Journal of Dairy Science最新文献

This study examined the effects of supplementation with increasing levels of RUP on performance, nitrogen metabolism, and mammary gland development in grazing dairy heifers. Twenty-eight 5/8 crossbred Holstein × Gyr dairy heifers (initial BW of 278 ± 50.4 kg) grazed on Megathyrsus maximus cv. BRS Quênia grass pastures for an experimental period of 84 d, divided into 4 subperiods of 21 d each. The experiment followed a completely randomized design in a 4 × 3 factorial arrangement, with 4 supplementation strategies (control [CON], or supplementation with 30% [RUP30], 48% [RUP48], or 66% [RUP66] RUP) and 3 initial BW classes (light, medium, and heavy). The supplement was administered at 0.5% of the animals' BW with a consistent CP content of ∼24% in all treatments. Sampling of pasture, feces, and urine was performed on 4 consecutive days in each period. On d 0 and 19 of each period, the animals were weighed and biometric measurements were recorded. Ultrasound images of the mammary gland and blood samples were taken on d 0, 42, and 84. On d 0, 42, and 84, the development of the reproductive tract was assessed by transrectal palpation using an ultrasound device. Liver tissue was sampled on d 0 and 84. Supplemented animals had higher DMI, DMI related to BW (g/kg of BW), and nutrient intake when compared with CON animals. An effect of RUP level was observed for supplement intake, pasture intake, and total DMI, with higher values noted in the RUP48 treatment. The supplemented animals had a significant increase in the digestibility of DM, CP, and OM. We observed a linear increase in NDF and OM digestibility across RUP level. Supplemented animals achieved higher BW, ADG, thoracic circumference, and rump height when compared with the CON animals. A quadratic effect of RUP level was observed for BW and ADG, with higher values in the RUP48 treatment. Supplemented animals had higher N intake, urinary and fecal N excretion, and microbial CP synthesis when compared with CON animals. A quadratic effect of RUP level was observed for N intake and fecal N excretion, with higher values in the RUP48 treatment. Supplemented animals had a lower pixel count in the mammary gland when compared with the CON animals, and no effect of RUP level was observed on this variable. Supplementation resulted in greater mean horn diameter and improved reproductive tract tone and score. An increasing linear effect was observed for uterine tone across the RUP levels. Nonsupplemented animals had higher liver expression of Glutamic-oxaloacetic transaminase 1 (GOT1) enzyme. Additionally, a quadratic effect was observed for GOT1 expression across the RUP levels, with lower expression in RUP48 and RUP66 treatments. In conclusion, a RUP level of 48% in the feed supplement is the optimal recommendation for grazing Holstein × Gyr crossbred dairy heifers, as it generally improves performance.

The objective of this study was to characterize the absorption, distribution, metabolism, and excretion (ADME) of iodoform in dairy cows through 3 complementary experiments. In study I, biological fluids (ruminal, duodenal, serum, milk, and urine) were collected from Danish Holstein dairy cows during a dose-response experiment conducted as a 4 × 4 Latin square design. The samples were used to determine the fate of iodoform and its metabolite, diiodomethane, by quantifying the amount of iodoform and diiodomethane in these samples. The cows were multi-cannulated and administered different iodoform doses (0, 320, 640, 800 mg/d) twice daily directly into the rumen. This experiment was originally designed to determine the methane-mitigating effects of iodoform, for which the methane production, milk yield, nutritional, and health status outcomes have been published separately. In the present analysis, iodoform concentrations were consistently below detection limits in all sampled matrices. However, diiodomethane was present in all matrices, though only at trace levels in milk and urine (below lower limit of quantification). To address remaining uncertainties about the ADME, additional experiments were performed. In study II, 3 rumen-cannulated Danish Holstein dairy cows received a single pulse dose of iodoform (640 mg) directly into the rumen, followed by serial blood sampling via an indwelling catheter in the jugular vein. Milk samples were collected from the subsequent milkings after dosing. Diiodomethane was above the limit of quantification in blood and milk. The apparent systemic availability of diiodomethane in blood serum ranged from 0.1% to 1.8% of the administered iodoform dose, with milk distribution at 0.06% ± 0.01% of the administered dose. In study III, an in vitro investigation of the degradation kinetics in ruminal fluid demonstrated that iodoform was rapidly metabolized (half-life [T_1/2] = 5 min), producing diiodomethane with a slower disappearance rate (T_1/2 = 94 min). The findings from all 3 studies demonstrate that iodoform is rapidly converted to diiodomethane in rumen fluid, and the metabolite is absorbed into circulation, transferred into milk (only at high doses of iodoform), and excreted only in small amounts via urine.

This study evaluated the production performance, milk fatty acid profile, nutrient digestibility, and enteric methane (CH₄) emissions of high-producing dairy cows fed high-forage (HF; 52% forage) or low-forage (LF; 37% forage) diets containing triticale silages harvested at either the boot (BT) or soft-dough (SFT) stage. The BT stage silage contained 16.7% CP, 51.1% NDF, 35.0% ADF, 3.7% ADL, and 2.2% starch, whereas the SFT stage silage contained 8.7% CP, 62.6% NDF, 46.1% ADF, 6.4% ADL, and 4.6% starch. The experiment followed a replicated 4 × 4 Latin square design with 21-d periods using 8 primiparous and 16 multiparous Holstein cows. Treatments followed a 2 × 2 factorial arrangement of forage inclusion level and triticale maturity stage. Forage maturity did not affect DMI in cows fed LF diets, but cows fed the HFBT diet consumed more DM than those fed the HFSFT diet (26.3 vs. 23.4 kg/d). Cows fed BT stage diets produced more milk than those on SFT stage diets (46.9 vs. 43.4 kg/d), whereas cows on LF diets produced more milk than those on HF diets (47.1 vs. 43.2 kg/d). The production of ECM did not differ between maturity stages but was greater for cows consuming LF diets compared with HF diets (49.1 vs. 45.6 kg/d). Cows consuming BT stage diets exhibited greater apparent total-tract digestibility of DM (69.3% vs. 67.3%) and NDF (59.4% vs. 54.5%) than SFT stage diets. Cows consuming HF diets exhibited greater digestibilities of DM (70.2% vs. 66.4%), NDF (60.3% vs. 55.8%), and starch (95.5% vs. 94.8%) than LF diets. Cows fed BT stage diets produced 23 g/d less CH₄ than cows on SFT stage diets (368 vs. 391 g/d), with no difference between HF and LF diets in absolute CH₄ output. However, CH₄ yield was lower in cows consuming BT stage diets compared with SFT stage diets on a DMI basis (13.6 vs. 15.2 g/kg DMI). Cows consuming LF diets exhibited reduced CH₄ yields compared with HF diets (13.2 vs. 15.6 g/kg DMI). In conclusion, dairy production appears relatively resilient to differences in triticale silage maturity. However, harvesting at the boot stage offers a methane mitigation strategy by reducing CH₄ yield. Low-forage diets improved milk yield and reduced CH₄ emissions at the expense of nutrient digestibility.

This study evaluated the fermentative performance of several yeast strains on the aqueous by-product of waste ice cream (WIC) to ethanol, comparing 3 reported lactose-utilizers, Kluyveromyces marxianus Y-329, Dekkera anomala Y-1414, and Kluyveromyces lactis 8585, with the non-lactose utilizer Streptomyces cerevisiae Y-45. Fermentation progression was monitored by weight loss, and HPLC was used to analyze the composition of the fermentates. Ethanol production reached >10% for S. cerevisiae and K. marxianus but was <5% for D. anomala and K. lactis, possibly due to catabolite repression from the hydrolysis of sucrose. Treatment of the WIC by-product with lactase increased the availability of fermentable carbohydrates, resulting in greater ethanol yields for all strains except K. marxianus Y-1414, which may be limited by its ethanol tolerance. A minimal medium supplemented with lactose, sucrose, or a combination of both sugars was used to test whether the yeast could metabolize lactose alone or in the presence of sucrose. Sucrose was utilized by all 4 strains and produced ethanol in the absence and presence of lactose. Lactose was only utilized by D. anomala Y-1414 and K. lactis 8585 in the absence of sucrose, confirming that the presence of sucrose can prevent lactose utilization by yeasts in this study. Fermentation efficiency was also determined, with S. cerevisiae Y-45 having achieved the greatest efficiency in sucrose alone, whereas K. lactis 8585 showed the greatest efficiency in lactose alone. Results from this study showed that S. cerevisiae remains the ideal candidate for the valorization of waste ice cream, as it had the highest ethanol yield in WIC by-product with lactose and increased when lactose was hydrolyzed with lactase, reaching 12.5% at 72 h.

In this study, a novel composite probiotic fermented milk was developed using Lactiplantibacillus plantarum P-8 and Lacticaseibacillus paracasei ProSci-92 strains with promising probiotic properties. Different proportions of the 2 strains were evaluated to identify the optimal coculture ratio. The physicochemical properties, storage stability, viable bacterial counts, and metabolomic profiles of the coculture fermented milk, single-strain fermented milk samples, and a commercial fermented milk (PYS-010) were compared. The results demonstrated that the ProSci-92&P-8 (1,000:1) coculture exhibited a significant synergistic effect. This coculture not only enhanced viable counts, acid production capacity, and water-holding capacity but also markedly improved the texture and flavor characteristics of the fermented milk. Untargeted metabolomic analysis further revealed the positive effect of cofermentation on the accumulation of various characteristic flavor-inducing compounds (acetoin, acetaldehyde, butyric acid, propionic acid, arachidonic acid) and functionally relevant AA (lysine, ornithine, phenylalanine, threonine, valine) in the fermented milk. Glutathione was identified as a potential metabolic biomarker associated with synergistic interactions between the strains. This study provides a theoretical foundation and technical support for developing next-generation fermented dairy products with desirable sensory attributes and health benefits.

This study investigated early postnatal weight dynamics in 19 Brown Swiss calves (11 male, 8 female) during their first week of life. It was hypothesized that high-frequency weight monitoring during the first week of life in neonatal calves could reveal patterns of postprandial weight loss and early growth dynamics, which may be used to estimate metabolic activity. Calves were housed individually in hutches on calibrated scales that recorded BW every 10 s, enabling high-resolution monitoring of growth and postprandial weight changes. All calves were fed their dam's milk twice daily in unrestricted volumes for 14 feedings. Urine was quantitatively collected and weighed to estimate the proportion of weight loss attributable to metabolization and evapotranspiration. Data were analyzed using generalized linear mixed models with sex, feeding number, hours postprandial, and their interaction as fixed effects, and calf ID as a random intercept. A first-order autoregressive correlation structure accounted for autocorrelation in repeated measurements. Based on significant differences in weight-loss dynamics, feedings were grouped into early (1-3) and later (4-14) feedings. Sawtooth-like growth curves were observed for weight development during the first week of life due to daily fluctuations in BW with maxima occurring after feeding and minima before the next feeding. The calves showed an ADG of 1.31 ± 0.28 kg during the first week of life. Postprandial weight loss ranged from 3.5% to 7.4% of BW over 10 to 14 h and was significantly influenced by the feeding event and the duration of the postprandial period. The rate of weight loss was lowest during the first 3 feedings (0.346% BW/h), increasing and stabilizing at 0.607% BW/h at later feedings. Fourth-degree polynomial models best described the hourly postprandial weight loss patterns for feedings 1 to 3 and 4 to 14 (R² = 0.994 and 0.999, respectively). The highest weight loss occurred in the first hour postprandial and weight loss continuously decreased thereafter. Metabolization and evapotranspiration losses, calculated by the separation of the collected urine amounts from total weight loss observed on the scales, accounted for 79% of total weight loss at the first feeding and 33% to 49% in subsequent feedings. Strong positive correlations were found between postprandial weight loss to urine excretion (r = 0.729), and milk intake (r = 0.811). The findings highlight the dynamic nature of BW and the value of high-resolution, continuous monitoring (1 measurement every 10 s) in early calf development.

3'-Sialyllactose (3'-SL) is a naturally occurring prebiotic in milk, known to regulate intestinal microbiota and prevent diseases. However, the mechanisms through which 3'-SL alleviates antibiotic-associated diarrhea remain poorly understood. In this study, an antibiotic-associated diarrhea model was established through the co-administration of ampicillin and neomycin. The effects of 3'-SL supplementation on diarrhea phenotype, inflammation, intestinal permeability, and barrier function were examined in antibiotic-associated diarrhea-model mice. Moreover, gut microbiota composition, metabolite profiles, and their alterations were analyzed using genomic and metabolomic approaches. The results demonstrate that 3'-SL increased body weight and aquaporin (AQP) 3 and AQP4 levels but reduced diarrhea rate, cecal mass, and fecal water content in the model mice, indicating its therapeutic effect on diarrhea. Furthermore, 3'-SL reduced serum levels of IL-6, tumor necrosis factor (TNF)-α, and IL-1β, while increasing IL-10 levels in the mice. Moreover, 3'-SL reduced intestinal permeability by enhancing both the mechanical barrier (ZO-1 and occludin mRNA expression) and the chemical barrier (MUC2 mRNA and protein expression) in the mice. 16S rRNA analysis revealed that mice in the 3'-SL group exhibited greater abundances of Akkermansia, Bacteroides, and Dubosiella, along with a reduced relative abundance of the diarrhea-associated bacterium Alloprevotella. Furthermore, metabolomics analysis indicated that 3'-SL promoted enrichment of purine metabolism, pyrimidine metabolism, nucleotide metabolism, and the pentose phosphate pathway, which may be associated with diarrhea development, inflammation amelioration, and barrier regulation. In conclusion, our findings suggest that 3'-SL ameliorates antibiotic-associated diarrhea by modulating gut microbiota and metabolite profiles.

Farmers can use automated milk feeders (AMF) to identify changes in the behavior of individual calves before they are clinically sick. However, other management factors, such as routine procedures, may affect group- and individual-level feeding behavior patterns in calves. This matched cohort study (n = 44; 22 pairs of booster-vaccinated calves matched to controls) evaluated the effects of a booster vaccination comprised of inactivated SalmonellaTyphimurium and SalmonellaDublin on feeding behavior and relative changes in behavior of Angus × Holstein calves reared at one calf-rearing facility. All calves were vaccinated with Bovilis Bovivac S on d 1 after farm arrival. Booster calves received a booster vaccination at 15 d after farm arrival (d 0 of the study). Control calves did not receive the booster. We pair-matched booster-vaccinated calves to controls by sex, the first day they independently drank from the feeder, and arrival weight (±6 kg). Daily feeding behaviors (milk intake, drinking speed, and rewarded visits) were recorded by an AMF (Foerster-Technik, Engen, Germany). Calves were offered a maximum of 3.0 L of milk replacer per meal with no daily limit, using a 2-h block between meals to limit size. Mixed linear regression models assessed the effects of booster status, day (days -2 to 4), pair, and the day × booster status interaction on calf feeding behavior, with calf as a random effect and day as the repeated measure. Models also assessed effects on relative changes in feeding behavior using the same model structure. Relative change was calculated as [(day of interest behavior - baseline behavior on day -2) ÷ baseline behavior] × 100, giving the percent change at the individual calf level. Significant day × booster interactions had mean differences adjusted using the Tukey method. We observed a milk intake × day interaction: booster calves consumed more milk than controls on d 0, 2, 3, and 4. For example, on the booster day, control calves consumed 8.26 L/d (95% CI: 7.78 to 8.75; LSM) compared with 10.5 L/d (95% CI: 9.31 to 10.28) in booster calves. Booster status was also associated with greater rewarded visits and faster drinking speeds (control 0.49 L/min, 95% CI: 0.47 to 0.51 vs. booster 0.52 L/min, 95% CI: 0.50 to 0.54), but there was no day × booster interaction for these metrics. Interestingly, booster status was not associated with relative changes in milk intake, drinking speed, or rewarded visits. This suggests that although booster-vaccinated calves, as a group, consumed more milk and drank faster, the magnitude of the within-calf behavioral change after a booster shot was not significant. We suggest that calves injected with a booster vaccine for inactivated SalmonellaTyphimurium and SalmonellaDublin did not experience individual changes in their behavior patterns, but group milk intake increases on the days after the booster shot.

Subclinical ketosis in dairy cows is accompanied by adaptive changes in the secretory function of the mammary gland. However, the molecular basis underlying this adaptation remains unclear. The secretory capacity of the mammary gland is closely linked to the activation of the unfolded protein response (UPR) and endoplasmic reticulum (ER) biogenesis, particularly the inositol-requiring enzyme 1α (IRE1α) pathway. Thus, this study aims to investigate whether BHB activates the IRE1α-XBP1 signaling axis to promote ER biogenesis, thereby sustaining casein synthesis. In this study, MAC-T cells were treated with 1.8 mM BHB for 0, 12, 24, or 48 h to mimic subclinical ketotic conditions. We first observed that BHB activated all 3 branches of the UPR without inducing the proapoptotic element of the UPR. Meanwhile, MAC-T cells treated with BHB show a significant increase in ER tracker staining and upregulated mRNA levels of ER biogenesis-related genes, such as choline kinase α (CHKA), choline-phosphate cytidylyltransferase (PCYT1A), and surfeit locus protein 4 (SURF4). Subsequently, BHB upregulated the mRNA abundance of genes related to ribosome biogenesis and the proregenerative phenotype in MAC-T cells. The MAC-T cells treated with 1.8 mM BHB also displayed increased protein abundance of β-casein, along with the β-casein (CSN2), κ-casein (CSN3), αs1-casein (CSN1S1), and αs2-casein (CSN1S2) milk protein genes. Compared with the 1.8 mM BHB group, KIRA6, an inhibitor of the IRE1α signaling pathway, significantly suppressed the BHB-induced increase in ER tracker fluorescence, ER biogenesis-related gene expression, and β-casein protein abundance. Silencing XBP1 via small interfering RNA inhibited BHB-induced ER biogenesis and β-casein synthesis, whereas the overexpression of XBP1 alleviated these effects. Furthermore, under BHB treatment, overexpression of XBP1 partially attenuated the suppressive effects of IRE1α inhibition on ER biogenesis and β-casein synthesis. Overall, our data demonstrate that BHB promotes ER biogenesis and milk protein synthesis in mammary epithelial cells through activation of the IRE1α-XBP1 signaling pathway, suggesting a protective and adaptive role for BHB in maintaining mammary gland function under subclinical ketotic conditions.

Understanding salt diffusion is essential for optimizing salt uptake during cheese production. Although multiple interacting factors complicate this process, the utilization of a model cheese system offers a controlled platform to evaluate their relative influence. This study developed a model using renneted gels prepared from micellar casein concentrate and investigated the use of salty whey, a secondary byproduct of Cheddar production, as an alternative salting medium. We assessed the effects of varying the pH, fat, and calcium contents of the model cheese and salting temperature on salt migration. Salt diffusivity was modeled using Fick's second law. Increasing calcium content during formulation of the model system (0%-1% wt/wt, weight basis) significantly increased salt penetration. Similarly, salting at 30°C significantly enhanced salt diffusion compared with salting at 20°C or 40°C. Diffusion coefficients of salt in the model cheese systems ranged from 3.1 × 10^-9 to 8.4 × 10^-9  m²/s. Increasing calcium level promoted a more continuous compact protein matrix, which in turn increased salt diffusion; in contrast, fat globules hindered salt movement within the matrix. Analysis of Fourier transform infrared spectra indicated that higher levels of salt migration corresponded to more ordered protein secondary structures with stronger hydrogen bonding. The diffusivity of salty whey, however, was less than that of brine, likely due to the higher osmotic pressure and viscosity of the former.