Journal of Dairy Research最新文献

The lactation curve expresses the pattern of milk production throughout the lactation period. Such a curve provides insights to assist in designing proper management strategies. Culling dairy cows directly influences the farm economy and animal welfare. The lactation curve components (LCC) of culled Holstein cows, compared with those of retained cows, have not been studied. This study aims to investigate the LCC in culled Holstein cows compared with those retained unculled in the same herd. This research included 27,297 complete lactation records for Holstein cows described as retained or culled for low milk yield, reproductive disorders, udder problems, metabolic disorders, locomotive problems, endemic diseases, respiratory diseases and unknown reasons. The incomplete gamma function was fitted to estimate LCC, as represented by initial milk yield (IMY), the rate of milk increase to peak, the rate of milk decline after peak, peak yield (PY), time to reach peak and persistency. The general linear model was applied to analyse the effects of stayability class (retained/culled) on LCC. Cows culled for reproductive disorders showed no significant differences in LCC compared to retained cows, but they spent more days in milk (54.9 weeks) than retained cows (48.9 weeks). Except for those with reproductive disorders, all culled cows exhibited shorter lactation lengths, higher rates of milk decline after peak, shorter times to attain PY and lower persistence than retained cows. In addition, cows culled for metabolic disorders exhibited higher initial milk (35 kg) and peak milk yields (44.2 kg) than the retained cows and those culled for other reasons. In conclusion, by linking culling causes to milk production trends, this research equips farmers to identify risks earlier, such as tracking milk decline onset and adapting management to retain healthier, high-value cows longer. This strategy could reduce costs, enhance milk output and improve herd welfare on dairy farms.

Biofilm formation is a prevalent contamination source in the dairy processing industry. It enhances the tolerance of bacterial cells and elevates the risk of product spoilage. Moreover, biofilms can present significant challenges to dairy processing equipment, thereby threatening the safety and efficiency of operations. In the dairy product processing environment, biofilms typically appear as mixed biofilms. Compared to single-species biofilms, mixed biofilms are characterized by high diversity, complex spatial distribution, strong antibiotic resistance and high adaptability to environmental conditions. Consequently, it is essential to comprehensively understand the formation mechanisms and characteristics of mixed biofilms and develop effective control strategies. This review provides an overview of the formation of common microbial biofilms and their mixed biofilms during dairy processing, describes the cellular interactions and characteristics, and finally outlines current common biofilm control measures. All of these efforts aim to provide valuable insights for reducing risks associated with mixed biofilms in the dairy environment.

Fermentation and storage are known to enhance the production of natural antioxidative and angiotensin-I converting enzyme (ACE)-inhibitory components in dairy products. In this study, the antioxidative potential (% ABTS and % DPPH inhibition) and ACE-inhibitory activity of fermented skim milk (fermented at 42°C for 24 h) using 10 Lactobacillus isolates, previously isolated and characterized from the traditional sweet curd of West Bengal, India were evaluated over a storage period of 7 days at 7 ± 2°C. Among all isolates, Lactobacillus delbrueckii subsp. indicus (JSL₂P₂) exhibited the highest functional activity, with ABTS and DPPH inhibition levels of 14.57 ± 0.67% and 14.43 ± 0.72%, respectively, and ACE inhibition of 47.86 ± 1.95% after 24 h of fermentation. These bioactivities further increased during storage. The findings scientifically validate the health-promoting properties of traditional Indian sweet curd prepared with Lactobacillus delbrueckii subsp. indicus, highlighting its potential for commercial application in functional dairy product development and its role in reducing the risk of lifestyle-related diseases.

A caseinomacropeptide (CMP) concentrate was produced from sweet whey by ultrafiltration (UF) and diafiltration (DF) using polyethersulfone (PES) membrane. Effects of the pH of whey feed and molecular weight cut-off of membrane (9 and 25 kDa) on permeate flux, recovery and purity of CMP were investigated. Before the UF, a pre-heat treatment at 90°C for 1 h and then acifidication to pH of 5 were applied to precipitate the major proteins in sweet whey. The pH value of UF feed was re-adjusted to different pH values (3, 4, 5, 7 and 9) to concentrate CMP molecule in the retentate and separate other whey proteins through permeate. Feed pH of 9 and 7 provided an adequate flux with 9 kDa- and 25 kDa-membrane, respectively. A volumetric concentration factor of 4 was reached with both membranes by UF and subsequent DF, but the process time was shorter with 25 kDa-membrane because of the higher permeate flux. One DF cycle was possible with 25 kDa-membrane as there was a substantial loss of CMP compared to four DF cycles with 9 kDa-membrane. About 58% of CMP in whey was recovered using 9 kDa-membrane while 33% of it was recovered with 25 kDa-membrane by the whole process. α-Lactalbumin, β-lactoglobulin, tyrosine and phenylalanine contents in the final concentrate, which are related to the purity of CMP were found similar in both cases. Sweet whey pre-treatment was the key point for purity of CMP concentrate before UF/DF. Both PES membranes can be used for the production of a CMP concentrate depending on desired recovery, composition and process time.

This research aimed to analyse the influence of Apis mellifera intermissa honey supplementation on the technological, physicochemical, microbiological and sensory characteristics of stirred goat yoghurt containing Lactiplantibacillus plantarum C78, a novel probiotic strain, during 28 days of refrigerated storage. Four formulations of yoghurt were prepared, with different honey contents (0.5 %, 10 % and 15 %), and all samples were inoculated with the probiotic strain. The colour, syneresis (52.45 ± 0.19%), viscosity (28 ± 0.25 Pa.s) and sensory acceptance were improved in samples having 15% honey. The viability of L. plantarum C78 in all yoghurt samples presented counts above 7 log CFU/mL until the day-28 of refrigerated storage and honey increased the count of probiotic culture to 8.5 and 8.7 log CFU/mL at day-14 and day-21 of storage. These results reveal a successful incorporation of both probiotic and honey and promote the nutritional and sensory properties of the new yoghurt formulation.

The quality of colostrum is essential for the successful transfer of passive immunity and the early development of the immune system in newborns. This research was conducted with the aim of evaluating the agreement between measurements from different equipment: colostrometer, digital Brix refractometer and optical Brix refractometer, using fresh colostrum samples maintained at 21°C. Colostrum samples were collected from two farms (n₁ = 31 and n₂ = 193). Farm 1 included females from second to ninth lactation, comprising 15 Holstein Friesian (HF), 5 Jersey and 11 Holstein × Jersey crossbreeds. Farm 2 had HF heifers and cows from first to seventh lactation. Immunoglobulin content was assessed indirectly with a colostrometer and both types of Brix refractometers (digital and optical). For the correlation analysis, Pearson's product-moment method was used to assess the linear association between the equipment, followed by a Student's t-test and comparison of the obtained values with specific correlation coefficients (50%, 70%, 90% and 99%). There was a 98% correlation between the refractometers on Farm 1, which was significantly higher (P < 0.0001) than the commonly used reference values for weak (50%), moderate (70%) and strong (90%) correlations, and statistically equivalent to a 99% correlation. This indicates a very high, positive linear association between the digital and optical Brix refractometers. On Farm 2, a 97% correlation was found between the refractometers, which was significantly higher (P < 0.0001) than the specific reference values of 50%, 70% and 90%, but significantly lower than a 99% correlation.

This research paper describes the effect of fermented substrates comprised of dairy by-products and underutilised cereals on murine faecal enzymes and faecal microbial profiles, and the development of the fermented substrate into a sour-spicy beverage for human consumption. A fermented substrate was made by using dairy by-products and underutilised cereals, whey and skim milk blend (60:40, v/v), germinated pearl millet flour and barley malt extract. The substrate was fermented with Lactobacillus acidophilus NCDC 13. The growth pattern of the organism in the composite substrate was satisfactorily described by a logistic-type equation. Faecal samples were obtained from 18 Swiss albino male mice that had been fed on either a control diet (n = 6), a diet based on an unfermented substrate, and a diet based on a fermented substrate (six in each group) and analysed. The fermented substrate caused a significant (P < 0.05) increment in faecal lactobacilli with a concomitant reduction in faecal coliform counts. Further, the fermented substrate caused a significant (P < 0.05) and sustainable decline in faecal enzyme β-glucuronidase activity in the mouse model, which is commonly considered a marker of colon cancer. The reductions in the numbers of coliform bacteria in faeces might explain the decline in faecal enzyme activity. Beta-glucuronidase is an enzyme produced by faecal bacteria that converts procarcinogens to potential carcinogens from available substrates. Bifidobacteria and lactobacilli generally have lower activities of these harmful enzymes, whereas β-glucuronidase is produced in high amounts by enterobacteria and clostridia spp. The fermented substrate was developed into a sour and spicy beverage for human consumption. The average TS, fat, protein, ash, starch and fibre contents of the beverage were 11%, 0.3%, 2%, 0.61%, 1% and 1.4%, respectively. The sensory score with an overall acceptability of 7.5, revealed that the product was sensory acceptable.

Diagnosis of cases of Mycoplasma mastitis is particularly challenging due to their unique biological characteristics, which complicate diagnosis and treatment. Hence, accurate and quick diagnostic tests for early detection of Mycoplasma mastitis are essential to initiate appropriate interventions or culling. The objective of this research is to estimate the diagnostic performance of the molecular microarray assay (MMA) against bacterial culture for the diagnosis of bovine intramammary infections (IMI) with Mycoplasma spp., using a gold standard approach and the Kappa agreement coefficient. A total of 395 quarter milk samples were collected from cows in 31 dairy herds with conventional milking systems in California, USA. Following dairy personnel practices, milk samples were collected from the lactating cows showing abnormal milk characteristics and shipped within 24 hours to the laboratory for bacterial culture and MMA examination. Milk samples with positive growth were confirmed via PCR test to eliminate misdiagnosis of Acholeplasma spp. Eighty-seven cows (22%) were positive for Mycoplasma spp. IMI and the test accuracy was 88.4%. The sensitivity of MMA was 90.8% (95% CI (Confidence Interval): 82.68-95.95), and the specificity was 87.66% (95% CI: 83.46-91.12). The positive predictive value of MMA in these herds was 67.52% (95% CI: 60.51-73.83), and the negative predictive value was 97.12% (95% CI: 94.57-98.49). Calculated Kappa coefficient was 0.70 (95% CI: 0.618-0.778). The high estimates of sensitivity and specificity of MMA suggest its usefulness as a routine and quick test for accurate diagnosis of Mycoplasma spp. IMI in dairy cows. Our findings indicate that MMA holds promise for enhancing the detection of Mycoplasma spp. and could potentially revolutionize diagnostic practices in the dairy industry and supports udder health management.

To determine the long-term effects of transition milk (TRANS), 30 female Holstein calves were allocated to two feeding groups (n = 15/group) after colostrum intake, receiving either 12 L of TRANS of their dam or 12 L of milk replacer (MR) per day. After 5 d of differential feeding, all calves received 12 L of MR/d. Until calving, heifers were weighed monthly. After calving, BW was recorded twice daily after milking. Body condition (BCS) and back fat thickness (BFT) were scored biweekly. Milk yield was recorded twice daily until d 200 in milk. Milk composition (protein, fat, and lactose), as well as somatic cell count (SCC) were analysed biweekly. Blood samples were taken 3 weeks before calving, at the day of calving and 3 weeks thereafter. Oxidative status was assessed as ferric reducing ability of plasma (FRAP) for antioxidative capacity, and as reactive oxygen metabolites via the dROM assay. Oxidative damage of lipids was measured via the thiobarbituric acid-reactive substances (TBARS) assay; peroxidized proteins were assessed using the advanced oxidation protein products (AOPP) assay. Performance until first insemination did not differ between the groups, as well as BW development until the first weeks of lactation. From week 7 of lactation onwards, TRANS had less BW than MR heifers but tended to have a higher BCS. Milk yield and composition did not differ between both treatments. Marker for oxidative stress showed typical patterns of increasing antioxidants before calving and increase in prooxidants after calving in both treatment groups. The results indicate that feeding TRANS in the first 5 days of life had no long-term effects on performance in the first lactation, except for lower postpartum BW in heifers fed TRANS than MR, under the current rearing and management conditions.

This study investigated yeast diversity and physicochemical changes during the production of Kargı Tulum cheese, a traditional Turkish cheese. Samples were collected at six key stages, from raw milk to the final product, and analysed for parameters including pH, titratable acidity, dry matter, fat, salt, protein, water-soluble protein and maturation index. During ripening, pH values ranged from 3.03 ± 0.017 to 3.70 ± 0.017, while titratable acidity increased from 0.91% ± 0.16% to 3.33% ± 0.17%. Dry matter and fat content increased significantly, reaching 50.41% ± 1.56% and 33.50% ± 5.41%, respectively. Salt content ranged from 0.58% ± 0.08% to 3.03% ± 0.58%, and protein content from 3.70% ± 0.93% to 20.63% ± 1.16%. The maturation index increased from 5.54% ± 0.71% to 16.26% ± 4.35%, indicating ongoing proteolysis. A total of 42 yeast isolates were phenotypically characterized and grouped by sugar fermentation ability, growth and salt tolerance. Internal transcribed spacer region sequencing identified key yeast species, including Kazachstania unispora, Pichia fermentans, Kluyveromyces lactis, Pichia membranifaciens and Geotrichum candidum. These species play significant roles in cheese maturation, contributing to flavour and texture. The results emphasize the importance of indigenous yeast populations in traditional cheese production and offer insights for improving fermentation and ripening processes to enhance cheese quality.