Journal of Dairy Science最新文献

This study established a systematic framework to isolate and functionally characterize lactic acid bacteria from camel milk collected in Western China, targeting strains exhibiting robust antioxidant properties. Among 199 isolates, Leuconostoc mesenteroides C8 exhibited high oxidative stress tolerance and superior antioxidant activity. Its incorporation into yogurt fermentation significantly improved product stability and antioxidant retention during 21-d storage, even under light and thermal stress. This dual-level validation-from functional screening to food system application-highlights C8's functional potential and positions camel milk-derived probiotics as valuable resources for developing antioxidant-enriched, value-added fermented dairy products.

This study aimed to evaluate the performance of published equations for estimating the BW of day-old beef × dairy (B × D) male calves based on morphological measures, and to develop, test, evaluate, cross-evaluate, and validate BW-predictive equations using body morphological measurements. Three hundred twenty B × D male calves were enrolled upon arrival at the calf-raising facility, and morphological measurements such as BW, heart girth (HG), hip height (HH), and hoof circumference (HC) were recorded from each calf within the first 24 h of life. Forty-six published peer-reviewed equations were evaluated against the development dataset using root mean squared error (RMSE), concordance correlation coefficient (CCC), and mean squared error decomposition (mean bias, slope bias, and residual error) to assess agreement between observed and predicted BW. Moreover, 3 linear equations were developed using a forward selection criterion for HG (Equation 1), HG and HH (Equation 2), and HG, HH, and HC (Equation 3). In addition to linear models, evaluation of quadratic, cubic, and exponential models was assessed to determine the relationship between BW and morphological traits. Among the tested models, the linear equation proved more effective and simpler than the quadratic, cubic, and exponential models and was ultimately selected for validation. Overall, 76% of the published equations demonstrated poor agreement with observed BW, as indicated by an average CCC (0.49) and an average BW RMSE of 107.00 kg. An additional 17% of the published equations achieved moderate agreement, with average CCC values between 0.50 and 0.60 and an RMSE for BW of 6.20 kg; only 7% (the top-performing published equations) had CCC values greater than 0.60 and an RMSE for BW of 4.50 kg. All 3 developed equations exhibit greater predictive performance than 43 (93%) of the published equations, with an average CCC of 0.75 and an RMSE for BW of 3.50 kg. Cross-evaluation of the 3 developed equations demonstrated moderate to high BW-predicting performance (RMSE = 3.80 kg; CCC = 0.74). The validation assessment using an independent dataset of 176-d-old B × D male calves that only included HG as a morphological measurement indicated that the HG equation (Equation 1) had a moderate to high performance (RMSE = 3.80 kg; CCC = 0.64) in predicting the BW of day-old B × D male calves. Thus, indicating that this developed equation (Equation 1) can be applied as an on-farm tool to predict the BW of day-old B × D male calves.

Co-fermentation using functional lactic acid bacteria strains provides a promising approach to improve the quality and health benefits of fermented dairy products. This study examined the effects of the commercial starter PYS-010 (containing Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus) and stabilizer on the physicochemical properties and metabonomics of brown fermented milk prepared using Lactobacillus helveticus H11, and the changes of metabolic flavor during storage. The combination of L. helveticus H11 and PYS-010 significantly shortened fermentation time, improved viscosity, water-holding capacity, and texture, and showed peak angiotensin-converting enzyme inhibitory activity on d 7 and 14 of storage. Nontargeted metabolomics revealed that the addition of PYS-010 significantly changed the metabolism of amino acids and fatty acids fermented by a single L. helveticus H11 strain. Further dynamic monitoring of the group fermented using L. helveticus H11 with 0.5% stabilizer and 0.003% PYS-010 during storage revealed that W5S, W2W, sourness, and saltiness sensor responses could serve as indicators for storage duration. On d 21, the contents of arachidonic acid, butyric acid, and l-malic acid increased significantly. This study provides a comprehensive view on the fermentation characteristics and metabolic changes of L. helveticus H11 during co-fermentation with PYS-010.

Female cattle with low-anti-Müllerian hormone (AMH) have fewer antral follicles and reduced in vitro embryo production (IVEP) potential than high-AMH females. In addition, granulosa cells of low-AMH females have a diminished responsiveness to FSH, despite elevated circulating FSH concentrations. However, AMH phenotype is generally not considered when establishing FSH dosage for ovarian superstimulation. Thus, this study aimed to assess the effect of FSH dosage on IVEP outcomes in high- and low-AMH female cattle. Pregnant Holstein heifers (~50 d of gestation) with high- (>331 pg/mL; n = 31) and low- (<192 pg/mL; n = 31) circulating AMH were enrolled at 2 different locations for experiment 1 and experiment 2, respectively. Heifers were assigned to receive 0, 280, or 525 IU of FSH in a crossover design at 14 d intervals. Follicular wave emergence was synchronized using follicular ablation and FSH treatments, comprising 4 decreasing doses administered 12 h apart, were initiated 36 h after follicular ablation. Cumulus oocyte complexes (COC) were retrieved using ovum pick-up (OPU) 40 h after the last FSH administration and subjected to IVEP. Data were analyzed using generalized linear mixed models and orthogonal polynomial contrasts. In high-AMH heifers, total follicles and COC increased in a linear FSH dose-dependent manner. Similarly, blastocyst percentage increased linearly with increasing FSH dose, resulting in a linear increase in blastocyst yield (0 IU: 2.8 ± 0.4; 280 IU: 4.9 ± 0.7; 525 IU: 6.5 ± 0.8). In low-AMH heifers, there was a quadratic effect of FSH dose on total follicles, whereby there was a greater increase in number of follicles between 0 and 280 IU of FSH than between 280 and 525 IU. Conversely, the number of COC increased linearly with increasing FSH dose. There was a quadratic effect of FSH dose on blastocyst percentage, whereby the blastocyst percentage increased between 0 and 280 IU of FSH but not between 280 and 525 IU. Nevertheless, the number of blastocysts produced increased linearly with FSH dose (0 IU: 2.0 ± 0.4; 280 IU: 3.8 ± 0.6; 525 IU: 4.8 ± 0.8). In conclusion, the administration of FSH before OPU enhances IVEP in both high- and low-AMH heifers in a dose-dependent manner. Notably, the FSH-driven improvement in oocyte developmental competence reached a threshold at 280 IU of FSH in low- but not high-AMH heifers, suggesting that the optimal FSH dosage to maximize IVEP efficacy may be less for low- than high-AMH phenotype heifers.

The rennet and acid coagulation properties of reconstituted micellar casein concentrate prepared using cold or warm microfiltration (MF), at similar casein contents, were investigated, with low-heat skim milk powder (LHSMP) as a control. The MF retentates had higher casein content (as % of total protein) compared with LHSMP, and heat-induced whey protein-casein aggregates were only present in LHSMP. All MF retentates showed shorter rennet coagulation times and higher gel strengths than LHSMP, which may be linked to lower levels of whey protein (either native or denatured). At similar casein contents, longer rennet coagulation times were evident for cold MF retentates compared with warm MF retentates, as the ratio of κ-CN as a function of total increased with the depletion of β-CN. In terms of acid-induced coagulation, all MF retentates coagulated at a pH >5, higher than the gelation pH of LHSMP (4.7-4.9), which was confirmed by microscopic and textural analysis. An inflection point (increase, followed by a decrease) in G' value was seen during the acidification of warm MF retentates, but not cold MF retentates; this may be related to structural rearrangements of the gel initiated by release of colloidal calcium phosphate and compacting of the structure of warm MF retentate gels as pH decreased. Both warm and cold MF retentates exhibited shorter rennet coagulation times, stronger rennet-induced gels and higher acid-induced gelation pH compared with LHSMP, which might influence their use for the manufacture of cheese or yogurt with tailored functionalities.

Listeria monocytogenes is a foodborne pathogen problematic for the dairy industry, prompting dairy manufacturers to seek antilisterial additives to reduce the risk in dairy products that support the survival and growth. Bacillus spp. have been explored as being potential producers of antilisterial metabolites to inhibit Listeria spp. Bacillus subtilis and Bacillus pumilus were cultured in a food-grade medium mimicking tryptic soy broth supplemented with yeast extract (FG-TSBYE) and processed into foamed cell-free supernatant (CFS-F) to produce a cultured ingredient. This cultured ingredient was evaluated for antilisterial activity in a 96-well broth assay against Listeria target strains (n = 3). Bacillus subtilis Y487 was found to completely inhibit growth of all 3 Listeria target strains, whereas B. pumilus strains (HD49A and VF0409D) produced inhibitory activity against 2 out of 3 strains. Bacillus CFS-F showed good reproducibility with no significant difference found between independent cultures on the same plate. Biological reproducibility was variable for Listeria strains in response to Bacillus CFS-F. Listeria monocytogenes WRLP42 showed some consistency of technical replication (same plate) and good biological replication (across plates), whereas Listeria innocua WRLP438 and L. monocytogenes WRLP96 showed high variability among technical replicates (same plate) and high variability among biological target replication (across plates). Cottage cheese was formulated with freeze-dried CFS-F (CFS-F-FD) and inoculated with Listeria target strains (n = 3) and stored at 7°C for 25 d. The CFS-F-FD from B. pumilus VF0409D and B. subtilis Y487 were effective in delaying the lag phase of L. monocytogenes WRLP96 in cottage cheese by 7 d; however, CFS-F-FD induced changes in the texture and appearance of the cottage cheese. This proof-of-concept study demonstrates the efficacy of Bacillus spp. cell-free supernatant as a potential Listeria control measure in dairy foods. Further research is necessary to optimize antilisterial production and cell-free supernatant processing to minimize product changes.

Lameness is a major welfare and productivity concern in dairy herds. This study investigated the influence of animal traits (parity, BCS) and environmental factors (farm, season) on locomotion score (LS) in lactating cows and assessed the impact of lameness on milking parameters using data from 3 Italian farms equipped with automatic milking systems (AMS). A total of 323 cows were evaluated biweekly for LS and BCS over 7 mo. The AMS data (n = 42,569 observations) were collected and analyzed with linear mixed models to assess relationships between LS and milking parameters. Multiple correspondence analysis was performed to explore variable associations, and a machine learning model (extreme gradient boosting) was trained to classify cows into 3 lameness classes. Cows in parity 3 or greater and thin cows showed significantly higher LS. Severely lame cows had reduced daily milk yield, fewer milkings per day, longer milking duration, and delayed milk flow, particularly in rear quarters. The machine learning algorithm, based on milking and cow-level features, achieved a balanced accuracy of 92% in classifying cows as nonlame, mildly lame, or severely lame. Shapley values revealed that BCS, parity, milk flow, and milking frequency were key predictive features. These findings confirm the potential of AMS and BCS data to support early detection of lameness. Integrating these data and machine learning offered an efficient approach to lameness monitoring without additional equipment.

With the world's population expected to reach 9 billion by 2050, there are growing concerns about the increasing inclusion of human-edible (HE) feedstuffs in the diets of ruminant livestock. Two experiments (a smaller scale study involving late lactation cows and a larger scale study involving early lactation cows) examined the impact of varying the human-edible fraction (HEF) of the concentrate on the performance of dairy cows offered grass silage-based diets. Changes in HEF were achieved by replacing the cereal and soybean meal component of the concentrate with byproduct feed ingredients, including sugar beet pulp, rapeseed meal, and distillers dark grains. The ingredient composition of the concentrates offered was similar in both experiments. Experiment 1, a 2-treatment, 2-period (duration of 4 wk each) balanced changeover design experiment involved 20 mid lactation Holstein dairy cows (mean 157 DIM, SD 7.0). Diets were offered as a total mixed ration comprising grass silage and concentrates (65:35 DM ratio), with the concentrate component of the diet having either a low HEF (0.18HE) or a high HEF (0.54HE) on a fresh basis. In experiment 2, 32 early lactation Holstein cows (mean 50 DIM, SD 4.9) were used in a 3-period (4-wk duration) partial Latin square design study. Cows were offered grass silage supplemented with one of 4 concentrate types (12 kg/d) differing in the proportions of HE ingredients which were offered via an out-of-parlor feeding system. The HEF of these concentrates were 0.17, 0.28, 0.38, and 0.48 (fresh basis). Reducing the HEF of the concentrate in experiment 1 increased total DMI and milk yield and decreased milk fat and protein concentration, but had no effect on ECM yield. Decreasing the HEF of the concentrate had no effect on total feed conversion rate but improved edible food conversion rate (eFCR), (daily HE feed output per daily HE input), and net food production (NFP; daily HE feed output - daily HE input). In experiment 2, reducing the HEF of the concentrate tended to decrease feed intake, but increased milk yield and ECM yield. Decreasing the HEF of the concentrate had no effect on either milk fat or protein concentration but increased both milk fat and protein yield. Reductions in the HEF of the concentrate resulted in a linear decrease in the total SFA concentration of milk and a linear increase in the MUFA and PUFA content of milk. Total DM and OM digestibility coefficients showed a linear increase with increases in the HEF in the concentrate. Cows offered concentrate with a lower HEF had a higher eFCR and NFP. In conclusion, reducing the HEF of the concentrate component of grass silage-based diets by replacing cereals and soybean meal with byproduct feeds effectively improved human-edible feed conversion efficiency.