Journal of Dairy Science最新文献

This study aimed to assess relationships of enteric methane (CH₄) yield (g/kg of DMI) with immune response, feed efficiency (ECM/DMI), and rumen microbiome in dairy cows, both in early and in late lactation. The DMI, BW, ECM yield, and CH₄ emission were measured in respiration chambers in early (n = 20, 32 ± 7 DIM) and nonpregnant late lactating (n = 14, 359 ± 90 DIM) multiparous Holstein cows. The in vitro immune response was studied in response to (1) LPS using whole blood, and (2) phytohemagglutinin and concanavalin A using peripheral blood mononuclear cells. The DNA was extracted from rumen content samples (esophageal tubing) for 16S rRNA microbial analysis. Cows were divided retrospectively into an equal number of cows with low (LMY) and high (HMY) CH₄ yield within each lactation group. In early lactation, CH₄ yields in LMY (n = 10) and HMY cows (n = 10) were on average (±SD) 18.8 ± 1.4 and 23.5 ± 2.8 g/kg of DMI, respectively. In late lactation, CH₄ yields in LMY (n = 7) and HMY cows (n = 7) were 20.8 ± 2.0 and 23.6 ± 1.7 g/kg of DMI, respectively. Statistical analysis was performed separately for each lactation group. In early lactation, we found that whole blood and isolated peripheral blood mononuclear cells from LMY compared with HMY animals were less responsive to stimulants in vitro. In addition, feed conversion efficiency was lower in LMY than HMY cows, and the relative abundance of the archaeal genus Methanospaera and the bacterial genus Marvinbryantia were higher. In late lactation, we observed no differences in immune response and feed conversion efficiency between LMY and HMY cows. Still, in LMY cows several bacterial genera including Prevotella 7, Ruminococcus gauvreauii group, and Shuttleworthia were enriched, whereas in HMY cows Methanobrevibacter, Veillonellaceae UCG-001, Succinivibrionaceae UCG-002, Rikenellaceae RC9, and CAG-352 were enriched. The results indicate that in early lactation the animals with low CH₄ yield reach energy balance faster, at the expense of an inadequate immune response. Meanwhile, increased CH₄ yield in early lactation may reflect higher rumen fermentation activity, fostering feed efficiency and energy availability for supporting immune function.

Ice cream is a popular dairy food in the United States. Unfortunately, substantial loss of product occurs during production, despite it being of acceptable quality. There are many valuable components in waste ice cream (WIC) that can be utilized if separated. To investigate the potential of wastewater treatment techniques as a means of recovering fat from WIC, a variety of flocculants were tested on 5 ice cream varieties. The flocculation procedure was able to concentrate 89% to 100% of the total fat in 50% to 70% of the original volume. The amount of fat recovered was consistently superior to that recovered from previous centrifugation techniques. Increasing ice cream temperature was effective in reducing the need for flocculant, but was not economical under current cost estimates. Additionally, the remaining aqueous stream was shown to support the growth of Streptococcus thermophilus B59671 and production of its broad-spectrum bacteriocin, thermophilin 110, as well as Saccharomyces cerevisiae Y45, resulting in the production of ∼10% ethanol. This study demonstrates the potential for utilizing flocculation strategies to efficiently concentrate fat from WIC for recovery and generate a defatted stream for use in ethanol and bacteriocin production.

To support the nutritional demands of fetal growth and the onset of milk production, dairy cattle mobilize body tissues; and though this has been established in multiparous animals, the extent of this mobilization is less understood in primigravid dairy cattle. The objectives of this study were to characterize the longissimus dorsi muscle depth (LDD) and extent of LDD and backfat mobilization, as well as to characterize the muscle histological differences in pre- and postpartum primigravid dairy animals with varying muscle reserves as they transition into their first lactation. This prospective cohort study enrolled 21 heifers that were post hoc divided into 2 groups: high muscle (HM; LDD > 5.28 cm, n = 10) and low muscle (LM; LDD ≤ 5.28 cm, n = 11), based on the day of enrollment of the study, 5 wk before calving. Weekly measurements of LDD, BW, BCS, and insulin were recorded from enrollment until 28 DIM. Milk weights and DMI were recorded daily, and milk components were measured weekly. Biopsies of the longissimus dorsi muscle were collected ∼3 wk before and after parturition. Biopsy samples were sectioned and analyzed for myofiber type profile and fiber type-specific cross-sectional area. The statistical model for repeated measures included the fixed effects of muscle group, time, their interaction, and the random effect of cow within group. The statistical model for single measurements per cow included the fixed effect of muscle group. Animals in the LM group produced 2.3 kg/d more milk compared with animals in the HM group, with no differences in component yields or ECM yield between groups across the first 4 wk in lactation. From 1 to 4 wk in lactation, HM cows lost 20 kg less BW than LM cows during the same time. The mean cross-sectional area of type I, IIA, or IIX myofibers was not different between groups in either the pre- or postpartum stage. Animals in the HM group had a greater proportion of type IIX fibers than LM cows, which had more type IIA fibers than HM cows. Animals with lower LDD before calving lost more BW through 4 wk in lactation but produced more milk compared with animals having higher LDD. Prepartum muscle depth affected BW loss, milk yield, and muscle fiber type in primigravid animals. These results indicate that greater abundance of glycolytic myofibers may limit milk yield at the onset of lactation due to greater glucose demands by muscle, suggesting that muscle amount and myofiber profile may be associated with differences in milk yield.

Prebiotics and probiotics are feed additives that can benefit the host by modulating the gut microbiome, which is crucial in digestion, immunity, and overall animal health. This study aims to evaluate the effects of supplementing prebiotics, probiotics, or synbiotics to preweaning Holstein calves on their future milk yield. This study is a retrospective analysis of milk yield records from dairy cows that were randomized at birth to 1 of 4 twice-daily treatments administered during the preweaning period: (1) control, no additive (CON), (2) prebiotic (PRE; 7 mL of Saccharomyces cerevisiae yeast culture), (3) probiotic (PRO; Bacillus subtilis and Lactobacillus plantarum, delivering ∼1 billion and 250 million cfu per head per day, respectively), or (4) synbiotic (SYN; combination of both PRE and PRO at the same dosages as the PRE and PRO treatments). The study was conducted on a dairy farm in Fresno County, California, between 2019 and 2023, involving 1,296 Holstein cows over their first 3 lactations for a total of 2,735 lactations. Monthly test day records for milk yield, fat, and protein were used to calculate ECM, standardized to 4% fat and 3.3% protein, totaling 26,464 monthly test day milk records. A 2-piece splines mixed-effect regression model evaluated the effect of treatments on ECM yield. For the first lactation, ECM yield was estimated at 28.66 kg on the first DIM, peaked at 42.1 kg, and declined to 21.34 kg by 305 DIM. For parity ≥2, ECM yield was 41.06 kg at 1 DIM, peaked at 54.2 kg, and 33.74 kg at 305 DIM. The SYN treatment increased ECM yield by 1.00 kg/d compared with CON. This increase was primarily due to an increase in milk fat yield, with 0.048 kg/d more fat produced compared with the control group. No differences in ECM yield between PRE, PRO, or CON were observed. These findings suggest that supplementing SYN during the preweaning period increased milk, milk fat, and ECM yield across lactations 1, 2, and 3.

The emergence of multidrug-resistant (MDR) Klebsiella pneumoniae as a major cause of bovine mastitis poses a critical threat to global dairy production, with conventional antibiotics increasingly failing to control infections. To address this crisis, a lytic phage vB_KpnP_ZH4 (ZH4) was isolated from dairy farm sewage and demonstrated to possess potent activity against prevalent MDR K. pneumoniae strains from mastitic cows in Shanghai farms. Morphological characterization revealed that ZH4 belonged to the Podoviridae family, whereas genomic analysis confirmed the absence of virulence, resistance, or lysogeny genes in its 36.2-kb genome. Phage ZH4 demonstrated strong lytic ability, evidenced by a short latency period (20 min) and high burst size (89 pfu/cell) in one-step growth analysis, and it exhibited exceptional stability across wide temperature, pH, and fetal bovine serum concentration ranges. In vitro, ZH4 reduced MDR K. pneumoniae loads by >3 log in raw milk within 24 h and blocked intracellular infection in bovine mammary epithelial (MAC-T) cells without cytotoxicity. In a murine mastitis model challenged with a hypervirulent MDR isolate (ZH-KP-4), a single intramammary ZH4 dose of 5 × 10⁶ pfu/gland achieved complete bacterial clearance in mammary tissue within 72 h, significantly outperforming cefotaxime sodium, which failed to reduce bacterial burdens. We found that ZH4 therapy resolved histopathological damage, downregulated key proinflammatory cytokines (IL-6, IL-1β, TNF-α) and toll-like receptors (TLR2 and TLR4), and crucially restored blood-milk barrier integrity, reducing fluorescein isothiocyanate-labeled BSA leakage into alveoli by >80% versus antibiotic-treated mice. Immunohistochemistry and titer quantification confirmed ZH4's self-limiting replication kinetics: phage density peaked at 24 h after treatment and declined to undetectable levels by 120 h after treatment, aligning with host bacterial load. No adverse effects were observed. These findings establish phage ZH4 as a safe and highly effective therapeutic against intractable MDR K. pneumoniae mastitis, uniquely combining rapid pathogen eradication with structural barrier preservation and offering a transformative alternative to failing antibiotics for sustainable dairy production.

In this work intergenerational and transgenerational effects of calving months on dairy performances of Italian Mediterranean river buffaloes were investigated. The EBVs for milk, fat, and protein yields, as well as fat and protein contents of 112,625 females (F₃) born between 1985 and 2022 were analyzed with a linear model that included the fixed effects of the calving month of their dams (F₂, 63,442 cows), granddams (F₁, 44,015 cows), and great-granddams (F₀, 33,452), the covariable of F₀ calving date, and the covariable of the F₁ EBV. For a subset of 53,706 F₃ buffaloes, further analyses were run including in the model the number of days with a temperature-humidity index larger than 70 during the last 100 d of their F₀ pregnancy. All the 5 considered traits were affected by the ancestor month of calving. The effect tended to decrease as the distance between generations increased. Buffaloes whose great-granddams calved in September showed the lowest LSM of EBV for dairy traits, whereas the largest values were exhibited by buffaloes whose F₀ had calvings in December. Similar pattern was observed for the F₁ calving month effect. An exception was found for the effect of F₂ calving month. The F₃ cows whose dams calved in December showed the largest average EBV for yield traits. This result seems to indicate that for adjacent generations, environmental conditions in the periconceptional period may be more important than in late pregnancy. Results of the present work confirmed previous reports of inter- and transgenerational effects of calving months of female ancestors in dairy cattle, suggesting the existence also for buffalo of mechanisms of epigenetic inheritance related to environmental conditions during pregnancy. A deeper understanding of the role of transgenerational and intergenerational epigenetic inheritance in the expression of phenotypes of economic interest would provide useful insights for the management and the breeding of river buffaloes.

Udder asymmetry is a clinical sign in dairy goats frequently linked to udder inflammation (mastitis). Therefore, goats identified with udder asymmetry should be examined and specifically checked for (past) mastitis. Ideally, all goats should be routinely monitored for udder asymmetry during milking. However, in many countries, dairy goat herds consist of hundreds to thousands of animals, which makes it practically impossible and too labor intensive to regularly examine all animals. Therefore, new automated solutions, including computer vision models, are highly desirable. In this study, we trained and validated a custom computer vision model to detect udder asymmetry in goats. To develop the model, 4,321 annotated goat backside udder images and 373 background images were collected during milking sessions on a dairy goat farm on 3 different days. The 3 ground truth labels for the goat udders-symmetrical, left asymmetry, and right asymmetry-were provided by 2 independent dairy goat veterinarians. The dataset was randomly split in 60% training, 20% validation, and 20% unseen test subsets. The model was trained for 300 epoch cycles including hyperparameter optimization for 300 iterations. The performance of our model (Udder_Asymmetry_Model) on the test dataset was satisfactory, with a mean average precision of 0.891 (mAP₅₀, indicating detection success with 50% overlap between the predicted and actual udder area), and 0.766 (mAP_50-95, the average performance across stricter localization requirements). Ninety-five percent CI were 0.869-0.912 and 0.747-0.789, respectively. In conclusion, the detection of udder asymmetry in dairy goats can be automated using a simple camera and our computer vision model. This solution can facilitate better udder health monitoring, ultimately leading to improvements in animal health, animal welfare, and milk quality.

Persistency in production traits provides an opportunity to extend the lactation period. Enhanced lactation periods significantly over 305 d have potential benefits for fertility, animal health, farm management, and economic outcomes. However, the random regression test-day model, which is currently used in Germany, only covers d 5 to 305 of lactation. This study focuses on increasing the genetic capacity for persistency in Holstein breeding animals for use in extended lactations. The solutions of the second-order Legendre polynomial for the animal effect were obtained using the standard EBV routine in Germany. The breeding value estimation involved 19 million phenotypic lactation records resulting in EBVs for 17 million females and 200,000 males. In a next step, these regression coefficients were used to define genetic slopes for various lactation intervals between d 9 and 245 and 305 after calving (b_g;x,305). The resulting dataset was combined with 955,345 Holstein cows with lactations extending to at least 400 DIM and having a calving interval of at least 550 d. For these cows, phenotypic slopes for each production trait and lactation between d 150 and 400 (b_p;150,400) were estimated. The combined dataset was subdivided into quartiles based on the genetic slopes (b_g;x,305) Finally, the DIM interval that best discriminated the phenotypic slopes (b_p;150,400) of cows according to top and bottom quartiles was used to determine the most appropriate breeding value for persistency. The interval between 150 and 305 DIM proved to be the most informative for predicting b_p;150,400 across all production traits. The final persistency index, called EBV persistency, combines the genetic slopes of protein and fat yield (kg) over the first 3 lactations with equal weighting, and it merges protein and fat persistency into a single index with a 2:1 weighting, reflecting the economic priorities of German breeding organizations. This EBV was officially introduced to the German Holstein breed in April 2023. The genetic basis of the EBV persistency, analyzed using the index theory, shows an estimated cumulative heritability of 0.34. Genomic EBV persistency shows negligible Pearson correlations with most traits in the total merit index. Only slight positive correlations are observed for the milk production index (0.24) and the longevity index (0.18). The new defined trait describes the genetic ability of animals for persistency in production traits, also in extended lactations.

Ketosis is a common metabolic disease affecting dairy cows during early lactation. β-Hydroxybutyrate, the predominant ketone body in the bloodstream of ketotic cows, has been linked to neutrophil dysfunction and a higher incidence of mastitis. Neutrophils, the first line of cellular defense against bacteria, rely heavily on carbohydrate metabolism. In this study, we investigated the effect of high BHB concentrations on glycolysis and on the functional response of bovine neutrophils to Staphylococcus aureus-a leading cause of mastitis worldwide-and to Pam₃CSK₄, a synthetic agonist of toll-like receptor 2/1 (TLR2/1), which is critical for S. aureus recognition by immune cells. At both 2.5- and 5.0-mM concentrations, BHB reduced basal glycolysis and restricted the glycolytic capacity of neutrophils following Pam₃CSK₄ stimulation. By pharmacological inhibition, we confirmed that bovine neutrophils depend on both glycolysis and glycogenolysis to mount effective responses to S. aureus and Pam₃CSK₄. Interestingly, both 2.5- and 5.0-mM BHB similarly impaired neutrophil responses against S. aureus and Pam₃CSK₄, including respiratory burst, neutrophil extracellular traps formation, matrix metallopeptidase 9 release, phagocytosis, and chemotaxis. Our findings suggest that BHB-mediated glycolytic restriction may constitute a central mechanism contributing to neutrophil dysfunction during ketosis, thereby increasing the susceptibility of dairy cows to mastitis in early lactation.