Journal of Dairy Science最新文献

{"title":"The flavor quality differences of infant formula: The synergistic effects of nutritional components and chemical reactions.","authors":"Jiaxin Zhang, Wen Tu, Longyu Wan, Huabing Wang, Xu Wang, Ming Ma, Jiayue Yang, Feng Zhao, Qianyu Zhao, Yujun Jiang","doi":"10.3168/jds.2025-26845","DOIUrl":"https://doi.org/10.3168/jds.2025-26845","url":null,"abstract":"<p><p>This study elucidates the interplay between nutritional composition and chemical reactions governing off-flavor formation in infant formula powder (IF). Sample Z, which is an IF of a raw bovine milk base with vegetable lipids (1,3-diolein-2-palmitin [OPO], sunflower, and flaxseed oils), showed accelerated oxidation (the oxidation products are twice those of sample J), generating propanal, pentanal, and hexanal, leading to metallic, fishy, and algae-like odors. Unsaturated lipids also promoted particle aggregation, vitamin degradation, and pungent aldehydes or ketones (2,4-octadienal, 1-octen-3-one). Sample J (IF of a raw caprine milk base with vegetable lipids [OPO, soybean, and corn oils]), containing γ-dodecalactone, exhibited floral or sweet notes but still retained fishy or metallic off-flavors. These findings underscore the crucial role of lipid composition in maintaining flavor stability, offering a practical approach for optimizing IF. By selectively incorporating oxidation-stable vegetable oils with balanced UFA profiles, off-flavor formation during storage can be minimized while ensuring adequate delivery of essential nutrients (e.g., docosahexaenoic acid, arachidonic acid, and eicosapentaenoic acid).</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102625","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 a blend of palmitic and stearic acid on transfer of preformed fatty acids into milk fat using an 18 C n-3 fatty acid perturbation model.","authors":"Y A Adeniji, S L Burtnett, M I Ibrahim, K J Harvatine","doi":"10.3168/jds.2025-26838","DOIUrl":"https://doi.org/10.3168/jds.2025-26838","url":null,"abstract":"<p><p>The transfer of dietary fatty acids (FA) into milk fat is variable and has been reported to be higher on lower fat diets, which may be a homeorhetic adaptation to support milk fat production. The objective of this study was to determine the effect of increasing dietary fat on the kinetics of transfer of preformed FA into milk fat using a perturbation model based on abomasal infusion of a bolus of n-3 FA. Eight ruminally cannulated multiparous Holstein cows (115 ± 32 DIM and producing 41.5 ± 4.43 kg of milk; mean ± SD) were used in a switchback design with three 21-d periods. Treatments were a low-fat basal diet (CON) and the basal diet supplemented with a blend of palmitic and stearic FA fed at 2% DM (Fat; 33.5% 16:0, 53.1% 18.0, and 6.2% 18:1n-9). Increasing dietary FA tended to increase milk yield by 2.2 kg/d and increased milk fat yield by 170 g/d. Yield of preformed FA in milk was increased 119 g/d but yield of <16 C and 16 C FA was not changed compared with CON. Apparent total-tract digestibility of DM, OM, NDF, and FA were not changed by FA supplementation. Transfer of dietary 18 C FA to milk fat was 110% of dietary fat consumed in CON and was decreased to 82% in the Fat treatment. On d 15 of each period, cows were abomasally infused with a free FA stock that provided 44 g of α-linolenic acid (ALA) and 20 g of stearidonic acid (SDA), and milk FA profile was observed over the following 7 d. Maximal enrichment of ALA and SDA in milk fat occurred at the second milking following the bolus (∼14 h) and returned to baseline concentrations by 74 h. Increasing dietary fat decreased total transfer of n-3 FA by 5.4 percentage units. Total transfer of infused ALA was 51.9% and SDA was 27.9% in the CON and decreased to 43.3% and 22.7% in the high-fat diet, respectively. Similar to previous work, the majority (81%) of the n-3 FA transferred to milk fat occurred in the first 24 h, which is expected to represent direct transfer of absorbed FA to milk fat and was not influenced by dietary fat. The greater than 100% transfer efficiency of 18 C FA to milk fat and the higher transfer efficiency of n-3 FA to milk fat when feeding a lower fat diet indicates dynamic partitioning of absorbed FA that is responsive to dietary FA supply.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102553","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":"Evaluating differences in uterine microbiome and inflammatory status at 1 month postpartum associated with metritis and antibiotic treatment.","authors":"Joao G N Moraes, Tamara Gull, Aaron C Ericsson, Monica O Caldeira, Tim J Evans, Scott E Poock, Matthew C Lucy","doi":"10.3168/jds.2025-26403","DOIUrl":"https://doi.org/10.3168/jds.2025-26403","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Ceftiofur treatment in cows with metritis enhances the likelihood of clinical cure but does not consistently improve subsequent pregnancy rates compared with healthy (nonmetritis) cows. We tested the hypothesis that ceftiofur treatment has no effect on uterine microbiota or endometrial inflammation at 1 mo postpartum in cows that were either healthy or diagnosed with metritis at 5 to 10 d postpartum. Cows diagnosed with metritis were matched with healthy cows in a 2 × 2 factorial design where they were either treated with an antibiotic (ceftiofur hydrochloride) or left untreated. Cows were slaughtered to collect the uterus at 1 mo postpartum, and the uterine microbiota was measured using bacteriology and 16S rRNA gene sequencing. The lumen of the uterus was examined visually for the presence of purulent material, and inflammation within the endometrium was assessed histologically. When bacteria were cultured from the lumen of the uterus at 1 mo postpartum, a greater number of species was isolated and a greater number of colonies formed from cows that were previously diagnosed with metritis compared with healthy cows. Antibiotic treatment administered at the time of disease diagnosis (5 to 10 d postpartum) had no effects on the abundance of culturable bacteria at 1 mo postpartum in healthy cows but reduced the number of culturable bacteria from the uterus of cows previously diagnosed with metritis. Based on 16S rRNA gene sequencing, cows originally diagnosed with metritis had an increased number of sequencing reads 1 mo postpartum than cows initially deemed healthy. Furthermore, antimicrobial treatment 5 to 10 d postpartum decreased the number of sequencing reads 1 mo postpartum irrespective of the initial disease diagnosis. The presence of purulent or metritis-like discharge in the uterine lumen 1 mo postpartum had a major effect on the uterine microbiota. Histopathological analysis revealed that the presence of purulent material in the uterus or signs of acute infection at 1 mo postpartum was associated with greater uterine inflammation compared with a clear uterine flush but minimally affected by treatment. Furthermore, antibiotic treatment had no main effect on α-diversity (Faith's phylogenetic diversity or Pielou's evenness), and no differentially abundant taxa were detected by analysis of composition of microbes. However, β-diversity analyses (unweighted UniFrac) showed a small but significant effect of treatment, with treated cows having lower within-group variability than untreated cows, suggesting a modest homogenizing effect on the uterine microbiota. A multinomial regression analysis revealed a marked reduction (145-fold) in the relative abundance of Fusobacterium in treated cows. This shift suggests a partial restoration of the microbial community in cows with metritis toward a profile resembling that of their healthy counterparts. Additionally, the analysis indicated that the uterine microbiota at 1 mo postpartum was collectivel","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102596","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":"Bull urine and semen as potential vectors of disease transmission for Leptospira borgpetersenii serovar Hardjo.","authors":"Camila Hamond, Nathan E Stone, Ellie J Putz, Luis G V Fernandes, Tammy Anderson, Patrick Camp, Jessica Hicks, Tod Stuber, Hans van der Linden, Priscyla Dos Santos Ribeiro, Darrell O Bayles, Jason W Sahl, David M Wagner, Jarlath E Nally","doi":"10.3168/jds.2025-27020","DOIUrl":"https://doi.org/10.3168/jds.2025-27020","url":null,"abstract":"<p><p>Bovine leptospirosis can result in infertility, abortion, placentitis, weak offspring, stillbirths, and decreased milk production. The leading cause of bovine leptospirosis globally is Leptospira borgpetersenii serovar Hardjo. Asymptomatic cattle with leptospirosis serve as reservoir hosts of infection that can shed infectious leptospires for months to years. Sites of bacterial colonization include the kidney or the genital tract, or both, in both cows and bulls. In this observational study, we investigated leptospirosis in a herd of asymptomatic bulls; 24.1% (14/58) were shedding leptospires via urine as confirmed by lipL32 real-time PCR (rtPCR). The viability of leptospires in selected rtPCR-positive bull urine samples was confirmed by culture. Given that bovine semen may also act as a vector of disease transmission, we investigated frozen semen samples for evidence of leptospires; 1.5% (4/268) were lipL32 rtPCR-positive, and, of these, one was culture-positive. All isolates cultured from bull urine or semen were classified as L. borgpetersenii serogroup Sejroe serovar Hardjo. The viability and infectivity of the semen isolate were confirmed in the hamster model of leptospirosis. Our results report for the first time the ability to culture serovar Hardjo directly from frozen semen and highlight the potential role for bull urine and semen in the transmission of bovine leptospirosis.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102632","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":"Dairy farmers' experiences with adopting social housing for milk-fed dairy calves.","authors":"Christine Kuo, Daniel M Weary, Marina A G von Keyserlingk","doi":"10.3168/jds.2025-27248","DOIUrl":"https://doi.org/10.3168/jds.2025-27248","url":null,"abstract":"<p><p>Rearing milk-fed dairy calves in pairs or groups (i.e., social housing) can be beneficial for their welfare, but individual housing remains the norm on many farms. Although some research has investigated farmer perceptions of social housing, to our knowledge no research has investigated farmers' experiences with transitioning from individual to social housing. We aimed to describe dairy farmers' experiences of transitioning from individual to social calf housing using the Innovation-Decision Process, a framework that includes the processes leading up to, implementing, and sustaining (or discontinuing) a practice. We conducted in-person semi-structured interviews with 17 dairy farmers from 15 farms in British Columbia, Canada, that transitioned calf housing during the milk feeding period from an individual to a social setup (n = 12 farms); as well as farms that returned to individual housing after the transition (n = 3 farms). Interviews averaged 86 min in length and were anonymized, transcribed, and thematically coded. Our findings indicate that the initial motivation to adopt social housing was influenced in part by participants' social environment, but also by calf-based (e.g., growth) and farm-based (e.g., labor saving) reasons. After implementing social housing, participants varied in the challenges (e.g., competition between calves for feed access) and benefits (e.g., improved calf growth) they experienced. Participants also discussed problem-solving approaches to improve outcomes, such as modifying housing and management practices, sometimes cycling through multiple approaches before settling on one that worked for them. The results of this research contribute to our understanding of farmer motivators, needs, concerns, and approaches when transitioning to social housing for calves. More generally, the results provide insights into how changes in farm practices occur, helping to inform the adoption of other practices on farms.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102638","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":"Going deeper in lipolysis: Prediction of individual free fatty acid contents in milk by mid-infrared spectroscopy.","authors":"Octave Christophe, Romain Reding, Julie Leblois, Clément Grelet, Denis Pittois, Hélène Soyeurt, Cedric Guignard, Frédéric Dehareng","doi":"10.3168/jds.2025-26829","DOIUrl":"https://doi.org/10.3168/jds.2025-26829","url":null,"abstract":"<p><p>The dairy sector deals with a recurring issue: a taste alteration due to degradation of fat, commonly called lipolysis. Lipolysis occurs after milking, through the physical shocks induced by freezing, pumping, transfer, and storage of the milk. Physical breaking of fat globules makes triglycerides accessible to enzymes and degrades into free fatty acids (FFA). Among them, the volatile short-chain FFA lead to organoleptic issues through undesired tastes. Currently, methods to measure FFA are very complex and time-consuming, incomplete, only provide information on the total amount of FFA, or a combination of these. To bring a new way of preventive and corrective action for dairies and farmers, this study aims to develop predictive models based on milk Fourier transform mid-infrared spectroscopy (FT-MIR) to quantify individual FFA, with a special focus on short-chain FFA. A total of 792 milk samples were collected from individual cows and in bulk tanks in 4 different countries (Luxembourg, Belgium, France, and Germany) and analyzed by FT-MIR spectroscopy as well as GC coupled with tandem mass spectrometry. When performing a random sampling of individual cows, and therefore relying only on spontaneous lipolysis, most of the samples showed that short-chain FFA under the limit of quantification and derived FT-MIR models had poor performance. In a second step, lipolysis was induced by 4 different mechanical processes of milk. Among them, time milk homogenization demonstrated a clear increase of short-chain FFA values leading to improved predictive performance of models. The predictions of short-chain FFA could be used for rough screening on the dairy population, especially C4 and total short-chain FFA as their models had a validation R² above 0.7. Unfortunately, the mid- and long-chain FFA models showed poor predictive performance. However, those results can still be considered positive because they may enable a better monitoring of taste defect mainly occurring from short-chain FFA.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102627","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":"Single-step genomic predictions for crossbred Holstein and Jersey cattle using metafounders.","authors":"I Ampofo, G Vargas, D Gonzalez-Peña, T L Passafaro, Y L Bernal Rubio, L M P Sanglard, N Vukasinovic, B O Fragomeni","doi":"10.3168/jds.2025-26594","DOIUrl":"https://doi.org/10.3168/jds.2025-26594","url":null,"abstract":"<p><p>The study examined the impact of incorporating metafounders (MF) in single-step genomic BLUP (ssGBLUP) models for the genetic evaluation of Holstein (HO) and Jersey (JE) cattle with their crossbreds (CROSS). The dataset included 23,736,975 records on 8,560,986 cows. Genotypic data on 181,379 JE, 1,905,292 HO, and 53,799 CROSS animals were used for the evaluation. The genetic evaluation included 5 production traits, namely, milk yield (MY), protein yield (PY), fat yield (FY), SCS, and daughter pregnancy rate (DPR), which were analyzed using a 5-trait repeatability model using ssGBLUP with or without MF. Three different MF scenarios were tested: 4 MF (based on breed), 24 MF (based on the combination of breed, sex, and year of birth), and 32 MF (similar to 24 MF but with CROSS as a separate genetic group). The 3 MF scenarios were compared with a conventional ssGBLUP model that did not include metafounders (NO_MF). Forward-in-time validation was carried out to evaluate predictability, inflation, and stability. For purebred Holstein and Jersey cows, the truncated dataset included phenotypes through December 2018, whereas for crossbreds, the cutoff was December 2015; the complete dataset extended through December 2022. Validation targeted genotyped cows lacking records in their respective truncated dataset but with at least one record in the complete dataset, yielding 96,295 Holsteins, 26,436 Jerseys, and 5,099 crossbreds for analysis. Results showed that including MF affected prediction metrics differently depending on the trait, breed, and MF configuration. While certain MF classifications (e.g., 4 MF) reduce bias and improve predictability in crossbreds for some traits, others show minimal effects, particularly in purebred Holsteins. For low h² traits (SCS, DPR), MF scenarios provided better predictive ability in CROSS animals. In contrast, for high h² traits (MY, PY, FY), stability tended to decrease in MF models, suggesting possible overfitting due to added model complexity. Overall, MF offers a promising strategy to address pedigree gaps in multibreed evaluations, but its application should be carefully tailored to trait architecture and population composition to avoid overfitting and ensure accurate genetic predictions.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102574","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 docosahexaenoic acid on milk fatty acid profile, fat globule size, and flavor characteristics.","authors":"Hongling Jiang, Chen Zhang, Yan Li, Feng Ye, Xueming Luo, Hongyun Liu","doi":"10.3168/jds.2025-27133","DOIUrl":"https://doi.org/10.3168/jds.2025-27133","url":null,"abstract":"<p><p>The n-3 PUFA, particularly docosahexaenoic acid (DHA), are crucial compounds for human health. This study investigated the effect of feeding dairy cows rumen-protected DHA (RP-DHA) on the milk fatty acid profile, active ingredients, milk fat globule size (MFG), and flavor characteristics. The results showed that RP-DHA supplementation significantly increased the ratio of eicosapentaenoic acid, docosapentaenoic acid, and DHA and decreased the content of malondialdehyde in milk. The RP-DHA significantly decreased the MFG surface area-dependent diameter D_[3,2], volume-dependent diameter D_[4,3], particle size parameters Dv(10), Dv(50), Dv(90), and the absolute value of zeta potential. The electronic tongue radar chart showed that the milk taste in the control group was mainly umami and sour and in the RP-DHA group was mainly salty and sweet. A total of 614 volatile substances were identified, and 68 volatile flavor compounds were selected according to the relative odor activity value. These compounds were divided into 13 alcohols, 12 aldehydes, 7 ketones, 9 esters, 10 terpenes, 3 heterocyclic compounds, 4 aromatics, 2 phenols, 6 acids, and 2 nitrogen-containing compounds. Volatile flavor analysis indicated that (-)-β-elemene and 3-methylphenol levels increased, while 5-amino-2-methyl-2H-tetrazole and pentadecanal decreased in the RP-DHA group. The results showed that RP-DHA could reduce the size of MFG and alter the milk fatty acid composition. These findings enhance our understanding of milk production using direct dietary supplementation of DHA to produce sustainable dairy products.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102598","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":"Grass forages grown under identical conditions and conserved as silage or barn-dried hay: Effects on feed intake, performance, apparent total-tract digestibility, and fecal microbiota in dairy cows.","authors":"Katrin Bauer, Thomas Hartinger, Mansour Eghbali, Andreas Haselmann, Birgit Fuerst-Waltl, Werner Zollitsch, Qendrim Zebeli, Wilhelm Knaus","doi":"10.3168/jds.2025-26992","DOIUrl":"https://doi.org/10.3168/jds.2025-26992","url":null,"abstract":"<p><p>While high-forage diets benefit net human food production, cows' responses to differently conserved grass forages (ensiling vs. barn-drying) may affect feed intake and performance and eventually the efficiency of forage utilization. In the present study, forages were obtained from the same fields, harvested at the same time after equal wilting conditions, and either ensiled in a bunker silo or artificially dried in the barn. At the onset of the feeding trial, 18 lactating Holstein cows were divided into 2 feeding groups based on daily milk yield, BW, parity, and DIM. Cows received either grass silage (38% DM) or hay ad libitum for 35 d in addition to a fixed allocation of 3.64 kg DM dairy concentrate per cow and day. Data were collected for 21 d, after a 14-d adaptation period. Chemical analysis showed similar composition of NDF assayed with a heat-stable amylase and expressed exclusive of residual ash (521 and 524 g/kg DM), but differences in CP (136 and 117 g/kg DM) and water-soluble carbohydrates (WSC; 23 and 177 g/kg DM) between grass silage and hay, respectively. Results showed that cows fed hay had a significantly higher DMI (+2.4 kg/d) when compared with the group receiving grass silage, presumably due to microbial metabolites from ensiling, as well as lower content of WSC and NFC. Butyric acid, as well as the silage's low lactic acid content and uncommon lactic to acetic acid ratio, may have affected palatability and limited feed intake. Consequently, dairy performance was significantly higher, that is, 28.1 kg ECM/d versus 25.2 kg ECM/d in hay-fed cows versus silage-fed cows, respectively. Milk fat concentration tended to be higher in the hay group than in the silage-fed cows, with 4.37% and 4.06%, respectively. Body condition and apparent total-tract digestibility of nutrients remained unaffected by the treatment. Likewise, fermentation profile and bacterial community in feces were similar between groups. In conclusion, conserving grass forages as hay rather than silage maintains the level of WSC and can significantly increase feed intake and the resulting nutrient and energy supply to cows when concentrates are fed restrictively. In practice, this can help reduce concentrate feed usage per kilogram of milk, increasing net food production. Further research is needed to evaluate the effect of different conservation methods of grass forages in high-producing dairy cattle.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102649","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 associations among blood β-hydroxybutyrate measured by 2 methods, milk composition, and reproductive traits in early-lactation Holstein cows.","authors":"Denyus Augusto de Oliveira Padilha, Rodrigo de Almeida, Lenira El Faro Zadra, Altair Antônio Valloto, Rodrigo de Almeida Teixeira, Laila Talarico Dias","doi":"10.3168/jds.2025-26811","DOIUrl":"https://doi.org/10.3168/jds.2025-26811","url":null,"abstract":"<p><p>This study aimed to estimate genetic parameters for blood β BHB concentrations and to characterize the epidemiology of hyperketonemia (HYK) using both laboratory and strip-based measurement methods at the onset of lactation in Holstein cattle. A second objective was to investigate the associations between BHB levels and milk components and reproductive traits. Understanding these genetic relationships will enable an assessment of the impact of selection for high milk yield on the occurrence of metabolic disorders and reproductive performance. The dataset encompassed BHB records from a total of 5,037 Holstein cows. These animals were born between 2000 and 2020 and were part of 18 experiments involving transition cows conducted at the Federal University of Paraná between 2009 and 2024, across 34 herds in the state of Paraná, Southern Brazil. Productive, reproductive and pedigree data were sourced from the milk recording service of the Holstein Cattle Breeders Association of Paraná State. Blood BHB levels were measured between 3 and 14 d postpartum using 2 distinct methods: β-ketone test strips (BHBstrip) and laboratory testing (BHBlab) employing enzymatic colorimetric methodology. Prevalence of HYK was estimated using BHB levels ≥1.2 mmol/L in the interval from 3 to 14 d postpartum. For genetic analyses, the BHB records were logarithmically transformed and treated as repeated measurements. Genetic parameters for daily milk yield, protein (PP), fat, and lactose percentages, fat:protein ratio (F:P), calving interval, days open, interval between first and last insemination (IFL), and interval between calving and first insemination were estimated using a linear animal model, applying the restricted maximum likelihood method and BLUPF90+ software. The prevalence for HYK was 22.97%. The heritability of BHB ranged between 0.10 ± 0.03 and 0.15 ± 0.03, and repeatability ranged from 0.32 ± 0.02 to 0.37 ± 0.02. Genetic correlations ranged from low to high magnitude, with the highest correlations being identified between BHBstrip and PP (-0.43 ± 0.03 to -0.83 ± 0.003) and BHBstrip and F:P (0.33 ± 0.04) for milk components, and between BHBlab and IFL (0.26 ± 0.03). These values evidence the existence of genetic variability for BHB and their genetic associations with milk components and reproductive traits. Therefore, indirect selection for animals less susceptible to HYK, using indicators such as BHB, PP, and F:P, can yield favorable correlated responses to reduce the occurrence of HYK in Holstein herds. Moreover, the genetic association between BHB and reproductive traits highlights the unfavorable relationship between HYK and reproductive performance.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102551","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}