Journal of Dairy Science最新文献

{"title":"ABCG2 in bovine and ovine milk extracellular vesicles: Evidence of substrate accumulation in a cellular model.","authors":"Alejandro Casado-Santos, Esther Blanco-Paniagua, Yaiza González-Rodríguez, Laura Álvarez-Fernández, Alicia Millán-García, Gracia Merino, Alberto Dávalos, Livia Balaguer, Vega Villar-Suárez","doi":"10.3168/jds.2026-28806","DOIUrl":"https://doi.org/10.3168/jds.2026-28806","url":null,"abstract":"<p><p>Milk-derived extracellular vesicles (EVs) are emerging as key mediators of molecular transfer within the mammary gland and may contribute to the secretion of bioactive compounds and xenobiotics into milk. The ATP-binding cassette transporter ABCG2 plays a central role in drug and metabolite secretion into milk; however, its presence and functionality in milk-derived EVs from livestock species remain poorly understood. In this study, EVs from bovine and ovine milk were isolated by ultracentrifugation and size exclusion chromatography and characterized by nanoparticle tracking analysis, transmission electron microscopy, and Western blot. ABCG2 was consistently detected in EV-enriched fractions from both species. While EV size distributions were similar (∼160-170 nm), significant differences in zeta potential may suggest species-specific vesicle properties. To investigate the association between ABCG2 expression and substrate accumulation, EVs derived from parental and ovine ABCG2-transduced MDCK-II cells were evaluated using topotecan as a model substrate. EV preparations derived from ABCG2-expressing cells contained significantly more topotecan than those obtained from parental cells. These findings demonstrate the presence of ABCG2 in EV-enriched fractions isolated from bovine and ovine milk and provide supportive in vitro evidence that ABCG2 expression in donor cells is associated with increased topotecan recovery in cell-derived EV preparations. The results identify a potential EV-associated mechanism with possible implications for xenobiotic transfer, dairy safety, and the development of EV-based delivery systems.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242176","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":"Aroma-active compounds in brown butter.","authors":"Anita Rae Best, Yaozheng Liu, David M Barbano, MaryAnne Drake","doi":"10.3168/jds.2026-29277","DOIUrl":"https://doi.org/10.3168/jds.2026-29277","url":null,"abstract":"<p><p>Brown butter has gained popularity as an ingredient, yet its flavor chemistry remains uncharacterized. This study characterized the aroma-active compounds and sensory properties of brown butter. Duplicate lots of salted and unsalted fresh butter were obtained from a manufacturer, and a standardized browning method was developed. Brown and unheated butters were evaluated by descriptive analysis and instrumental color analysis. Volatiles were extracted using headspace solid-phase microextraction and direct solvent extraction followed by solvent-assisted flavor evaporation and analyzed by gas chromatography-mass spectrometry, gas chromatography-olfactometry, and gas chromatography-tandem mass spectrometry. Aroma extract dilution analysis, stable isotope dilution analysis, sensory threshold determination, odor activity values, and model systems were used to identify, quantify and determine key aroma contributors. Brown butter exhibited higher intensities of cooked-nutty, caramel, and brown-toasted flavors compared with unheated butters. Brown butter was characterized by browned color, Maillard reaction derived volatiles, lipid oxidation products, and select sulfur compounds, while other low molecular weight volatiles decreased. Furaneol, diacetyl, and 2-nonanone as well as other aldehydes, ketones, lactones and sulfur compounds were identified as key contributors to brown butter aroma. These findings provide a comprehensive chemical and sensory framework for understanding brown butter flavor development and highlight the importance of thermal processing conditions in shaping butter aroma and flavor through Maillard reaction and lipid degradation pathways.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242195","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 2-D Monte Carlo simulation to predict the pasteurization survival and subsequent growth of the bulk tank raw milk bacterial community in high-temperature, short-time pasteurized milk.","authors":"Leonie Kemmerling, Chenhao Qian, Samuel Reichler, Nicole Martin, Martin Wiedmann","doi":"10.3168/jds.2026-29168","DOIUrl":"https://doi.org/10.3168/jds.2026-29168","url":null,"abstract":"&lt;p&gt;&lt;p&gt;It generally is assumed that HTST pasteurization kills most bacteria in milk aside from thermodurics and bacterial spores. However, HTST pasteurization was developed to achieve a 5-log reduction of the most heat-resistant bacterial pathogen found in raw milk (i.e., Coxiella burnetii), and not for the reduction of spoilage microorganisms. Even a single surviving psychrotolerant cell can grow to cause spoilage. In this work, we modeled the HTST pasteurization reduction and subsequent growth of bulk tank raw milk (BTRM) bacterial communities. To account for uncertainty in our input parameters, we designed our model as a 2-dimensional Monte Carlo simulation. Existing aerobic plate count data from raw milk were used to fit a normal distribution of the microbial load in BTRM, and data from literature, as well as expert elicitation, were employed to determine the 20 most common and relevant bacterial taxa in raw milk and their relative abundances. Expert elicitation was also used to estimate the log reduction during HTST pasteurization of each genus. Subsequent growth under transport and storage conditions was modeled using data from previous growth experiments or inferred from literature. The output of our baseline model, which simulates a Northeastern US supply chain, predicted a median proportion of 5% of containers showing evidence of bacterial concentrations reaching 1 million cells/mL at d 21 of shelf life, with a 5th percentile of 0% and a 95th percentile of 21% spoiled containers. Validation against historic shelf-life data supports that our model is able to accurately predict the net log reduction of BTRM bacterial communities, as well as the bacterial concentration in containers after pasteurization. However, the simulated median spoiled proportions on shelf-life d 14 and 21 (i.e., 0%, 12%) deviated from observed proportions (i.e., 5%, 29%), which indicates that the developed model should be used for relative comparisons of scenarios rather than absolute predictions. A sensitivity analysis showed that the predicted proportion of spoiled containers is strongly influenced by the relative abundance and log reduction of Paenibacillus, the bacterial concentration in BTRM, and the time/temperature conditions at several supply chain stages. Assessment of different what-if scenarios showed that microbial spoilage due to members of BTRM bacterial communities can be reduced through substantial reductions of the microbial load before pasteurization and strict temperature control along the supply chain. Additionally, our model predicted that 0.87% of half-gallon containers will contain at least 1 cell of a heat-sensitive psychrotolerant organism following pasteurization, which was simulated to grow above the spoilage threshold by shelf-life d 7 in 5% of occurrences and by shelf-life d 21 in 50% of occurrences, suggesting that there is a meaningful residual risk of spoilage by these organisms even after pasteurization. The model developed in this wor","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242255","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":"Optimizing embryo transfer management in cows: Ultrasound-based pre-transfer screening and management of non-eligible recipients.","authors":"Jinbang Xiao, Manyuan Tian, Bo Wang, Haohao Mu, Haitao She, Heqiang Li, Hui Chen, Yonghong Jia, Yongsheng Wang, Yaping Jin, Pengfei Lin","doi":"10.3168/jds.2026-28857","DOIUrl":"https://doi.org/10.3168/jds.2026-28857","url":null,"abstract":"<p><p>A single pre-transfer ultrasound screening cannot capture dynamic changes from estrus to ovulation. This may leads to inaccurate recipient selection and undetected reproductive abnormalities in non-eligible cows. We established a dynamic ultrasound monitoring (DUM) protocol with examinations on estrus day D0 (estrus detection), D1 (ovulation confirmation), and D6 (morphological assessment of the corpus luteum [CL]), and provided stage-specific management for non-eligible recipients. A total of 2,329 cows were randomly assigned to a control group (n = 1,165; a single ultrasonographic evaluation at the time of embryo transfer [ET]) or DUM group (n = 1,164). Before ET, first-service cows received a Presynch11/Ovsynch protocol, whereas second- and third-service cows were either observed for estrus or treated with an Ovsynch protocol based on whether or not they were observed in estrus up to pregnancy diagnosis of the previous breeding. In the control group, all non-eligible cows uniformly received Ovsynch + timed artificial insemination (AI). In the DUM group, non-eligible cows received stage-specific treatments based on ultrasound findings. In both groups, non-eligible cows were subsequently bred only via AI. The DUM group had a higher proportion of reconfirmed pregnancies per ET (43.2% vs. 37.4%). Among DUM cows, larger follicle diameter on D0 increased the proportion of reconfirmed pregnancies per ET (OR = 1.504), while severe bleeding at transfer reduced it (OR = 0.464). The non-eligible rates were similar between groups (28.9% in the control group and 28.2% in the DUM group). In the control group, the reasons for non-eligibility were predominantly absent CL (70.9%) or poor CL quality (17.2%), based on the single D7 evaluation. In the DUM group, the reasons were distributed across time points: 31.6% on D0 (presence of a large CL), and on D6, 26.7% due to no CL and 23.4% due to poor CL quality. Among non-eligible cows, the DUM group had a higher proportion of pregnancies per subsequent AI (42.9% vs. 28.5%), fewer services per pregnancy (2.53 vs. 2.82) and shorter days open (130.10 vs. 135.88). The cost per successful pregnancy in eligible recipients was $78.69 lower in the DUM group than in the control group. In conclusion, the DUM protocol improves both ET success and subsequent fertility of non-eligible recipients, offering an efficient management strategy for dairy herds.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242409","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":"Maternal grape pomace-containing silage in dairy goats: Effects on doe-kid metabolic responses, milk quality, and offspring meat and gut-liver morphology.","authors":"Angela Gabriella D'Alessandro, Roberta Savina Dibenedetto, Alessio Di Luca, Salvatore Desantis, Siria Tavaniello, José Manuel Moreno-Rojas, Giovanni Martemucci","doi":"10.3168/jds.2026-28943","DOIUrl":"https://doi.org/10.3168/jds.2026-28943","url":null,"abstract":"<p><p>This study evaluated the effects of supplementing lactating goats with polyphenol-containing silage produced from agro-industrial byproducts, including grape pomace, wheat straw, cheese whey, and molasses, on physiological responses and product quality in a dairy goat doe-kid system. Twenty-four lactating goats (49.8 ± 2.8 kg BW) at parturition and their single kids were randomly assigned to 2 dietary treatments (n = 12): a control diet (CON) and a diet including the silage (SIL-BP). Following a 14-d dietary adaptation period, the experimental period lasted 28 d. At the end of the feeding trial (d 42), blood samples from does and kids were collected to assess biochemical, inflammatory, and oxidative stress parameters, and milk samples from does were collected to determine composition and antioxidant capacity. Pooled milk was used for fresh cheese production, and cheese composition and antioxidant capacity were evaluated as descriptive outcomes. A subset of male kids (n = 3 per treatment; 47 d of age; BW 8.9 ± 0.8 kg) underwent slaughter to evaluate meat composition, fatty acid profile, and intestinal and liver histomorphology. Goats receiving SIL-BP showed lower plasma total and HDL cholesterol and reactive oxygen metabolites (dROMs), whereas other metabolic parameters, total oxidant status, and inflammatory cytokines remained unaffected. Kids from SIL-BP-fed dams had lower plasma cholesterol, alanine aminotransferase activity, and dROMs. The SIL-BP diet increased milk fat concentration and antioxidant capacity and was associated with higher antioxidant properties in fresh cheese. In kid meat, differences in fatty acid composition were observed between treatments, with higher polyunsaturated fatty acids and lower monounsaturated fatty acids in the SIL-BP group. In the offspring of SIL-BP-supplemented does, intestinal morphology showed reduced duodenal villus height and goblet cell density, along with increased cecal crypt depth. No impairment of liver histomorphology was observed, and the biological significance of the intestinal alterations remains uncertain. Overall, supplementing lactating goats with this co-silage was associated with selected metabolic and oxidative responses in does and kids, higher milk antioxidant capacity, and changes in the fatty acid composition of kid meat, whereas cheese results showed similar descriptive trends.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242421","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":"Whey protein gel particles as clean-label pickering stabilizers in frozen yogurt.","authors":"Samantha Morris, Changhua Su, Mengshi Lin, Bongkosh Vardhanabhuti","doi":"10.3168/jds.2026-29293","DOIUrl":"https://doi.org/10.3168/jds.2026-29293","url":null,"abstract":"<p><p>Emulsifiers and stabilizers are essential ingredients in frozen desserts, creating microstructures that enhance texture and storage stability by stabilizing air bubbles and increasing unfrozen matrix viscosity. The clean label movement has prompted the food industry to seek natural alternatives to synthetic emulsifiers and certain stabilizers. Pickering stabilization using biopolymer microgels has emerged as a promising approach, offering superior long-term stability for food emulsions and foams. Frozen yogurt was used as the model system in this study because its lower fat content and lower pH, relative to ice cream, place greater demands on stabilization of the air and fat phases, offering a rigorous test of the functionality of the gel particles. This study investigated the effects of whey protein gel particles on frozen yogurt properties, examining both the mix and final product characteristics. Whey protein gel particles were prepared by heating whey protein concentrate (WPC) at pH 7.0 and 85°C for 30 min, followed by sonication and pH adjustment to 4.0, 4.5, or 5.0. Partial replacement of nonfat dry milk (NDM) with WPC gel particles in frozen yogurt mixes resulted in smaller fat globule sizes, increased overrun, and enhanced foam stability. The most notable improvement was in melting properties, as evidenced by a prolonged induction time and reduced drip-through rate. Descriptive sensory analysis indicated that WPC gel particle-containing frozen yogurts exhibited slower meltdown, though with elevated intensities of cardboard flavor and astringency relative to the control, attributable to the thermal processing of the gel particles. These off-flavor attributes represent a key area for formulation refinement. The enhanced foaming properties were attributed to the combined mechanisms of increased continuous phase viscosity and Pickering stabilization by the gel particles.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242294","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":"Hydrocolloid-specific structuring of whey and rice protein systems under pH conditions relevant to dairy foods.","authors":"Jagoda O Szafrańska","doi":"10.3168/jds.2026-29241","DOIUrl":"https://doi.org/10.3168/jds.2026-29241","url":null,"abstract":"<p><p>Hydrocolloids are widely used to control stability and texture in dairy and hybrid dairy formulations, but their effects depend strongly on protein type, pH, and polysaccharide structure. This study investigated how 3 structurally distinct hydrocolloids, acacia gum (AG), gellan gum (GG), and xanthan gum (XG), modulate pH-dependent colloidal organization and rheological functionality in whey protein concentrate (WPC80), whey protein isolate (WPI), and rice protein (RP) systems. Protein-gum mixtures containing 2.0% protein and 0.2% polysaccharide were prepared at pH 3.0, 4.0, 5.0, 6.8, and 7.4 and characterized using turbidity measurements, visual observations, oscillatory and steady-shear rheology, dynamic light scattering (DLS), and principal component analysis (PCA). Hydrocolloid type strongly determined system behavior. XG-containing systems exhibited high turbidity and elevated viscosity over a broad pH range, indicating viscosity-dominated structuring of the continuous phase. GG promoted the strongest elastic-dominated rheological response, particularly in whey protein systems at pH 4.0. In contrast, AG-containing systems were characterized by large hydrodynamic diameters and limited elastic response, indicating particle-rich heterogeneous systems rather than elastic-dominated structuring. DLS and PCA confirmed that particle growth and rheological structuring were distinct phenomena, as large hydrodynamic diameters did not necessarily correspond to increased elasticity. These results show that hydrocolloid architecture and pH determine whether protein systems develop dispersed, large-particle, viscosity-dominated, or elastic-dominated functional states. For dairy formulation, the findings indicate that turbidity or particle size alone cannot predict texture-forming capacity; rheology and particle-size distribution should be evaluated together during preformulation screening of acidified whey-protein-based and hybrid dairy-type systems.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242358","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":"Meta-analysis of the effects of supplementing hydroxychloride compared with sulfate sources of trace minerals on performance in dairy cows.","authors":"J B Cardoso, J B Daniel, J A Metcalf, W P Weiss, T R Overton, H M Dann, K J Harvatine, Z Sarwar, J E P Santos","doi":"10.3168/jds.2026-28932","DOIUrl":"https://doi.org/10.3168/jds.2026-28932","url":null,"abstract":"<p><p>The objectives of this study were to review the literature and use meta-analytical methods to determine the effects of supplementing hydroxychloride (HTM) compared with sulfate (STM) sources of Cu, Mn, and Zn on production performance of dairy cows. The literature was systematically reviewed, searching for randomized experiments that replaced STM with HTM in diets fed to lactating dairy cows. A total of 7 experiments met the inclusion criteria, of which 5 were Latin square designs and 2 were continuous designs, representing 283 unique cows and 518 experimental units. The individual cow data were obtained from investigators and data were computed as means per experimental unit. Responses of interest included intake of DM and trace minerals, yields of milk and milk components, feed efficiency, body weight, body condition score, and mineral concentrations in tissues. Predictors included treatment, if STM or HTM, the experimental design, if Latin square or continuous, and the experiment itself. Dietary ingredients were entered into the NASEM (2021) software to estimate the NEL content of each diet to calculate energy balance. Data were analyzed using mixed-effects models including the fixed effects of treatment, experimental design, and the interaction treatment and experimental design, and the random effect of experiment nested within experimental design. Treatment did not affect the daily intakes of DM (STM = 24.5 vs. HTM = 24.9 ± 0.9 kg/d), Cu (STM = 494 vs. HTM = 500 ± 27 mg/d) and Zn (STM = 2,235 vs. HTM = 2,272 ± 213 mg/d); however, cows fed HTM consumed 118 ± 22 mg/d more Mn than those fed STM (STM = 1,754 vs. HTM = 1,872 ± 95 mg/d). Yields of milk, fat, and true protein tended to increase 1.0 ± 0.6, 0.044 ± 0.023, and 0.031 ± 0.016 kg/d, respectively, in cows fed HTM compared with STM, whereas yield of ECM and the amount of net energy secreted as milk increased 1.1 ± 0.5 kg/d and 0.76 ± 0.39 Mcal/d, respectively, in cows fed HTM compared with STM. Source of trace mineral did not affect feed efficiency, body weight, body condition score, or net energy balance of cows. Source of trace minerals did not affect the concentrations of Cu, Mn, or Zn in serum of cows. There was no evidence of an interaction between source of trace mineral and design of experiment for any of the responses evaluated. Furthermore, there were no indication of heterogeneity or publication bias. These results suggest that supplementing HTM compared with STM as sources of Cu, Mn, and Zn in diets of lactating dairy cows benefits production performance.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242441","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 summer thermal conditions on physiological responses, lying behavior, and weight gain in preweaning Holstein dairy heifer calves in a humid continental climate.","authors":"L M Benn, V Ouellet, D C Tulpan, T J DeVries","doi":"10.3168/jds.2026-29114","DOIUrl":"https://doi.org/10.3168/jds.2026-29114","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Dairy calves raised in humid continental climates experience intermittent exposure to high temperatures and humidity during several months of the year. The objectives of this observational study were to determine whether summer heat intensity and persistency in a humid continental climate trigger physiological responses indicative of heat stress in preweaned calves, and whether this heat exposure leads to changes in lying behavior and reductions in calf growth. Holstein heifer calves (n = 138) were enrolled at birth from 2 commercial dairy farms in Ontario, Canada between June and August of 2024. Calves were housed in indoor pens or individual outdoor hutches at farm 1 and 2, respectively. Farms were visited 3 x/wk and calves were monitored for the first 9 wk of life. Calf respiration rate, rectal temperature, and skin temperature were measured at each visit and averaged per calf per wk. Accelerometers recorded individual calf lying behavior for the duration of the study period. Calves were weighed weekly until weaning to determine average daily gain (ADG). Data loggers, placed within pen at calf level, recorded ambient temperature and relative humidity at 10-min intervals. Climatic data were used to determine the temperature-humidity index (THI) for each 10-min interval. Various THI measures were calculated and averaged per wk, including average and maximum daily THI and h/d THI exceeded 65, 69, and 72. To assess thermal variability, a coefficient of variation (CV) was also determined for each of these weekly THI measures, in addition to within-d THI CV. Weekly data were analyzed using repeated measures, mixed-effect linear regression models. Weekly THI averaged 65.3 ± 4.7 (mean ± SD), ranging from 49.4 to 74.3. Weekly maximum THI averaged 73.5 ± 4.6, ranging from 58.9 to 82.9. Calf respiration rate and average and maximum skin temperature were positively associated with all THI measures. All THI measures were associated with changes in lying behavior, including decreased daily lying time, more frequent lying bouts/d, and reduced durations of lying bouts. Greater thermal variability was also associated with respiration rate, skin temperature, and lying behavior. Calf weekly ADG averaged 0.8 ± 0.55 kg/d. Average daily THI tended to be associated with reduced ADG, such that for each 1-unit increase in the average THI, ADG was reduced by 0.01 kg/d. Maximum daily THI and h/d THI &gt;72 were also associated with reduced ADG. For each 1-unit increase in maximum THI, ADG was reduced by 0.01 kg/d. For every 1 h increase in the h/d THI &gt;72, ADG was reduced by 0.02 kg/d. These findings demonstrate that preweaned dairy calves in a humid continental climate are exposed to THI at or above thresholds associated with heat stress, and that heat intensity and variability are associated with physiological, behavioral, and growth responses. These results highlight the importance of heat mitigation strategies for preweaned calves in temperate regions where heat ","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242297","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":"Effect of conditions and diseases associated with systemic inflammation on the plasma concentration of growth differentiation factor 15 (GDF15) in dairy cows.","authors":"S L Giesy, J Opgenorth, S Rodriguez-Jimenez, L H Baumgard, T H Swartz, L K Mamedova, B J Bradford, L N Ferro, T R Overton, C Rial, J O Giordano, Y R Boisclair","doi":"10.3168/jds.2026-29128","DOIUrl":"https://doi.org/10.3168/jds.2026-29128","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Plasma growth differentiation factor 15 (GDF15) was analyzed in dairy cows during the transition period, following treatment with the endotoxin lipopolysaccharide (LPS), during heat stress, and in the presence of infectious diseases. Events associated with these conditions include systemic inflammation and reduced appetite. GDF15 may be relevant to these conditions given its discovery as an overexpressed cDNA in an activated immune cell line and its emergence as an anorexic signal. An i.v. LPS bolus to early lactating cows increased plasma GDF15 from a baseline concentration of 45.2 ± 7.7 pg/mL to a peak concentration of 511.1 ± 92.2 pg/mL within 3 h of administration followed by a return to baseline concentration 33 h later. Dry matter intake over the first 24 h post LPS was negatively related to the area under the curve of plasma GDF15. LPS increased GDF15 expression by 6-fold in liver but had no effect on GDF15 concentration after ex vivo addition to whole blood, identifying liver and not circulating immune cells as a source. In dairy heifers, mammary parenchyma and uterus expressed GDF15 at levels comparable to that of liver, suggesting the capacity of these tissues to increase GDF15 production in response to local endotoxins. In support of this hypothesis, administration of intramammary LPS to early lactating cows raised plasma GDF15 from a baseline concentration of 46.1 ± 4.1 to a peak of 189.3 ± 30.0 pg/mL 9 h later followed by a decline to baseline concentration over the next 15 h. Intramammary LPS caused a 2.1-fold increase in GDF15 expression in liver and a 9.3-fold increase in the mammary gland. We next asked whether plasma GDF15 was increased by naturally occurring events leading to endotoxin exposure (e.g., transition period, heat stress, and infectious diseases). In dairy cows free of clinical diseases, plasma GDF15 increased progressively over the last 3 wk of gestation from 32.6 ± 5.7 pg/mL to a peak of 96.5 ± 22.8 pg/mL on the day of parturition; plasma GDF15 returned to baseline levels by d 3 of lactation and remained at that level over the next 18 d of lactation. Plasma GDF15 was measured over a 7-d period in cows fed ad libitum under thermoneutral or heat stress conditions and in cows fed under thermoneutral conditions to the intake of heat-stressed cows. The reduction of feed intake in pair-fed and heat-stressed cows caused a time-dependent increase in plasma GDF15, but heat stress had no additional effect. Finally, plasma GDF15 was measured in early lactating dairy cows remaining heathy or diagnosed with retained placenta, metritis, or mastitis. Relative to healthy cows, cows with metritis and mastitis had 1.7- and 2.7-fold greater plasma GDF15 concentrations, respectively, whereas cows with retained placenta did not differ. Overall, these data show upregulation of GDF15 production by conditions associated with the presence of endotoxins and raise the possibility that GDF15 may be a member of a highly redundant system ","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149242341","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}