Bulk Milk Research Articles

Ruminal microbiota, carbohydrate-active enzymes and milk bioactive compounds in Italian Mediterranean dairy buffaloes fed total mixed ration with or without green forage

The aim of the present study was to determine the effect of including green forage in the diet of Italian Mediterranean dairy buffaloes on the ruminal microbiota, CAZymes profile, functional biomolecules and total antioxidant activity in bulk milk. Sixteen buffaloes were randomly assigned according to lactation number and daily milk production to two homogeneous groups, and for 60 days received each: Group 1, a standard total mixed ration (TMR) or group 2, TMR + ryegrass green forage (30% of diet). The diets of the two groups were iso-nitrogenous and iso-energetic and differed only in the proportion of green forage. Buffaloes that received TMR + green feed had a higher (p < .01) representation of bacteria belonging to the orders Veillonellales, Selenomonadales and Bradymonadales compared with buffaloes that received TMR. The former buffaloes also had a greater (p < .01) abundance of CAZymes of the GT class (GHT4, GT14, GT20, GT26, GT39) and AA class (AA1, AA3, AA6). The milk of buffaloes that received TMR + green feed had a higher (p < .01) antioxidant capacity and greater (p < .01) amounts of the functional biomolecules l-carnitine, propionyl-l-carnitine, acetyl-l-carnitine and δ-valerobetaine. The findings have provided evidence for metabolic and biosynthetic pathways that link green forage with rumen bacteria, CAZymes and the synthesis of amino acids and functional biomolecule in buffaloes.

Bulk milk urea as an indicator of herd dietary nitrogen surplus and nitrogen use efficiency on Canterbury dairy farms.

Bulk milk urea as an indicator of herd dietary nitrogen surplus and nitrogen use efficiency on Canterbury dairy farms.

The Relationship Between the Knowledge, Attitudes and Practices of Herders on Hygienic Milking and The Contamination Risk of Milk with Cryptosporidium Oocyst in Kaduna State, Nigeria

Dairy products are consumed by millions on daily basis worldwide and as such the potential for foodborne illness is a major concern. This study investigated the occurrence of Cryptosporidium oocyst in cow bulk milk and the knowledge, attitudes, and practices of herders towards hygienic milking in selected Local Government Areas (LGAs) of Kaduna State, Nigeria. A total of 120 milk samples were collected for this study. Detection of Cryptosporidium oocyst in milk samples was carried out by concentration technique using Magnesium Sulphate (MgSO4) solution and stained with Modified Ziehl Neelsen method. Sixty (60) structured questionnaires were administered to herders in the study area to identify possible risk factors and assess their knowledge, attitudes and practices toward hygienic milking. The overall prevalence of Cryptosporidium oocysts in cow bulk milk was 11.7% (14/120). Questionnaires administered showed that the majority of the respondents had poor knowledge (88.3%), negative attitudes (85.0%) and adopted unsatisfactory practices (95.0%) to hygienic milking. The occurrence of Cryptosporidium oocysts in cow bulk milk from this study suggests that the dairy cattle in these LGAs have a high potential for transmitting Cryptosporidium to humans. Hence the findings of this study are of great public health significance as these group of animals sampled produce milk for consumption in both urban and rural communities. Therefore, inhabitants of these LGAs should be informed and educated on the need to improve sanitary measures while milking these animals and the need for adequate pasteurization of milk before consumption.

Particle size distribution of total mixed rations fed to Italian Mediterranean buffaloes measured by the PSPS: impact on milk quality and digestibility

Buffalo breeding in Italy is becoming increasingly economically attractive, with milk production in the Lazio region growing by 15% since 2004. However, the optimal physical characteristics of total mixed rations (TMR) have not been thoroughly investigated. This lack of research suggests the need for greater attention to the physical characteristics of diet, which, combined with its chemical properties, may negatively impact milk yield (MY) and milk quality (MQ), as seen in dairy cows. Therefore, the objective of this study was to assess the effect of diet composition, with a particular focus on the physical component, on MY and MQ, and apparent digestibility (AD) of dairy buffaloes. The study was conducted on 10 dairy buffalo farms in Amaseno valley (Italy). Monthly samples of TMR, faeces, and bulk milk were collected over a 12-month period, alongside interviews with farmers to gather information on MY and diet composition. The results revealed a high variability in the physical-chemical composition of diets across farms, attributable to differences in feeding management practices. Both chemical and physical component were found to be associated with MY, MQ and AD changes. A ration poor in roughage and rich in concentrate negatively affected MQ showing lower milk fat, and higher somatic cells count and milk urea, while a greater presence of coarse particles and high fibre were associated with lower MY. Nevertheless, coarse particles and aNDF were positively associated with milk clotting parameters and aNDF digestibility. Our study emphasised the high importance of fibre for improving MQ of dairy buffaloes.

Analysis of the hard rennet cheese microbiota at different stages of the technological process

The purpose of the research was microbiological screening using MALDI-TOF technology starting from bulk raw milk to the finished dairy product and analyzing microorganisms that were being detected during the technological process of production of Ukrainskyi hard rennet cheese and which were clinically significant for human and animal health. Methods. Microbial detection was performed by accumulation and inoculation using the sector inoculation method on differential media for aerobic and anaerobic microorganisms with further MALDI-TOF identification. Sampling was carried out at 7 stages of cheese production: starting from bulk raw milk to bactofugation, after bactofugation to a mixture normalized in fat content, a pasteurized mixture, a mixture prepared for coagulation, cheese after pressing, and cheese after maturation. Microflora studies were repeated three times, with 405 samples examined. Microbiological studies of Ukrainskyi hard rennet cheese using Maldi TOF technology starting from raw materials to finished dairy products showed the presence of microorganisms at all stages of production – from bulk milk to the finished product. During the entire period of experiments, 43 species of various microorganisms have been isolated and identified. However, the number and individual types of microorganisms differed at different stages of production. Some microorganisms that have been isolated in raw milk are also found in the final product, such as Acinetobacter baumannii and Escherichia coli. In total, 18 types of microorganisms have been isolated and identified in the final product – hard rennet cheese, including Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli, which are of particular concern in the context of safe consumption of this cheese.

Effectiveness of pasteurization for the inactivation of H5N1 influenza virus in raw whole milk

Highly pathogenic avian influenza (HPAI) clade 2.3.4.4b H5Nx viruses continue to cause episodic incursions and have been detected in more than 12 taxonomic orders encompassing more than 80 avian species, terrestrial and marine mammals, including lactating dairy cows. HPAI H5N1 spillover to dairy cattle creates a new interface for human exposure and raises food safety concerns. The presence of H5N1 genetic material in one out of five retail pasteurized milk samples in the USA has prompted the evaluation of the pasteurization processes for the inactivation of influenza viruses. Our study examined whether pasteurization could effectively inactivate HPAI H5N1 spiked into raw whole milk. First, we heated 1 mL of non-homogenized cow milk samples to attain an internal temperature of 63°C or 72°C and spiked with 6.3 log10 EID50 of clade 2.3.4.4b H5N1 virus. Complete inactivation was achieved after incubation of the H5N1 spiked raw milk at 63°C for 30 min. In addition, viral inactivation was observed in seven of eight experimental replicates when treated at 72°C for 15s. In one of the replicates, a 4.44 log10 virus reduction was achieved, which is about 1 log higher than the average viral quantities detected in bulk milk in affected areas. Therefore, we conclude that pasteurization of milk is an effective strategy for mitigation of the risk of human exposure to milk contaminated with H5N1 virus.

Influence of Temperature-Humidity Index, Annual, and Seasonal Scenarios on Performance, Bulk Milk Portfolio, and Financial Impacts of Egyptian Holstein Cows

Influence of Temperature-Humidity Index, Annual, and Seasonal Scenarios on Performance, Bulk Milk Portfolio, and Financial Impacts of Egyptian Holstein Cows

Comparison of Extraction Methods for the Detection of Avian Influenza Virus RNA in Cattle Milk.

Since early 2024, a multistate outbreak of highly pathogenic avian influenza H5N1 has been affecting dairy cattle in the USA. The influenza viral RNA concentrations in milk make it an ideal matrix for surveillance purposes. However, viral RNA detection in multi-component fluids such as milk can be complex, and optimization of influenza detection methods is thus required. Raw bulk tank milk and mastitis milk samples were artificially contaminated with an avian influenza strain and subjected to five extraction methods. HCoV-229E and synthetic RNA were included as exogenous internal process controls. Given the high viral load usually observed in individual raw milk samples, four out of five tested methods would enable influenza detection in milk with normal texture, over a time window of at least 2 weeks post-onset of clinical signs. Nevertheless, sample dilution 1:3 in molecular transport medium prior to RNA extraction provided the best results for dilution of inhibitory substances and a good recovery rate of influenza RNA, that reached 12.5 ± 1.2% and 10.4 ± 3.8% in two independent experiments in bulk milk and 11.2 ± 3.6% and 10.0 ± 2.9% on two cohorts of mastitis milk samples. We have also shown compatibility of an influenza RT-qPCR system with synthetic RNA detection for simultaneous validation of the RNA extraction and RT-qPCR processes.

The stability of fatty acids in yoghurts produced from bulk milk samples intentionally selected according to dairy production systems

The stability of fatty acids in yoghurts produced from bulk milk samples intentionally selected according to dairy production systems

Identification of Enterococcus spp. by MALDI-TOF mass spectrometry isolated from clinical mastitis and bulk tank milk samples

BackgroundThroughout a three-year study period, 1,577 bovine clinical mastitis samples and 302 bulk tank samples were analyzed from ten Brazilian dairy herds. Enterococcus spp. was isolated and identified in 93 (5.9%) clinical mastitis samples. In addition, 258 Enterococcus spp. were isolated from the bulk tank samples of the same herds. The identification of Enterococcus spp. isolated from bulk tanks and milk samples of clinical mastitis were accomplished by phenotypic characteristics and confirmed by MALDI-TOF Mass Spectrometry (MS). Fisher test was performed to verify the difference between bulk tanks and mastitis samples.ResultsThe following species were identified from clinical mastitis: E. saccharolyticus (62.4%), E. faecalis (19.4%), E. faecium (15.1%), E. hirae (1.1%), E. mundtii (1.1%), E. durans (1.1%). Furthermore, from 258 bulk tank milk samples, eight enterococci species were isolated: E. faecalis (67.8%), E. hirae (15.1%), E. faecium (4.6%), E. saccharolyticus (4.6%), E. mundtii (3.1%), E. caseliflavus ( 2.7%), E. durans (1.2%), E. galinarum (0.8%).ConclusionsThe difference in species predominance in bulk tank samples (67.8% of E. faecalis) and clinical mastitis (62.4% of E. saccharolyticus) was unexpected and caught our attention. Although Enterococcus spp. are traditionally classified as an environmental mastitis agent, in the present study, E. saccharolyticus behaved as a contagious agent of mastitis, which consequently changed the control patterns to be implemented.

Inactivation of Highly Pathogenic Avian Influenza Virus with High-temperature Short Time Continuous Flow Pasteurization and Virus Detection in Bulk Milk Tanks

Infections of dairy cattle with clade 2.3.4.4b H5N1 highly pathogenic avian influenza virus (HPAIV) were reported in March 2024 in the U.S. and viable virus was detected at high levels in raw milk from infected cows. This study aimed to determine the potential quantities of infectious HPAIV in raw milk in affected states where herds were confirmed positive by USDA for HPAIV (and therefore were not representative of the entire population), and to confirm that the commonly used continuous flow pasteurization using the FDA approved 72 °C (161°F) for 15 s conditions for high−temperature short time (HTST) processing, will inactivate the virus. Double-blinded raw milk samples from bulk storage tanks from farms (n = 275) were collected in four affected states. Samples were screened for influenza A using quantitative real-time RT-PCR (qrRT-PCR) of which 158 (57.5%) were positive and were subsequently quantified in embryonating chicken eggs. Thirty-nine qrRT-PCR positive samples (24.8%) were positive for infectious virus with a median titer of 3.5 log10 50% egg infectious doses (EID50) per mL. To closely simulate commercial milk pasteurization processing systems, a pilot-scale continuous flow pasteurizer was used to evaluate HPAIV inactivation in artificially contaminated raw milk using the most common legal conditions in the US: 72 °C (161°F) for 15 s. Among all replicates at two flow rates (n = 5 at 0.5 L/min; n = 4 at 1 L/min), no viable virus was detected. A mean reduction of ≥5.8 ± 0.2 log10 EID50/mL occurred during the heating phase where the milk is brought to 72.5 °C before the holding tube. Estimates from heat-transfer analysis support that standard U.S. continuous flow HTST pasteurization parameters will inactivate >12 log10 EID50/mL of HPAIV, which is ∼9 log10 EID50/mL greater than the median quantity of infectious virus detected in raw milk from bulk storage tank samples. These findings demonstrate that the US milk supply is safe when pasteurized.

Risk factors for the introduction of Salmonella spp. serogroups B and D into Dutch dairy herds

Salmonella spp. infections in animals are a concern due to their zoonotic nature, welfare effects and economic impact on the livestock industry. To enable targeted surveillance, it is important to identify risk factors for the introduction of Salmonella spp. in a herd. Since 2009, Dutch dairy processors require herds delivering milk to their plants to participate in a Salmonella programme. In this programme, bulk milk is tested three times a year (i.e. test rounds) by ELISA on presence of antibodies against Salmonella spp. serogroups B and D. Based on these bulk milk results we identified newly infected herds, and aimed to identify associated risk factors. Effects of putative risk factors for becoming newly infected were studied using a multivariable population average logistic regression (PA-GEE) model with binomial distribution. Per test round in 2019–2021, 0.85–4.10 % of the Dutch dairy herds at risk became newly infected, with large regional differences. Several risk factors for becoming newly infected in the context of the low herd-level prevalence were identified. The most evident risk factors that were identified were having at least one infected or recently recovered dairy herd within 500 m (OR = 2.67), on-farm presence of pigs (OR = 1.63), introduction of more than 2 cattle from other herds in the previous 12 months (OR = 1.17), being in an area with a relative soil moisture of >0.54 % (OR = 1.31), being located in an area with a high water surface area (>2 %; OR = 1.14) and a larger herd size (OR = 1.65). These results indicate that, in addition to introduction of cattle, local transmission plays an important role in the between-herd transmission of Salmonella spp. Information on risk factors for becoming newly infected based on regularly collected data, can be used to improve surveillance and to implement targeted control measures against salmonellosis.

Foodborne bacteria in milk and milk products along the water buffalo milk chain in Bangladesh

Controlling foodborne pathogens in buffalo milk is crucial for ensuring food safety. This study estimated the prevalence of nine target genes representing seven critical foodborne bacteria in milk and milk products, and identified factors associated with their presence in buffalo milk chain nodes in Bangladesh. One hundred and forty-three milk samples from bulk tank milk (n = 34), middlemen (n = 37), milk collection centers (n = 37), and milk product shops (n = 35) were collected and analyzed using RT-PCR. Escherichia (E.) coli, represented through yccT genes, was the most prevalent throughout the milk chain (81–97%). Chi-squared tests were performed to identify the potential risk factors associated with the presence of foodborne bacteria encoded for different genes. At the middleman level, the prevalence of E. coli was associated with the Mymensingh, Noakhali, and Bhola districts (P = 0.01). The prevalence of Listeria monocytogenes, represented through inlA genes, and Yersinia (Y.) enterocolitica, represented through yst genes, were the highest at the farm level (65–79%). The prevalence of both bacteria in bulk milk was associated with the Noakhali and Bhola districts (P < 0.05). The prevalence of Y. enterocolitica in bulk milk was also associated with late autumn and spring (P = 0.01) and was higher in buffalo-cow mixed milk than in pure buffalo milk at the milk collection center level (P < 0.01). The gene stx2 encoding for Shiga toxin-producing (STEC) E. coli was detected in 74% of the milk products. At the middleman level, the prevalence of STEC E. coli was associated with the use of cloths or tissues when drying milk containers (P = 0.01). Salmonella enterica, represented through the presence of invA gene, was most commonly detected (14%) at the milk collection center. The use of plastic milk containers was associated with a higher prevalence of Staphylococcus aureus, represented through htrA genes, at milk product shops (P < 0.05). These results suggest that raw milk consumers in Bangladesh are at risk if they purchase and consume unpasteurized milk.

Detection and Phenotypic Antimicrobial Susceptibility of Salmonella enterica Serotypes in Dairy Cattle Farms in the Po Valley, Northern Italy.

The presence of Salmonella spp. in dairy cattle farms poses a major risk to animal health and welfare. This study focused on Salmonella detection in dairy farms located in the Cremona and Mantua provinces (northern Italy) in samples collected and submitted to laboratories in 2021-2022. A total of 2710 samples from different sources, including calf carcasses/organs (n = 128), rectal swabs (n = 1937), feces (n = 390), bulk milk (n = 93), and overshoes/swabs (n = 127) for environmental sampling, were analyzed for the presence of Salmonella spp. and were included in the present study. Our results indicate that Salmonella was most commonly firstly identified from calf carcasses and organs (61.67%) and that the serotypes most frequently detected in dairies were S. Dublin (38.33%), S. Typhimurium (23.33%), and S. Typhimurium monophasic variant (14.17%). The most common pathological findings in calf carcasses were enteritis, hepatosplenomegaly, and pneumonia. The antimicrobial resistance pattern analyzed using the MIC assay of 51 Salmonella isolates revealed the presence of multi-resistant strains, which pose a major risk to public and animal health.

Establishing a surveillance programme for Salmonella Dublin in Austrian dairy herds by comparing herd-level vs. individual animal detection methods

Due to its increasing occurrence in cattle farms in various countries, leading to significant economic losses in affected livestock, Salmonella enterica subspecies enterica serovar Dublin (S. Dublin) has become a highly investigated pathogen in cattle production. In Austria, there have been occasional human cases of S. Dublin as well as an increase in laboratory-confirmed cases in cattle, indicating the need for a screening programme to determine the current status in Austria. The aims of this study were, firstly, to determine the seroprevalence of S. Dublin in dairy herds through bulk milk screenings in two federal states (Salzburg, Tyrol) of Austria. Secondly, the study aimed to identify the infection status of the herds through individual animal and herd level detection, comparing microbiological, molecular and serological detection methods. The results of the study will allow the development of a sampling strategy for a surveillance programme in Austria.A total of 6973 dairy farms were tested through serological bulk milk screening. The seroprevalence for the federal state of Tyrol was 14.8 % and for Salzburg it was 18.2 %, resulting in an average seroprevalence of 16.5 %. At an individual animal level, 205 (11.3 %) animals tested positive for shedding of S. Dublin in the faeces through microbiological detection, and 268 (17.0 %) animals had positive values (ct value ≤ 38) by qPCR. The association between microbiological and molecular detection was statistically significant (p < 0.001), with a calculated kappa value of 0.65 ± 0.27 (p ≤ 0.001), assuming a substantial level of agreement. In 17 herds, where an individual animal tested positive for shedding of S. Dublin, environmental sampling and testing were carried out. At a herd level 16 (94.1 %) out of the 17 participating herds, tested positive for S. Dublin either microbiologically or by molecular assay in boot swab samples. Bulk milk samples from 14 out of the 17 participating herds were analysed for antibodies to S. Dublin and 12 samples (85.7 %) were positive. In total 111 (18.9 %) out of 587 blood samples tested positive for S. Dublin antibodies, demonstrating a statistically significant correlation (p < 0.001) both with microbiological (κ = 0.32 ± 0.49; p ≤ 0.001) and molecular (κ=0.23 ± 0.06; p ≤ 0.001) findings.It was possible to identify S. Dublin by culture from boot swabs in 14 (82.4 %) out of 17 herds and by molecular assay using qPCR in 15 (88.2 %) out of 17 herds, indicating a suitable sample type for screening on a herd level-basis for acute infections, but not for identifying chronic infections or asymptomatic carriers. Other environmental samples, such as sponge-sticks, are only suitable to a limited extent for the detection of S. Dublin. The results of this study demonstrate a moderate S. Dublin prevalence in dairy herds in the selected Austrian regions, signalling further screening and management programmes for the future.

Multispecies pasture diet and cow breed impacts on milk composition and quality in a seasonal spring-calving dairy production system

In recent years, there has been significant emphasis on the composition of pasture-based cow feed and the potential benefits of incorporating multispecies swards to improve sustainability and biodiversity. This study compared the effects of a conventional perennial ryegrass (PRG) monoculture supported by high chemical nitrogen (N) usage with a low chemical N application multispecies sward system (MSS) on the composition and quality of milk across lactation using spring-calving Holstein-Friesian (HF) and Jersey Holstein-Friesian (JFX) cows. Bulk milk samples (n = 144) were collected from each group at morning and evening milking on a weekly basis (n = 36) throughout lactation and analyzed for gross composition and physico-chemical properties. Cow breed had a significant impact on milk profile, with milk from HF cows having significantly smaller milk fat globule (MFG) size, higher instability index values, higher yield, and lower total solids levels, compared with JFX cows. Notably, HF cows had increased milk total solids and fat levels when fed on MSS, as opposed to the PRG-fed HF cows. Feeding MSS pasture increased creaming velocity values in mid and late lactation, and resulted in similar milk gross composition to PRG. In comparison to PRG, MSS-fed groups showed significantly increased total solids yield, including higher levels of protein and fat yield. In late lactation, MSS feeding was associated with reduced MFG size. All physicochemical properties studied (MFG size, creaming velocity, instability index) showed decreasing values from early to late lactation stage. Overall, these findings demonstrate the significant effects of cow diet, breed and stage of lactation on compositional and physico-chemical characteristics of milk, with important implications for milk processing and dairy product quality.

The microbiota of ensiled forages and of bulk tank milk on dairy cattle farms in northern Sweden

Factors contributing to variations in the quality and microbiota of ensiled forages and in bulk tank microbiota in milk from cows fed different forages were investigated. Nutritional quality, fermentation parameters and hygiene quality of forage samples and corresponding bulk tank milk samples collected in 3 periods from 18 commercial farms located in northern Sweden were compared. Principal coordinates analysis revealed that the microbiota in forage and bulk milk, analyzed using 16S rRNA gene-based amplicon sequencing, were significantly different. The genera Lactobacillus, Weissella, and Leuconostoc dominated in forage samples, whereas Pseudomonas, Staphylococcus, and Streptococcus dominated in bulk milk samples. Forage quality and forage-associated microbiota were affected by ensiling method and by use of silage additive. Forages stored in bunker and tower silos (confounded with use of additive) were associated with higher levels of acetic and lactic acid and Lactobacillus. Forage ensiled as bales (confounded with no use of additive) was associated with higher DM content, water-soluble carbohydrate content, pH, yeast count, and the genera Weissella, Leuconostoc, and Enterococcus. For bulk tank milk samples, milking system was identified as the major factor affecting the microbiota and type of forage preservation had little effect. Analysis of common amplicon sequence variants (ASV) suggested that forage was not the major source of Lactobacillus found in bulk tank milk.

Low Effectiveness of Mid-Infrared Spectroscopy Prediction Models of Mediterranean Italian Buffalo Bulk Milk Coagulation Traits.

This study evaluated the potential use of mid-infrared spectroscopy to predict milk coagulation traits in bulk milk from Mediterranean Italian buffaloes. A total of 1736 bulk milk samples from 55 farms in central Italy were collected during the official milk quality testing system. The prediction models were developed based on modified partial least-squares regression with 75% of the samples and validated with the remaining samples. All bulk milk samples coagulated between 7.37 and 29.45 min. Average values for milk coagulation traits in the calibration set were 17.71 min, 3.29 min, and 38.83 mm for rennet coagulation time, curd firming time, and curd firmness, respectively. The validation set included samples with similar mean and standard deviation for each trait. The prediction models showed the greatest coefficient of determination of external validation (0.57) and the ratio of prediction to deviation (1.52) for curd firmness. Similar fitting statistics of the prediction models were obtained for rennet coagulation time and curd firming time. In conclusion, the prediction models for all three coagulation traits were below the threshold to consider the prediction models adequate even for rough screening of the samples.

Influence of the season on the main components of cow milk in Ukraine

The quality of dairy products depends on the safety and quality of raw materials, therefore, the analysis of physicochemical and sanitary indicators of raw cow milk is of great importance. The composition of bulk milk of three technological groups of cows: early lactation (5–60 days in milk), primiparous cows and all other cows starting from the second lactation was studied according to seasons. Regardless of the group of animals, the fat content in bulk milk was significantly lower in summer than in other seasons of the year, and the highest in winter. In each group of animals, the lowest somatic cell count was observed in the fall, while the highest indicator of the study of bulk milk of cows in early lactation and primiparous was determined in the winter, and in the spring of cows from the second lactation. The lowest milk urea content in all groups of animals was noted in summer. The lowest protein level was observed in autumn (3.27 ± 0.11%), and the highest in winter (3.39 ± 0.11%) in the bulk milk of cows in early lactation. The ratio of fat to protein in summer 1.12 ± 0.03 was significantly lower compared to other seasons of the year. The highest level of somatic cells was recorded in this group in winter (290 ± 82 * 103 cells/mL), which was twice as much as in autumn (141 ± 54 * 103 cells/mL), and by 56.8% more than in summer (185 ± 39 * 103 cells/mL). The milk urea content in the summer was 194.0 ± 17.6 mg/kg, which is significantly lower than the indicators in other seasons of the year in the group of early lactation. In the summer period, the lowest protein content (3.23 ± 0.06%) in the bulk milk of primiparous cows was observed compared to other seasons of the year. The winter was characterized by the highest level of somatic cell count in milk (221 ± 49 * 103 cells/mL), which was almost twice as high as the autumn period (116 ± 31 * 103 cells/mL). The highest urea content in the milk of primiparous cows was found in autumn (228.6 ± 21.9 mg/kg), which exceeded the summer figure by 14.5%. The lowest protein content (3.29 ± 0.06%) and the highest in winter (3.44 ± 0.09%) was observed in the bulk milk of cows of the second lactation and older. The somatic cell count in milk in autumn (160 ± 69 * 103 cells/mL) was lower than the winter and spring indicators by 37.5% and 49.3%, respectively. The milk urea content in the summer (198 ± 22 mg/kg) was significantly lower than the autumn and winter indicators. In further studies, to improve the sanitary quality of milk, it is planned to use different hygienic means for processing the udder of cows depending on the season.

Milking system and diet forage type effect on milk quality of Italian Holstein-Friesian

Moving from conventional (CMS) to automatic (AMS) milking systems could affect milk quality. Moreover, the type and preservation methods of the forages used in the TMR, such as alfalfa hay (HTMR) or corn silage (STMR) have been demonstrated to modify milk composition. Thus, this study investigated the effect of implementing AMS and different diet forage types on the quality of Italian Holstein-Friesian bulk milk. Milk samples (n = 168) were collected monthly from 21 commercial farms in northern Italy during a period of 8 mo. Farms were categorized into 4 groups according to their milking system (CMS vs. AMS) and diet forage type (HTMR vs. STMR). Milk quality data were analyzed through the mixed procedure for repeated measurement of SAS with the milking system, diet forage type, and sampling day as fixed effects. Milking through the AMS led to lower milk fat, freezing point, and β-LG A; longer coagulation time; and higher K content, pH, and β-LG B than CMS. Cows fed STMR produced milk with greater fat, protein, casein, Mg content, titratable acidity, and β-LG A, but with reduced curd firming time, freezing point, and β-LG B than those fed HTMR. In conclusion, milk quality is not only altered by the diet's forage type and characteristics but also by the milking system.