Journal of Dairy Research最新文献

This study examined the effects of fat content (0.1%, 1.5%, 3%, and 3.5%), heat treatment (pasteurization and UHT), and vitamin D supplementation on the physicochemical, microbiological, and sensory characteristics of yoghurt over 21 days. Yoghurts with higher fat content generally received higher sensory acceptability scores (7-8), exhibited less syneresis (14.75-22.48%) and higher whiteness index; 0.1%-fat had the highest syneresis (51.28%) and lowest whiteness (80.77) (p < 0.05). Although pasteurised yoghurt exhibited slightly better firmness (1.77 N) than UHT (1.61 N), no significant effect of heat treatment was found (p > 0.05). Sensory preference was for 3% and 3.5%-fat and pasteurised variety, especially for consistency. All yoghurts maintained viable lactic acid bacteria counts >10⁷ cfu/g throughout the storage period. The vitamin D addition resulted in a 6% average higher syneresis rate (p > 0.05) and a nearly 4% higher whiteness index (p < 0.05). This study shows that it is possible to obtain yoghurts with enhanced properties by optimizing the fat content and heat treatment conditions applied, and it also directs future studies on the effect of vitamin D addition on yoghurt properties.

Biometric identification represents a transformative, advanced technology with significant implications for herd management. Its adoption addresses the critical requirement of accurate identification methods along with upgraded approaches on higher traceability, disease control, genetic management, and economic returns. In this work, a database of muzzle images was collected from 264 Vrindavani cattle, with ages ranging from 6 months to 10 years. To assess the accuracy of muzzle print as a biometric means of identification, this study investigated the efficiency of a 68-layer convolutional neural network called SqueezeNet for the identification of Vrindavani cattle (a crossbred developed in India) using 2,640 muzzle images. It was observed that SqueezeNet gives a harmonious blend of superior accuracy and minimal complexity, rendering it an optimal option for devices with constrained specifications and computing power. Further, the results of this study showed an identification accuracy of 97.22% with a remarkably small model size (<4 MB). This compact size makes it significantly advantageous compared to other models.

The aim of this study was to evaluate the kinetics of local and systemic immune cell populations in mammary secretions and blood samples from cows free of intramammary infections (IMI) and chronically infected with Staphylococcus aureus during active involution. Cows in late lactation that were either uninfected or with chronic S. aureus IMI were included in this study. The percentages of CD14⁺ cells in blood samples were significantly higher in S. aureus-infected animals than in uninfected animals at days 7 and 21 post-drying-off. However, the percentages of these cells in the mammary secretions from S. aureus-infected quarters were significantly lower compared with those of the uninfected quarters in all evaluated periods. The percentages of CD4⁺ cells were similar between uninfected animals and S. aureus-infected animals at all involution times in both blood and mammary secretion samples. The percentages of CD8⁺ cells decreased significantly in mammary secretions of S. aureus-infected quarters compared with those of the uninfected quarters at all involution stages. The percentages of CD21⁺ cells decreased in blood samples of S. aureus-infected animals compared with uninfected animals at day 21. In secretion samples, the percentages of CD21⁺ cells decreased in S. aureus-infected quarters at day 7 compared with those of the uninfected quarters. In conclusion, chronic S. aureus IMI induces a significant increase in the number of CD14⁺ cells in the blood circulation; however, these cells do not appear to migrate to the mammary secretion being potentially retained in the tissue. Although CD4⁺ and CD8⁺ lymphocytes did not vary between S. aureus-infected and uninfected animals throughout involution, the decrease in CD8⁺ cells in mammary secretion from S. aureus-infected animals suggests that these cells are retained in the mammary tissue, fulfilling their specific functions to eliminate intracellularly infected cells. The low number of CD21⁺ lymphocytes in mammary secretions of infected animals would reduce the humoral defence potential of the gland.

In recent years, measuring hair cortisol concentration in dairy cows has gained popularity as a welfare indicator. The aim of this study was to evaluate the usefulness of measuring hair cortisol concentration (HCC) in dairy cows as an indicator of dairy cow welfare. A total of 290 cows from six commercial herds located in Spain, Italy and Finland (two herds each) were included in the study. A hair sample was taken from each cow and cut into two parts (study period T1 and T2). HCC was measured using an automated assay based on a competitive solid phase chemiluminescent enzyme immunoassay. Data relevant to each animal and its welfare (animal-based assessment according to the Welfare Quality protocol, veterinary treatments, meteorological data, cows' parity and stage of lactation) were collected during the study. The welfare data were used to categorize cows into three welfare classes at each study period (T1 and T2), representing animals with good, medium and poor welfare. Analytical validation of the HCC automated assay was performed on a sub-sample of collected hair and included determination of accuracy, precision, sensitivity and stability of the method. A linear mixed model was fitted to explore the associations between log transferred HCC and welfare class, herd, stage of lactation, parity and season. The results of analytical validation showed that the HCC automated assay method was accurate and able to measure HCC in a linear manner with inter- and intra-assay precision with CVs less than 15%. HCC was explained by the variables herd, cow parity and study period (T1 or T2). We found no evidence that lactation stage and welfare class explained HCC at the individual animal level. This study highlights the challenges of using HCC as an indicator of animal welfare on commercial farms.

Improving udder health on dairy farms requires knowledge about the prevailing mastitis pathogens in order to take appropriate measures. The aim of this research communication was to evaluate the association between two sampling approaches for determining the prevalence of mastitis pathogens in dairy herds. Sampling approaches tested included (a) bacteriological investigation of randomly selected cows independent from stage of lactation (random sampling) and (b) sampling of cows two weeks prior to drying off (dry-off sampling). Using linear regression, the prevalence of mastitis pathogens were compared on herd-level for groups of specific pathogens. Associations between the prevalence estimated by the two approaches were found for Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus uberis and Gram-negative bacteria but not for other esculin-positive streptococci. This study indicated that both sampling approaches provide farmers with an overview of the prevalence of mastitis pathogens in their herds, with the dry-off results also being used to target antibiotic use to infected quarters.

The productivity of dairy animals is heavily reliant on the timely access to sufficient, high-quality fodder. This study analyzes the ex-post impact of Model Fodder Villages on the livelihood security of dairy farmers in Bundelkhand region of central India. The study used cross-sectional data from 437 farmers and employed the inverse-propensity-weighting regression adjustment (IPWRA) method for impact evaluation and verified the robustness of the results through matching methods. The findings show that dairy farmers in model fodder villages are 14-19% more likely to improve habitat security, 19-21% more likely to enhance economic security, and 13-16% more likely to increase food security. Our findings also indicate that factors such as age, education, household size, dependency ratio, off-farm income, adult cattle units, and access to roads, markets, credit, and training play significant roles in adopting improved fodder practices. The study's methodology provides a reliable approach to evaluating the impact of interventions that improve access to fodder and related resources, aiming to enhance the livelihoods of dairy farmers and agricultural communities.

This study evaluated the effects of replacing ground corn with cassava root silage (CRS) in the supplement of grazing dairy cows on production yield, physicochemical characteristics, sensory attributes, and profitability of Minas Frescal cheese. Ten primiparous Girolando cows, with a mean weight of 373.45 ± 63.55 kg, a mean milk production of 12.48 ± 1.58 kg/d, and 76 days of lactation, were distributed into two 5 × 5 Latin squares. The animals were placed in the following five treatments: I, grazing without supplementation (WOS); II to V, grazing receiving 5 kg of dry matter (DM) of supplement without CRS (0 g/kg DM CRS) and with 260, 520 and 780 g/kg DM of CRS. Inclusion level of CRS did not affect (P > 0.067) physicochemical characteristics, sensory attributes, and production yield of cheese. However, cheese produced from supplemented animals had greater levels of protein (P = 0.025) and individual cheese production (kg of cheese/animal/day; P < 0.001) compared to WOS animals. Finally, the inclusion of CRS at up to 520 g/kg DM maximized cheese production by 0.73 kg of cheese/animal/day and gross revenue by 3.49 US$/animal/day, compared to WOS animals. In conclusion, replacement of ground corn with CRS in the supplement of dairy cows did not impact physicochemical characteristics and sensory attributes of Minas Frescal cheese. In addition, inclusion of CRS at up to 520 g/kg DM replacing ground corn in the supplement may be a suitable strategy for enhancing the profitability of Minas Frescal cheese production.

This research article addresses the hypothesis that vehicles used for cattle transport are contaminated with Escherichia coli, a potential foodborne pathogen, despite current regulations on sanitation practices. Dairy cattle and calves are regularly transported to auction markets, calf rearers and slaughterhouses. UK Government guidelines require livestock transport vehicles to be cleaned and disinfected within 24 hours of use or before re-use within that period. It is feasible, however, that if cleaning fails to eradicate bacteria, then transport vehicles can act as a fomite in the spread of antimicrobial resistance (AMR) pathogens. In this study, 13 trailer-loads (TLs) of calves were transported for 40-60 minutes. Trailers were then cleaned and disinfected within 20 minutes of unloading. Five sites within the trailer were swabbed after pressure washing and again 30 minutes after application of disinfectant. A bacterial count for E. coli was performed through growth on selective agar, and species identification was confirmed by MALDI-TOF. A subset of 30 isolates was selected for antibiotic susceptibility screening to a panel of veterinary and human antibiotics. E. coli were recovered from all TLs and sites; however, not all sites were contaminated in each TL. E. coli count was significantly reduced, but not eliminated, following application of disinfectant. Furthermore, high prevalence of resistance to sulphonamides, first-generation cephalosporins, and tetracyclines was observed. Forty percent of screened isolates were also classified as multidrug-resistant (MDR) (i.e. resistant to at least one antibiotic from three or more antibiotic classes). Application of disinfectant did not increase the risk of recovering an MDR isolate. This study demonstrates that livestock trailers can harbour potential zoonotic pathogens with AMR properties. Disinfection in accordance with current guidelines is an important step in reducing, but not eradicating, bacterial populations in these vehicles. Improved cleaning and/or disinfection policies are required to mitigate the potential for AMR transmission.

Yogurt acid whey (YAW) contains significant amounts of calcium as well as small amounts of protein, thus the idea of its reintroduction, especially of its calcium content, to the food chain is attractive. Calcium in milk is mainly complexed with casein micelles, whereas YAW contains only small amounts of protein, with no caseins at all, differing substantially from milk in the form in which calcium occurs. Therefore, the objective of the present research paper was to evaluate whether calcium bioavailability differs between YAW and milk. Following the INFOGEST protocol for simulated digestion and by coupling it with the Caco-2 model for intestinal absorption, calcium in YAW had higher bioaccessibility than calcium in milk. However, there were no differences in calcium transport by the intestinal cells and the transcription level of calcium absorption-related genes (VDR, TRPV6, S100G and PMCA1). Lastly, there were no differences in calcium bioaccessibility and the transcription of the calcium absorption-related genes between YAW samples of bovine, ovine or caprine origin obtained from Greek dairy products enterprises. In conclusion, despite the major differences in the protein profile between YAW and milk, there were no differences in calcium transport by the cells, but YAW was associated with higher calcium bioaccessibility, which ultimately may result in higher amount of absorbed calcium.

This study aimed to identify and quantify the various stem-like cell types in dairy cows' colostrum and milk at the onset of lactation. Five second parity Holstein cows were monitored from calving until the seventh-day postpartum. Mammary secretions were collected immediately after calving, then every 3 h until 12 h during day (d) 0, and during morning milking on d 1, d 2, d 4 and d 7. Cells were prepared from mammary secretions and analysed by flow cytometry using relevant cellular markers. The highest total and viable cell concentrations were observed in colostrum collected at calving and up to 6 h, with these concentrations decreasing substantially in samples collected later at d 0. Then, the concentrations of both total and viable cell populations continued to slowly decrease until d 7, the kinetic curves reaching a baseline plateau. Flow cytometry showed that the CD49f^posCD24^pos population, which identifies mammary epithelial stem cells, represented about 0.9% of viable cells at calving and about 0.1% 12 h later, the mammary epithelial stem cell concentration therefore being at its highest level in the very first colostrum. In contrast, the percentage of mesenchymal stem-like cells, defined as the population of CD34^negCD105^posCD90^posCD29^pos cells, was roughly constant (≈0.3%) during the first two milkings and decreased mainly during the first day to a basal level close to 0. Concerning haematopoietic stem-like cells, defined as the CD45^negCD34^posCD117^posCD90^pos cell population, they were only observed in the colostrum collected at calving. All the types of stem cells studied here were therefore only present in substantial quantities in the colostrum of the very first hours after calving, a period during which the calf's intestine is permeable, possibly allowing the transfer and integration of these cells in the tissues of the newborn calf.