Journal of Dairy Science最新文献

{"title":"Does the choice of beef bull influence dairy cow survival in a beef × dairy system?","authors":"S M Jepsen, P Sørensen, R B Stephansen","doi":"10.3168/jds.2026-28983","DOIUrl":"https://doi.org/10.3168/jds.2026-28983","url":null,"abstract":"<p><p>The increasing use of beef sires in dairy herds, largely enabled by reproductive technologies such as sexed semen, has created new dynamics in dairy production, including a surplus of replacement heifers. This has driven widespread adoption of beef × dairy breeding strategies to reduce the surplus of dairy heifers and increase meat output without compromising milk production. However, this practice introduces new challenges, particularly concerning dairy cow survival. A key concern is whether dairy cows inseminated with beef semen experience higher mortality, and if so, whether this can be addressed through genetic selection on the paternal side. Genetic variation was investigated among 223 Danish Blue sires used on 145,513 Holstein cows, covering 209,523 multiparous calvings. The focus is on cow survival at d 50 post-calving (SURV50), alongside survival to next lactation. A bivariate model of these survival traits and a 4-trait multivariate model (calving ease, calf survival at birth, calf size, SURV50) was examined. Both models included fixed effects (herd-year, year-month, calf sex, parity, cow age at calving nested within parity) along with random additive genetic effect of sire. Results revealed a significant additive genetic sire variation with a low heritability (<0.01), high genetic correlation (0.92; SE: 0.22) between survival traits, and a moderate favorable genetic correlation between SURV50 and calving ease (-0.65 ± 0.30). Furthermore, SURV50 can be defined as a genetic residual SURV50 trait that is genetically independent of the aforementioned calving traits (gSURV50). For the residual gSURV50 trait, 57% of the additive genetic sire variation remained of the SURV50 trait, suggesting that early-lactation survival of dairy cows inseminated with beef semen is not solely affected by calving-related traits. Effectively, that means selection on gSURV50 targets early lactation dairy cow survival effects beyond calving outcomes. Using simulated profitability estimates, one genetic standard deviation improvement in gSURV50 corresponded to €6.25, which potentially could contribute substantially to the Nordic breeding goal for beef sires used on dairy cows. Overall, the results of this study demonstrate additive genetic sire variation in dairy cow survival among Danish Blue sires under Danish production conditions. Incorporating gSURV50 into beef × dairy breeding objectives, could potentially enhance robustness, reduce mortality, and improve both animal welfare and economic efficiency.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073070","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":"Graduate Student Literature Review: Gut integrity under heat stress in dairy cows-Biological mechanisms and the protective role of methionine.","authors":"R Schmith, M M Campos, R G Tonucci, M A C Danés","doi":"10.3168/jds.2026-28907","DOIUrl":"https://doi.org/10.3168/jds.2026-28907","url":null,"abstract":"<p><p>Heat stress represents a major challenge for dairy production, impairing animal performance, health, and welfare. Among the affected systems, the gastrointestinal tract has emerged as a central site in the pathophysiology of this condition, as multiple mechanisms contribute to the loss of intestinal integrity, including redistribution of splanchnic blood flow to the periphery, tissue hypoxia, oxidative stress, mast cell activation, and alterations in hydration status and osmotic homeostasis. These processes compromise epithelial barrier function, favoring the translocation of luminal components, which triggers systemic inflammation, oxidative stress, and the redirection of nutrients from productive functions toward maintenance and defense. In this context, methionine has been proposed as a functional amino acid with the potential to support intestinal health. Through its role in one-carbon metabolism, methionine contributes to the synthesis of key compounds such as glutathione and taurine, associated with antioxidant defense and inflammatory modulation; polyamines, related to epithelial proliferation and renewal; and phosphatidylcholines, essential for membrane stability. In addition, methionine may support mucosal barrier homeostasis by regulating goblet cells and mucin expression and may also influence the intestinal microbiota. Although these mechanisms are well established in other species, important knowledge gaps remain regarding the effects of heat stress on intestinal barrier function in ruminants, as well as the role of methionine and optimal supplementation strategies in lactating dairy cows. Therefore, this review aims to discuss the mechanisms by which heat stress impairs intestinal barrier function and to evaluate the potential of methionine as a nutritional strategy to mitigate its effects in dairy cows.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073080","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":"Factors influencing the physical and chemical stability of whey permeate powders: A correlational study based on industry samples.","authors":"Didem Sözeri Atik, Job Ubbink","doi":"10.3168/jds.2026-28819","DOIUrl":"https://doi.org/10.3168/jds.2026-28819","url":null,"abstract":"<p><p>Whey permeate is an important co-product of cheese manufacturing, commonly converted into a powder (WPP) through evaporation, lactose crystallization, and spray drying. The composition of whey permeate powders (WPPs) varies and is influenced by the properties of the cheese produced and the processing parameters used during manufacturing. WPPs may undergo physical and chemical changes, including the Maillard reaction and caking, during storage and transportation, thereby impacting the functional and physical properties of the final product. Therefore, this work aims to establish correlations between parameters related to the physical and chemical stability of whey permeate powders (WPPs) and the content of major and minor constituents, including lactose, monosaccharides, organic acids, protein and nitrogen-containing compounds, and minerals. For this purpose, 15 commercial WPPs were collected from 4 different producers in the United States and subjected to compositional analysis and a shelf-life test for 6 mo at T = 25 ± 2°C and a relative humidity (RH) of 50 ± 5% to induce browning. From the compositional analysis of the 15 WPP samples, it was established that their range in composition is representative of literature values for WPPs, allowing us to generalize our results. The observed correlations were analyzed in the form of a correlational heat map and by principal component analysis (PCA). We find that the glass transition temperature (T_g), which serves as a proxy for molecular mobility and which is related to the propensity of powder caking, positively correlates with the lactose content, while it negatively correlates with the content of glucose, galactose, and lactic acid, which are all strong plasticizers. We observe that the color change (ΔE*) during storage, which is used as a proxy for the degree of Maillard browning, negatively correlates with the lactose content, demonstrating the critical impact of molecular mobility on the rate of browning. ΔE* positively correlates with the content of glucose, galactose, and lactic acid. This is expected specifically for glucose and galactose, which are both reducing sugars and strong plasticizers. The protein and peptide content only weakly correlates with both T_g and the degree of browning, while the impact of minerals is more complex, in particular in relation to the physical stability of WPPs. Overall, our results improve the understanding of compositional variability of WPPs and its effect on instability, providing concrete direction for process optimization and reformulation, and constitute a basis for further mechanistic studies.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073082","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 biochar supplementation in dairy cows on milk composition, processing characteristics, and butter quality.","authors":"Franziska Witte, Lisa Garvels, Alexander Weinberg, Jan Berend Lingens, Dana Carina Schubert, Christian Visscher, Andreas Juadjur, Volker Heinz, Jochen Weiss, Nino Terjung","doi":"10.3168/jds.2026-28969","DOIUrl":"https://doi.org/10.3168/jds.2026-28969","url":null,"abstract":"<p><p>This study investigated the effects of dietary biochar supplementation on raw milk characteristics and butter quality in German Holstein cows. Thirty-nine cows were assigned to 3 dietary treatments containing 0.0, 0.5, or 1.0% biochar (dry matter basis, included as part of the total mixed ration); 11 pre-designated primary cows per group were used for individual-level analyses, and 2 additional cows per group were maintained as reserve cows. Raw milk was collected before the start of supplementation (d-14), during the feeding period (d0, 35, and 70), and 14 d after supplementation (d70+14) to evaluate temporal responses and potential reversibility. Milk composition and physicochemical properties were analyzed, and milk was processed into butter to assess processing performance, color, moisture, and fatty acid composition. From a pooled sample, sensory and physicochemical attributes were analyzed. In an exploratory maximum-contrast comparison of the 0.0 and 1.0% groups, biochar supplementation affected raw milk composition, with increases observed in protein fractions, particularly casein and β-lactoglobulin, as well as a tendency toward higher milk fat content. In contrast, biochar had little to no effects on butter processing performance and butter quality parameters. Variations in churning time, butter yield, moisture, and instrumental color attributes were predominantly driven by sampling day and stage of lactation rather than biochar supplementation. Sensory evaluation of pooled butter samples revealed no adverse effects on flavor or odor perception, while moderate differences in color intensity and texture were observed, that were mainly associated with sampling day though. Overall, dietary biochar supplementation did not impair butter quality or sensory acceptance and correlated with increased protein and fat content in raw milk, the economically most relevant milk components. These findings indicate that biochar can be incorporated into dairy cow diets without negative effects on downstream dairy processing, while increasing key milk components important for butter production.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073088","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":"Feeding Ascophyllum nodosum meal or ethylenediamine dihydroiodide to transition dairy cows: Effects on milk yield and plasma concentrations of thyroid hormones and markers of metabolic status.","authors":"D C Reyes, K R Johnston, M A Rahman, K V Almeida, E A Cruz, A L Konopka, N N Price, P S Erickson, A F Brito","doi":"10.3168/jds.2026-28524","DOIUrl":"https://doi.org/10.3168/jds.2026-28524","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Ascophyllum nodosum (ASCO) is a brown seaweed rich in I and bioactive compounds. Previous research demonstrated that feeding incremental amounts of ASCO meal linearly decreased the plasma concentrations of nonesterified fatty acids (NEFA) and cortisol in lactating dairy cows, suggesting that ASCO may improve cows' metabolic status during the transition period. We aimed to investigate the effects of supplementing transition dairy cows with ASCO meal or ethylenediamine dihydroiodide (EDDI) on plasma concentrations of thyroid hormones and markers of metabolic status, DMI, and milk yield and composition. Forty pregnant Holstein cows averaging (mean ± SD) 3.2 ± 1.1 lactations were blocked by expected calving date and assigned to 1 of 4 treatments 28 d before parturition through 28 DIM as follows: 1) control (CON): 11 mg/d of EDDI to meet the NRC (2001) recommended I concentration of 0.5 mg of I/kg of DMI (actual I = 0.70 mg/kg of DMI), 2) low seaweed (LSW): CON plus 57 g/d of ASCO meal (3.13 mg of I/kg of DMI), 3) high seaweed (HSW): CON plus 113 g/d of ASCO meal (5.52 mg of I/kg of DMI), and 4) high EDDI (HEDDI): CON plus 124.8 mg/d of EDDI to match the I concentration of the HSW diet (5.55 mg of I/kg of DMI). All cows were fed the same pre- and postpartum basal TMR with forage:concentrate ratios of 72:28 and 56:44, respectively. The I sources were top-dressed into the TMR, manually mixed to ensure uniformity, and offered once daily during the morning feeding. Blood samples were collected once weekly prepartum and on d 0, 1, 7, 14, 21, and 28 postpartum. Preplanned, nonorthogonal contrasts were used to compare treatment effects using ANOVA, with df partitioned into linear and quadratic effects of ASCO meal supplementation and I source (HSW vs. HEDDI diet). Prepartum BW, BCS, and plasma concentrations of BHB, glucose, insulin, and thyroid hormones did not change linearly or quadratically in response to ASCO meal supplementation or I source. Whereas plasma concentration of NEFA linearly increased in cows fed graded levels of ASCO meal, it was not affected by I source. Dry matter intake, yields of milk and milk fat and lactose, and milk fat and true protein concentrations were not affected linearly or quadratically by ASCO meal. However, milk lactose concentration and true protein yield tended to respond quadratically. Cows fed HSW tended to have lower DMI than those fed HEDDI. Contrarily, milk fat concentration tended to increase and that of MUN increased in HSW versus HEDDI cows. Total I intake and milk I concentration and yield linearly increased with ASCO meal supplementation but did not differ between I source. Postpartum plasma concentrations of NEFA, BHB, glucose, insulin, and thyroid hormones were not impacted linearly or quadratically by ASCO meal. In contrast, HSW cows had greater plasma free triiodothyronine and lower total thyroxin concentrations than HEDDI cows. Overall, ASCO meal linearly increased prepartum concentration of plasma N","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073112","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 offering a second colostrum feeding and delivery method on transfer of passive immunity, health, and behavior in neonatal calves.","authors":"Whitney A Knauer, Destiny Smith, Kenson Boelke, Isabela Karels, Robert Schell, Adam Geiger, Sandra M Godden","doi":"10.3168/jds.2026-28959","DOIUrl":"https://doi.org/10.3168/jds.2026-28959","url":null,"abstract":"<p><p>Our objective was to describe the effect of providing a second feeding of maternal colostrum (MC) or colostrum replacement (CR), using either an esophageal tube or nipple bottle delivery method, on transfer of passive immunity, and on measures of calf health and behavior during the first 3 d of life, as compared with providing a milk replacer control. Eligible newborn dairy and dairy x beef calves on a commercial Minnesota dairy were weighed, placed in a bedded pen, then fitted with a tri-axial accelerometer. All calves were tube-fed a first feeding of pooled heat-treated MC (average IgG = 84 ± 10g/L; μ ± SD) approximately one hour after birth, with smaller calves (27.3-36.3 kg) receiving 2.85L and larger calves (36.4-52.3 kg) receiving 3.8L. Calves (n = 31/group) were then randomly assigned to the second colostrum feeding, delivered 8 ± 0.2 h after the first feeding: milk replacer by bottle (MRB; 1.9L MR), MC by bottle (MCB; 1.9L of MC with 57.7 ± 6.5 g/L IgG), MC by tube (MCT; 1.9L of MC with 58.9 ± 6.3 g/L IgG), CR by bottle (CRB; 1L CR with 100g/L IgG), or CR by tube (CRT; 1L CR with 100 g/L IgG). For bottle fed calves, the bottle was offered for 15 min with refusals (mL) recorded. Venous blood samples were collected at 0, 8, and 24h for serum IgG measures (g/L) using RID analysis. MC samples from the first and second feeding were collected and frozen for IgG analysis. Calf health was evaluated through daily health scoring by study technicians, as well as farm-reported treatments. Behavior was continuously collected over the 72 h. Voluntary intake of milk replacer (mL) was recorded for all calves at the first milk bottle feeding provided the morning after enrollment. The effect of treatment on serum IgG at 24h was evaluated with linear models, and on refusals and farm reported treatments with logistic models. The effect of treatment on daily health scores and behavior was evaluated with repeated measures models. We observed very high and similar serum IgG concentrations at 24h among all treatment groups (g/L, MRB - 37.8 ± 1[μ ± SE]; MCT - 39.0 ± 1; MCB - 38.4 ± 1; CRT - 39.3 ± 1; CRB- 37.7 ± 1). We observed no difference among treatments for recorded health outcomes. Fewer calves in the CRB group refused > 25% of their first milk feeding (16.3%) compared with MCB (51.2%) or MRB (58.0%) the morning following enrollment, with no other appetite differences observed among groups. Transient differences in behavior were observed such that bottle fed calves stood longer and took more steps around feeding compared with tube fed calves. Under the conditions of this study, a second feeding of MC or CR at 8 h did not improve 24 h serum IgG, but no evidence of short-term adverse effects on measured health or behavior outcomes were detected.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073117","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":"Genetic parameters for novel behavioral traits for cows housed under automatic milking systems with a focus on learning.","authors":"Julia Stuhlträger, Frank Rosner, Larissa E Behren, Laura Breitmeier, Sven König, Hermann H Swalve","doi":"10.3168/jds.2026-29045","DOIUrl":"https://doi.org/10.3168/jds.2026-29045","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Automatic milking systems (AMS) are increasingly used in dairy farming, highlighting the importance that cows adapt to this technical environment. This study characterized novel AMS traits related to learning behavior and milking temperament and evaluated their phenotypic and genetic properties to assess their suitability for breeding. It was investigated whether pre-lactational familiarization to AMS is related to cow-robot-performance and behavior during 1st parity and to what extent cow-AMS-interactions develop across parities (1st - 5&lt;sup&gt;th+&lt;/sup&gt; parity). AMS-derived traits rejected milkings (RM) and visiting intervals (VI) were used to investigate learning behavior, i.e., cows' ability to voluntarily visit the robot, while udder scan time (UST) and connecting time (CT) were used to characterize temperament behavior inside the AMS. Data comprised of 17,288 Holstein cows with 41,581 lactations from 24 German dairy farms. To assess pre-lactational familiarization effects, animals were grouped by the number of pre-lactational visits to the AMS: group 0 (none, n = 14,840), group 1 (1-7 visits before 1st parity at AMS, n = 1,294), group 2 (&gt;7 visits before 1st parity at AMS, n = 1,154). It could be shown that pre-lactational familiarization influenced later AMS performance: intensive familiarization (group 2) resulted in high RM and short VI, whereas cows with minimal familiarization (group 1) showed the lowest RM. Cows without familiarization (group 0) exhibited decreasing RM with increasing milking experience. UST showed negligible differences between groups, while CT was shortest in non-familiarized cows. To investigate the cow-AMS-interactions across parities, only non-familiarized cows (group 0) were considered. Across parities, clear learning and age effects were observed. Primiparous cows exhibited the highest RM (LSM = 3.09 ± 0.04) and longest VI (LSM = 389.59 ± 1.78 min), with limited improvement during the first 99 d in milk. Cows in 2nd parity adapted more rapidly, showing a decrease in RM from 2.94 ± 0.05 to 1.58 ± 0.06 during the first 99 d as well as a decrease in VI from 366.23 ± 2.22 min to 352.56 ± 2.57 min. RM further declined consistently across the 2nd to 4th parity, indicating both short-term and long-term learning effects. UST and CT were highest in early lactation and declined during the first 100 d, reflecting increasing familiarity with the milking process. Differences between parities were small but consistent: older cows required less time for UST and CT. Genetic analyses revealed heritabilities of 0.1 ± 0.005 for RM and 0.25 ± 0.007 for VI, with a highly negative genetic (-0.98) and phenotypic (-0.81) correlation between them. UST and CT exhibited low heritabilities (0.04 ± 0.003 and 0.07 ± 0.005), indicating stronger environmental influence. A positive genetic correlation (0.76 ± 0.06) suggests underlying temperament that may influence AMS efficiency. Overall, AMS-derived behavioral and temperament traits captu","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073135","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":"Visualization of changes in relationships among traits over time; example in type traits.","authors":"M Misztal, S Tsuruta, I Misztal, J Graham, S Comstock, J Bewley, D Lourenco","doi":"10.3168/jds.2026-28881","DOIUrl":"https://doi.org/10.3168/jds.2026-28881","url":null,"abstract":"<p><p>Genetic evaluations usually include many correlated traits. Their evaluation and use in the selection index rely on genetic parameters that change over time, with these changes potentially accelerating under genomic selection. However, estimating the changes with current methods and large genomic information is computationally prohibitive, and interpreting changes in relationships among many traits is difficult. The purpose of this study is to present a methodology to visualize changes in complex relationships among traits over time. Data included genetic correlations among 18 linear conformation traits of US Holsteins, computed by GPP (Genetic Parameters via Predictivity), for yearly time slices from 2010 to 2020, using all available pedigree, phenotypic, and genomic information. GPP relies on predictivity of adjusted phenotypes from validation population on EBV from reference population and allows estimation by time slices using complete commercial data. In 2010, the reference population included cows born in 2000-2008, and the validation population included cows born in 2009-2011. In subsequent years, the population advanced by one year. Using genetic correlations for the year 2020, each trait was regressed on 2, 3, and 4 remaining conformation (also known as type) traits chosen by the best fit (R²). Regression coefficients were then recomputed for the years 2010-2019. Graphs of the coefficients over time for each trait and 2-4 traits in the regression indicated changing relationships among the traits over time. For example, with 2 traits in the regression, fore udder attachment was estimated as a function of udder depth and rear udder width (R² = 0.84); the addition of stature increased R² by 0.03 and adding body depth increased R² by an additional 0.04. Biplots of 2 principal components in the 4-trait model indicated that the impact of rear udder width was similar to that of body depth and stature in 2010 but more differentiated in 2020. In general, predictions with 4 traits were less stable. Changes in the dynamics of correlated traits can be visualized by regression coefficients from equations involving 2 to 4 correlated traits and corresponding biplots of the 2 principal components.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073150","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":"Breed differences in milk fatty acid composition across lactation in grazing Holstein-Friesian, Jersey, and Holstein-Friesian × Jersey crossbred cows.","authors":"Yaliska Moreno-González, Daniel Donaghy, Ignacio F López, Benjamin Carter, Stephen E Holroyd, Alastair MacGibbon, Nicolas López-Villalobos","doi":"10.3168/jds.2026-28804","DOIUrl":"https://doi.org/10.3168/jds.2026-28804","url":null,"abstract":"<p><p>This study evaluated breed differences in milk fatty acid (FA) composition and assessed whether breed differences in FA composition change across stages of lactation in Holstein-Friesian (F), Friesian × Jersey (F × J), and Jersey (J) cows managed under a pasture-based system. Ninety spring-calving cows (33 F, 31 F × J, and 26 J) were sampled during the 2023-2024 lactation season. Monthly herd test records (n = 790) were analyzed to characterize milk yield and composition. Composite milk samples were collected for determination of fat, protein, and mid-infrared spectra. Fatty acid concentrations (g FA/100 g of milk) were predicted using partial least squares models calibrated against 120 samples with FA measured by gas chromatography. Lactation patterns were described using random regression with orthogonal polynomial functions. Stage of lactation was the dominant source of variation, with short-chain, medium-chain, and saturated FA increasing from early to late lactation, while preformed FA declined. Jersey cows had the highest total fat concentration (6.29%), followed by F × J (5.50%) and F (5.32%), and produced approximately 23% more saturated FA than F cows (+0.80 g FA/100 g of milk). When averaged across lactation, F × J generally resembled F for most FA groups, although the crossbred response was FA-specific: F × J was intermediate for short-chain FA but resembled F for medium-chain FA. Breed differences were more pronounced within lactation stages than in pooled analyses. Breed × stage interactions reflected changes in the magnitude of breed differences rather than changes in ranking, with the saturated FA difference between J and F widening by about +0.11 g FA/100 g of milk from early to late lactation. These results demonstrate that crossbred FA profiles are FA-specific and stage-dependent and cannot be predicted as simple parental averages.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073100","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":"Restoration of lactose metabolism in Lacticaseibacillus rhamnosus GG for dairy fermentation applications.","authors":"Zifan Xie, Hyunjoon Oh, Yong-Su Jin, Michael J Miller","doi":"10.3168/jds.2026-29059","DOIUrl":"https://doi.org/10.3168/jds.2026-29059","url":null,"abstract":"<p><p>Lacticaseibacillus rhamnosus GG (LGG) is a widely used probiotic but has limited applications in dairy fermentation because of its poor lactose utilization. Here, we generated a lactose-positive LGG derivative using the LGG endogenous CRISPR-Cas system achieving a marker-free, scarless 20-bp deletion to disrupt the t1 transcriptional terminator upstream of the lactose operon. Using lactose-based selection, lactose-positive derivatives were then isolated and confirmed a restored functional lacG allele by sequencing. After curing the editing plasmid, the final strain, MJM570, was obtained. Whole-genome sequencing verified the intended terminator deletion and lacG reversion. MJM570 grew robustly on lactose, supported growth and acidification in milk, and showed improved proliferation and viability in yogurt fermentation and refrigerated storage compared with the wild-type LGG. This marker-free strategy leaves no foreign DNA in the final strain and provides a practical platform for developing dairy-compatible probiotic cultures with improved performance in fermented dairy applications. Overall, this study demonstrates the potential of endogenous CRISPR-Cas systems for food-relevant genome editing for developing dairy-compatible probiotic cultures.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149073118","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}