The Middle East and Africa are home to the majority of camels, while small populations can be found elsewhere in the world (Abdelazez et al., 2024). Through the provision of vital resources including meat, wool and milk, camels have historically been integral to the lives of pastoral people (Omar et al., 2018).

Over the past few decades, consumer’s perceptions of meat have changed from viewing meat products as merely a source of necessary nutrients to viewing meat as a supplement that promotes health (Kadim et al., 2020). The primary motivator of consumer demand for any meat products on the market is their health advantages. Consumers' interest in camel meat products stems from its potential as an alternative health food due to their functional qualities. In this regard, the meat industry has made a noteworthy effort to improve the nutritional content and overall health of meat products (Decker and Park, 2010). For animals, heat stress has negative health effects (Abri and Faye, 2019; Bouhaddaoui et al., 2019).  But even in the most severe and difficult weather, camels have evolved to produce wholesome meat.

The growing popularity of camel milk can be attributed to its unique intrinsic properties as well as its nutritional and medicinal benefits (Habtegebriel et al., 2020).   Despite its importance, camel milk only makes up 0.2% of the world's milk supply whereas cow milk makes up about 85% and sheep, goat, and buffalo milk make up 11.0, 2.3 and 1.4% of the total (Olmedilla-Alonso et al., 2017).

Lipids, total protein, lactose, dry matter and ash are among the typical composition components of camel milk; their approximate ranges are 3.82 ± 1.08, 3.35 ± 0.62, 4.46 ± 1.03, 12.47 ± 1.53, and 0.79 ± 0.09 (g/100 mL) respectively (Al haj and Al Kanhal, 2010). Lactoperoxidase, hydrogen peroxide, lactoferrin, lysozyme, immunoglobulin and free fatty acids are among the bioactive fractions it contains that support human health (Izadi et al., 2019).

Dromedary camels are susceptible to udder infections like clinical and subclinical mastitis (SCM), just like other dairy animals (Matofari et al., 2003).  a prevalent and expensive disease that affects dairy camels and has a major effect on hygiene, milk production and household finances (Seligsohn et al., 2021).  Mastitis, an acronym for breast inflammation (mast = breast, itis = inflammation), is characterized by physical, chemical and typically bacteriological changes in the milk (Archana et al., 2014) and is defined as inflammation of the mammary gland or udder in dairy animals including cows and camels, regardless of the cause (Djeddi et al., 2024; Geresu et al., 2021).

Subclinical mastitis must be diagnosed indirectly (Matofari et al., 2003). According to Tibarya and Anouassi (2000), there is an evidence that subclinical mastitis contributes to the animal's suffering, lowers milk production, changes the milk's characteristics, hinders processing and preservation and poses a health risk to camel milk consumers. Moreover, altered milk immune cell composition and milk supply have been linked to subclinical mastitis (Djeddi et al., 2024). Additionally, it is estimated to affect more than 40% of lactating she-camels (Regassa et al., 2013).

The somatic cell count (SCC) is a key indicator of udder health and is widely used to detect mastitis or intramammary infection (IMI) (Schukken et al., 2003). Monitoring SCC helps establish an early checkpoint for disease entry within the herd. Somatic cells mainly consist of leukocytes (neutrophils, lymphocytes and macrophages) and milk-secreting epithelial cells. Several SCC thresholds have been proposed with the International Dairy Federation (1971) reporting 500,000 cells/mL as the cut-off for subclinical infection (Tolle, 1971). More recent studies suggested lower thresholds including 310,000 cells/mL (Jadhav et al., 2018) and 472,500 cells/mL for camels (Aljumaah et al., 2019)

The gold standard for detecting mastitis is still the Somatic Cell Count (SCC). It has been demonstrated that there may not always be a positive link between SCC and the severity of mastitis (Schepers et al, 1997). It is crucial to understand that bacterial culture is a labour-intensive and time-consuming procedure and that SCCs sensitivity and specificity in detecting subclinical mastitis are insufficient (Shirazi-Beheshtiha et al, 2012). In order to diagnose subclinical mastitis, new biomarkers with greater diagnostic value and quicker turnaround times are therefore required (Akerstedt et al, 2007; Shirazi-Beheshtiha et al, 2012).

Immuno-protective proteins such as immunoglobulin G (IgG), lactoferrin (LTF) and lactoperoxidase (LPO) are found in varied levels in camel milk (Mohamed et al., 2022). According to Akhtar et al., (2020), cytokine release is a reliable indicator of udder health since cytokine concentrations in milk vary in response to physiological or pathological changes. The innate immune response against intramammary infections is triggered by Th1 cytokines such as TNF-α and IL-6 which are significantly elevated in both clinical and subclinical mastitis (Akhtar et al., 2020; Serdal et al., 2021). Conversely, the Th2 cytokine IL-10 controls immune responses and protects host tissues via suppression of Th1 cytokine production, T-cell activation and effector activities (Šerstņova et al., 2022).

Scientific interest in camel milk is expanding but little is known about trustworthy biomarkers that capture the immunological and physicochemical alterations linked to subclinical mastitis (SCM) in dromedary camels. The disease complexity might not be sufficiently described by relying only on somatic cell count (SCC).

Therefore, the purpose of this study was to find potential biomarkers associated with SCC, bacteriological and immune response in order to develop a more precise method for early (SCM) diagnosis in camels.

Study Area and Animals

The Qassim University Animal Ethics Committee in Saudi Arabia gave its approval to all of the experimental methods employed in this work (23-32-04). A total of 133 lactating camels between the ages of 4 and 10 years from various places in the Qassim region of the Kingdom of Saudi Arabia (KSA) were used in this study. The climate in this region is dry, with summertime highs usually between 40 and 45 °C. Rainfall occurs from November to February. For the rest of the year, the pastures in the region are considered arid. This study was conducted between November 2021 and August 2022. After being chosen at random, the animals were kept in grazing and supplement farming systems. The camels were kept indoors for milking and given extra feed after grazing in the open areas surrounding the property from sunrise until noon. Dry hay, ranging from 3 to 4 kg per day, depending on the farm and concentrates, which included the same ration of barley and cottonseed meal, made up the used feed. The animals were watered on a regular basis. The majority of calvings occur during the winter. Three separate subspecies of she-camels were identified based on their lack of systemic diseases or deformities (Abdallah and Faye 2012): Majaheem (black) n = 43, Shaele (yellow) n = 43 and Wadaha (white) n = 47. The farms used the same management and feeding strategies. Animals are similar in terms of housing, feeding and nutrition sources.

Sample Collection

Animal owners and herders were informed of the study's objectives and sampling procedures prior to sampling, and their verbal consent to participate was obtained. Participants were informed of the study's anonymous participation policy and their freedom to withdraw at any time. The samples were taken early in the morning and put into sterilized tubes after the teats had been cleaned with water, disinfected with alcohol (70°C) and the initial streams removed. After that, these were quickly labelled. The test tube's tilt was adjusted to about 45 degrees. In addition, the samples were delivered to the lab within two to four hours after being stored in ice bags within a special box. Each milking was thoroughly mixed and 500 mL were removed for examination. Following transportation, the samples were separated and put in a small 2 mL tube. The milk and fat were then extracted by centrifuging the tube for 10 minutes at 10,000 rpm. Samples of skim milk were defatted and refrigerated until they could be examined further.

Camel blood was extracted using venipuncture tubes (10 mL) and the samples were kept at room temperature. Centrifugation at 3000 rpm for 15 minutes was used to recover the serum from the blood samples that were taken. After that, the samples were divided and stored at -20 °C to evaluate the cytokine and immunological parameters.

Somatic Cell Count

Within three hours at most, the somatic cells were counted using a direct microscopic method and an automatic cell counter. Ten minutes at 10,000 rpm were spent centrifuging 1.0 mL of raw milk. The pellet was reconstituted in 1.0 mL of phosphate-buffered saline (PBS) after the creamy component and supernatant were removed. The cellular suspension was diluted with ten microliters using 125 microliters of Turk's solution, which is methylene blue in distilled water and 1% to 2% acetic acid. A hemocytometer measuring 10 mL of the diluted pattern was used to count somatic cells.

Bacteriological Examination

The milk samples were immediately chilled at 4°C as they arrived at the lab until the analysis process began. The milk samples were serially diluted using sterile peptone water and 1.0 mL aliquots were added to each Petri dish that was used again. Each Petri dish was filled with 15-20 mL of agar. The resulting plates were thoroughly combined, let to solidify and then incubated at 32˚C for a full day.

Violet Red Bile Glucose Agar (VRBG, Neogen) was used to count Enterobacteriaceae in accordance with the ISO 21528-2 formulation and Plate Count Agar (PCA, Oxoid) was used for Total Plate Count (TPC) in accordance with the ISO4833-1 formulation. Total coliform (TCC) is counted using violet, red bile lactose agar (VRBL, Neogen) in compliance with ISO 4832. E. Coli were counted using tryptone bile x-glucuronide agar (TBX, Neogen) in compliance with ISO 16649-2. The plates were counted using a colony counter and the result was expressed as cfu/mL. A biological safety cabinet was used to house everything and the bacteria were cultured for 48 hours ±2.0 at 37°C for Enterobacteriaceae and TCC and 44°C for E. coli.

Immunological and Cytokine Determination

The commercial enzyme-linked immunosorbent assay (ELISA) kits (Sunlog Biotech, Hangzhou, Zhejiang, China; Cat. No. SL0030cm for CamTNF-α and SL0032cm for Cam-IL-6, respectively) were used to quantify the serum concentrations of Cam-TNF-α and Cam-IL-6 in accordance with the manufacturer's instructions. The test's sensitivity was 0.5 and 0.1 pg/mL, and its intra-assay variability CV was less than 10% and the inter-assay variability CV was less than 12%. For CamTNF-α and CamIL-6, the detection ranges were 3-200 pg/mL and 1-70 pg/mL, respectively. A commercial ELISA kit (Wuhan Fine Biotech Co., Ltd, Optics Valley Biomedical Industrial Park, Fine Biotech Co., Ltd, Optics Valley Biomedical Industrial Park, Wuhan, China; Cat. No. ECM0010) was used to measure the concentration of Cam-IL-10 in accordance with the manufacturer's instructions. The intra-assay was less than 8%, and the inter-assay was less than 10%. The detection range was 15.625-1000 pg/mL, while the sensitivity was 9.375 pg/mL. A commercial ELISA kit (Sunlog Biotech, Hangzhou, Zhejiang, China; kits, Cat. Nos. SL0050cm, SL0051cm, and SL0039cm, respectively) was used to measure the concentrations of IgG, LTF and LPO in accordance with the manufacturer's instructions. The assay's accuracy (intra-assay variation) and sensitivity were set at 0.06 μg/mL for IgG, 0.05 ng/mL for LTF and 6 pg/mL for LPO. The intra-assay variance was less than 12% and the assay's CV was set at less than 10%. The IgG, LTF and LPO detection ranges were 0.3-20 μg/mL, 0.3-20ng/mL and 30-2000pg/mL, respectively.

Physicochemical Analysis

The milk samples were brought straight from the farm or desert to the laboratory, where they underwent physical and chemical investigation. FT₃ MilkoScanTM. utilizing a gyrometer to determine the specific gravity. Formaldehyde titration is used to determine the total protein. Additionally, a factor of 1.74 was used to compute total protein. Using the oven drying method, the total solids of milk were determined and the percentage of total solids was computed as follows:

Total fat percentage was determined by the Roese-Gottlieb method as follows:

Total fat (%) = Weight of the vial containing fat - Weight of the vial after washing off the fat sample weight x 100

Additionally, the MilkScan^TM FT3 has been used to assess casein, lactose, urea, citric acid, FPD, FFA, density and acidity. A clever new method for dairy analysis is provided by MilkoScan^TM FT3, which can analyze a range of liquid and semi-solid dairy products. Exceptional uptime, low cost of ownership and results that have never seen before. It can examine samples in a matter of seconds. Additionally, it uses a unique intelligent flow line to test products with varying viscosities. Fat (g/d), protein (g/d), lactose (g/d) and adjusted milk for energy were the computed parameters that were employed. Taking into account that milk has an energy value of 0.74 litters per kilogram of milk the latter was computed as ECM (kg/d) = 12.55 x fat (kg/d) + 7.39 x protein (kg/d) + 0.2595 x weight of milk (kg/d).

Statistical Analysis

Mean±SE was used to represent the values. The different parameters and breeds will be subjected to a one-way ANOVA in order to identify any significant differences. The groups were compared using post hoc analysis and the Mann-Whitney test. GraphPad 7 was used to conduct the analyses. The significance threshold that was applied was P<0.05, P<0.01 and P<0.001.

The current study is the third in a series of ongoing investigations (Almulhim et al., 2024; Zaki and Albarrak, 2025) about the risk factors for dromedary camel subclinical mastitis (SCM). The current study incorporates a wider analytical perspective, focusing on bacteriological, physicochemical, and immunological parameters whereas the previous two publications focused on the impact of demographic and management-related factors specifically age, parity, milking frequency, geographic location, housing and feeding systems. The findings are shown in an organized order that corresponds to Tables (1 - 10), each showed details of the observed changes in immunological biomarkers and milk composition under various experimental settings. To ascertain the degree of significance among the parameters under study, statistical analyses were performed. The mean values were presented as Mean ± SE and assessed at the P < 0.05, P < 0.01 and P < 0.001 confidence levels. Significant trends and relationships related to the occurrence of subclinical mastitis (SCM) were identified through the interpretation of comparisons between variables within each risk factor. As a result, this part presents the findings in a clear, data-driven approach before moving into a detailed discussion that focuses on biological interpretations and literature linkages to support the observed results.

The Majaheem breed's correlation study Table (1) showed some notable relations between SCC and markers of milk quality. SCC had a positive correlation with lactose, solid nonfat (SNF), and total solids (TS), suggesting that minor changes in milk composition were associated with greater cell counts. A negative correlation between fat and urea suggests that metabolic activity is altered during subclinical inflammation. Citric acid, TS, SNF and casein all showed strong positive relations with one another, indicating a steady dependency of the main milk constituents. Furthermore, lactose showed favourable associations with citric acid, TS and SNF, indicating that it is a crucial compositional characteristic influenced by the health of the udder. In terms of immunological characteristics, SCC showed a negative correlation with milk lactoperoxidase (LPO) and serum and milk lactoferrin (LTF), suggesting a reduction of local immune defence factors during inflammation. Both serum LPO and milk LTF and milk LTF and LPO showed positive correlations, indicating that the serum and milk compartments' immune responses were coordinated.

Table (1): Correlation matrices of SCC to bacteriological, physicochemical and immunological parameters of Majaheem breed

*, **, *** are significantly different at P≤0.05, P≤0.001, and P≤0.001, respectively

The Majaheem breed's TNF-α correlation matrix with IL-6, IL-10, lgG, LTF and LPO was examined Table (2). There was no obvious association between Majaheem's SCC and TNF-α, IL-6 or IL-10. LPO serum and Majaheem LTF milk showed a significant positive connection (P<0.01). Furthermore, Majaheem's LPO and LTF milk showed a strong positive connection (P<0.01). Additionally, IL-6 and Majaheem LTF milk showed a strong positive connection (P<0.05).

Table (2): Correlation matrix of TNF-α to IL-6, IL-10, lgG, LTF and LPO of Majaheem breed:

The Waddah breed's correlation matrix Table (3) showed a number of noteworthy relationships between immunological, physicochemical and bacteriological parameters. SCC and total plate count (TPC) showed a substantial positive connection, indicating that microbial load and somatic cell activity are closely related. Additionally, TPC demonstrated a high correlation with coliform and Enterobacteriaceae counts, suggesting that subclinical inflammation is influenced by general bacterial contamination. Fat, protein, and casein all exhibited consistent positive associations with each other as well as with urea and total solids (TS) among physicochemical measures, indicating that the compositional components of milk are interdependent under mastitis conditions. A little decrease in the synthesis of carbohydrates during inflammation was shown by the minor negative correlation between lactose and TS. Milk lactoperoxidase (LPO) and SCC had a negative correlation for immunological features, suggesting that as cell counts rise, local antimicrobial defence activity decreases. In Waddah camels with subclinical mastitis, a positive correlation between milk and serum lactoferrin (LTF) levels indicates both local and systemic immunological coordination.

Table (3): Correlation matrices of SCC to bacteriological, physicochemical and immunological parameters of Waddah breed

The Waddah breed's TNF-α correlation matrix with IL-6, IL-10, lgG, LTF and LPO was shown Table (4). TNF-α, IL-6 and IL-10 did not significantly correlate with Waddah breed SCC. TNF-α and Waddah breed LTF milk were shown to be significantly positively correlated (P<0.05). Furthermore, there was a substantial positive (P<0.05) association between Waddah breed LTF milk and LTF serum.

Table (4): Correlation matrix of TNF-α to IL-6, IL-10, lgG, LTF and LPO of Waddah breed

Several observed relationships between milk quality parameters were displayed by the Shaele breed's correlation analysis Table (5). Total plate count (TPC) and coliform count had a high correlation, suggesting a strong link between overall bacterial load and contamination level. Casein, SNF, urea and citric acid all exhibited high positive associations with fat, indicating that the components of milk composition react collectively in subclinical mastitis settings. However, casein showed negative correlations with SNF, urea and citric acid indicating slight compositional abnormalities during udder inflammation, whereas protein showed positive correlations with lactose, SNF, urea and citric acid. Furthermore, the metabolic dependency of carbohydrates and solid nonfat is indicated by the positive correlations between lactose, SNF and citric acid. Additionally, positive correlations between Free fatty acid (FFA), density and acidity were discovered, demonstrating the close association between Shaele camels' physicochemical markers of milk quality.

Table (5): Correlation matrices of SCC to bacteriological, physicochemical and immunological parameters of Shaele breed:

The Shaele breed's TNF-α association matrix with IL-6, IL-10, lgG, LTF, and LPO was shown Table (6). There was no clear relationship between Shaele breed SCC and IgG, LTF, or LPO. SCC and Shaele breed IL-6 were shown to be significantly positively correlated (P<0.01). Furthermore, there was a substantial positive association (P<0.05) between the Shaele breed's IL-10 and LPO serum.

Table (6): Correlation matrix of TNF-α to IL-6, IL-10, lgG, LTF and LPO of Shaele breed:

Significant positive correlations between a number of immunological and milk quality measures were found by the North location breed's correlation study Table (7). The characteristics of bacterial interactions affecting SCC levels were confirmed by the strong correlations found between TPC and Enterobacteriaceae and between TPC and coliforms. Protein displayed positive relation with urea and citric acid, whereas fat displayed negative associations with urea, suggesting metabolic changes linked to udder inflammation. Positive correlations between lactose, TS and SNF indicate continuous structural interrelation. Positive correlations between serum and milk lactoferrin (LTF) and lactoperoxidase (LPO) were observed in immunological markers, indicating a harmonized systemic and local immune reaction. On the other hand, milk's IgG showed a negative correlation with both LTF and LPO suggesting that the immune system was locally suppressed throughout the infection.

The mammary gland's subclinical inflammatory responses were highlighted by cytokine correlations that showed positive connections between SCC and both IL-6 and IL-10.

Table (437): Correlation matrices of SCC to bacteriological, physicochemical and immunological parameters of North location

The North location breed's correlation study Table (8) showed a number of distinguishable connections between immunological markers and cytokines. Serum LTF and milk LPO and serum LTF and IL-10 were shown to be positively correlated, suggesting that systemic immune components and mammary cytokine activity interact strongly. Additionally, serum LPO showed a positive correlation with both milk LTF and IL-10, indicating that the blood and milk compartments' inflammatory communication was in the same time. On the other hand, IgG in milk showed a negative correlation with both LTF and LPO, indicating that Fluid-phase immunity was locally suppressed in the mammary gland. The positive correlation between milk LTF and LPO emphasizes how these antimicrobial proteins work together to defend against subclinical mastitis.

Table (8): Correlation matrix of TNF-α to IL-6, IL-10, lgG, LTF and LPO of North location

SCC did not exhibit any significant associations with bacteriological parameters, according to the South location breed's correlation study Table (9). SCC, citric acid and acidity showed positive relationships, indicating slight compositional and metabolic alterations linked to breast inflammation. Total solids (TS), lactose and urea showed high correlations with fat, protein and casein, suggesting that the constituents of milk react collectively to subclinical stress. Modified nitrogen metabolism in infected animals may be seen in negative relationships between fat and urea and between casein and urea. Lactose showed a persistent positive correlation with urea, citric acid and SNF, indicating that it is sensitive to changes in udder health. In terms of immunology, there was a significant correlation between SCC and serum LPO and a positive correlation between IgG and LTF in milk, which indicated an activation of local immunological defence mechanisms. These results support the idea that immunological and physicochemical markers work together to detect subclinical mastitis in southern herds.

Table (9): Correlation matrices of SCC to bacteriological, physicochemical and immunological parameters of South location

Table (10) showed the correlation matrix of TNF-α to IL-6, IL-10, lgG, LTF and LPO of the South breed. The obtained results declared that TNF-α, IL-6 and IL-10 do not significantly correlate with SCC. IgG serum and LTF serum of the South location breed showed a strong negative connection (P<0.05). Furthermore, there was remarkable positive association (P<0.05) between the LPO serum of the South location breed and IgG milk and strong positive correlation (P<0.01) between LPO serum and LTF milk of the South location breed. LPO milk and the South location breed's IL-10 had a considerably positive (P<0.05) association (Table 10).

Table (10): Correlation matrix of TNF-α to IL-6, IL-10, lgG, LTF and LPO of South location:

The Majaheem breed's observed correlations Table (1) showed high relationship between somatic cell count (SCC) and a number of important immunological and milk composition parameters. SCC is positively correlated with lactose, solids-not-fat (SNF) and total solids (TS), suggesting that subclinical inflammation influences milk production, possibly via cellular and osmotic regulatory mechanisms. Abnormal lactose metabolism and changes in milk solid composition due to reduced mammary epithelial function frequently accompany higher SCC. Lower metabolic efficiency and a deterioration in the body's natural antimicrobial defence during inflammation are indicated by the negative correlations found between fat and urea, as well as between SCC and lactoferrin (LTF) and milk lactoperoxidase (LPO). In response to subclinical mastitis, the local innate immunity is weakened, which is reflected in the inhibition of important iron-binding and antimicrobial proteins, LTF and LPO (El-Deeb and Fayez, 2022).

The observed character of the synthesis of milk components is shown by the positive correlations between citric acid, TS, SNF and casein. As a compensating mechanism to preserve udder homeostasis, the positive correlation between serum and milk LPO and LTF further implies that systemic immune activation resembles local mammary responses. Overall, these interrelationships underline the complex nature of subclinical mastitis in camels, where physicochemical alterations in milk composition are closely linked to immune regulation and metabolic stress within the mammary gland.

The Majaheem breed's cytokine correlations Table (2) demonstrated how complex immunological interactions takes place during subclinical mastitis (SCM). The primary pro- and anti-inflammatory cytokines (TNF-α, IL-6, and IL-10) did not significantly correlate with SCC however, the positive correlations between LTF milk and LPO and between LPO serum and milk LTF indicate that antioxidant and antimicrobial proteins in the mammary gland actively Determine their local immunological responses. The idea that lactoferrin and lactoperoxidase work together to control oxidative stress and prevent bacterial development in inflammatory circumstances is supported by this pattern (El-Deeb and Fayez, 2022). Furthermore, the positive correlation found between IL-6 and LTF milk suggests that IL-6 may enhance nonspecific defensive mechanisms by promoting the production or secretion of lactoferrin, a recognized acute-phase glycoprotein that rises during breast inflammation. The participation of macrophages and neutrophils in the udder has been connected to the simultaneous activation of the IL-6 and LTF pathways, which helps to control infection (El-Deeb and Fayez, 2022). Overall, these correlations showed that local defence proteins, rather than systemic cytokine fluctuations, largely control immune regulation during subclinical mastitis in Majaheem camels. This reflects a balanced protective response meant to preserve milk secretion while reducing tissue damage.

Clear relationships between somatic cell activity, bacterial burden and milk composition regarding subclinical mastitis are shown by the correlation results in the Waddah breed Table (3). The substantial positive correlation between SCC and TPC suggests that higher bacterial contamination is correlated with increasing somatic cell activity. This result is in line with earlier studies that found higher SCC is associated with microbial stress in camel milk (El-Deeb and Fayez, 2022). The microbial diversity characteristic of subclinical mastitis is also seen in the high associations of TPC with Enterobacteriaceae and coliforms (Rahmeh et al., 2022). Fat, protein and casein all exhibited strong relationships within the physicochemical parameters and had positive correlations with urea, solids nonfat (SNF) and total solids (TS), suggesting metabolic change in the composition of milk during infection. These connections showed that protein synthesis pathways and food partitioning are affected by mastitis, leading to changes in composition that are consistent with an inflammatory mammary environment (Khaliq et al., 2024). The negative correlation between SCC and milk lactoperoxidase (LPO) gives credibility to the immunological theory that increased cellular activity reduces the activity of local antimicrobial enzymes. The positive relationship between serum lactoferrin (LTF) levels and milk, on the other hand, points to interlinked systemic and local immune regulation, in which the elevated expression of milk defence proteins is correlated with serum immune activation. An adaptive mechanism that preserves udder homeostasis while minimizing tissue injury is probably reflected in this reaction (Alhafiz et al., 2022). With all variables considered, these associations highlight how closely microbial load, milk composition and immune function interact. They showed that Waddah camels use a combination of physiological responses, including compositional alterations and Adaptive immune regulation to adjust to subclinical mastitis.

The Waddah breed's correlation analysis Table (4) showed complex immunological relationships between immune-related milk proteins and cytokines in subclinical mastitis circumstances. TNF-α and milk lactoferrin (LTF) had a strong positive link, which means that pro-inflammatory cytokine activation may promote lactoferrin synthesis as part of the mammary gland's local defence response, even though TNF-α, IL-6 and IL-10 did not significantly correlate with SCC. During inflammatory periods, TNF-α increases the expression of the LTF gene in immunological and epithelial cells, which is consistent with previous findings (El-Deeb and Fayez, 2022; Al-Qudah et al., 2023). The presence of systemic and local immune responses is further supported by the high positive association seen between serum and milk LTF. In addition to its antibacterial properties, lactoferrin is an immunomodulator that affects cytokine balance, lowers excessive TNF-α release, and preserves tissue integrity (Redwan et al., 2023). According to observations in dromedary camels that demonstrate species immune adaptation to persistent subclinical infection, the lack of significant correlations between TNF-α and the anti-inflammatory cytokines IL-6 and IL-10 may suggest that natural humoral mediators like LPO and LTF are more important for regulating inflammation in Waddah camels than cytokine (Rahmeh et al., 2022). All of these relationships declare the possibility that Waddah camels preserve a healthy immunological community during subclinical mastitis, where milk-borne antimicrobial proteins closely regulate cytokine activity to avoid too much inflammation and maintain mammary function as well.

The Shaele breed's correlation patterns Table (5) showed complex relations between the immunological, physicochemical and bacteriological factors linked to subclinical mastitis. The strong positive correlation between total plate count (TPC) and coliform count showed that the total bacterial load in camel milk is strongly associated with contamination by pathogens and reflects the microbial complexity characteristic of subclinical diseases (Rahmeh et al., 2022). The change in the composition of milk during inflammatory conditions is shown by the strong positive correlations observed between fat, casein, urea and citric acid. These findings supported previous studies that found that protein and fat fractions are particularly susceptible to breast stress, often exhibiting interdependent changes due to disrupted synthetic and metabolic activities in mammary epithelial cells (Khaliq et al., 2024; El-Deeb and Fayez, 2022). Protein denaturation or unbalanced casein micelle production under inflammatory stress may be indicated by the found negative associations between casein and SNF, urea and citric acid. Furthermore, the positive correlations observed among lactose, SNF and citric acid showed metabolic relation between carbohydrates and nonfat solids, suggesting that udder health condition simultaneously influences energy related metabolites. The physicochemical measures of milk quality serve as sensitive markers for early inflammatory alterations in camel milk, as seen by the favourable correlations found between FFA, density and acidity (Alhafiz et al., 2022). Immunologically, SCC did not exhibit a high link with either LTF or LPO however, the mild correlations between these parameters suggest a limited local immune response. According to many scientific reports, IL-6 upregulation is an early signal for mammary inflammation, the activation of IL-6, which exhibited a strong positive relationship with SCC (P<0.01), showed that IL-6 may function as an early immunological biomarker of subclinical mastitis in Shaele camels (Al-Qudah et al., 2023). In general, the obtained results illustrated the complex interactions between compositional and immune indicators in Shaele camel milk, which supports the use of combined biochemical and immunological profiling for early identification of subclinical mastitis.

The Shaele breed's correlation matrix Table (6) showed that immunological markers and cytokine activity interact selectively during subclinical mastitis. The lack of a substantial correlation between SCC and immunoglobulin G (IgG), lactoferrin (LTF), and lactoperoxidase (LPO) suggests that cell destruction may not always be accompanied by observable alterations in systemic immune proteins. However, as IL-6 is one of the first cytokines released during mammary infection, encouraging leukocyte recruitment and acute-phase protein synthesis, the high positive connection between SCC and IL-6 (P < 0.01) indicates an active inflammatory response (Al-Qudah et al., 2023; Singh et al., 2024). Additionally, an anti-inflammatory mechanism was shown by the substantial positive association (P < 0.05) between serum LPO and IL-10. Controlling peroxidase enzymes like LPO, IL-10 was known to strengthen antioxidant defences while reducing overproduction of pro-inflammatory signals (such as TNF-α). According to the obtained results, Shaele camels have a healthy immune system that prevents tissue injury and maintains the antibacterial activity of the mammary gland (Redwan et al., 2023; El-Deeb and Fayez, 2022). In line with research showing species immunological differentiation in other dromedary breeds, TNF-α and immunological proteins (LTF, LPO) did not significantly correlate, indicating that local mammary signaling rather than systemic cytokine pathways may be the primary mechanism of cytokine regulation in Shaele camels. (Rahmeh et al., 2022). While LTF and LPO represent antioxidant and immune protective responses, these findings collectively demonstrate that IL-6 and IL-10 may be useful early indicators for subclinical mastitis in Shaele camels.

The complex nature of subclinical mastitis was confirmed by the North location breed Table (7), which showed considerable interrelationships between bacteriological, physicochemical and immunological markers. The idea that somatic cell elevation is directly related to bacterial burden and microbial diversity within the mammary gland was supported by the strong positive correlations observed between total plate count (TPC), Enterobacteriaceae and coliforms (Rahmeh et al., 2022). These bacterial relationships agreed with previous research that demonstrated that microbial contamination enhances inflammatory responses., resulting in elevated SCC and changed milk quality (El-Deeb and Fayez, 2022).

Regarding composition of milk, protein exhibited strong positive relationships with both urea and citric acid, whereas fat had a negative relationship with urea. According to Khaliq et al., (2024) and Hamed et al., (2024), these data suggest metabolic reprogramming of the mammary gland during inflammatory stress, which may be a reflection of nitrogen redistribution and lipolytic activity during infection. Consistent with these findings in dairy camels and cattle, the positive correlations between lactose, total solids (TS) and solids nonfat (SNF) showed that compositional dependency is constant even during early subclinical mastitis (Singh et al., 2024). Positive immunological correlations between serum and milk lactoferrin (LTF) and lactoperoxidase (LPO) indicate that systemic and local immune responses are linked. This integration enhances antibacterial protection in both channels and has been identified as a characteristic of camel natural immunity (Redwan et al., 2023; Al-Qudah et al., 2023). On the other hand, milk IgG showed negative associations with both LTF and LPO demonstrating the local suppression of immune function within the mammary gland. This process most likely aims to prevent the activation of excessive numbers of inflammatory cells (Alhafiz et al., 2022). Strong positive relationships between SCC and IL-6 (P < 0.01) and IL-10 (P < 0.05) were found by the cytokine analysis. These findings showed that IL-6 plays a critical pro-inflammatory role during subclinical infection, while IL-10 acts as an anti-inflammatory regulator, maintaining immunological regulation. A similar interaction between IL-6 activation and IL-10-mediated reduction has been observed in mastititic dairy species, which is believed to be essential for minimizing tissue injury and sustaining milk production (Al-Qudah et al., 2023; Singh et al., 2024). According to these findings, the North location camels' response to subclinical mastitis appears to be an integrated physiological mechanism that combines immunological regulation, bacterial control, and metabolic adaptation. This demonstrates the camel mammary immune system's resistance to environmental and microbiological stress.

Significant interactions between cytokines and immunological markers were found in the North location breed, according to the correlation matrix Table (8), which indicates that the immunological control of the mammary gland is effectively regulated. To maintain udder physiological equilibrium, local anti-inflammatory action is linked to systemic antimicrobial defences, according to positive correlations found between serum lactoferrin (LTF) and both milk lactoperoxidase (LPO) and IL-10 (El-Deeb and Fayez, 2022; Redwan et al., 2023). Similarly, immunological signaling that is regulated between the milk and blood sections is made possible by the positive association between serum LPO and milk LTF (Elmahallawy et al., 2023). On the other hand, milk IgG negative correlations with both LTF and LPO suggest localized immune suppression during subclinical infection, which is probably meant to reduce tissue damage while maintaining the effectiveness of the immune system (Khaliq et al., 2024; Younas et al., 2022). The cooperative antibacterial activity of milk LTF and LPO in preserving milk quality under inflammatory stress is further shown by the considerable positive association between both parameters (Al-Juboori et al., 2024).

The correlation study for the South location breed Table (9) showed no significant associations between SCC and bacteriological measures, which agreed with research showing that subclinical mastitis can develop even when there is no observable bacterial growth (Ahmed et al., 2023; Mohamed et al., 2022). But SCC was positively correlated with acidity and citric acid, which probably reflects changes in composition and metabolism linked to oxidative stress and subclinical inflammation in mammary tissues (Bouwman et al., 2024). Total solids (TS), lactose, urea and the main milk proteins (fat, protein and casein) have all been shown to positively correlate with one another. This indicates that milk components cooperate to maintain nutritional composition and osmotic balance under inflammatory stress (Maqsood et al., 2023; Ben Chedly et al., 2022). Altered nitrogen metabolism in stressed or infected mammary glands may be indicated by negative correlations between fat and urea and between casein and urea (Al-Dughaym et al., 2024). Additionally, as previously noted in dromedary mastitis research, lactose positive connection with urea, citric acid and solids nonfat (SNF) indicates that it continues to be a sensitive indication of udder health (Elzaki et al., 2024). From immunology point of view, the positive link between SCC and serum lactoperoxidase (LPO) and the association between milk lactoferrin (LTF) and IgG suggests that immune defense mechanisms are activated locally. The idea that physicochemical and immunological markers work together to aid in the early diagnosis of subclinical mastitis is supported by the interaction between enzymatic antioxidants and immunoglobulins (Al-Majali et al., 2023; Raziq et al., 2024).

These results support the idea that milk composition influences both natural and adaptive immune responses, and that combining immunological and biochemical profiles can improve the sensitivity of diagnosis for subclinical mastitis in southern camel herds.

The South location breed's correlation study Table (10) showed complex relationships between immunological markers and cytokines that represent both systemic and local immune regulation during subclinical mastitis. Compatible with previous research on dairy cows and camels, the lack of significant correlations between SCC and pro-inflammatory cytokines (TNF-α, IL-6 and IL-10) raises the possibility that inflammatory signalling is localized and unrelated to total somatic cell activity (Mekonnen et al., 2023; El-Sayed et al., 2022). A significant negative correlation (P<0.05) between IgG serum and LTF serum suggests a potential regulatory balance between humoral and innate immune components. There have been reports of antagonistic relationships in which antimicrobial proteins like lactoferrin may be suppressed by high IgG activity (Shahin et al., 2023). On the other hand, the positive associations found between blood LPO and milk IgG (P<0.05) and LTF (P<0.01) demonstrated how antioxidant enzymes and immunoglobulins improve udder defense (Faye and Abdelgadir, 2022; Al-Shaikh et al., 2024). The importance of anti-inflammatory cytokines in supporting lactoperoxidase-mediated mucosal protection during subclinical infections is further shown by the substantial correlation (P<0.05) between milk LPO and IL-10 (Zaher et al., 2023). All of these results declared that the South African breed's innate immunity (LTF, LPO) and cytokine responses (IL-10) working together to maintain udder health and control localized inflammatory stress.

The current study emphasizes the complex relationships between the somatic cell count (SCC) and immunological, physicochemical and bacteriological characteristics of dromedary camel milk. Although SCC alone is unable to adequately characterize the state of udder health, it can more accurately reflect the variables and nature of subclinical mastitis (SCM) when paired with biomarkers like lactoferrin (LTF), lactoperoxidase (LPO) and cytokines (IL-6, IL-10). The relations between serum and milk immunological markers reflect a systemic response linked to local inflammation.  These findings improve our understanding of the pathophysiology of SCM in camels and contribute to the development of more precise diagnostic and preventative methods to improve milk quality, animal welfare and camel herd productivity.

Conflict of interest

The authors state that there is no conflict of interest.

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