Journal of Dairy Science最新文献

Heat shock protein 70 (HSP70) has emerged as a potential physiological indicator of heat stress (HS), recognized for its substantial upregulation in response to increased temperatures and cellular stress. The accurate measurement of HSP70 is crucial for its application in research and on-farm monitoring. Commercial ELISA kits are widely available and exhibit high sensitivity; however, their limited working ranges require the dilution of high-concentration samples, which can potentially introduce variability. A recently developed in-house competitive ELISA provides a cost-effective alternative, previously validated for bovine HSP70 detection; however, its performance across various biological matrices has not been systematically evaluated against commercially available systems. A secondary objective was to determine whether HSP70 levels measured in less-invasive matrices such as milk and saliva, correspond to those obtained from blood. This study compared an in-house competitive ELISA to a commercial sandwich ELISA kit for detecting HSP70 in milk, blood, and saliva samples of dairy cows. Samples were analyzed with optimized methods, and assay performance was evaluated using descriptive statistics, Pearson correlations, and linear regression models. As expected for assays using different formats and calibration systems, the in-house ELISA indicated elevated absolute concentrations across all matrices; however, these differences were systematic and did not affect the strong agreement between methods. Blood samples had the lowest CV in both assays (2.76% in-house; 5.89% commercial), indicating greater repeatability than milk (5.69% and 10.24%) and saliva (7.5% and 9.95%). The consistently lower CV for the in-house method across all fluids indicates that it is more precise and can lead to higher statistical power than commercial assays for a given sample size. Strong positive correlations were observed between assays across all matrices (milk r = 0.91; blood r = 0.88; saliva r = 0.87). Regression analysis validated these relationships, with R² values of 0.777, 0.833, and 0.752 for milk, blood, and saliva, respectively. The findings indicate that the in-house ELISA closely aligns with the performance of the commercial kit. Despite the lower detectable minimum concentration of the commercial assay, the in-house assay provides a more economical alternative for evaluating physiologically high and moderate HSP70 levels; however, the commercial kit remains widely available for purchase. Among biological matrices, plasma exhibited the highest cross-assay correlation, whereas milk and saliva showed consistent relative trends, indicating their potential as noninvasive alternatives for HS monitoring in dairy cows.

Rapid and accurate prediction of milk yield plays an important role in the breeding of dairy goats. We improved the Mask R-CNN deep learning model based on Feature Channel Attention, anchor refinement module, and so on, making it more applicable for predicting milk yield in dairy goats. The accuracy, recall, and mIoU of the improved model for udder segmentation of dairy goats reached 92.21% ± 0.02%, 85.39% ± 0.02%, and 76.28% ± 0.01%, respectively. The predicted mean absolute error, mean squared error, and mean absolute percentage error for the milk yield in the test set were 0.149 ± 0.009, 0.042 ± 0.018, and 9.62 ± 0.014, respectively. We further validated that the udder contour features of dairy goats can serve as a basis for predicting milk yield. The method proposed in this study for predicting milk yield in dairy goats based on udder images is feasible and plays an important role in breed selection.

Subclinical (SCE) and clinical endometritis (CE) are distinct manifestations of reproductive tract inflammatory disease in dairy cows. The development of both conditions stems from postpartum dysregulation of the inflammatory response or a shift in the composition of the uterine microbiome. To gain further insight into the host responses associated with these distinct conditions, we aimed to identify changes in the endometrial transcriptomic landscape in healthy postpartum dairy cows compared with those diagnosed with SCE or CE. Twenty-four multiparous Holstein cows were evaluated for uterine health status at 35 or 36 d postpartum using vaginal discharge scoring (Metricheck) and endometrial cytology (cytobrush). Based on these evaluations, cows were classified into 3 groups: healthy (n = 12; clear or no vaginal discharge and ≤5% endometrial PMN), SCE (n = 6; clear or no vaginal discharge and >5% PMN), and CE (n = 6; mucopurulent or worse discharge and >5% PMN). Endometrial samples collected via cytobrush were stored at -80°C and total RNA was isolated; RNA sequencing was performed using an Illumina NextSeq 500 platform, generating 75 bp single-end reads. Differentially expressed genes (DEG) were identified using DESeq2 with a significance threshold of P < 0.05 and |fold change| > 2. Pathway enrichment analyses were performed using the OmicShare platform to identify enriched biological pathways among the DEG. A total of 250 DEG were identified between healthy and SCE cows, 1,291 between healthy and CE cows, and 829 between SCE and CE cows. In SCE (as compared with healthy) cows, TNF, IL-17, NOD-like receptor signaling, and cytokine-cytokine receptor interaction pathways were upregulated, whereas the FoxO signaling pathway was downregulated. In CE compared with healthy cows, upregulated DEG were enriched in IL-17, TNF, chemokine, NOD-like receptor, NF-kappa B, and toll-like receptor signaling pathways, whereas downregulated DEG were enriched in PI3K-AKT, MAPK, AMPK, Wnt, PPAR, and metabolic pathways. In CE compared with SCE, upregulated DEG were enriched in NOD-like receptor, IL-17, chemokine, B cell receptor, and cytokine-cytokine receptor interaction pathways, and downregulated DEG were enriched in the metabolic pathways, fatty acid metabolism, insulin signaling pathway, and adipocytokine signaling pathway. These findings underscore that CE and SCE conditions involve an inflammatory event but likely arise from different mechanisms. The enrichment of immune signaling pathways in CE reflects a classic infectious response, whereas the metabolic and regulatory pathway alterations in SCE suggest a dysregulated inflammatory state linked to impaired resolution mechanisms. These results highlight the need for tailored prevention and treatment strategies, such as modulating immune regulation in SCE and targeting bacterial dysbiosis and tissue damage in CE cases.

This study evaluated the supplementation of phytogenic additives and inactivated yeast, either alone or in combination with a blend of fermentation residues, on DM and nutrient intake, apparent total-tract digestibility, feed particle sorting, milk yield and composition, blood metabolites, and nitrogen utilization in dairy cows during summer. Thirty-nine mid- to late-lactation cows (174 ± 76.0 DIM; 31.0 ± 3.42 kg/d milk yield, 630 ± 72.5 kg BW) were grouped into 13 blocks based on DIM, milk yield, BW, and parity, and assigned to the following treatments: control (CON), phytogenic compounds + sanguinarin and magnolia extract, fed at 1.94 g/kg DM (Heat Stress Solution, ADM Animal Nutrition; PHY); and phytogenic compounds + blend of fermentation residues (mycelium strains, Aspergillus niger), fed at 1.94 g/kg DM (Thermal Care R, ADM Animal Nutrition; BLD). Cows were subjected to a 2-wk covariate period and treatments were provided during the following 9 wk. Data were analyzed as repeated measures, modeling the fixed effects of treatment, time, and their interaction, as well as the random effect of block. Covariate measures were included in the model as fixed effects and treatment means were compared through orthogonal contrasts (CON vs. PHY + BLD and PHY vs. BLD). The temperature-humidity index during the experiment was 73.9 ± 1.37. Cows supplemented with phytogenic additives and inactivated yeast, either alone or combined with a blend of fermentation residues, tended to have lower DM intake, which consequently led to reduced intake of CP, ether extract, and starch. Digestibility of NDF was decreased in cows fed phytogenic additives (PHY and BLD). Digestibility of DM tended to decrease and the selection of medium-sized feed particles (4-8 mm) was greater in the PHY group compared with BLD. No significant differences were found in milk yield, milk composition, nitrogen utilization, or excretion of purine derivatives. However, supplemented cows showed greater feed efficiency (FCM yield ÷ DM intake), and a trend toward reduced MUN levels, indicating improved nitrogen utilization. These results suggest that these additives can enhance feed efficiency and nutrient utilization without compromising milk yield in dairy cows during summer.

The objective of this study was to evaluate the effects of parity on early embryonic development and placentation in Holstein cattle. Pregnant cows were classified as nulliparous (n = 16), primiparous (n = 7), or multiparous (n = 8) after estrous synchronization for timed artificial insemination (d 0 = day of timed AI). Pregnancy was confirmed on d 28 after AI via transrectal ultrasonography. Cervical epithelial cells were collected daily from d 14 to 20 to assess ISG15 and MX2 mRNA abundance. Blood samples were collected on d 0, 4.5, 7, 10, and 12 and daily from d 14 to 30; additional samples were collected every 12 h from d 18 to d 24 to assess circulating pregnancy-associated glycoproteins (PAG) concentration. Data were analyzed using mixed-effects models for repeated measures, one-way ANOVA, and Pearson correlation, with Tukey-adjusted comparisons and significance set at P < 0.05. There was only an effect of time for MX2 abundance peaking on d17 and decreasing thereafter. For ISG15, mRNA abundance was greater in primiparous and multiparous compared with nulliparous on d 17, and greater in primiparous than nulliparous on d 18. Concentrations of PAG started to increase earlier in nulliparous heifers (d 18.9 ± 0.1) compared with primiparous (d 20.0 ± 0.3) and multiparous cows (d 20.6 ± 0.3). Overall, PAG was greater in nulliparous than primiparous from d 20 to 21.5 and in nulliparous than multiparous from d 19.5 to 22. Concentrations of progesterone (P4) were greater in nulliparous heifers from d 4.5 to 12, and greater P4 concentration was associated with earlier increase in PAG. In conclusion, this study demonstrates that parity influences early embryonic development, with earlier trophoblast differentiation and acquisition of PAG secretory capacity in nulliparous compared with primiparous and multiparous lactating cows.

Maintaining a dietary supply of limiting AA such as Lys, Met, and His during heat stress-induced reduction of DMI may help meet lactation requirements. Twelve lactating Holstein cows were allocated into 2 plots based on parity: (1) primiparous (n = 6; 29.5 ± 1.2 kg milk/d; 95.2 ± 16.2 DIM; mean ± SD) and (2) multiparous (n = 6; 40.3 ± 5.5 kg milk/d; 86.8 ± 10.2 DIM; 3.5 ± 1.6 parities). Within each parity, cows were allocated to 3 treatments, according to a replicated Latin square design with 14-d periods and 7-d washouts. Treatments were (1) heat stress (HS; 16.8% CP; maximal temperature-humidity index [THI] = 84), conventional diet estimated to supply (g/d) 107 Lys, 33 Met, 37 His, and 1,712 MP at expected DMI nadir (d 7-14), (2) HS with a diet balanced to supply, at expected DMI nadir, 179, 58, 44, and 1,740 g/d of Lys, Met, His, and MP, respectively (HS+AA; 16.9% CP; maximal THI = 84), or (3) pair feeding in thermoneutrality (PF; same diet as HS; maximal THI = 64; same diet as HS group). Peak rectal temperature (at 1700 h) was 2.0°C greater in HS (39.8°C) than in PF cows (37.9°C) from d 1 to 14, whereas it was 0.72°C lower in HS+AA (39.2°C) relative to HS from d 7 and 14. Respiratory rate was 2.7-fold greater over the 14-d period in HS relative to PF, but HS and HS+AA did not differ. The DMI decreased progressively in all groups, reaching a nadir at 34% reduction. Milk and milk component yields decreased over time in all groups but more pronouncedly in HS compared with PF, being 3.9 kg/d and 180, 186, and 205 g/d for milk, fat, protein, and lactose yields, respectively, from d 3 to 14. Milk and component yields did not differ between HS and HS+AA, although protein concentration increased in HS+AA on d 10 and 14. Heat stress increased pre- and postprandial insulin concentrations by 40% and 31%, respectively, relative to PF on d 7 and 14. Relative to HS, preprandial insulin concentrations were reduced in HS+AA by 18% on d 14, whereas postprandial insulin concentrations were reduced by 15% on d 7 and 14 in HS+AA. Plasma 3-methylhistidine concentrations increased in HS relative to PF by 24% and 41% on d 7 and 14, respectively, but were unaffected by HS+AA. Leu and glucose kinetics were determined via jugular vein infusion of labeled bicarbonate, Leu, and glucose on d13. The MUN and Leu oxidation decreased in HS+AA, indicating reduced AA catabolism. Glucose rate of appearance (RA) was not affected by treatments, but the proportion of glucose RA used for lactose secretion tended to decrease in HS compared with PF. Relative to PF, plasma growth hormone and IGF-1 were 28% and 13% higher in HS, respectively, whereas HS+AA reduced both relative to HS by 27% and 11%, respectively. Increasing supply of Lys, Met, and His during HS reduced hyperthermia and AA catabolism, which reduced systemic inflammation but did not improve lactation performance.

Training of new employees on dairy farms is often inadequate due to limited time, staff, expertise, and language barriers. This study evaluated the acceptance and learning outcomes of e-learning courses as a training tool for dairy farm workers. We developed an online course series based on standard operating procedures for 8 key tasks in calf care (neonatal care, emergency care, measuring colostrum quality, bottle feeding colostrum, tube feeding colostrum, disbudding, identification of sick calves, and cleaning and disinfection) and made it available to farmers and their employees (n = 301). Courses were published sequentially over a period of 3 mo. Five embedded questionnaires, including an open text field ("What was the most important thing you learned?"), were used to assess demographics, knowledge, and perceptions. A mixed methods approach combined quantitative analysis with qualitative content analysis of feedback. The main objectives of the study were to (1) explore dairy employees' pretraining knowledge using qualitative approaches, (2) assess the effectiveness of the course in improving explicit and implicit knowledge of calf care, and (3) examine participants' perceptions of e-learning as a format for continuing education. Results showed that employees were highly motivated to learn but often lacked essential basic knowledge in calf care such as time and volume of colostrum feeding or importance of general hygiene and measurement of colostrum quality. Self-perceived learning effects were high (49%-80% agreement), especially in the emergency care course. Interest was initially high but declined in later published courses. In terms of participation 24 h after publishing, emergency care was the most popular, whereas cleaning and disinfection was the least. In the final evaluation (n = 120), 90% rated the courses as easy to use and 97% as understandable. More than 85% expressed strong interest in continuing education via online courses, despite 68% (n = 301) never having taken one before. A chi-squared analysis revealed a significant association between future interest in e-learning and both education level and job position, with employees and higher-educated participants showing greater interest. These findings suggest that e-learning can effectively fill training gaps in dairy farming and support workforce development in the sector.

Reducing the sodium content in processed cheese (PC) is a major nutritional goal, whereas maintaining its functional and sensory quality remains challenging. The current study evaluated the impact of potassium-based emulsifying salts (ES; dipotassium hydrogen phosphate, DKP; tetrapotassium pyrophosphate, TKPP; pentapotassium triphosphate, KTPP) at different concentrations (2.0%, 2.5%, and 3.0% wt/wt) on the physicochemical, mechanical (viscoelastic, textural, and mechanical vibration damping), thermal, and sensory properties of model PC samples (40% wt/wt DM and 50% wt/wt fat in DM contents) during a 60-d storage period at 6°C ± 2°C. Selected types of sodium-based ES (disodium hydrogen phosphate, DSP; tetrasodium pyrophosphate, TSPP; pentasodium triphosphate, STPP) were also prepared for comparison reasons. All tested samples exhibited a gel-like, predominantly elastic behavior, with functional responses dependent on ES type and concentration. Hardness increased with longer (potassium or sodium) phosphate chains: DKP (or DSP) < TKPP (or TSPP) < KTPP (or STPP), with KTPP producing the firmest PC samples. Mechanical vibration damping measurements were consistent with hardness and complex modulus (G*) results. In addition, storage period slightly decreased samples' pH and yellowness. The results of the differential scanning calorimetry indicated enhanced water binding with higher potassium content. Furthermore, the use of potassium-based ES significantly lowered sodium levels in the resultant PC without compromising sensory quality. The obtained results highlighted that potassium-based ES could be considered as a beneficial alternative to sodium-based ES, offering an effective strategy to reduce dietary sodium intake while preserving key functional and sensory properties of PC.

Use of unconventional feeds is an important way to solve the shortage of traditional forage resources in dairy production. This study evaluated the effects of replacing alfalfa hay with Lycium barbarum branches (LBB) in dairy cow diets on the lactation performance, milk fatty acid (FA) composition, nutrient digestibility, rumen fermentation, and blood metabolites. Forty-five midlactation Holstein cows with a milk yield of 26.5 ± 8.37 kg/d and parity of 2.1 ± 0.37 were assigned to a randomized complete block design to 3 groups: 0LBB, 50LBB and 100LBB, with LBB replacing 0%, 50%, and 100%, respectively, of alfalfa hay in cow diet (on a DM basis). The study lasted for 75 d (15-d adaptation + 60-d treatment). Results showed that replacing alfalfa hay with LBB did not affect DMI and feed efficiency. When compared with cows receiving 0LBB, those on the 100LBB treatment had a higher yield of 4% FCM (32.5 kg/d vs. 29.9 kg/d) and protein (1.12 kg/d vs. 1.01 kg/d), and cows on 50LBB or 100LBB had a greater milk fat yield and content. The total de novo FA proportion in milk fat was higher in cows fed 50LBB (31.5%) or 100LBB (32.2%) than 0LBB (30.7%). The total PUFA was higher in 100LBB (4.81%) compared with the 0LBB (4.63%) or 50LBB (4.66%) treatments. However, the proportion of mixed FA (C16), preformed FA, SFA, and MUFA in milk fat did not change significantly with LBB inclusion. When compared with cows receiving 0LBB, cows fed 50LBB or 100LBB had a higher whole-tract digestibility of DM and OM, and those fed 100LBB had a higher whole-tract digestibility of ADF, NDF, and CP. Rumen fluid pH was lower, but the contents of total VFA, acetate, propionate, and butyrate were higher, and acetate molar proportion and acetate-to-propionate ratio and ammonia N were lower in cows receiving 100LBB compared with 0LBB. Compared with 0LBB, cows receiving 100LBB had a greater albumin content and superoxide dismutase and total antioxidant capacity activities in blood. The results indicated that replacing alfalfa hay with LBB improved the performance, apparent nutrient digestibility, ruminal fermentation, and antioxidant capacity in lactating Holstein cows.

Early-life growth and development are crucial for the future performance of replacement heifers. Optimizing growth enhances immediate performance and establishes the foundation for long-term productivity, improving overall efficiency in milk production. This study retrospectively investigated the associations between growth rates during the first 2 mo of life and feeding behavior during the preweaning period, overall growth, and first-lactation performance in Holstein heifers under a high milk allowance. In this study, 42 female Holstein calves were retrospectively grouped based on their ADG before weaning during an intensified milk replacer (MR) program (12 L MR/d for 8 wk, followed by gradual weaning until wk 14). Two clusters were obtained: (1) maximum daily gain (MAX; n = 21; 1.06 ± 0.06 kg/d, mean ± SD) and (2) moderate daily gain (MOD; n = 21, 0.84 ± 0.05 kg/d). The MAX calves had significantly higher preweaning MR intakes and 1.20-fold better feed efficiency (gain:feed ratio in kg/Mcal) during the first 2 wk of life (individual housing, 2 meals per d). During the subsequent group housing period, the calves had access to automatic feeders for both MR and concentrate. At weaning (wk 14), the MAX calves were 16 kg heavier than the MOD calves (MAX: 149 ± 9.3 kg; MOD: 133 ± 7.3 kg). Similarly, concentrate intake for MAX was greater in wk 10 to 12. During the MR-feeding period, MAX calves visited the MR-feeding stations more frequently than MOD calves, both in total and relative to their visits at the concentrate feeder. A random forest analysis showed that the ratio of visits to the MR and concentrate stations can serve as an indicator of growth rate during both the preweaning and weaning periods. The MAX heifers remained heavier than the MOD heifers, reaching the 400 kg of BW threshold for first insemination 42 d earlier than the MOD group. In all 3 stages (early, mid, and late) of their first lactation, the milk yield of MAX exceeded that of MOD. The daily milk yield of MAX heifers averaged 37.5 ± 4.7 L across lactation, which was 3.8 L/d more than MOD (33.7 ± 4.7 L/d). This also resulted in a higher 305-d milk yield for MAX, reaching 11,511 ± 821 kg (MOD: 10,242 ± 1,088 kg). Milk composition differed between the groups, with lower MUN and a trend toward higher lactose concentrations in MAX heifers. In this long-term study, preweaning ADG under an intensified MR-feeding program proved to be a robust predictor of subsequent growth, reproductive maturity, and milk yield in the first lactation, enabling data-driven selection of optimal replacement heifers. The integration of sensor data on automated feeding behavior enhances precision management of high-potential animals and supports sustainable improvements in herd productivity and profitability.