Journal of Dairy Science最新文献

{"title":"Genetic parameters and genome-wide association studies of milk infrared spectra from Lacaune dairy ewes","authors":"C. Marie-Etancelin,&nbsp;R. Rupp","doi":"10.3168/jds.2025-26259","DOIUrl":"10.3168/jds.2025-26259","url":null,"abstract":"<div><div>Fourier-transform infrared spectroscopy is a widely used analytical tool in dairy production—either in cattle or small ruminant—for predicting milk composition and quality. Nevertheless, not all the information contained in the spectrum is used for its predictions. This study examined the genetic parameters and GWAS of all wavelengths of infrared milk spectra in Lacaune dairy ewes to explore their genetic determinism and compare it with that of milk composition traits predicted by the spectra. Data from 1,063 ewes were collected during their first lactation over 9 yr (2014–2022) at 5 milk recording controls, including infrared spectra with 1,060 wavelengths and predicted milk composition (fatty acids and proteins). The ewes were genotyped with a 54K SNP chip. Heritability estimates across the infrared spectrum ranged from 0.26 to 0.69, with higher values observed in the late lactation stages. Genome-wide association study revealed significant QTL for both spectra wavelengths and predicted milk traits, with some loci being specific to milk IR spectra. Key regions on <em>Ovis aries</em> (OAR) chromosome 3 (OAR3, around <em>Socs2</em>) and OAR11 were associated with both milk composition and spectral traits. Additionally, novel QTL for milk urea (OAR6) and certain fatty acids (OAR17) were identified, as well as QTL within spectra on 4 chromosomes (OAR1, OAR10, OAR13, and OAR20). This study demonstrates that direct GWAS on infrared spectra provides complementary insights to traditional approaches on predicted milk composition traits, uncovering new genetic regions of interest and advancing our understanding of milk composition's genetic architecture. These findings highlight the potential of milk spectra as a tool for enhancing genetic selection in dairy sheep.</div></div>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":"108 8","pages":"Pages 8648-8665"},"PeriodicalIF":3.7,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694307","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":"Rumen metagenome as a genomic selection target to reduce enteric methane emissions","authors":"B.J. Sepulveda ,&nbsp;O. González-Recio ,&nbsp;A.J. Chamberlain ,&nbsp;M. Khansefid ,&nbsp;B.G. Cocks ,&nbsp;J. Wang ,&nbsp;C.P. Prowse-Wilkins ,&nbsp;L.C. Marett ,&nbsp;S.R.O. Williams ,&nbsp;J.L. Jacobs ,&nbsp;A. García-Rodríguez ,&nbsp;J.A. Jiménez-Montero ,&nbsp;J.E. Pryce","doi":"10.3168/jds.2024-25436","DOIUrl":"10.3168/jds.2024-25436","url":null,"abstract":"<div><div>Ruminant digestion emits methane, a potent greenhouse gas contributing to global warming and reducing feed efficiency. Reducing enteric methane emissions (EME) through breeding decisions is theoretically possible, yet measuring these emissions on commercial farms is currently challenging and costly. It is common for EME to be measured using different technologies, which may show weak correlations between them, complicating the combination of reference populations, especially between countries. Here, using the same sequencing strategy, we identified a group of ruminant metagenomic features (a core) present in at least 90% of 410 dairy cows in Australia and 434 in Spain. With subsets of this core (the breeding core subsets) we estimated larger reductions on EME than using direct selection on EME. A combination of direct selection on EME and indirect selection on the breeding core subsets was estimated to produce even larger reductions. Combining the principal components of the core with some genera, Kyoto Encyclopedia of Genes and Genomes ontology and Clusters of Orthologous Groups could enhance EME reductions in breeding programs. We estimated an EME reduction of 0.41 phenotypic standard deviations per generation by selecting the top 30% of individuals with desirable ruminal microbiota profiles. An R Shiny application to estimate those reductions is provided. Additionally, the breeding core subsets could predict EME irrespective of each population's EME trait (sulfur hexafluoride in Australia and sniffers in Spain). These results suggest that rumen metagenome features could be used as selection criteria for genomic selection programs to reduce EME, as many of these features are heritable and correlated with EME. Features in the core could connect EME from different cattle populations, irrespective of the methane phenotype used in those populations. We propose that our methodology should be applied to much larger datasets to improve the accuracy of identifying a breeding core. Therefore, we propose a global effort to validate a common core of EME-associated ruminal features.</div></div>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":"108 8","pages":"Pages 8619-8636"},"PeriodicalIF":3.7,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694306","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":"Biofilm Formation in Dairy: A Food Safety Concern—Introduction","authors":"Denis Roy ,&nbsp;Mérilie Gagnon","doi":"10.3168/jds.2025-27015","DOIUrl":"10.3168/jds.2025-27015","url":null,"abstract":"","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":"108 8","pages":"Pages 8098-8100"},"PeriodicalIF":3.7,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695192","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":"INTERPRETIVE SUMMARIES, AUGUST 2025","authors":"","doi":"10.1016/S0022-0302(25)00525-9","DOIUrl":"10.1016/S0022-0302(25)00525-9","url":null,"abstract":"","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":"108 8","pages":"Pages viii-xvii"},"PeriodicalIF":3.7,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144695121","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":"Exploring splice variants in milk leukocytes of dairy cows with subclinical intramammary infection due to Prototheca spp. and Streptococcus agalactiae.","authors":"Alice Vanzin, Vittoria Bisutti, Angela Cánovas, Alessio Cecchinato, Luigi Gallo, Diana Giannuzzi, Sara Pegolo","doi":"10.3168/jds.2025-26508","DOIUrl":"https://doi.org/10.3168/jds.2025-26508","url":null,"abstract":"<p><p>Alternative splicing events lead to different mRNA isoforms, potentially translated into proteins with altered structures or impaired functions, or both. This phenomenon may influence the resistance or susceptibility to diseases, such as mastitis. To explore this aspect, this study aims to analyze transcript expression, focusing on cases where multiple mRNA isoforms are present, in milk somatic cells from Holstein cattle affected by subclinical intramammary infection caused by Prototheca spp. (P+, n = 11) or Streptococcus agalactiae (Sa+, n = 11), compared with uninfected animals (Neg, n = 9). The RNA-sequencing data were analyzed using the CLC Genomics Workbench (Qiagen) with a large gap read mapping approach and Bos taurus ARS-UCD1.3 reference genome to identify the differentially expressed transcripts (DET) among the groups. In addition, a functional analysis of the identified DET, combined with the identification of functional variants within the expressed regions, was performed. The comparison P+ versus Neg revealed 27 annotated DET, 11 annotated DET with novel length, and 7 novel DET with no previously annotated associated gene or length. These DET mainly originated from immune-related genes involved in pathways strictly linked to the immune and inflammatory responses (i.e., antigen presentation pathway, MHC class II antigen presentation pathway, macrophage classical activation signaling pathway). In contrast, the Sa+ versus Neg comparison revealed a total of 26 DET, including 17 annotated transcripts, 8 annotated transcripts with a novel length, and 1 novel transcript from a nonannotated gene. In this case, a predominance of enriched pathways related to metabolism and detoxification processes was observed (i.e., FXR/RXR activation, xenobiotic metabolism general signaling pathway, glutathione-mediated detoxification). Functional variants were identified in regions overlapping DET encoded by KRT78, CSN1S1, and MYBPC1, which were downregulated in P+ when compared with Neg group and potentially related to mastitis resistance/susceptibility traits. The transcripts and associated functional variants identified in this study may contribute to a better understanding of bovine mastitis pathogenesis and development, providing useful insights for improving animal health and management strategies.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705952","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":"Fertility in lactating dairy cows following timed embryo transfer with fresh in vitro-produced embryos derived from conventional or sex-sorted semen.","authors":"E M Murphy, A D Crowe, L Thompson, S G Moore, M McDonald, E Hordern, B Bertholdi, F Randi, E Rojas Canadas, P Lonergan, S T Butler","doi":"10.3168/jds.2025-27056","DOIUrl":"https://doi.org/10.3168/jds.2025-27056","url":null,"abstract":"<p><p>The objectives of this study were to (1) compare in vitro embryo production using conventional (CONV) or sex-sorted (SS) semen for in vitro fertilization (IVF) of oocytes collected from elite genetic merit dairy and beef donors, and (2) compare pregnancy per embryo transfer (P/ET) in lactating dairy cows following transfer of fresh DAIRY or BEEF embryos derived from CONV or SS semen. Oocytes were collected once weekly for a period of 4 successive weeks using ultrasound-guided transvaginal ovum pick-up from the ovaries of elite beef (Angus, n = 37) and dairy (Holstein-Friesian, n = 51) heifers and cows. Following in vitro maturation, oocytes were fertilized with frozen-thawed CONV or SS semen from a panel of beef (n = 6) or dairy (n = 9) sires of proven fertility and cultured in vitro to the blastocyst stage. A total of 507 grade 1 blastocysts (n = 468 fresh, n = 39 frozen-thawed) were transferred to lactating Holstein-Friesian recipients that had been synchronized using a 10 d progesterone-Ovsynch protocol. Recipients were blocked based on parity, DIM, and Economic Breeding Index, and randomly assigned to receive a single BEEF-CONV, BEEF-SS, DAIRY-CONV, or DAIRY-SS embryo. Pregnancy diagnosis was carried out using transrectal ultrasound on d 32 after synchronized estrus and confirmed on d 63. Pregnancy loss was characterized as loss between d 32 and d 63. The number of oocytes recovered per ovum pick-up session (14.9 vs. 8.1), blastocyst yield (28.7% vs. 16.1%) and the number of blastocysts produced per IVF session (2.8 vs. 1.0) were greater for beef donors than dairy donors. Overall, blastocyst yield and the number of blastocysts produced per IVF were similar for CONV (20.0% and 1.7) and SS (24.7% and 2.1) semen. Pregnancy per ET on d 32 and d 63 was not different between BEEF and DAIRY embryos (d 32: 55.3% and 61.3%; d 63: 46.4% and 56.0%, respectively) or between embryos derived from CONV and SS semen (d 32: 58.8% and 57.9%; d 63: 50.1% and 52.3%, respectively). Pregnancy loss was not different between DAIRY and BEEF embryos or between embryos derived from CONV and SS semen. There was no association between serum progesterone concentration on d 7 and pregnancy rate on d 32 or d 63. In conclusion, oocyte recovery and blastocyst development were greater for beef donors compared with dairy donors. Blastocyst development was similar when CONV and SS were used for IVF, and P/ET was similar for DAIRY and BEEF embryos and for embryos derived from CONV and SS semen.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705954","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":"Improving dairy calf health through inclusion of diarrhea and respiratory health data into a US national genetic evaluation.","authors":"Mahesh Neupane, Kristen L Parker Gaddis, Sajjad Toghiani, Asha M Miles, Jason R Graham, Javier F Burchard, João W Dürr, John B Cole, Jeffrey R O'Connell, Curtis P Van Tassell, Paul M VanRaden","doi":"10.3168/jds.2025-26497","DOIUrl":"https://doi.org/10.3168/jds.2025-26497","url":null,"abstract":"<p><p>Calf diarrhea (DIAR) and respiratory illnesses (RESP) are leading causes of calf mortality. This study aimed to develop a comprehensive US national genomic evaluation for these important calf health traits using producer-recorded data from the National Cooperator Database. Analyses included 207,602 calf records for DIAR (age 3 to 60 d) and 681,741 records for RESP (age 3 to 365 d) from all breeds (97.5% data from Holstein and Jersey calves) born between 2013 and 2024. Both traits were modeled as binary variables (0 = diseased, 100 = healthy) with breeding values expressed as disease resistance in percentage points. Overall incidence was 14.46% for DIAR and 16.05% for RESP, with Jerseys showing higher incidence than Holsteins. Heritability estimates from the all-breed model were 0.026 (DIAR) and 0.022 (RESP). Genomic PTA reliabilities exceeded pedigree PTA reliabilities, with young sires (born ≥2020) exhibiting high reliability for genetic improvement opportunities in calf health. Holsteins exhibited higher genomic reliabilities for both traits compared with Jerseys, likely due to the larger dataset. A moderate genetic correlation (0.22) was observed between DIAR and RESP, and correlations with heifer livability, another currently evaluated calf health trait, were 0.13 (DIAR) and 0.35 (RESP). Correlations of these health traits with other traits were low. These findings demonstrate the feasibility of including DIAR and RESP in the US national genetic evaluation system, enabling more effective breeding strategies to improve calf health and survivability.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705973","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":"Rumen-protected dry grape extract supplementation enhances milk production, behavior traits, and immunometabolism of mid-lactating Fleckvieh cows under naturally occurring heat stress.","authors":"Annalisa Amato, Carmelo Cavallo, Andrea Minuti, Erminio Trevisi, Paul Engler, Hoa Bui, Enrico Gugliandolo, Lola Llobat, Jimena Laporta, Giovanni Emmanuele, Luigi Liotta, Vincenzo Lopreiato","doi":"10.3168/jds.2025-26830","DOIUrl":"https://doi.org/10.3168/jds.2025-26830","url":null,"abstract":"<p><p>Heat stress (HS) in dairy cows disrupts homeostasis and thermoregulation, negatively affecting milk production, health status, and metabolism. Dietary supplementation with phytoextracts such as polyphenols may offer an effective dietary strategy by stimulating the immune system, reducing oxidative stress, and ultimately enhancing welfare, metabolic function, and milk performance. This study aimed to evaluate the effects of supplementing mid-lactating Fleckvieh cows with rumen-protected grape extract (Nor-Grape BP-O, Nor-Feed) on milk performance, rectal temperature (RT), behavior, immunometabolism, rumen fermentation, and innate immune response under naturally occurring HS conditions (temperature-humidity index >72). Thirty cows were balanced by days in milk, milk yield, and parity, and randomly assigned to receive either 470 mg/cow per day of Nor-Grape BP-O supplementation (NG-BPO, n = 15) or a control diet without supplementation (CTR, n = 15) and monitored for 35 d. Both groups were cooled daily using forced ventilation and fans. Temperature-humidity index, milk yield, heavy breathing (HB), rumination, and eating time were recorded daily. Milk, blood, and rumen fluid samples were collected at different time points, and RT was measured. The NG-BPO cows exhibited greater milk production, fat-corrected milk, energy-corrected milk, and yields of fat and protein, alongside lower SCC compared with CTR cows. The NG-BPO cows exhibited improved thermoregulatory responses, reflected by significantly lower RT and reduced HB. Supplementation with Nor-Grape BP-O lowered inflammatory status and enhanced innate immune responses, as indicated by higher plasma zinc and myeloperoxidase levels, lower haptoglobin concentrations, and increased phagocytic activity of neutrophils and monocytes compared with CTR cows. These findings were supported by higher levels of proinflammatory cytokines TNF-α and IL-1 β during peak HS periods, compared with CTR cows. In addition, the NG-BPO group had lower circulating platelet and eosinophil counts compared with the CTR group. In conclusion, supplementation with a low dose of rumen-protected dry grape extract-rich in low-molecular-weight polyphenols (oligomeric and monomeric flavanols, anthocyanins)-effectively supported milk production and quality in heat-stressed dairy cows. Moreover, supplementation improved thermotolerance during heat waves and enhanced innate immune functions while reducing inflammatory responses. These findings suggest Nor-Grape BP-O as an effective dietary strategy to mitigate the negative effects of heat stress by enhancing cow performance and welfare during periods of elevated environmental temperatures.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705975","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":"The impact of sward type and inorganic nitrogen application rate on the rumen metabolome of dairy cows as determined by nuclear magnetic resonance.","authors":"Nisha J Suthar, Eoin Wims, Raghunath Pariyani, Denis Lynch, Lorraine M Bateman, Anita R Maguire, James A O'Mahony, Michael Dineen, Tom F O'Callaghan","doi":"10.3168/jds.2025-26678","DOIUrl":"https://doi.org/10.3168/jds.2025-26678","url":null,"abstract":"<p><p>This study examined the effects of pasture species and inorganic nitrogen application rate on the rumen fluid metabolome of spring-calving dairy cows. Twelve rumen-cannulated Holstein Friesian cows were randomly assigned to 1 of 4 treatments in a 2 × 2 incomplete crossover design. The dietary treatments consisted of: (1) perennial ryegrass (PRG) receiving 25 kg inorganic N/ha per cut; (2) PRG receiving 50 kg inorganic N/ha per cut; (3) PRG-white clover (WC) receiving 0 kg inorganic N/ha per cut (PRG_WC_L); and (4) PRG-WC receiving 25 kg inorganic N/ha per cut (PRG_WC_H). Milk and rumen fluid samples were collected, milk samples were analyzed for composition using MilkoScan, whereas rumen fluid metabolome was analyzed using proton nuclear magnetic resonance spectroscopy. Metabolomic profiles analyzed using a mixed-effects model and multivariate analysis demonstrated that pasture species had a greater effect on the rumen fluid metabolome than inorganic nitrogen application rate within treatments. Specifically, cows fed PRG-WC diets exhibited significantly higher concentrations of VFA, including isobutyrate, isovalerate, and valerate, indicating enhanced rumen fermentation. Additionally, concentration of alcohols, particularly isopropanol and methanol, were also higher in cows fed PRG_WC compared with cows fed PRG which could be due to presence of bioactive compounds in WC. Conversely, cows fed PRG diets had increased levels of nucleosides and nucleotides, likely due to controlled microbial growth, increased turnover, and nucleic acid release compared with PRG-WC. Other metabolites that were affected by treatment were fumarate and dimethylamine. Both were previously reported to have an effect on methane emission. Fumarate is associated with reduced methane emission, while dimethylamine is associated with an increase in methane emission. Furthermore, Pearson correlation analysis demonstrated that milk fat percentage was correlated with choline (r = 0.58), glucose (r = 0.58), maltose (r = 0.54), glutamate (r = -0.54), and nicotinate (r = -0.55). Milk urea was positively correlated with VFA, p-cresol (r = 0.67) and phenyl acetate (r = 0.75). These findings emphasize the strong relationship between experimental treatment and rumen metabolic processes, highlighting the potential benefits of incorporating WC into pasture systems to enhance rumen fermentation efficiency.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705978","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 progesterone supplementation using 2 different intravaginal devices during a 7 day Ovsynch protocol in lactating dairy cows.","authors":"R Frenkel, P L Venjakob, W Heuwieser, M Hölper, S Borchardt","doi":"10.3168/jds.2024-25764","DOIUrl":"https://doi.org/10.3168/jds.2024-25764","url":null,"abstract":"<p><p>The objective of this study was to evaluate the effect of progesterone supplementation using 2 different commercially available intravaginal progesterone (P4) devices during a 7 d Ovsynch protocol on pregnancy per/artificial insemination (P/AI) in lactating dairy cows. We hypothesized that cows receiving an intravaginal device with 1.55 g of P4 have increased P/AI compared with untreated controls or cows supplemented with 1.0 g of P4 and that there is an association between vaginal discharge score (VDS) after removal of intravaginal device and vaginal pH. A total of 731 lactating dairy cows, including 1,064 inseminations were randomly assigned to a modified Ovsynch protocol. Cows in the control group (n = 353) received no P4 supplementation during Ovsynch protocol (control: d 0 GnRH; d 7 PGF; d 8 PGF; d 9 GnRH). Cows in the bovine intravaginal device (DIB) group (n = 354) received an intravaginal P4 releasing device with 1.0 g P4 from d 0 until d 8 during the Ovsynch protocol as described, and cows in progesterone releasing intravaginal device (PRID) group (n = 357) were supplemented with a device containing 1.55 g P4. On d 0, transrectal ultrasound assessment of the ovaries was performed to determine the presence and size of a corpus luteum (CL). On d 8, after removal of the devices, VDS was evaluated and pH value from vaginal discharge was measured. All cows received timed AI ∼16 h after the second GnRH treatment. Pregnancy diagnosis was performed using transrectal ultrasound at d 38 ± 3 after AI and reconfirmed at d 80 ± 7 after AI. Pregnancy per AI at d 38 ± 3 did not differ among treatments. For cows without a CL at enrollment, there was a tendency toward a treatment effect regarding P/AI at d 38 ± 3 (control 26.1% ± 4.0%; DIB 29.2% ± 4.4%; PRID 38.1% ± 4.8%). Cows treated with an intravaginal P4 releasing device containing 1.55 g P4 had increased P/AI at d 38 ± 3 compared with untreated controls. For cows receiving a P4 device containing 1.0 g P4, there was no difference in P/AI compared with control cows or cows receiving a PRID device. The distribution of VDS at d 8 of the protocol differed among treatments. More cows in the control group had a VDS of 0 (62.0% [199/321]) compared with DIB (1.5% [5/330]) or PRID (2.1% [7/334]) cows. Vaginal discharge had no effect on P/AI at d 38 ± 7 or 80 ± 7 after AI. Pregnancy loss was not affected by VDS. Vaginal pH was affected by VDS at d 8. Vaginal pH differed among the different VDS significantly (VDS 0 = 7.87 ± 0.08; VDS 1 = 7.70 ± 0.02; VDS 2 = 7.18 ± 0.11). Cows without a CL at the beginning of the timed AI protocol benefited the most from supplementing 1.55 g of P4 for 8 d, whereas cows with CL at enrollment had no advantage regarding fertility outcomes.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144705951","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}