Journal of Dairy Science最新文献

{"title":"Graduate Student Literature Review: Implications of preweaning social housing for long-term dairy cattle performance and welfare.","authors":"Emily E Lindner, Emily K Miller-Cushon","doi":"10.3168/jds.2026-28835","DOIUrl":"https://doi.org/10.3168/jds.2026-28835","url":null,"abstract":"<p><p>Dairy calf housing remains a focal point of discussion for producers, consumers, and animal welfare scientist. As animal welfare and animal care priorities shift, understanding the impacts social housing types has on the success of dairy heifers is vital for herd longevity and farm economics. Historically, dairy calves are reared in social isolation which can impair performance, behavior, and physiological development. Conversely, social housing of dairy heifers has yielded numerous short-term benefits surrounding cognitive and behavioral development, performance, and the formation of social bonds, particularly during the pre-weaning and weaning periods. While research remains limited, studies tracking long-term effects have shown variable performance benefits extending into lactation. This narrative review synthesizes what we currently know regarding the short- and long-term benefits of early-life social housing and discussion of the factors influencing longer-term behavioral and production outcomes in our dairy heifers.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Holstein male sale barn calves evaluated for total serum protein concentrations.","authors":"Ting Liu, Jiang Hu, Bingang Shu, David P Casper","doi":"10.3168/jds.2026-28560","DOIUrl":"https://doi.org/10.3168/jds.2026-28560","url":null,"abstract":"<p><p>Calves are born with minimal to no immune defense. Colostrum consumption by the calf is critical for transferring immunity from the mother to the newborn calf. Neonatal Holstein male dairy calves are routinely sold off the dairy operation to calf raisers and feedlots for meat production. Recently, recommendations were published for female dairy calves, but no recommendations were given for male dairy calves. A simple method for assessing the transfer of passive immunity is measuring total serum protein (TSP) concentrations within the first days of life. Total serum proteins are routinely measured in our contract research operation studying neonatal calf nutrition. The TSP concentrations for 1,327 Holstein male calves from the past 6 years across 19 separate experiments were measured using an optical with change to digital refractometer in 2021 summer. The mean TSP concentration was 5.40 g/dL with a range from 2.8 to 8.6 g/dL with a CV of 14.2% and SD of 0.77. Mean TSP concentrations increased with year (4.94, 5.40, 5.37, 5.42, 5.58, 5.62 g/dL for 2020, 2021, 2022, 2023, 2024, and 2025, respectively) indicating that dairy producers are improving their colostrum program for newborn Holstein male calves. The latest heifer immunity transfer status recommendations are excellent (>40%), good (>30%), fair (>20%), and poor (>10%), but these data percentages for Holstein male calves were, 14.4, 13.2, 37.0, and 35.5%, respectively for this summary. Thus, a large percentage of the male calves being sold through sale barns are in the poor and fair TSP categories. However, the percentage of poor TSP status has declined with time (60.0, 33.3, 33.2 30.1, 27.7, and 22.3%, for 2020, 2021, 2022, 2023, 2024, and 2025, respectively). Death loss was 4.0% across years and experiments. The death loss within TSP categories was 3.8, 15.1, 35.9, and 45.3% for excellent, good, fair, and poor, respectively. In conclusion, dairy operations are improving the colostrum management of Holstein male calves to minimize failure of passive immunity, but further management improvements are needed to achieve standard recommendations for heifers. A value proposition for calf buyers would be to test Holstein male calves for TSP concentrations at the sale barn before being sold. This would create potential value to both the buyer and seller.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of dietary protein level and rumen-protected methionine on lactation performance and blood metabolites in postpartum cows.","authors":"A C C Chuang, C Lee","doi":"10.3168/jds.2026-28710","DOIUrl":"https://doi.org/10.3168/jds.2026-28710","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Lactation responses, such as milk and milk protein yield, to rumen-protected Met (RP-Met) have been inconsistent in studies especially with transition cows and may depend on the MP supply. The objective of this study was to evaluate the interactive effects of RP-Met supplementation with dietary CP levels on lactation performance and blood metabolites in postpartum cows. Sixty-eight pre-fresh Holstein cows, including 36 multiparous and 32 primiparous cows, were blocked by parity and expected calving date in a randomized complete block design. Immediately after parturition, cows within each block were assigned to one of the 4 diets in a 2 × 2 factorial arrangement and remained until 28 DIM: LPD, a low-CP diet (16.5% on a DM basis); HPD, a high-CP diet (18.5%); LPDM, LPD supplemented with RP-Met (25 g/d of Smartamine M); HPDM, HPD supplemented with RP-Met (15 g/d). For LPDM and HPDM, the RP-Met was mixed with TMR. The MP and EAA supplies relative to the requirements were estimated for the diets according to NASEM (2021) using actual DMI, BW, and milk yield and components. In multiparous cows, LPD was deficient in MP (87%), and the MP deficiency was moderate for HPD (99%). In primiparous cows, LPD was moderately deficient in MP (94%), whereas HPD exceeded the MP requirement (110%). The LPD and HPD diets were deficient in Met, while LPDM and HPDM were adequate or nearly adequate in Met. Three-way interactions of CP × RP-Met × parity were detected for DMI, milk yield per unit of DMI, ECM, and milk fat and protein yields. In multiparous cows, DMI tended to be greater for HPDM compared with HPD (21.2 vs. 19.7 kg/d) but tended to be lower for LPDM compared with LPD (20.2 vs. 21.8 kg/d). In contrast, DMI was greater (16.9 vs. 15.0 kg/d) for LPDM compared with LPD in primiparous cows. Consistent with the response pattern of DMI, HPDM increased ECM in multiparous cows compared with HPD (50.2 vs. 45.3 kg/d) and LPDM in primiparous cows increased ECM compared with LPD (42.2 vs. 37.5 kg/d). Plasma AA profiles were not affected by dietary CP, but RP-Met supplementation increased plasma Met concentration regardless of dietary CP or parity. Postpartum BW change and plasma NEFA concentrations also showed 3-way interactions, where RP-Met supplementation decreased both BW loss (-4.10 vs. -4.96 kg/d) and NEFA concentration (233 vs. 357 μEq/L) under HPD, but increased both responses for LPD in multiparous cows (-5.46 vs. -3.96 kg/d; 298 vs. 214 μEq/L). In primiparous cows, RP-Met only increased NEFA concentration under HPD (306 vs. 219 μEq/L) with no effect on BW change. In conclusion, increases in DMI and production responses to RP-Met supplementation occurred under marginally deficient MP supply during early lactation, suggesting the need to group postpartum cows by parity. Furthermore, avoiding deficient or excessive MP supply from the basal diet may result in more consistent positive responses to supplemental RP-Met. Further studies with a larger number of an","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phenotypic variation in responses to methane-reducing additives in early-lactation first parity Holstein cows.","authors":"T de Evan, W Wang, M H Kjeldsen, L Foldager, P Lund, M R Weisbjerg","doi":"10.3168/jds.2026-28919","DOIUrl":"https://doi.org/10.3168/jds.2026-28919","url":null,"abstract":"&lt;p&gt;&lt;p&gt;The phenotypic traits that determine between-cow variability in response to CH&lt;sub&gt;4&lt;/sub&gt; mitigating feed additives, such as nitrate and 3-nitrooxypropanol (3-NOP) in dairy cows, require further investigation. This study examined the relationship between CH&lt;sub&gt;4&lt;/sub&gt; emissions and several phenotypic traits in dairy cows supplemented with nitrate or 3-NOP, to identify which ones affected the individual responses to these additives. A total of 201 first-lactation Holstein cows were used in a 3 × 3 Latin square design with 3 treatments: control diet (CON), diet containing nitrate (NIT; 8.57 g NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;/kg of DM), and diet containing 3-NOP (NOP; 60 mg/kg of DM). Each 21-d period included 2 adaptation weeks and 1 sampling week. Enteric gas emissions, feed intake, milk production, and BW were recorded. Additionally, ruminal content samples were collected to determine fermentation parameters, milk samples to assess composition, and blood samples to monitor methemoglobin in response to nitrate. Statistical differences were determined using a linear mixed model, where treatment, period, their interaction, and the week of experiment were included as fixed effects and cow as a random effect. Random cow estimates (RCE) of different variables and residuals for CH&lt;sub&gt;4&lt;/sub&gt; yield (g/kg of DMI), DMI (kg/d), and ECM yield (kg/d) were extracted and correlated to determine each cow's deviation from model predictions and explore phenotypic differences in response to the additives. The yield of CH&lt;sub&gt;4&lt;/sub&gt; was reduced by 19% and 29% when the NIT and NOP diets were fed, respectively, while CH&lt;sub&gt;4&lt;/sub&gt; intensity (g CH&lt;sub&gt;4&lt;/sub&gt;/kg of ECM) decreased by 20% and 28%. When the NIT diet was fed, DMI was maintained, but decreased by 4% when cows were fed the NOP diet compared with CON, contributing to a greater BW loss with NOP. This was reflected in milk production, which decreased with NOP but remained stable with NIT. Correlations with RCE revealed that cows with a high CH&lt;sub&gt;4&lt;/sub&gt; yield exhibited higher CO&lt;sub&gt;2&lt;/sub&gt; yield, milk fat concentration, total ruminal VFA, acetic and butyric acids proportions, and ruminal ammonia. Conversely, cows with low enteric CH&lt;sub&gt;4&lt;/sub&gt; emissions showed higher DMI, milk, and ECM yields, and higher proportions of propionic and valeric acids. Regression analyses revealed that cows with higher DMI, milk yield, ECM yield, or ECM/BW exhibited greater CH&lt;sub&gt;4&lt;/sub&gt; yield reduction with NOP, while NIT was more effective in reducing CH&lt;sub&gt;4&lt;/sub&gt; yield in cows with high CH&lt;sub&gt;4&lt;/sub&gt; yield, milk yield, or BW. Cows with high ruminal propionic acid proportions evidenced poorer CH&lt;sub&gt;4&lt;/sub&gt; yield reduction responses to NIT. Ruminal phenotypes also influenced the effect of additives on DMI; NOP reduced DMI more in cows with high ruminal butyrate proportions, whereas NIT reduced DMI more in cows with low ruminal ammonia concentrations. Effects on ECM yield varied similarly, with higher ECM yield when NO","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A smarter lung ultrasonography solution for lung consolidation classification in dairy calves using a deep learning approach.","authors":"Marina Madureira Ferreira, Keshawa M Dadallage, Tyler Ward, Hannah McCray, Ryan M Ye, Jennifer J Sun, Francisco A Leal Yepes","doi":"10.3168/jds.2026-28434","DOIUrl":"https://doi.org/10.3168/jds.2026-28434","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Lung ultrasonography (LUS) is a valuable tool for diagnosing pneumonia in calves, allowing early detection and prompt treatment. However, despite its value, the technique is not yet fully established as a routine herd health monitoring practice on farms. A key limitation is the presence of inter-rater differences when classifying lung consolidation based on LUS, particularly considering small thresholds of consolidation. The objective of this study was to develop a deep learning (DL) classification model for LUS image analysis in dairy calves. A secondary objective was to compare the performance of the different DL models. The LUS videos from 126 preweaning Holstein calves in a commercial dairy farm in NY State were recorded and used for frame extraction. Frames were annotated according to lung consolidation extension as normal, lobular, and lobar by trained personnel, and a panel diagnosis was compiled as the reference standard for evaluating the model's performance. The data set was divided into training (68%), internal validation (12%), and an independent testing set (20%). Augmentation was applied only to the training set to mitigate overfitting and improve model robustness. The final sets comprised 57,704 training frames and 2,545 internal validation frames from 96 calves, and 4,196 testing frames from 30 calves. Two DL classification models were evaluated: You Only Look Once (YOLO) and Vision Transformer (ViT). Both models achieved overall high accuracy of 0.98 (95% CI: 0.98-0.99) and 0.97 (0.96-0.98), respectively. The performance metrics for the YOLO model were precision 0.94 (95% CI: 0.92-0.95), recall 0.95 (0.93-0.96), and F1-score 0.94 (0.93-0.96). The ViT model precision was 0.88 (0.86-0.90), recall 0.93 (0.92-0.95), and F1-score 0.90 (0.88-0.92). The YOLO model consistently outperformed ViT across all evaluated metrics. At the class level, lobular consolidation yielded the lowest precision for both models, 0.84 (0.80-0.88) for YOLO and 0.69 (0.64-0.74) for ViT, compared with above 0.90 for both the normal and lobar classes. Because the original data set was inherently imbalanced across classes, reflecting the disease distribution on the farm, both models were retrained on a class-balanced subset. Precision, recall, and F1-score exceeded 0.90 for the normal and lobar classes, in both YOLO and ViT, consistent with the original imbalanced data set. However, performance for the lobular class declined on balanced training, with precision dropping from 0.84 (0.80-0.88) to 0.74 (0.69-0.79) for YOLO, and from 0.69 (0.64-0.74) to 0.57 (0.52-0.62) for ViT. Similarly, the F1-score dropped from 0.88 (0.85-0.91) to 0.81 (0.77-0.85) for YOLO, and from 0.78 (0.74-0.82) to 0.70 (0.66-0.74) for ViT. In conclusion, both YOLO and ViT models demonstrated high accuracy in correctly classifying normal lungs and lobar consolidation in preweaning calves, but were less reliable at detecting lobular consolidation. The results demonstrate the potential o","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gastric emptying performance shapes divergent amino acid kinetics of camel and bovine milk: Insights from in vitro and mini-pig models.","authors":"Yi Chai, Xiyu Qin, Caiziyu Yu, Lili Qiu, Jinghua Yu, Pengjie Wang, Yi Wang, Yan Zhang, Xiaoyu Wang","doi":"10.3168/jds.2026-28805","DOIUrl":"https://doi.org/10.3168/jds.2026-28805","url":null,"abstract":"<p><p>Camel milk has attracted growing attention for its functional properties, yet its protein digestion and absorption kinetics remain less understood compared with bovine milk. This study combined in vitro digestion with in vivo experiments in Bama minipigs to assess proteolysis and amino acid kinetics. In vitro assays showed similar hydrolysis between 2 milks, but in vivo camel milk digestion was delayed: at 105 min, it formed denser gastric coagula, and whey fragments (10-17 kDa) persisted in duodenal effluents for over 6 h. Plasma amino acid peaks occurred later (bovine milk at 30 min vs camel milk at 60 min), accompanied by weaker cholecystokinin (CCK) and delayed ghrelin responses, indicating reduced gastric emptying performance. These findings highlight a key difference between camel and bovine milk that gastric emptying is the primary determinant of amino acid release, underscoring the importance of physiological regulation and providing guidance for the design of functional dairy products.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composition and interfacial functionality of casein-rich powders recovered from dairy side-streams.","authors":"R Medeiros, E Ekoh, J P Leite, M V Loureiro, M Salema-Oom, A P Serro, H C Vasconcelos, R Galante","doi":"10.3168/jds.2026-29121","DOIUrl":"https://doi.org/10.3168/jds.2026-29121","url":null,"abstract":"<p><p>Casein-rich powders recovered from dairy side-streams may provide functional milk protein ingredients, but their composition-dependent interfacial performance remains insufficiently characterized. This study recovered casein-rich powders from skim milk, spoiled skim milk, whole milk, and antibiotic-withdrawal raw milk by acid precipitation and compared them with commercial casein. The recovered powders were characterized by proximate composition, Fourier-transform infrared spectroscopy with attenuated total reflectance, sodium dodecyl sulfate-PAGE, differential scanning calorimetry, thermogravimetric analysis, emulsifying capacity in 3 vegetable oils over 48 h, foaming performance over 60 min, water- and oil-holding capacity, and preliminary cytocompatibility in NIH/3T3 fibroblasts. Skim milk- and spoiled skim milk-derived powders were strongly enriched in protein and showed amide I and II bands, electrophoretic profiles, and thermal degradation patterns broadly comparable to commercial casein. In contrast, whole milk- and antibiotic-withdrawal raw milk-derived powders contained higher residual lipid fractions, reflected by ester carbonyl and aliphatic C-H bands and lipid-associated thermal transitions. These compositional differences were associated with lower early emulsifying capacity and reduced foam stability, particularly in the whole milk-derived powder, whereas skim-derived powders showed interfacial performance closer to commercial casein. Cell viability remained above the cytotoxicity threshold under the tested in vitro conditions, but these data do not establish food or biomaterial safety. Overall, the results show that acid precipitation can recover casein-rich powders from heterogeneous dairy streams, but their interfacial functionality varied with co-recovered constituents, especially residual lipids and mineral-associated material. These findings support further development of dairy side-stream-derived casein-rich powders as composition-tunable ingredients for colloidal food and related interfacial systems.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148987492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mammary immune allocation strategies under low-input systems: Density preservation versus volume-driven immune output in indigenous and crossbred dairy cows.","authors":"H Almusheal, S Moussa, G Alkhayer","doi":"10.3168/jds.2026-28812","DOIUrl":"https://doi.org/10.3168/jds.2026-28812","url":null,"abstract":"<p><p>Little is known about the allocation of immune resources by dairy breeds under low-input systems, especially when the immune density and functional secretion are measured concomitantly. This experiment examined physiological trade-offs among milk production, immune protein level, functional immune response, milk composition, and electrical conductivity (EC) in native Syrian Golani cows and Golani crossbreds with Friesians. Using a longitudinal repeated-measures design across colostrum and established lactation, we evaluated immunoglobulins (IgG, IgA, IgM), lactoferrin, immune density (g/L), functional immune secretion (g/day), milk composition, and EC. The effect of lactation stage (colostrum vs. milk) on all immune markers was highly significant which confirms the pronounced physiological change between early and established lactation. Effects of breed were selective. Golani cows were found to have greater immune concentrations of the selected markers, and crossbred cows were found to have greater functional immune secretion which was mainly due to increased milk yield. Notably, there were important Breed x Lactation stage interactions on IgM and lactoferrin, which showed breed-specific differences in the extent of the transition between colostrum and milk. Conversely, IgG did not indicate any significant interaction implying a more conserved pattern of stage-related decline among breeds. The relationship between immune concentration and milk yield was found to be negative, which is in line with the dynamics of dilution through secretion. Crossbred cows optimized the overall daily immune production, and Golani cows retained greater immune density per unit of milk and lower EC values, which suggest improved mammary ionic stability. The results show that the immune-production associations can be more effectively viewed in terms of integrative longitudinal models, which present a biologically sound method of assessing adaptive efficiency in successful dairy systems.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148975177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"By comparing the effects of Lactobacillus paracasei KL1 and BK56 strains on yogurt quality, the optimal consumption time for 2 compound fermented yogurts was determined.","authors":"Yu Tian, Yanan Wang, Jian He, Hongxing Zhang, Yuanhong Xie, Shaoyang Ge, Baolei Li, Hua Liu, Junhua Jin","doi":"10.3168/jds.2026-28883","DOIUrl":"https://doi.org/10.3168/jds.2026-28883","url":null,"abstract":"<p><p>This study investigated the effects of 2 Lactobacillus paracasei strains, KL1 and BK56, on the physicochemical properties, microstructure, texture characteristics, and sensory quality of a compound fermented yogurt system (GK107: L. paracasei KL1, Leuconostoc mesenteroides G12S, Chr. Hansen Commercial Starter Culture; G56107: L. paracasei BK56, L. mesenteroides G12S, Chr. Hansen Commercial Starter Culture), and further integrated genomic and metabolomic analyses to infer their shelf-life and optimal consumption period. The results showed that GK107 yogurt maintained stable quality throughout the 28-d storage period (at d 28: pH 4.07; titratable acidity 93.25 °T; exopolysaccharide content 0.31 g/L; water-holding capacity 53.05%; sensory score 83), and rapidly formed a stable gel structure that persisted for an extended duration. In contrast, the quality of G56107 yogurt deteriorated during the later stage of storage (at d 28: pH 4.0; titratable acidity 98.4 °T; exopolysaccharide content 0.31 g/L; water-holding capacity 51.3%; sensory score 67). Genomic analysis revealed that, compared with the L. paracasei KL1 strain, the L. paracasei BK56 strain carried loss-of-function mutations in multiple key genes associated with flavor synthesis, polysaccharide metabolism, and proteolysis, including alsS, prtP, glpO, AWC33_RS01450, AWC33_RS00855, AWC33_RS01070, and AWC33_RS01805. These mutations may have played a role in the gradual flavor deterioration, and weak post-acidification control observed in G56107 yogurt during prolonged storage. Based on the above results, it is reasonable to suggest that GK107 yogurt is suitable for long-term storage with an optimal consumption period of 14 to 28 d, whereas G56107 yogurt is more suitable for short-term storage and recommended for consumption within the first 14 d.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148928737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Consensus design and in silico screening of GH42 β-galactosidase for enhanced catalytic hydrolysis of whey lactose.","authors":"Simeng Ding, Jiajia Li, Jiahui Li, Huayu Nie, Yongxin Li, Zheng Guo, Renjun Gao","doi":"10.3168/jds.2026-29005","DOIUrl":"https://doi.org/10.3168/jds.2026-29005","url":null,"abstract":"<p><p>This study addresses a major bottleneck in dairy waste management by engineering a highly efficient, thermophilic enzyme for lactose hydrolysis, transforming the cheese manufacturing by-product whey into a high-value resource. While traditional glycoside hydrolase family 2 (GH2) enzymes suffer from poor industrial thermostability, thermophilic GH42 alternatives lack the catalytic efficiency required for practical processing. To bridge this gap, a synergistic engineering strategy combining consensus sequence design and virtual binding energy screening was applied to Tn1577, a home-discovered GH42-galactosidase from Thermotoga naphthophila RUK10. Through homologous sequence analysis and iterative saturation mutagenesis, a superior triple mutant designated M10 (H271Q/V357G/Q340E) was successfully developed. Molecular dynamics (MD) simulations revealed that M10s performance is driven by 3 key structural alterations. First, a remodeled substrate tunnel accelerates lactose entry and product release while minimizing molecular congestion in the active cavity. Second, consensus mutations rigidify the catalytic pocket to preserve its geometry under thermal stress. Finally, a distal Q340E mutation rearranges local hydrogen bonding and forms a new anion-π interaction, anchoring the protein backbone to stabilize the overall conformation via allosteric regulation. This engineered rigidity introduces a beneficial kinetic trade-off: it drastically accelerates catalytic turnover by intentionally weakening substrate affinity, preventing enzyme stagnation and ensuring continuous catalytic cycling. Consequently, mutant M10 achieves a remarkable 6.5-fold increase in lactose hydrolysis activity at 55°C compared with the wild-type enzyme. Response surface methodology established ideal industrial parameters: 52.7°C, pH 5.5, and an enzyme dosage of 2.9 U/mL. Under these conditions, M10 accomplishes near-complete lactose hydrolysis of raw whey within a brief 2-h window. Operating at a temperature below the thermal unfolding point of core whey proteins (∼60°C), this mild thermal regimen shortens processing times and prevents the thermal denaturation of other valuable whey components, demonstrating M10s immense potential for high-efficiency, stable lactose-free dairy processing.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148928752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}