Journal of Dairy Science最新文献

Yogurt, one of the most consumed fermented dairy products, is produced with Lactobacillus and Streptococcus thermophilus as classical starter cultures. The enumeration of their viable bacterial cells is extremely important for yogurt production and supervision. This study developed 2 novel oligonucleotide probes (NOP), along with flow cytometry (FC) method for rapid and simultaneous quantification of the 2 probiotics. The NOP exhibited excellent specificity, as validated by 5 Streptococcus thermophilus strains, 11 Lactobacillus strains, and 32 other bacterial strains, and the FC method could accurately identify viable cells. This NOP-FC method achieved high recovery rates for Lactobacillus and Streptococcus thermophilus, showing good repeatability and strong linear relationship with the plate-based method. The entire method, including sample pretreatment, fluorescent staining, and FC analysis, could be completed within 2 h, outperforming all the current methods in time efficiency. In conclusion, this study innovatively established a NOP-FC method for rapid and simultaneous quantification of viable bacteria. The developed method is successfully applicable for the detection of yogurt during fermentation and the shelf life, providing a reliable foundation for fermentation monitoring and quality assessment of yogurt.

The objective of this study was to evaluate the effects of supplementation with Bacillus licheniformis 809 and Bacillus subtilis 810 on DMI, colostrum quality, milk yield and composition, nutrient digestibility, feeding behavior, metabolic, and health parameters of dairy cows during the transition period. Sixty multiparous Holstein cows were divided into 2 groups: a control group (CG) receiving no additives and a Bacillus group (BG) receiving 3 g of a direct-fed microbial (DFM; 3.2 × 10⁹ cfu/g of DFM). Monitoring was carried out from 30 d before to 60 d after calving, including assessments of milk production, colostrum quality and composition, milk composition, DMI, BW, BCS, energy balance, blood biochemical parameters, feeding behavior, and nutrient digestibility. Milk production was corrected to 3.5% fat (FCM), and feed efficiency was calculated for both milk yield and FCM. Data were analyzed using JMP Pro 14 software, with significance declared at P < 0.05. Results demonstrated that BG cows had greater pre- (14.0 vs. 13.4 kg) and postcalving (20.6 vs. 20.1 kg) DMI, milk yield, fat yield, protein yield, and ECM yield (40.38 vs. 39.56 kg/d), with no differences in feed efficiency. Negative energy balance was reduced in the BG (-3.99 vs. -5.81 Mcal/d), whereas SCC (529.0 vs. 819.1 × 10³ cells/mL) and the percentage of cows with SCC >200,000 cells/mL was reduced (48.2% vs. 75.0%) for BG versus CG. Colostrum quality was also improved in the BG, with higher average Brix values (26.5% vs. 23.9% Brix) and a greater percentage of cows with ≥23% Brix (86.96% vs. 56.52%). No differences were observed in urinary pH, BCS, or most metabolic parameters, except for a trend toward increased leptin and IgA levels in the BG. Fecal scores were improved in the BG during the prepartum period, as was NDF digestibility throughout the entire trial. Lastly, time spent eating (min/d) during before and after calving also tended to be greater for BG cows. Hence, It is concluded that Bacillus spp. supplementation increases DMI, milk production, and fiber digestibility, and colostrum quality. It also reduces milk SCC and negative energy balance and favors immune response, with a trend toward higher serum IgA levels.

Preservation and storage of colostrum on farm is challenging, since cold temperature storage facilities (refrigerators and freezers) often cannot accommodate the volume of colostrum required to feed calves. Potassium sorbate preservative (PSP) is a readily available food grade preservative used in wine and cheese production; shown to be very effective at preserving colostrum at both refrigeration and ambient temperatures. Aims of the current work were to determine the optimal concentration and inclusion volume rate (IVR) of PSP to preserve bovine colostrum for feeding to neonatal calves. Twenty individual cow 'point of feeding' colostrum samples were collected and frozen at -20°C for 4-6 weeks before testing (purposively selected). Three PSP concentrations were created (25.4%, 32.2%, and 39.1%) by mixing potassium sorbate crystals with 100 mL of distilled water. For each of these concentrations 50 µL (1% by volume) and 25 µL (0.5% by volume) were added to each 5 mL aliquot of colostrum to create 2 different IVR. For each concentration and IVR, one aliquot was stored at ambient temperature (AT = temperature monitored in the laboratory between 23.1°C and 24.6°C) and one aliquot was refrigerated (RF = temperature monitored in refrigerators between 3.1°C and 4.2°C). Baseline bacteria counts were also measured for each colostrum sample. Aliquots were tested for degree of bacterial contamination at 24 h, 72 h and 168 h. Mixed linear regression models were constructed using total coliform counts (TCC) and total bacteria counts (TBC) as outcomes of interest, with concentration (30 g/100 mL; 40 g/100 mL or 50 g/100 mL), IVR (1% inclusion volume and 0.5% inclusion volume) and temperature (RF = 3.1-4.2°C or AT = 23.1-24.6°C) as predictors of interest. Survival analysis (with sample as a random effect term) was also used to account for bacteria counts too numerous to count (TNTC, assigned as 10,000,000 cfu/mL for TBC and 11,000 cfu/mL for TCC as these exceeded the highest measures). Bacteria TNTC was analyzed as a 'failure event' and the time frame at which these 'failures' occurred was analyzed. There was a statistically significant temperature by IVR interaction for the TCC outcome. RF was more effective than AT at preventing bacterial proliferation at 24 h and 72 h. Survival models showed a lower hazard of high contamination at IVR of 1% and concentration of 50 g/100 mL. In all cases, 50 g/100 mL concentration was more effective than concentrations of 30 g/100 mL and 40 g/100 mL or no preservative and 1% IVR was more effective than 0.5% IVR or no preservative at preventing bacterial proliferation at 24 and 72 h. A large number of samples in this work were initially contaminated with total bacterial species and this may have biased results, however this is representative of the current situation on most dairy farms.

This study evaluated the effects of feeding a probiotic-postbiotic blend on transcript abundance in circulating neutrophils following an intramammary (IMM) LPS challenge in lactating dairy cattle. Lactating Holstein cows (n = 16 at 57 ± 4 DIM) with a SCC <250,000 cells/mL received either 28 g/d of probiotic-postbiotic (PB; n = 8, Dairyman's Edge PRO, Papillon Agricultural Company) or no PB (NP; n = 8) for 27 d before intramammary infusion of 200 µg Escherichia coli O111:B4 LPS into both rear quarters. Blood PMN were isolated at 0 (30 min before the IMM LPS challenge), 24, and 72 h following the IMM LPS infusion for transcript abundance analysis using real-time reverse transcription quantitative PCR (RT-qPCR). PB had 32% less PMN in blood compared with NP, and IMM LPS resulted in a 59% and 63% reduction in blood PMN across both NP and PB at 24 and 72 h, respectively, relative to 0 h. Transcript abundance for SOD2, S100A8, and S100A9 increased 3.0, 7.0, and 5.0-fold, respectively, at 24 h relative to 0 h but no longer differed at 72 h. TLR4, STAT3, IL1β, and CXCR1 transcript abundance were downregulated at 24 h and 72 h compared with 0 h. CXCL8 expression was reduced at 24 h relative to 0 h, but not at 72 h relative to 0 or 24 h. There was no effect of diet, time, or the interaction on the expression of transcripts for TLR2, IL6, IL10, TNFα, and MPO. There was a diet × time interaction detected for NFκβ such that NP at 0 h tended to be greater than PB at 0 h (P = 0.061) and was greater than all other treatments at 24 and 72 h and PB at 0 h did not differ from PB or NP at 24 or 72 h. In conclusion, IMM inflammation coincided with decreased PMN count in blood and was associated with a downregulated proinflammatory transcript abundance profile in circulating PMN based on the genes analyzed. This attenuated molecular phenotype may reflect accelerated PMN turnover and an increased proportion of immature PMN in circulation or alternatively, a regulatory mechanism aimed at minimizing systemic inflammation and preserving peripheral tissue homeostasis during localized immune activation. Although PB reduced PMN abundance in blood there was no measurable effect on PMN transcript abundance for the genes measured.

Dairy cows are highly susceptible to heat stress, which has a detrimental effect on milk production, fertility performance, and animal welfare. These adverse effects will increase as dairy-producing regions continue to be affected by climate change. To address this, Australia implemented a genetic evaluation for heat tolerance in 2017, which was updated in 2024. The objective of this study was to assess the relationship between heat tolerance solutions from the official genetic evaluation and other important traits in Australian Holsteins and Jerseys. In addition to heat tolerance solution, genetic correlations were estimated for mean yield (cow solution for intercept) of milk, fat, and protein yields with 11 conformation traits, 2 body size composites, and 2 fitness traits using a multivariate animal model. To compare the correlation of heat tolerance solution with the traits considered in this study, we also calculated the correlations of heat tolerance adjusted for mean milk, fat, or protein production. Of the conformation traits considered, angularity had the strongest genetic correlation with the heat tolerance solution for milk of -0.26 ± 0.03 and -0.38 ± 0.04 for Holstein and Jersey, respectively. Comparatively, when the genetic correlation between angularity and the adjusted heat tolerance solution was corrected for milk, the correlations reduced to -0.11 ± 0.06 for Holstein and -0.12 ± 0.14 for Jersey. Both calving interval and survival had strong genetic correlations with the heat tolerance solution compared with other traits studied. When comparing heat tolerance solutions with heat tolerance solutions adjusted for mean production, the effect of milk, fat, and protein yield on the relationship between heat tolerance and conformation traits is driven by milk, fat, and protein yield. Production strongly influences the relationship of the current Australian phenotype for heat tolerance due to the calculation of heat tolerance phenotype via yield deviation under heat stress. Given these results, conformation traits have minimal value as a predictor of heat tolerance in Australian Holstein and Jersey cattle.

This study used a data fusion approach, combining rumen and milk metabolomic profiling, to investigate the biochemical effects of 3-nitrooxypropanol (3-NOP), an effective methanogenesis inhibitor. A controlled feeding trial was conducted in 2 phases (i.e., summer and fall) with Holstein dairy cows (n = 30/phase) fed a diet supplemented for 9 wk with 60 mg/kg DM of 3-NOP or a placebo. Rumen fluid and milk samples were collected at the end of the experimental phases and analyzed using ultra-HPLC coupled with high-resolution mass spectrometry. Metabolomic profiles from the cows supplemented with 3-NOP and the control group were compared to assess the influence of 3-NOP on rumen fermentation and milk composition. Both 3-NOP and the experimental phase significantly influenced rumen metabolites, whereas no significant differences were observed in the milk metabolome with 3-NOP supplementation. Untargeted metabolomic analysis, supported by supervised and unsupervised multivariate statistics, identified significant alterations in rumen metabolites. Results confirmed that 3-NOP significantly alters rumen fermentation by reducing methanogenesis-related compounds (e.g., methyl-coenzyme M and coenzyme B) and influencing nitrogen and nucleic acid metabolism, indicative of changes in microbial fermentation and protein synthesis. Regarding the milk metabolome, changes in certain discriminant metabolites, such as glycerophospholipids, small peptides, and nucleic acids, reflect alterations in rumen fermentation. Although 3-NOP supplementation induced marked changes in the rumen metabolome, including pathways related to methanogenesis and nitrogen metabolism, these alterations were not reflected in major changes in milk quality or its overall metabolomic profile.

The objective of this observational study was to investigate the association between the duration of labor, calving assistance, and uterine diseases, as well as estimate a reference time to be used as a guideline for providing calving assistance based on the health outcome of metritis. Holstein cows (n = 496) were enrolled approximately 3 wk before their expected calving date. Cameras were used to record calving behavior of a subset of cows (n = 286), where the occurrence of calving assistance (forced extraction lasting a minimum of 5 s), calving location, and pen movement during labor were recorded. Calf weight was recorded at birth, retained fetal membranes (RFM) was diagnosed 24 h after calving and metritis was diagnosed based on vaginal discharge measured at 6 and 12 DIM. Subclinical and clinical endometritis (SCE) was based on cytological examination and vaginal discharge at 40 ± 5 DIM. Duration of stage II labor was estimated as the time from the appearance of the amniotic sac until the calf was expelled. Calving was assisted for 14% of cows. Duration of labor ranged from 11 to 173 min (mean ± SD = 57.2 ± 32.0) in unassisted cows and 49 to 232 min (122.7 ± 51.2) in assisted cows. As calf weight increased, the duration of labor increased (slope, m = 1.16 ± 0.34). For every 5-kg increase in calf weight, there was 1.47 greater odds of RFM (95% CI = 1.38-2.08). Cows assisted during labor were at 3.67 higher odds of metritis when compared with unassisted cows (95% CI = 1.92-7.05). A quadratic relationship existed between metritis and duration of labor for assisted cows, where the predicted probability of metritis was greatest at the shortest (49 min; 69.2%) and longest (232 min; 100%) durations of labor, but the lowest predicted probability of metritis (22.1%) was at approximately 130 min. Predicted probability of metritis in unassisted cows was not affected by duration of labor. Neither duration of labor nor the occurrence of calving assistance was associated with the development of RFM or SCE. Providing assistance either too early or too late during stage II labor may result in an increased risk of metritis; the results of this study suggest that intervention 130 min after the appearance of the amniotic sac may be associated with a reduced incidence of metritis. Further research is required to determine how progression of labor and timing of intervention affects the development of uterine diseases.

The study aimed to develop and characterize composite hydrogels composed of polymerized whey protein (PWP, 10% wt/vol) and Grifola frondosa polysaccharide (GFP, 0%-4% wt/vol) as a natural functional additive for yogurt. The hydrogel structure change was elucidated at the molecular level using simultaneous rheology and Fourier-transform infrared spectroscopy. Results indicated that GFP significantly enhanced the hydrogel's network density and thermal stability through hydrogen bonding and electrostatic interactions, as evidenced by increased particle size, zeta potential, and endothermic peak temperature. Yogurt formulated with 2% PWP-GFP exhibited superior texture (e.g., elasticity and cohesiveness) and water-holding capacity (up to 70.12% ± 1.19% with 3% GFP). Electronic tongue and nose analyses further revealed enhanced umami and overall flavor profile. This study provides a theoretical and practical foundation for the application of natural protein-polysaccharide complexes in high-quality dairy products.

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.