was elevated compared to that in the control group, without alterations in albumin concentration. At 6 weeks of age, calves born to cows administered 50 g of soapwort root daily exhibited a reduced albumin level, although their total protein levels remained the same. These results suggest the effective use of colostrum in calves whose dams were administered soapwort root supplement. Calf immune systems are underdeveloped at birth; animals cannot generate adequate antibodies independently until they reach 3–6 weeks of age. Consequently, its immunity is directly reliant on the intake of high-quality colostrum [37].

Furthermore, a physiological increase in total protein and albumin levels was observed with the age of the calves, which is a normal phenomenon. The calves’ feeding method and liver function influenced these parameters. Albumins are synthesised primarily in the liver; therefore, their concentration depends on the maturity and functional capacity of this organ [38]. In the blood serum of calves on the third day of life, the protein level is physiologically 36.9–94.8 g/L, and albumin is 17.6–35.8 g/L. In cows, 21 d before the expected calving date, the protein concentration was 47.1–86 g/L, and albumin was 22.3–37.2 g/L [33]. Low total protein levels in cows’ blood serum can be associated with insufficient protein in their feed or absorption disorders [39]. The results obtained for protein and albumin in the blood serum of cows and calves were within the physiological range and were consistent with data from the literature. In calves, the progressive increase in both total protein and albumin concentrations with age reflects the gradual maturation of hepatic synthetic capacity and the establishment of efficient intestinal absorption of immunoglobulins and nutrients after colostrum intake and is considered a hallmark of successful adaptation to extrauterine life. We found a significant increase in total protein level and albumin concentrations between calves during ageing, which was in accordance with previous results [40,41].

Plant saponins, which are natural triterpenoids or steroid glycosides, exhibit a broad spectrum of biological activities in ruminant organisms by enhancing nutrient utilisation through CH₄ reduction and rumen protozoa elimination, which promotes bacterial protein synthesis and improves nitrogen (N) efficiency. Yucca extract, which is high in saponins, can bind NH₄ during elevated ruminal NH₄ concentrations and subsequently release it when ruminal NH₄ levels are low, thereby ensuring a consistent and sufficient supply of NH₄ for microbial protein synthesis [42]. Saponins may control internal parasites in ruminants. Saponins can inhibit the activity of proteases, lipases, and chitinases, which degrade egg membranes that are important for the hatching process of nematode eggs [43]. Saponins also act as immunostimulants by activating immune cells and boosting antibody production, particularly through mechanisms such as enhancing macrophage phagocytic activity and natural killer cell cytotoxicity [44] and can improve intestinal barrier function and reduce inflammation [45]. Dietary supplementation with tea saponins decreased the plasma concentration of malondialdehyde (MDA) and increased the concentration of superoxide dismutase (SOD), indicating that saponin supplementation reduced oxidative stress.

The inclusion of saponin extracts from Agave americana and Quillaja saponaria in the diet can lead to a reduction in blood glucose and cholesterol levels in animals [11]. In contrast, tea saponin supplementation at doses of 20, 30, and 40 g/day in dairy cows did not significantly affect serum levels of total protein, triglycerides, cholesterol, albumin, or globulins, but reduced oxidative stress [44]. A similar hypolipidemic effect was observed in calves administered an aqueous extract of Angelica sinensis root, containing natural saponins, which resulted in a significant reduction in total serum cholesterol levels [46]. In contrast, in fattening cattle and heifers, no changes in plasma ammonia or urea concentrations were observed after supplementation with Yucca schidigera extract at a dose of 250 mg/kg feed for steers and 20 and 60 g/day for heifers [7]. In in vitro studies of rumen fermentation, the use of Saponaria officinalis resulted in a reduction in ammonia production, which may be associated with a decrease in blood urea in animals [15]. In sheep, supplementation with saponins from tea leaves at a rate of 180 mg/kg of dry matter in the feed led to an increase in blood glucose and total protein levels, without affecting cholesterol levels [47]. These data indicate that the metabolic effects of saponins depend on the animal species, type of compound, dose, and form of administration. In our studies on calves at 6 weeks of age, a decrease in LDL levels was observed in group E2.

During the transition period, high-yielding dairy cows experience significant metabolic changes. Increased AST and ALT enzyme activity in the serum of these animals is a sensitive marker of liver damage, mainly caused by fatty liver disease. This condition can lead to decreased appetite and development of ketosis during early lactation [48]. According to other authors, saponins extracted from cherry tomatoes used in a mouse diet can alleviate liver damage caused by a high-fat diet, and a decrease in serum ALT and AST levels was observed [49]. However, Yang et al. [50] found that the biochemical profile remained unaffected by alfalfa saponins used in sheep nutrition.

The study indicated that the addition of soapwort root to the diets of cows during the dry period reduced the levels of ALT, AST and ALP in the serum of their calves, whereas no significant changes were observed in the liver parameters of the cows themselves. A decrease in the activity of ALT, AST and ALP is a beneficial phenomenon that can prevent oxidative stress by neutralising reactive oxygen species and may indicate good liver health [51]. In contrast, on the day of calving, cows showed a time-dependent increase in AST, ALP, and GGT enzyme activities. These increases are often interpreted as markers of hepatic stress or increased hepatic metabolic demand at calving. Reference intervals from Holstein cows around this period show elevated AST, ALP and GGT around calving [52]. We observed that ALT, AST, ALP, and GGT activities significantly decreased in calves with ageing. A plausible explanation is that the initially elevated levels reflect contributions of colostral enzymes (especially GGT) and possibly immature hepatic function, which gradually stabilise as the calf’s liver matures. The study of Thompson and Pauli [53] found that GGT levels in newborn calves are extremely high post-colostrum ingestion, and take about 5 weeks to decline to adult levels.

Metabolic and lipid disorders in cows and calves can manifest as higher levels of bilirubin, GGT, urea, creatinine, uric acid, cholesterol, triglycerides, HDL and VLDL in blood serum [7,39].

Our research found no clear effect of adding Saponaria officinalis on the levels of these indicators in the blood serum of cows and their offspring, suggesting that supplementation avoided metabolic disturbances and burdens on excretory and lipid systems. This information is important from the perspective of the safety of using Saponaria officinalis as a feed additive. We observed decreases in total cholesterol, LDL, HDL, and VLDL on the day of calving relative to 21 days before. This aligns with documented drops in lipoproteins and cholesterol at calving, associated with the negative energy balance, mobilisation of fat reserves, and possibly reduced feed intake, and hypocholesterolemia around calving is a known phenomenon [52].

Colostrum and milk intake also provoke changes in the nutritional status of the neonatal calves, including changes in serum lipid profile values. In calves, TG, LDL, VLDL, and cholesterol all increased significantly in a time-dependent manner in all groups. This is in harmony with the development of lipid metabolism systems, including lipoprotein production, dietary fat uptake, and possibly increasing FA content in feed. Our results are consistent with previous studies on newborn calves showed that colostrum and milk ingestion causes a gradual increase in plasma total cholesterol, LDL cholesterol and triglyceride concentrations during the first week of the calf’s life [54]. In contrast, we observed slight changes in HDL concentration in groups E2 and E3 between 3 days and 6 weeks after birth.

We found increases in urea and total bilirubin at calving, but no effect of sampling time on creatinine or uric acid. Elevated bilirubin around calving has been reported, possibly reflecting hepatic load from conjugation of breakdown products of heme, or mild hepatic dysfunction during the periparturient transition [52]. We also found that total bilirubin declines with calf’s age, which reflects resolution of neonatal hyperbilirubinemia: newborns often have elevated bilirubin due to immature hepatic uptake, conjugation, and excretion processes. Calves from groups E1 and E2 showed higher bilirubin levels over time. However, they were still within the reference ranges. In healthy calves <72 h old, total bilirubin may be as high as 25.65 μmol/L and up to 13.68 μmol/L in 1-week-old calves. The concentration of direct bilirubin is usually <5.13 μmol/L in young calves [38,55]. The patterns for urea and creatinine (declines with age) likely reflect decreasing catabolic rates (postnatal adaptation), improving kidney function, and changing protein metabolism as the calf grows. The initial decrease in uric acid and its later increase could relate to shifts in purine metabolism and dietary components, though I did not find specific studies in calves matching this exact pattern.

4.2. Colostrum and Milk

Mastitis is one of the most common diseases in dairy cows and significantly affects not only milk production but also the quality of colostrum and milk [56,57]. The somatic cell count is a basic indicator for assessing milk quality. According to the current standards of the European Union, the maximum permissible SCC value in milk is 4 × 10⁵ cells/mL [58]. Subclinical mastitis, which does not cause significant changes in the appearance of the udder or the macroscopic characteristics of milk, is often associated with an elevated level of CCS, even above 2 × 10⁵ cells/mL [57]. Animals affected by subclinical mastitis show a reduced milk production of 60 to 140 L per cow annually [59]. In the clinical form of mastitis, there are clear local symptoms, such as redness, pain, and swelling of the affected quarter of the mammary gland. Milk from the affected part of the udder shows visible changes, such as flakes, clots, pus, or watery milk, and exhibits a significant increase in SCC above 4 × 10⁵ cells/mL [60]. In our research, the herd of cows was under constant veterinary supervision, and no udder diseases were observed, and SCC in the milk did not exceed 4 × 10⁵/mL.

In the case of colostrum, no uniform standards have been established for somatic cell count. It usually has a higher SCC level than milk from cows with subclinical and clinical mastitis. According to Pikhtirova et al. [56], Staphylococcus and Streptococcus infections do not occur in colostrum at an SCC level of 2.5 × 10⁶/mL. However, Zachwieja et al. [4] reported SCC levels ranging from 2.4 × 10⁶ to 9.7 × 10⁶ cells/mL. High SCC levels in colostrum and milk are associated with an increase in overall protein content and a decrease in lactose level. These changes affect whey proteins, whereas the proportion of casein proteins decreases. This change in protein proportions negatively affects the quality of mammary gland secretion [61,62].

Saponins can improve udder immunity and reduce inflammation, resulting in a lower SCC in milk [44,63]. In in vitro studies, Saponaria officinalis has been shown to have antibacterial activity against E. coli, S. aureus, E. faecalis, and S. enteritidis strains, which can cause mastitis [17,18]. The use of saponins in cow nutrition can also affect the milk composition. According to the research findings of Wang et al. [44], the use of tea saponins does not affect the protein level in milk, but it does increase the lactose content. However, Durmuş et al. [64] and Liu et al. [63] did not observe a significant effect of Yucca schidigera supplementation on cow milk composition. However, Szczechowiak-Piglas et al. [13] observed an increase in protein, fat, and lactose in the milk of cows fed Saponaria officinalis.

The results of our research indicate that the addition of Saponaria officinalis to the cow diet during the dry period can differentially modulate the chemical composition of mammary gland secretions. In group E2, an increase in SCC in the colostrum was observed, which may suggest activation of the udder’s immune system. However, in the milk of cows receiving Saponaria officinalis, the SCC level decreased, which may indicate a long-term beneficial effect of the additive on udder health. Furthermore, reduced protein levels in the milk of cows in experimental groups may be associated with a lower SCC. In the cows’ milk receiving the supplement, an increase in lactose concentration was observed, which may be the result of improved functioning of the mammary gland secretory cells.

Short-chain fatty acids (from C4 to C14) are synthesised de novo in the mammary glands of cows and are produced from acetate and butyrate derived from the end products of fermentation in the rumen [65]. Reduced levels of SFA are associated with increased levels of fat in milk [66]. In our research on cow colostrum in group E1, an increase in fat content was observed, as well as an elevated proportion of SFA with chain lengths from C10 to C16. The proportion of SFA also increased in the same group, but decreased in group E2. In contrast, the milk of the cows in group E2 showed the highest levels of short-chain fatty acids—C4:0 (butyric acid), C6:0 (caproic acid) and C16:0 (palmitic acid). Szczechowiak-Piglas et al. [13] observed a decrease in the content of short-chain fatty acids, mainly C8:0 and C16:0, as well as monounsaturated fatty acids (MUFA) and cis-9, trans-11 C18:2 in milk, whereas the levels of cis-9, cis-12 C18:2 increased in cows fed Saponaria officinalis. In contrast, the use of tea saponins in cow nutrition does not affect the fatty acid profile of milk [44].

Newborn calves possess minimal energy reserves. The elevated fat content in colostrum, which comprises saturated and monounsaturated fatty acids, phospholipids, and cholesterol, offers digestible energy required to sustain homeostasis and facilitate calf growth and development [67]. Unsaturated acids, particularly omega-3 and omega-6, positively influence the development of the nervous system and cell membrane function. They contribute to the regulation of inflammatory and immune responses, which are crucial for a calf’s acquisition of passive immunity via colostrum [68]. Unsaturated fatty acids play a protective role in cancer development and contribute to the reduction in blood cholesterol and triglyceride levels [69,70].

The most significant changes in the proportion of UFAs were observed in our study. Colostrum from E2 cows contained higher levels of several UFAs, including C15:1, C17:1, C18:2n6c, C18:3n6, C22:6n3, and CLA. This indicates the potential hypolipidemic and antioxidant activity of the soapwort root, which could contribute to improving the quality of milk fat from a nutritional and health perspective for calves. Simultaneously, a decrease in the levels of some unfavourable trans isomers, such as C18:2n6t, was observed in the E2 group. Higher values of C18:1n9t and C18:3n6 were observed in the control group, which may be the result of the absence of a modulating effect of the saponins. In milk, similar to colostrum, group E2 had a higher level of C18:2n6t and a lower level of C16:1, without affecting other FAs.

This study has some limitations. Interest in saponins in ruminant nutrition has grown because of their properties, such as anti-protozoal effects, the ability to modulate rumen microbial populations, the possible reduction of CH₄ emissions, and improved nitrogen utilisation [71]. However, despite these promising attributes, the practical adoption of saponins in ruminant feeding systems is constrained by several limitations related to effectiveness, safety, economic feasibility, and consistency. Saponins are a diverse class of plant secondary metabolites, and their concentration in plants is highly variable and influenced by both intrinsic and extrinsic factors such as developmental stage, temperature, light intensity, humidity, soil nutrients, and altitude, which play a key role in regulating biosynthesis pathways; therefore, the final dosage must be adapted for each case [72,73]. Furthermore, the use of saponin in feed may result in diverse health effects depending on the breed, as well as diet formulation (high roughage vs. high concentrate), and interplay with other feed additives (probiotics, buffers, etc.) [11]. Bitter taste or other undesirable sensory properties of saponins or saponin-rich plant material can reduce feed palatability, leading to lower voluntary feed intake [11]. Another potential limitation of our research was the time of the experiment, up to three months under controlled/uniform conditions, and the number of time points analysed. We showed a positive effect of soapwort during its application period; however, the long-term effects under commercial agricultural conditions need evaluation. Furthermore, the microbial composition of the rumen (species present, community structure) plays a big role in response, so animals with different rumen microbiota (due to diet, geography, or breed) may show different responses [11,71].

5. Conclusions

Our findings suggest that supplementing the diet of Ukrainian Black and White (Holsteinised) dairy breed cows with Saponaria officinalis root during the dry period can improve colostrum quality without significantly affecting milk quality. Supplementation of cows’ diet enhances the total protein concentration and liver enzyme profile in their calves. Furthermore, it does not have adverse metabolic consequences in cows or their progeny. The colostrum of cows in the experimental group (E2) exhibited elevated amounts of UFAs, including advantageous acids such as C18:2n6c, C22:6n3, and CLA, along with a reduction in trans isomers, which could signify the hypolipidemic and antioxidant properties of the saponins. Administration of Saponaria officinalis preparation, at doses of 20 g and 50 g per day, reduced SCC in cow’s milk, suggesting improved udder health and a prolonged anti-inflammatory action of the supplement. Based on our findings and the experimental conditions, we conclude that a dosage of 50 g provided more favourable results regarding animal health and milk parameters. Increasing the dosage above this threshold requires additional investigation, as supplementation occurs during the dry period, and elevated saponin levels may induce adverse consequences in pregnant cows. Furthermore, addressing the limitations described above via carefully designed research will be essential for turning saponins into reliable and widely used feed additives.