Received: 29/09/2025 Accepted: 27/12/2025 Published: 09/01/2026 1 of 8 https://doi.org/10.52973/rcfcv-e361807 Revista Cientíﬁca, FCV-LUZ / Vol. XXXVI ABSTRACT Sustainable feeding strategies are needed to improve the quantity and quality of sheep milk. This study evaluated the impact of partially substituting conventional concentrate with date by– products, with or without the addition of Saccharomyces cerevisiae, on the physicochemical composition of milk produced by Ouled Djellal ewes. 30 ewes were randomly divided into 5 groups. All ewes received wheat straw (1 kg·ewe -1 ) as roughage (66.66%). In addition to wheat straw, the control group received 33% concentrate (33CON), and the 4 experimental groups received different levels of date by–products and concentrate: 8.33% date by–products + 25% concentrate (8.33 date by–products), 25% date by–products + 8.33% concentrate (25 date by–products), 16.6% date by–products + 16.6% concentrate (16.6 date by– products), and 16.6% date by–products + 16.6% concentrate with Saccharomyces cerevisiae (16.6 date by–products sc). The milk samples were analyzed to determine their fat, protein, lactose, total solids, and non-fat solids content. Milk fat content (P<0.01) and total solids (P=0.025) were signiﬁcantly higher in the experimental groups than in the control group, particularly in the 25 date by– products and 16.6 date by–products sc rations. Protein and non-fat solids content increased numerically without reaching statistical signiﬁcance, while lactose levels remained relatively stable in all treatments. Partial substitution of concentrate with date by– products improved milk quality, indicating that date by–products can be a sustainable feed resource for dairy ewes, thereby adding value to their milk products. Key words: Dietary Supplements; milk composition; Saccharomyces cerevisiae; date by product; milk ewes RESUMEN Se necesitan estrategias de alimentación sostenibles para mejorar la cantidad y la calidad de la leche de oveja. Este estudio evaluó el impacto de la sustitución parcial del concentrado convencional por subproductos de dátiles, con o sin la adición de Saccharomyces cerevisiae, en la composición ﬁsicoquímica de la leche producida por ovejas Ouled Djellal. 30 ovejas fueron divididas aleatoriamente en 5 grupos. Todas las ovejas recibieron paja de trigo (1 kg·oveja $1–1 ) como forraje (66,66 %). Además de la paja de trigo, el grupo de control recibió un 33 % de concentrado (33CON), y los 4 grupos experimentales recibieron diferentes cantidades de subproductos de dátiles y concentrado: 8,33 % subproductos de dátiles + 25 % C (8,33 subproductos de dátiles), 25 % subproductos de dátiles + 8,33 % C (25 subproductos de dátiles), 16,6 % subproductos de dátiles + 16,6 % C (16,6 subproductos de dátiles), y 16,6 % subproductos de dátiles + 16,6 % C con Saccharomyces cerevisiae (16,6 subproductos de dátiles sc). Las muestras de leche fueron analizadas para determinar su contenido de grasa, proteína, lactosa, sólidos totales y sólidos no grasos. El contenido de grasa de la leche (P<0,01) y los sólidos totales (P=0,025) fueron signiﬁcativamente más altos en los grupos experimentales que en el grupo de control, particularmente en las raciones de 25 subproductos de dátiles y 16,6 subproductos de dátiles sc. El contenido de proteínas y sólidos no grasos aumentó numéricamente sin alcanzar signiﬁcancia estadística, mientras que los niveles de lactosa se mantuvieron relativamente estables en todos los tratamientos. La sustitución parcial del concentrado por subproductos de dátiles mejoró la calidad de la leche, lo que indica que los subproductos de dátiles pueden ser un recurso alimenticio sostenible para las ovejas lactantes, añadiendo así valor a sus productos lácteos. Palabras clave: Suplementos dietéticos; composición de la leche; Saccharomyces cerevisiae; subproductos de dátiles; leche de oveja Physicochemical characteristics of ewe’s milk following partial substitution of concentrate with Date by–products and Saccharomyces cerevisiae Características ﬁsicoquímicas de la leche de oveja tras la sustitución parcial del concentrado con subproductos de dátiles y Saccharomyces cerevisiae Tarek Boussaada 1 * , Salha Amira Benatallah 2 , Boukaous Leyla 2 , Kaouthar Lakhdari 1 , Abdelhamid Djekoun 2 , Nedjoua Lakhdara 3 1 Scientiﬁc and Technical Research Centre for Arid Areas (CRSTRA). Biskra 07000, Algeria. 2 Pharmaceutical Sciences Research Center (CRSP). Constantine 25000, Algeria. 3 Université des Frères Mentouri Constantine 1, Institut des Sciences Vétérinaires El – Khroub, Laboratoire de Recherche Gestion Santé et Productions Animales (GSPA). Constantine 25000, Algeria. Corresponding author: boussaadatarek@gmail.com

Physicochemical characteristics of Ewe’s Milk / Boussaada et al._______________________________________________________________ 2 of 8 INTRODUCTION In Algeria, sheep (Ovis aries) farming is a strategic component of food security, It plays a vital role in animal production systems [1]. However, climate change has exacerbated nutritional challenges, leading to chronic or seasonal undernutrition and, consequently, suboptimal productivity in sheep [2]. Addressing this issue requires rethinking traditional feeding practices, particularly through the use of locally available agro– industrial by–products as alternative feed resources. Such by– products can reduce livestock dependence on human–edible cereals and lower feed costs and waste management expenses [3]. Among these, date palm by–products represent a promising energy- rich resource for ruminant feeding [4, 5]. Their high energy content makes them especially suitable for lactating ewes, which experience a signiﬁcant energy deﬁcit during early lactation [3, 6]. However, due to their low crude protein content, supplementation with additional protein sources is necessary to achieve a balanced diet [7]. Recent studies have also demonstrated the beneﬁcial effects of Saccharomyces cerevisiae as a dietary additive. When administered in adequate amounts, this yeast can enhance rumen microbial activity, improve nutrient utilization, and support the overall health and productivity of ruminants [8, 9]. The formulation of balanced diets for ewes at the end of gestation is essential to ensure maternal health and optimize milk quality. Conventional diets often rely on ingredients such as maize and soybean, valued for their energy and protein content [10]. However, in regions where these feedstuffs are not locally produced, reliance on imports can be costly and unsustainable. The use of abundant, low–cost agro–industrial by–products thus represents a sustainable alternative, contributing to feed cost reduction and adding value to local dairy and meat products [11]. Several international studies have investigated the incorporation of date residues in ruminant diets to improve milk production and composition [12, 13, 14, 15]. However, limited research has focused on the partial replacement of concentrate with date by– products (DBP) in ewes of the Algerian breed of Ouled Djellal and its speciﬁc effect on milk quality. Most previous work has emphasized growth performance and metabolic responses [5, 16]. This study aims to promote optimal lactation by encouraging the production of milk rich in essential nutrients for lambs. It does this by evaluating the impact of partially replacing concentrate with DBP and S. cerevisiae on the chemical composition of milk from Ouled Djellal ewes, thereby encouraging the use of locally available resources for sustainable sheep production. MATERIALS AND METHODS Experimental design, animal management, and feeding strategy The experiment was carried out at El Baraouia farm (14 km SE of Constantine, 2 km NW of El–Khroub) in a semi-intensive housing system ensuring welfare standards, natural light, and ventilation. Thirty healthy Ouled Djellal ewes (2–4 years, 62.92 ± 5.10 kg), both multiparous and primiparous, were selected at the last month of gestation and monitored until two months postpartum. Animals were dewormed with fenbendazole (5 mg·kg -1 , per os), and ivermectin 1% (1 mL·50 -1 kg body weight, injectable solution for subcutaneous administration), supplemented with a multivitamin preparation containing Vit. A, Vit. D₃, Vit. E, Vit. B₁, Vit. B₂, Vit. B₆, Vit. PP, d–panthenol, and Vit. B₁₂, administered as a 3–5 mL subcutaneous or intramuscular injection, and randomly assigned to ﬁve groups (six ewes each). Feed was offered once daily, with water ad libitum. A 15–day (d) adaptation period preceded the trial, with gradual introduction of DBP and yeast. Representative feed samples (100 g) were collected for analysis. The composition of the control and experimental diets, including the concentrate, DBP, and S. cerevisiae, are presented in TABLE I. Analytical methods for the determination of chemical composition in forage samples In this study, the chemical composition of feeds offered to ewes was analyzed using standard forage protocols [17]. Samples were ground, stored in airtight containers, and analyzed at the Scientiﬁc Research Center for Biotechnology and the accredited laboratory “Catalyse Lab,” with each test performed in triplicate. The chemical composition of the three feed ingredients is presented in TABLE II. TABLE I The food rations oﬀered to the ewes in the experimental groups and the control group, in percentage and grams Groups Rations Concentrate Date by-product Wheat straw Saccharomyces cerevisiae (g/ewes) % g % g % G Experimental 8.33 DBP 25 375 8.33 125 66.66 1000 0 25 DBP 8.33 125 25 375 66.66 1000 0 16.66 DBPsc 16.66 250 16.66 250 66.66 1000 2 16.66 DBP 16.66 250 16.66 250 66.66 1000 0 Control 33.33 CON 33.33 500 0 0 66.66 1000 0 Ration 8.33 DBP: Wheat straw + concentrate and date by product (66.66%: 25%: 8.,33%). Ration 25 DBP: Wheat straw + concentrate and date by product (66.66%: 8.33%: 25%). Ration 16.6 DBPsc: Wheat straw + concentrate + date by product + Saccharomyce cerevisiae (66.66%: 16.66%: 16.66%: 2 g S. cerevisiae /ewes). Ration 16 DBP: Wheat straw + concentrate and date by product (66.66%: 16.66%: 16.66%). Ration 33.3 CON: Wheat straw + concentrate (66.66%: 33.33%)

_______________________________________________________________________________________________Revista Cientiﬁca, FCV-LUZ / Vol. XXXVI 3 of 8 Milk sampling and physicochemical analysis in lactating Ouled Djellal ewes Milk sampling and analysis were conducted during the ﬁrst week of lactation on Ouled Djellal ewes from the ﬁve and the milk produced is intended exclusively for breastfeeding lambs. Following the removal of foremilk, individual 20 mL samples were collected aseptically each morning at 7:00 a.m. into sterile dry tubes and stored at 4°C. After homogenization, samples were analyzed using the Milkoscan™ Minor infrared spectrophotometer (FOSS Electric, Hillerød, Denmark) at the Constantine Biotechnology Research Center. This device enabled simultaneous quantiﬁcation of key physicochemical parameters, including fat content, protein, lactose, total solids, and non–fat solids. Statistical analysis Data entry and statistical analyses were performed using XLSTAT 2018.1.1. These tools were used to calculate means, standard deviations, and standard errors for quantitative variables, as well as to compare percentages and means. A descriptive analysis was ﬁrst conducted, followed by a one-way analysis of variance (One-Way ANOVA). When signiﬁcant differences were detected, the Newman–Keuls post–hoc test at a 5% significance level was applied to identify homogeneous groups. Differences were considered statistically signiﬁcant at P<0.05. RESULTS AND DISCUSSION Influence of rations on milk quality in Ouled Djellal ewes The variations in the chemical parameters of milk are presented in TABLE III. Milk Fat composition According to the results of milk fat content in TABLE III. A highly signiﬁcant difference (P=0.0002) was observed between the milk produced by ewes receiving the ﬁve different dietary treatments: 8.33 DBP, 25 DBP, 16.6 DBPsc, 16.6 DBP, and 33.3 CON. The highest values were recorded in the rations supplemented with DBP and DBP with S. cerevisiae, particularly in the 25 DBP (10.34%) and 16.6 DBPsc (10.22%) groups, compared to the other treatments and the control group 33.3CON (4.38%). TABLE II Chemical composition of the three feeds (wheat straw, concentrate, date by–products) Chemical composition (% DM) Concentrate Date by–product (Date waste) Wheat straw Dry matter (DM) 90.86 91.34 87.69 Ether extract (EE) 2.95 1.48 2.37 Organic matter (OM) 97.29 95.87 93.62 Mineral matter (MM) 2.7 4.12 6.37 Crude proteins (CP) 10 4.28 5.68 Neutral Detergent Fiber (NDF) 33.8 32.5 68 Acid Detergent Fiber (ADF) 28.7 28.1 37.9 Acid Detergent Lignine (ADL) 11.7 6.69 5 Crude ﬁbre (CF) 8.8 6.66 23.98 Cellulose 17 21.41 32.9 Hemicellulose 5.1 4.4 30.1 TABLE III Variations in the chemical parameters of milk according to the incorporation of date by–products and Saccharomyces cerevisiae in the ration at the beginning of lactation Chemical parameters (%) 8.33DBP 25 DBP 16.6 DBP sc 16 DBP 33CON P Milk fat (MF) 7.52 ± 0.78 b 10.34 ± 0.70 a 10.22 ± 0.78 a 7.52 ± 0.78 b 4.38 ± 0.78 c 0.0002 Crude proteins (CP) 14.55 ± 2.52 a 13.96 ± 2.52 a 13.48 ± 2.52 a 14.49 ± 2.52 a 5.90 ± 2.52 a 0.118 Lactose 3.11 ± 0.51 a 3.23 ± 0.46 a 3.57 ± 0.51 a 3.33 ± 0.51 a 3.84 ± 0.51 a 0.856 Total solids (TS) 25.26 ± 2.62 a 26.62 ± 2.34 a 26.19 ± 2.62 a 25.63 ± 2.62 a 14.77 ± 2.62 b 0.025 Not-fat solids (NFS)% 16.66±1.71 a 16.31 ± 1.53 a 15.86 ± 1.71 a 16.84 ± 1.71 a 10.35 ± 1.71 a 0.075 abc :Diﬀerent lowercase letters (a. b. c) in the same row indicate a signiﬁcant diﬀerence (P<0.05). Ration 8.33 DBP: Wheat straw + concentrate and date by product (66.66%: 25%: 8.33%). Ration 25 DBP: Wheat straw + concentrate and date by product (66.66%: 8.33%: 25%). Ration 16.6 DBPsc: Wheat straw + concentrate + date by product + Saccharomyces cerevisiae (66.66%: 16.66%: 16.66%: 2 g S. cerevisiae / ewes). Ration 16 DBP: Wheat straw + concentrate and date by product (66.66%: 16.66%: 16.66%). Ration 33.3 CON: Wheat straw + concentrate (66.66%: 33.33%)

Physicochemical characteristics of Ewe’s Milk / Boussaada et al._______________________________________________________________ 4 of 8 The milk fat content observed in this study exceeded the values reported by Abaidia et al. [18], who also supplemented Ouled Djellal ewes with DBP but did not ﬁnd a signiﬁcant effect on milk fat (5.08 g·L -1 ). However, Iqbal et al. [13] reported increased milk fat in Damani ewes with varying levels of date supplementation (3.8 at 10%, 4.07 at 20%, and 4.84 at 30%). In contrast, Al–Dobaib et al. [15] found no impact of date supplementation on milk fat content in goats. Other studies reported fat content values of 8.66% [19] and 6.83% [20] in Ouled Djellal sheep without date supplementation. Similarly, Valenti et al. [21] observed 8.29% fat after supplementing ewes with pomegranate pulp. According to Zebeli et al. [22] milk fat concentration is closely linked to diet composition and ruminal metabolism, serving as an indicator of rumen health and ﬁber adequacy in dairy animals. Kholif and Olafadehan [12] attributed the increase in fat content to the fact that, during the in vitro digestibility of date scraps, the degradation of ﬁbers produces volatile fatty acids (VFA), mainly acetic acid. This acid is the main precursor of fatty acid synthesis in the mammary gland, thus promoting the increase of milk fat. Another study by Urrutia et al. [23] shows that the intake of acetate in the diet signiﬁcantly increases the concentration and fat yield of milk, conﬁrming its key role in this process. The ﬁndings also demonstrate that S. cerevisiae supplementation improved milk fat concentration. This agrees with Zaleska et al. [24], who reported a signiﬁcant increase in milk fat at d 28 and 70 of lactation in ewes receiving S. cerevisiae. Similarly, Giger– Reverdin et al. [25] observed higher milk fat content in dairy goats following yeast supplementation. According to Dobicki et al. [26], yeast improves ruminal microbiota, enhances ﬁber degradation, and stimulates milk production by improving nutrient utilization and energy balance. Furthermore, You et al. [27] showed that S. cerevisiae can produce fatty acids, and through genetic modiﬁcations such as overexpression of acetyl–CoA carboxylase, thioesterase, and malic enzyme they achieved a 4.7–fold increase in fatty acid production compared to wild–type strains, suggesting potential beneﬁts in animal nutrition. In another study on dairy ewes (Chios), Mavrommatis et al. [28] tested the addition of 2 g of live yeast (ActiSaf) per animal, from pre–partum to post–partum. The results show a trend towards increased milk production, an improvement in the fatty acid composition of milk, and better use of energy. Conversely, Arambel and Kent [29] found that stimulation of cellulolytic bacteria did not affect milk yield or composition, likely due to the already adequate ADF content in the ration, which may have masked any additional effects on fat synthesis. Milk protein content As summarized in TABLE III, a non–signiﬁcant increase was observed between groups. The control group (33CON) exhibited the lowest protein content (5.90%), whereas higher values were recorded in the groups supplemented with date by–products, either alone or in combination with S. cerevisiae: 8.33 DBP (14.55%), 25 DBP (13.96%), 16.6 DBPsc (13.48%), and 16.6 DBP (14.49%). These values exceed those reported by Abaidia et al. [18], who, using the same breed, found no signiﬁcant effect between the control batch and the batch supplemented with date by– products (4.60% vs 4.88%). Iqbal et al. [13] observed a gradual increase in milk protein content in Damani ewes as dietary date waste levels increased (3.58, 3.63, 3.69% for 10, 20 and 30% supplementation, respectively). Similarly, Al-Dobaib et al. [15] reported a signiﬁcant rise in milk protein concentration in goats fed date by–products compared to control groups (3.05 vs 2.85%). Other studies on Ouled Djellal ewes receiving 500 g·d -1 of concentrate reported protein values of 0.84% [19]. However, supplementation with S. cerevisiae in the present study did not signiﬁcantly influence protein levels, consistent with the ﬁndings of Zaleska et al. [24] in Polish ewes and Milewski et al. [30] in Kamieniec ewes. Dann et al. [31] also reported no increase in milk protein content in dairy cows after yeast supplementation at 60 g·d -1 . In accordance with Al–Musawi et al. [32], The increase in protein content in the experimental groups is possibly explained by the addition of DBP, rich in easily fermentable carbohydrates. These carbohydrates increase the activity of rumen microorganisms. This results in increased production of ammonia (NH3–N) and VFA, promoting the growth of bacteria from the rumen, resulting in better ruminal fermentation. According to Khattab and Anele [33] Increased synthesis of microbial proteins augmented linearly as rejection dates increased in the ration (0 g:94.4 mg–93 g: 103 mg–187 g: 108 mg–280 g–121mg). Several studies have shown that milk protein levels, particularly casein, are influenced by the diet and nutritional status of the ewes. For example, Couteils [34], emphasizes the strong correlation between total protein content and caseins, while Coulon et al. [35] found that insufﬁcient energy intake in ewes can lead to reduced casein synthesis and overall milk protein. Milewski et al. [30] noted shifts in casein fractions, with reduced β–casein and increased κ– casein following S. cerevisiae supplementation, suggesting potential improvements in milk quality and cheese yield. Additionally, Sevi et al. [36] reported that as lactation progresses and ambient temperatures rise, milk volume tends to decrease while fat and protein concentrations increase, driven by reduced energy reserves and greater metabolic demands for thermoregulation. Lactose Content TABLE III present the variations in milk lactose content as influenced by the different diets. Statistical analysis revealed no signiﬁcant differences among the ﬁve groups, with lactose values remaining relatively close across treatments: 8.33 DBP (3.11%), 25 DBP (3.23%), 16.6 DBPsc (3.57%), 16.6 DBP (3.33%), and 33CON (3.84%). These ﬁndings align with those of Iqbal et al. [13], who also reported no signiﬁcant impact of DBP supplementation on lactose content. According to Grieve et al. [37], milk lactose composition appears largely unaffected by the energy content of the diet. Similarly, Yabrir [20] described lactose as the most stable and constant milk component compared to others. Kozloski [38] noted that higher concentrate levels in ruminant diets increase ruminal propionic acid production, enhancing glucose availabilitythe main precursor for lactose synthesis.

_______________________________________________________________________________________________Revista Cientiﬁca, FCV-LUZ / Vol. XXXVI 5 of 8 However, the present study did not reflect this effect, which agrees with ﬁndings by Kalantzopoulos [39], who emphasized that lactose is the principal osmotically active component of milk, generally remaining constant throughout lactation in healthy animals. Fernandes et al. [40] observed no change in milk lactose content in Santa Inês sheep supplemented with concentrate during pre and postnatal periods. Campos et al. [41] reported higher lactose levels in ewes receiving greater concentrate supplementation (0.4 vs. 0.8% of body weight), indicating that both pre – and postnatal nutrition directly affect milk quality and yield. Fredeen [42] further emphasized that lactose levels correlate more strongly with overall milk production than with diet composition alone, indicating that an increase in lactose is generally associated with a higher milk yield. In the present study, supplementation with S. cerevisiae did not signiﬁcantly affect milk lactose levels. This aligns with previous ﬁndings, which reported no increase in milk lactose in ewes with a dose of 3 g·kg -1 of feed·d -1 [24] 1g/head/d [43] and goats with a dose of 0.2 g·head -1 ·d -1 [25, 44] receiving yeast supplements. In contrast, Christodoulou et al. [45] observed a signiﬁcant rise in lactose in Chios and Lacaune ewes during the ﬁfth week of live yeast (1 g·d -1 ) supplementation. Abd El–Ghani [46] found a non-signiﬁcant increase in lactose levels with the increase in doses of S. cerevisiae between the supplemented batches at 3 g·d -1 and 6 g·d -1 (4.52 vs 4.65%). Jiménez–Sobrino et al. [47] noted a negative correlation between lactose content and both milk fat and protein concentrations in ewes. In the present study, lactose values remained within physiological norms, in line with those reported by Chachoua et al. [19] (2.98 g·L -1 ) and Rouissi et al. [48] (3.89%), and lower than those documented by Yabrir [20] (4.76%) and Sevi et al. [36] (5.21–4.70%). Total solids TABLE III illustrates the total solids (TS) content of milk collected from ewes subjected to different dietary treatments. A statistically signiﬁcant increase (P=0.025) in TS was observed in the milk of ewes fed rations supplemented with date by–products, with or without S. cerevisiae. The highest TS values were recorded in the following groups: 25 DBP (26.62%), 16.6 DBPsc (26.19%), 16.6 DBP (25.63%), and 8.33 DBP (25.26%), while the control group (33CON), which received 500 g of concentrate, showed a markedly lower value (14.77%). Al–Musawi et al [32] found that the energy and nutrients available from dates in the sheep diet can affect digestion and nutrient absorption and the efﬁciency of rumen microbes, by increasing the production of VFA and ammonia, essential for the synthesis of milk fats and proteins, thus contributing to the increase in TS. Contrary to our results, Abaidia et al. [18] did not observe a signiﬁcant effect of DBP supplementation on TS in milk from Ouled Djellal ewes. However, Campos et al. [41] reported higher TS levels (15.61%) in Santa Inês ewes supplemented with concentrated feed at 0,8% of body weight, suggesting that energy–dense diets may contribute to increased TS content. The elevated TS levels observed in the present study is likely influenced by the partial substitution of concentrate with DBP. The control diet (33CON), was insufﬁcient to maintain high TS content, indicating the potential nutritive value of DBP in enhancing milk quality. Similarly, Salama et al. [49] and Baiomy [50] found no signiﬁcant effect of S. cerevisiae supplementation on TS in dairy goats (0.9 g·d -1 : 13.2%) and Ossimi ewes (3 g·d -1 : 18.8%–6 g·d -1 : 19.5%), respectively. Conversely, Abd El–Ghani [46] reported an increase in total solids with increasing yeast doses in goat diets (3 g: 12.40%–6 g: 12.57%), highlighting the dose-dependent response of TS to yeast supplementation. According to Yabrir [20], coagulation time (CT) in milk is more closely related to TS and fat content than to physical properties such as pH or density. Higher TS and fat levels improve gel ﬁrmness and reduce CT, which suggests that the dietary treatments in our study could enhance the technological properties of ewe milk for cheese-making and other value–added products. Ochoa–Cordero et al. [51] reported a negative correlation between milk yield and TS content, known as the dilution effect, which may also contribute to variations observed across diets. Overall, the TS values of the control group and experimental groups obtained in our study exceed those previously reported on Ouled Djellal ewes, citing the results of Abaidia et al. [18], which were fed only from steppe pastures (19.6 g·L -1 ); Chachoua et al. [19], where the ewes were fed with 500 g·day -1 of concentrate (11.8 g·L -1 ); and Yabrir [20], where the ewes were fed with natural pasture, silage, and barley (16.65%), highlighting the positive impact of the tested rations on milk production. Non–fat solids The results related to the not-fat-solids content (NFS), presented in TABLE III, show a non-signiﬁcant increase associated with the inclusion of DBP in the diets. The lowest NFS value was recorded in the control group (33CON: 10.35%), while the groups receiving date-supplemented rations exhibited higher and relatively similar values, ranging from 15.86 to 16.84%. The NFS content in the control group aligns with physiological norms reported by Yabrir [20] (10.64%) and Selmi et al. [52] (10.92%). In contrast, NFS values observed in the groups supplemented with date by product were higher than these references but lower than those reported by Abaidia et al. [18] (17.83% g·L -1 ) in ewes of the same breed fed DBP at a rate of 400 g·animal -1 /day. These ﬁndings are consistent with those of Iqbal et al. [13], who demonstrated a proportional increase in NFS with increasing levels of date inclusion: at 10, 20, and 30%, NFS values were 8.40, 9.22, and 9.76%, although the absolute values were lower in their study. Conversely, Shariﬁ et al. [53] found no signiﬁcant effect on NFS in Saanen goats with low-quality date supplementation at different percentage: 12, 16, 18%, with values of: 8.07, 8.16, 8.06%. Campos et al. [41] reported a signiﬁcant increase in NFS in ewes receiving high-concentrate diets (0.4 and 0.8% of live weight), with values of 11.37 and 11.57%, compared to the control group 11.19%. According to Saleh et al. [54] The high soluble sugar and ﬁber content of discarded data can enhance the activity of ﬁbrolytic bacteria, leading to increased acetic acid production and reduced propionic acid levels, which improves the efﬁciency of nutrient conversion into fat and milk solids.

Physicochemical characteristics of Ewe’s Milk / Boussaada et al._______________________________________________________________ 6 of 8 Supplementation with S. cerevisiae did not signiﬁcantly influence NFS. However, a slight decrease that is not signiﬁcant was observed when comparing the yeast-supplemented ration (16.6 DBPsc: 15.86%) to the equivalent non-yeast ration (16.6 DBP: 16.84%). This observation aligns with ﬁndings by Baiomy [50] and Masek et al. [43], who reported no signiﬁcant impact on SNF in ewes supplemented with 3–6 g·d -1 and 1g of yeast. Similarly, Abd El–Ghani [46] observed no signiﬁcant difference in SNF in dairy goats even with increasing yeast supplementation (3 g·d -1 : 8.33%; 6 g·d -1 : 8.26%). According to Hachana et al. [55], NFS plays a direct role in the binding capacity between milk fat and water, and a high-protein diet does not induce an increase in NFS; only an increase in energy intake can increase NFS, which corroborates the trends observed in the present study. CONCLUSION The statistical evaluation of milk quality in ewes fed experimental diets revealed a signiﬁcant increase in milk fat content and total solids in animals receiving rations supplemented with date by– products and/or S. cerevisiae, compared to the control group. The 25 DBP and 16.66 DBPsc groups exhibited the highest fat concentrations, while all date-supplemented rations yielded higher total solids. In contrast, protein content, lactose and NFS, differences were not statistically signiﬁcant. These ﬁndings indicate that partial substitution of concentrate with DBP, with or without S. cerevisiae, can enhance the compositional quality of ewe’s milk, particularly in terms of solids and milk fat, offering potential beneﬁts for dairy product valorization. This work has demonstrated that DBP (date waste), a sustainable local resource treated as waste, can be used as an acceptable partial substitute in the diet of ewes in late gestation and lactation, replacing expensive imported concentrate and helping to reduce the high cost of imported feed paid by the state. ACKNOWLEDGEMENTS The authors would like to thank the farm workers of El Baraouia Farm for their valuable assistance in animal care and management during the study. Conflict of interest The authors declare no conflict of interests. BIBLIOGRAPHIC REFERENCES [1] Belkheir B, Ikken L, Benhamed N, Ghozlane F, Benidir M, Bousbia A, El Bouyahiaoui R. 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