In dairy sheep milk urea concentration (MUC) is highly and positively correlated with dietary crude protein (CP) content and, to a lesser extent, with protein intake. However, the effect of dietary energy and carbohydrate sources on MUC of lactating ewes is not clear. Thus, the objective of this study was to assess the effects of diets differing in energy concentration and carbohydrate sources on MUC values in lactating dairy ewes. Two experiments were conducted (experiment 1, E1, and experiment 2, E2) on Sarda ewes in mid and late lactation kept in metabolic cages for 23 d. In both experiments, homogeneous groups of five ewes were submitted to four (in E1) or three (in E2) dietary treatments, consisting of pelleted diets ranging from low energy (high-fiber diets: 1.2–1.4 Mcal of net energy for lactation (NE_L)) to high energy (high-starch diets: 1.7–1.9 Mcal of NE_L) contents, but with a similar CP concentration (18.4% dry matter (DM), on average). Each diet had a different main ingredient as follows: corn flakes, barley meal, beet pulp, or corn cobs in E1 and corn meal, dehydrated alfalfa, or soybean hulls in E2. Regression analysis using treatment means from both experiments showed that the best predictor of MUC (mg/100 mL) was the dietary NE_L (Mcal/kg DM, MUC = 127.6 − 51.2 × NE_L, R² = 0.85, root of the mean squared error (rmse) = 4.36, p < 0.001) followed by the ratio CP/NE_L (g/Mcal, MUC = −14.9 + 0.5 × CP/ NE_L, R² = 0.83, rmse = 4.63, p < 0.001). A meta-regression of an extended database on stall-fed dairy ewes, including the E1 and E2 experimental data (n = 44), confirmed the predictive value of the CP/ NE_L ratio, which resulted as the best single predictor of MUC (MUC = −13.7 + 0.5 × CP/NE_L, R² = 0.93, rmse = 3.30, p < 0.001), followed by dietary CP concentration (MUC = −20.7 + 3.7 × CP, R² = 0.82, rmse = 4.89, p < 0.001). This research highlights that dietary energy content plays a pivotal role in modulating the relationship between MUC and dietary CP concentration in dairy sheep.

The fatty acid profile, vitamins A and E, cholesterol, antioxidant power colour and the phenols profile of Sarda sheep milk from 11 commercial sheep flocks managed under permanent grassland were investigated. In each farm, the structural and managerial data and milk samples were collected during four periods (sampling dates, SD): January, March, May, and July. Data from the milk composition (fat, protein, casein, lactose, and somatic cell count), 68 fatty acids, 7 phenols, 1 total gallocatechin equivalent, ferric reducing antioxidant power, vitamins A and E, cholesterol, degree of antioxidant protection, and the colour (b *, a * and L *) were analyzed by multivariate factorial analysis using a principal component analysis approach. A proc mixed model for repeated measurement to point out the studied factors affecting significant macro and micro milk composition was also used. Only the first five components were detailed in this paper, with approximately 70% of the explained variance detected. PC1 presented the highest positive loadings for milk lactose, de novo FA synthesis and the BH intermediate, whereas OBCFA had negative loadings values. The PC2, LCFA, UFA, MUFA, vitamins E, and DAP showed positive loadings values, while SFA had a negative value. The PC3 showed a high positive loading for total phenols and non-flavonoids. PC4 presented a high positive loading for the milk macro-composition and negative values for n-3 FAs. The PC5 is characterized by high positive loadings for the a * and L * colour parameters whereas negative loadings were detected for the milk flavonoids content. These preliminary results could help to establish future threshold values for the biomarkers in milk sourced from grazing dairy sheep in natural, permanent pasture-based diets.

Seasonal variability in feed availability in Mediterranean dairy sheep systems can compromise animal performance and welfare, highlighting the need for reliable, high-frequency monitoring tools. Live weight (LW) is a key indicator of nutritional status, but conventional measurements are labour-intensive and poorly suited to dynamic conditions. Walk-over-weighing (WoW) systems integrated with electronic identification (EID) enable automated, continuous, individual-level LW monitoring. This study assessed the sensitivity of a WoW system to detect nutritionally driven LW changes in Sarda dairy ewes under indoor and grazing conditions. Two experiments were conducted: an indoor short-term nutritional challenge involving 24 non-lactating ewes and a grazing trial with contrasting pasture access times involving 48 lactating ewes. In both experiments, the WoW system detected consistent LW differences between nutritional treatments (p < 0.001), capturing both short-term responses and sustained LW dynamics. Differences were approximately 5%, indicating that the WoW system was sensitive to nutritionally induced LW variation under the experimental conditions of the present study, before marked changes in body condition score (BCS) became detectable. These results demonstrate that WoW systems can reliably capture LW trajectories in response to nutritional variation. However, LW responses should be interpreted cautiously, as short-term variation may also reflect gut fill and hydration dynamics, and intake information was not fully available at the individual level because some feed intake components were measured at the group level or estimated indirectly. Integrating automated LW data with production and management information may support group-level nutritional decisions and early detection of animals deviating from expected LW trajectories in precision dairy sheep systems.

This study evaluated the effects of replacing alfalfa hay with sulla [Sulla coronaria (L.) B.H. Choi & H. Ohashi] hay or sulla haylage in pasture-based diets for lactating Sarda ewes on milk production, milk composition, and nutrient utilization efficiency. Seventy-two mid-lactation ewes were assigned to three dietary treatments for 56 days—alfalfa hay (AH), sulla hay (SH), or sulla haylage (SHL)—all combined with 3 h/day grazing and a fixed amount of supplemental concentrate. The diets were formulated to be theoretically isoenergetic and isoproteic. Pasture nutritive value was generally comparable among the groups throughout the experimental period. Milk yield did not differ among treatments; however, fat- and protein-corrected milk (FPCM) and milk fat and protein concentrations were higher in AH compared with the sulla-based diets. Actual nutrient intake differed among treatments, with nitrogen intake (NI) being greatest in AH, consistent with the higher milk urea concentration observed in this group. Estimated apparent energy utilization efficiency (FPCM/UFL intake) showed treatment-associated differences in exploratory analyses, with lower values observed in SH compared with AH and SHL. Similarly, exploratory estimates of apparent nitrogen utilization efficiency (Milk N/NI) were highest in SHL, intermediate in SH, and lowest in AH (p < 0.001). Condensed tannins were not detected in the conserved sulla forages under the analytical conditions adopted in this study. Therefore, the observed responses were unlikely to be directly associated with detectable condensed tannin activity. Overall, the results suggest that forage conservation method may influence milk composition and estimated apparent nutrient utilization indices, with sulla haylage showing higher exploratory estimates of apparent nitrogen utilization efficiency without negative effects on milk yield under the conditions of the present study.

Accurate estimation of individual herbage intake in grazing ruminants is essential for improving feeding efficiency and animal performance, yet it remains challenging under field conditions. This study evaluated the association between live weight dynamics recorded by an automated walk-over-weighing (WoW) system and equation-derived herbage dry matter intake (HDMI) in dairy ewes and whether this association changed throughout lactation. The study was conducted over two years (2023–2024) using 92 Sarda dairy ewes managed under part-time grazing with two daily pasture access times (2 or 6 h day⁻¹). Live weight was recorded daily before and after pasture access, and daily live weight change was averaged weekly. HDMI was estimated using a published prediction equation based on milk yield, herbage neutral detergent fibre concentration, and pasture access time. Live weight change was partitioned into between-animal (DW_mean) and within-animal (DW_dev) components, allowing persistent differences among animals to be distinguished from short-term within-animal fluctuations, and analysed using linear mixed-effects models. In the pooled model, both components were positively associated with equation-derived HDMI (p < 0.001), while the significant DW_dev × days-in-milk interaction (p = 0.004) indicated that the association between within-animal live weight change and equation-derived HDMI decreased as lactation advanced. However, pasture access-time-specific sensitivity analyses showed that the associations with DW_mean and DW_dev persisted within AT-6h but were not detected within AT-2h, while adjustment for milk yield attenuated the within-animal association, which was no longer statistically significant, and also removed statistical support for the DW_dev × days-in-milk interaction. The mixed-effects model explained a substantial proportion of the variability in equation-derived HDMI (marginal R² = 0.64; conditional R² = 0.94), and equation-derived and model-fitted HDMI were positively correlated (r = 0.77). These findings indicate that WoW-derived live weight dynamics provide non-invasive information associated with equation-derived HDMI under the conditions of this study, but independent validation against directly measured individual herbage intake is required before their use for individual intake estimation.

This study evaluated the effects of replacing alfalfa hay with sulla (Sulla coronaria (L.) B.H. Choi & H. Ohashi) hay or sulla haylage in pasture-based diets for lactating Sarda ewes on milk production, composition, and nutrient utilization efficiency. Seventy-two mid-lactation ewes were assigned to three dietary treatments: alfalfa hay (AH), sulla hay (SH), or sulla haylage (SHL), all combined with 3 h/day grazing and concentrate supplementation. Diets were formulated to be theoretically isoenergetic and isoproteic. Pasture quality was comparable among groups throughout the experimental period. Milk yield did not differ among treatments; however, fat- and protein-corrected milk (FPCM) and milk components were higher in AH compared with sulla-based diets. Nitrogen intake (NI) was greatest in AH, as reflected by higher milk urea concentration. Energy utilization efficiency (FPCM/UFL intake) differed among treatments, with lower values in SH compared with AH and SHL. Protein utilization efficiency (Milk N/NI) was highest in SHL, intermediate in SH, and lowest in AH (p < 0.001). Condensed tannins were not detected in conserved sulla forages, suggesting that conservation processes may reduce the characteristic tannin-related nutritional effects of fresh sulla. Results indicate that forage conservation method influences nutrient utilization efficiency, with sulla haylage improving nitrogen efficiency without impairing milk yield.