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IntroductionThe spread of antimicrobial resistance (AMR) is a major threat to human and animal health. Therefore, new solutions are needed to prevent returning to a world without effective antibiotics. Mastitis in dairy cows is a major reason for antimicrobial use in food animal production, and mastitis-causing bacteria have the potential to develop AMR. In this study, acoustic pulse technology (APT) was explored as an alternative to antimicrobials for the treatment of mastitis in dairy cows. APT involves the local transmission of mechanical energy through soundwaves which stimulate anti-inflammatory and angiogenic responses in the udder. These responses promote udder recovery and enhance resistance to bacterial infections.MethodsWe examined 129 Israeli dairy cows with mastitis in this prospective, controlled study to assess the efficiency of APT treatment on cure and recovery rates. An accurate diagnosis of suspected or confirmed infectious mastitis was made from cows having clinical signs of mastitis and/or somatic cell count (SCC) of above 400,000 cells/mL. The cows were divided into three groups: Group 1 (n = 29), cows with no bacterial findings (NBF); Group 2 (n = 82), cows with clinical signs of mastitis or SCC >400,000 cells/mL in the most recent test; and Group 3 (n = 18), cows with chronic mastitis (two or more tests with SCC >400,000 cells/mL within 3 months). All the cows received APT treatment, which involved 400 pulses on two sides of the infected quarter, delivered in three phases over 3 days. The cure for the mammary gland was indicated by the absence of bacterial growth in post-treatment cultures and recovery by a decrease in SCC to < 250,000 cells/mL in two of three post-treatment tests.Results and discussionIn Group 2, cure and recovery rates were 67.1 and 64.6%, respectively, and were not significantly different between Gram-negative and Gram-positive infections. A similar recovery rate was found in NBF cows. However, in cows with chronic mastitis, both the cure and recovery rates were significantly lower (22.2 and 27.8%, respectively). These results have important implications for dairy farmers, as APT treatment could lead to substantial savings of up to $15,106/year in a 100-cow herd, considering the national estimated prevalence of mastitis and the cost of individual treatment. APT should be further investigated as a viable and sustainable alternative to antimicrobial therapy for mastitis, offering economic benefits to dairy producers and the possibility of preventing AMR.

The effect of acoustic pulse technology (APT) on recovery, culling, milk yield, and economic benefits for 118 cows with subclinical mastitis was compared with a no-treatment control (59 vs. 59), and another 118 APT-treated cows with clinical mastitis were compared with antibiotic-treated controls (59 vs. 59). Recovery was defined as a decrease in somatic cell count (SCC) to &lt, 250 × 103 cells/mL in at least two out of three monthly milk recordings after treatments. For the subclinically infected cows, APT treatment resulted in 65.5% recovery, 0% culling, and additional milk yield of 2.74 L/cow per day compared to 35.6% recovery and 5.1% culling in the no-treatment controls. For the clinically infected cows, APT treatment resulted in 67.8% recovery, 6.8% culling, and additional milk yield of 3.9 L/cow per day compared to 35.6% recovery and 32.2% culling in the antibiotic-treated group. Bacteriological analysis was run for 95 (80%) cows with clinical mastitis (APT-46, AB-49). For cows with Escherichia coli infection, 85.7% (18/21) treated with APT recovered vs. 17.6% (3/17) in the antibiotic-treated group, for cows with streptococcal infection, 66.0% (12/18) in the APT-treated group recovered vs. 44.4% (8/18) in the antibiotic-treated group.

In 2 epidemiological studies, we evaluated the effect of mastitis induced by gram-positive Streptococcus and gram-negative Escherichia coli on impaired reproductive performance in lactating Holstein cows. In the first study, 52,202 cows from 178 dairy farms throughout Israel were divided into groups based on infection before first artificial insemination (AI) with Streptococcus or E. coli, 3 groups with elevated somatic cell count (SCC) without infection by those pathogens [low SCC (200-400) × 103 cell/mL; medium SCC (401-1,000) × 103 cell/mL; high SCC, >1,000 × 103 cell/mL], and uninfected controls. Pregnancy per first AI (P/1stAI) and pregnancy rate at 300 d in milk (PREG 300) were analyzed by the GLIMMIX procedure (SAS); number of AI per pregnancy (AI/P), days open, and rest days (calving to first AI) were analyzed by the MIXED procedure (SAS Institute Inc., Cary, NC). Values of P/1stAI were similarly low for Streptococcus and E. coli (27-28%) versus 42% in controls; PREG 300 was lower for Streptococcus (76%) than for E. coli (79%) versus 88% for uninfected controls and a mean 83% for the elevated SCC groups. Days open and number of AI/P were higher than in controls and similar in Streptococcus and E. coli groups. The second study included 778 cows on 6 dairy farms; the cows were infected before first AI by Streptococcus or E. coli or uninfected. Resumption of cyclicity was determined by an automated activity-monitoring system, and data were sorted by time of infection before or after cyclicity resumed. The Streptococcus group had lower P/1stAI before and after cyclicity (26 and 27%, respectively) than the E. coli group (31 and 34%, respectively) and uninfected controls (42%). Notably, PREG 300 in the Streptococcus group before (73%) and after (67%) cyclicity was much lower than for the E. coli group (85 and 93%, respectively) and the controls (95%). A marked rise in day of cyclicity resumption (∼80 d) was observed in cows that were infected early on. Number of AI/P was higher in the mastitic groups than in uninfected controls. Uterine disease postpartum, although more prevalent among Streptococcus cows, did not substantially alter the larger reduction in P/1stAI and PREG 300 in Streptococcus versus E. coli cows. Thus, long-term Streptococcus-induced mastitis disrupted fertility more than short-term acute E. coli-induced mastitis, resulting in a much higher percentage of Streptococcus cows in late lactation that did not conceive due to reproduction failure.

The effects of subclinical intramammary infection (SCIMI) in sheep are ignored in most cases by both the farmers and the industry. Due to the high prevalence of coagulase negative staphylococci (CNS) and the lack of feasibility to treat the infection during lactation, prominent actions must concentrate on its prevention. On the sheep level, SCIMI caused by CNS clearly reduces milk yield and changes milk composition that directly influence the product’s properties. High proportion of milk from infected glands in the milk tank is associated with higher losses of fat and protein in the whey during the coagulation process. Moreover, extended storage of milk, irrespective of its initial quality, deteriorates its final quality for cheese making and extended storage of low-quality milk before processing, further increases this deterioration. Studies related to the quality of cheese and yogurt indicated that milk composition has been changed owing to the presence of different bacteria. The review aims to draw attention to the effects of SCIMI in sheep caused by CNS on milk production losses along with changes in its composition that influences milk coagulation properties and chasse yield.

A cow with mastitis has a high somatic cell count (SCC) in its milk. Cow-share-contribution of somatic cells to the bulk milk tank (BMTSCC) refers to the relative addition made by each cow’s milk to the bulk tank’s SCC. Since bulk milk is graded and priced according to the BMTSCC, high-yielding cows with mastitis are the main contributors to penalizations in milk price. The benefits of acoustic pulse technology (APT) application to tissues are well documented, including its anti-inflammatory effect and restoration of tissue function by triggering natural healing processes. An APT-based device was developed specifically for treating mastitis in dairy cows. It enables rapid and deep penetration of the acoustic pulses over a large area of the udder in a single session. A study was performed on six farms with a total of 3,900 cows. One unit of cow-share-contribution equaled the addition of 1,000 cells to each mL of the bulk milk volume above the mean BMTSCC. A total of 206 cows were selected: 103 were treated with APT and 103 served as controls. All of the cows contributed over 1.5 units to the BMTSCC at the time of treatment. Seventy-five days after APT treatment, 2 of the 103 treated cows (1.9%) were culled, compared to 19 (18.5%) of the 103 control cows, as well as infected quarter dry-off in 5 others (4.85%). Overall success was defined as a decrease of >75% in cow-share-contribution from treatment time in two of the three monthly milk recordings following treatment. Results indicated 57.3% success for the APT-treated cows vs. 14.6% for the untreated control groups. Highest share-contribution provide an additional tool for the farmer’s decision of how to control BMTSCC. Because the cow-share-contribution value is relative to herd size and BMTSCC, this study included a similar number of cows, with similar SCC and milk yield from each of the six herds.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Differentiation of cells by flow cytometry provides informative somatic cell counts (SCCs) that allow analyzing leukocyte population patterns in udder infections of different etiologies. Postulating that this approach also enhances the statistical power to detect genetic variants linked to cell levels in milk of healthy mammary glands, we used monoclonal antibodies anti-CD18, anti-CD4, anti--CD14, and anti-PMN to count cells presenting these surface antigens, and performed a genome-wide association study of these counts in 125 Israeli Holsteins genotyped using SNP BeadChips. We identified an informative haplotype of 15 SNPs in the centromeric end of BTA3 that was strongly associated with CD18 cells (p &lt, 2.3 &times, 10&minus, 9). Within this region, examination of the network of genes interacting with ITGB2 (CD18) indicated an Fc-&gamma, receptor gene cluster, including FCGR2A (CD32). Sanger-sequence analysis of FCGR2s-linked exon 3 variation to CD18 counts. Meta-analysis of RNA-Seq data revealed a significant negative correlation (R = &minus, 0.51) between expression of CD32 and CD18 in milk. Assembly of DNA-Seq reads uncovered FCGR copy-number variation and a variant, designated V7, was abundant in dairy cattle, probably reflecting adaptation to selection pressure for low SCC in Holstein milk.

The mammary immune and physiological responses to distinct mammary-pathogenic E. coli (MPEC) strains were studied. One gland in each of ten cows were challenged intra-mammary and milk composition (lactose, fat, total protein, casein), biochemical (glucose, glucose-6-phosphate (Glu6P), oxalate, malate, lactate, pyruvate and citrate, malate and lactate dehydrogenases, lactate dehydrogenase (LDH), nitrite, lactic peroxidase, catalase, albumin, lactoferrin, immunoglobulin) and clotting parameters were followed for 35 days post-challenge. Challenge lead to clinical acute mastitis, with peak bacterial counts in milk at 16–24 h post-challenge. Biochemical and clotting parameters in milk reported were partially in accord with lipopolysaccharide-induced mastitis, but increased Glu6P and LDH activity and prolonged lactate dehydrogenase and Glu6P/Glu alterations were found. Some alterations measured in milk resolved within days after challenge, while others endured for above one month, regardless of bacterial clearance, and some reflected physiological responses to mastitis such as the balance between aerobic and anaerobic metabolism (citrate to lactate ratios). The results suggest that E. coli mastitis can be divided into two stages: an acute, clinical phase, as an immediate response to bacterial infection in the mammary gland, and a chronic phase, independent of bacteria clearance, in response to tissue damage caused during the acute phase.

Colostrum samples of first, second, and third milking were collected from 72 cows. Immunoglobulins were determined by colostrometer, Brix refractometer, online Afilab spectrometer, and ELISA. Corre...

We studied the mammary immune response to different mammary pathogenicEscherichia coli(MPEC) strains in cows, hypothesising that the dynamics of response would differ.E. coliis a major aetiologic agent of acute clinical bovine mastitis of various degrees of severity with specific strains being associated with persistent infections. We compared challenge with three distinct pathogenic MPEC strains (VL2874, VL2732 and P4), isolated from different forms of mastitis (per-acute, persistent and acute, respectively). A secondary objective was to verify the lack of mammary pathogenicity of an environmental isolate (K71) that is used for comparison against MPEC in genomic and phenotypic studies. Twelve cows were challenged by intra-mammary infusion with one of the strains. Cellular and chemokine responses and bacterial culture follow-up were performed for 35 d. All cows challenged by any of the MPEC strains developed clinical mastitis. Differences were found in the intensity and duration of response, in somatic cell count, secreted cytokines (TNF-α, IL-6 and IL-17) and levels of milk leucocyte membrane Toll-like receptor 4 (TLR4). A sharp decrease of TLR4 on leucocytes was observed concomitantly to peak bacterial counts in milk. Intra-mammary infusion of strain K71 did not elicit inflammation and bacteria were not recovered from milk. Results suggest some differences in the mammary immune response to distinct MPEC strains that could be correlated to their previously observed pathogenic traits. This is also the first report of anE. colistrain that is non-pathogenic to the bovine mammary gland.

Upon entry into the mammary gland, mammary pathogenic strains of Escherichia coli rapidly grow using milk as a nutrient source, in a manner highly dependent on the expression of the ferric-dicitrate system by these bacteria. Intra-mammary challenge with distinct mammary pathogenic E. coli (MPEC) strains result in development of clinical acute mastitis, with peak bacterial counts in milk at 16-24 h post-challenged and profound immune changes found in the milk. The main biochemical changes measured in milk were partially in accord with lipopolysaccharide-induced mastitis, with increased glucose-6-phosphate and lactate dehydrogenase activity or prolonged lactate dehydrogenase, and Glu6P/Glu alterations. Changes also reflect physiological responses to inflammation in the mammary gland, as in the balance between aerobic and anaerobic metabolism (citrate to lactate ratios). Some alterations measured in milk resolved with days after challenge but other remained for above one month, regardless of bacterial clearance. The results suggest that E. coli mastitits can be divided into two stages: an acute, clinical phase, as an immediate response to bacterial infection in the mammary gland and a chronic phase, independent of bacteria clearance, and in response to the tissue damage caused in the first phase.

The current study measured the influence of milk of subclinically infected glands by different bacteria species on the cow’s milk and suggests different parameters for milk payment. The effects of bacterial infection or inflammation on gland milk yield were related to the bacteria species that caused the infection. The volume of milk of the inflamed gland from the cow’s milk yield was significantly lower (P) for the glands previously infected byEscherichia coli(PIEc) and those infected withStreptococcus dysgalactiae.Coagulation properties, rennet clotting time (RCT) and curd firmness (CF) also depended on the bacteria causing the infection. RCT values of all the inflamed glands were significantly longer (P) and CF values were significantly lower than that of the healthy ones. Moreover, in the whole milk, CF was also significantly lower and not proportional to the volume of the milk from the inflamed gland of the cow’s milk. Calculating the predicted 40% dry matter curd weight (PCW) on the cow level, including the healthy and inflamed glands or the healthy glands alone, found that for 9 of 13 PIEc cows, the presence of the affected gland’s milk in the whole cow milk resulted in a negative PCW value. Likewise, 5 of 20 cows infected byS. dysgalactiaehad negative delta values. Unlike the latter bacteria, PCW from milk of glands infected with CNS increased, although in a lower magnitude than in the healthy glands. No correlation was found between logSCC in the whole cow milk (healthy and inflamed glands) and PCW.

This study focused on the need for bulk milk tank somatic cell count (BMTSCC) thresholds and cut-off levels indicating a decrease in milk quality that consequently influences product quantity and quality. First, 226 ewes and 231 goat bulk tank milk samples were collected from different Israeli herds and coagulation properties were determined. Second, soft cheese was produced. No correlation of coagulation properties was found with BMTSCC for sheep milk up to 3264 × 103 and goat milk up to 6452 × 103 cells mL−1. Coagulation properties of goat milk with cell count higher than the latter resulted in a significant decrease in curd firmness. For breeds and management system in Israel, 2500 × 103 cells mL−1 is suggested as the cut-off level for sheep and 3500 × 103 cell mL−1 for goats. The cell count cut-off level and milk price according to BMTSCC should be tested and then determined for every breed and management and final dairy product.

Mastitis, particularly in its subclinical form, is a widely spread disease that reduces the fertility of lactating cows. A major cause of poor conception risk has been associated with delayed ovulation of a large subgroup of subclinical mastitic cows. This study examined 2 approaches to improve fertility in this subgroup. Subclinical mastitic cows were defined by somatic cell count elevated above a threshold of 150,000 cells/mL of milk determined in all monthly test day samples collected before AI. Uninfected (control) cows were defined by somatic cell count below threshold. In experiment 1, we examined a hormonal approach aimed to correct the timing of ovulation in mastitic cows in which it would otherwise be delayed. The probability of conception of mastitic and uninfected groups following Ovsynch (OVS) and timed AI versus AI following detected estrus (E) was examined (n=1,553 AI) and analyzed by a multivariable, logistic model statement using the GLIMMIX procedure of SAS. The OVS protocol significantly elevated the probability of conception of mastitic cows to a level similar to that of their uninfected counterparts. Actual mean conception risks for uninfected-E, subclinical-E, uninfected-OVS, and subclinical-OVS groups were 41.8, 26.4, 39.3, and 40.5%, respectively. The OVS protocol did not improve probability of conception in cows diagnosed with uterine disease postpartum. In experiment 2, a management approach aimed to better synchronize timing of ovulation with timing of AI in subclinical mastitic cows was examined. A second AI was added 24h after the first (routine) AI, following detection of natural estrus. Probability of conception did not differ between subclinical mastitic cows inseminated once or twice. Lack of improvement in conception risk might be related to low preovulatory LH surge in mastitic cows, which is likely to induce not only delayed ovulation but also disruption of oocyte maturation. Thus the OVS protocol can improve fertility of subclinical mastitic cows, probably due to "corrected" timing of ovulation in cows in which it would otherwise be delayed.

The aim of the current study was to verify the existence of a significant correlation between bacterial isolation (or not) and mammary gland inflammation, using traditional bacterial culturing and PCR, milk leucocytes distributions, and tissue histology. Twenty-two cows were tested at the level of the individual gland for bacteriological culture and real-time PCR (RT-PCR), milk composition, somatic cells count (SCC), and cell differentiation. Post-slaughter samples of teat-ends and mammary tissues were tested for histology and bacteriology by RT-PCR. The 88 glands were assigned to either outcome: 1. Healthy&mdash, no inflammation and no bacterial finding (NBF) (n = 33), 2. Inflammation and NBF (n = 26), 3. Inflammation and intra-mammary infection (n = 22) with different bacteria. Bacteriology of milk samples and that of the RT-PCR showed 91.4% agreement. In the lobule&rsquo, s tissues of healthy glands, ~50% were milk producers and the other glands had dry areas with increased fat globules with a low number of leukocytes. In contrast, ~75% of the infected glands were identified as inflamed, but with no isolation of bacteria. Infiltration of mononuclear cells and neutrophils into the connective tissue was observed but not in the lobule&rsquo, s lumen. In summary, the study confirms that not every mastitis/inflammation is also an infection.

Clinical and subclinical mastitis affects 30% of cows and is regarded as the most significant economic burden on the dairy farm reducing milk yield and quality and increasing culling rate. A proprietary Acoustic Pulse Therapy (APT) device was developed specifically for treating dairy cows. The APT device was designed to produce deep penetrating acoustic pulses that are distributed over a large treated area at a therapeutic level. This paper presents findings from a clinical assessment of this technology for the treatment of dairy cows with subclinical and clinical mastitis. In subclinical mastitis, a group of 116 cows from 3 herds were identified with subclinical intramammary infection and enrolled in the study; 78 cows were assigned to the treatment group and 38 cows to the control group. Significant differences (P

Escherichia coli are major bacterial pathogens causing bovine mastitis, a disease of great economic impact on dairy production worldwide. This work aimed to study the virulence determinants of mammary pathogenic E. coli (MPEC). By whole-genome sequencing analysis of 40 MPEC and 22 environmental (“dairy-farm” E. coli [DFEC]) strains, we found that only the fec locus (fecIRABCDE) for ferric dicitrate uptake was present in the core genome of MPEC and that it was absent in DFEC genomes (P < 0.05). Expression of the FecA receptor in the outer membrane was shown to be citrate dependent by mass spectrometry. FecA was overexpressed when bacteria were grown in milk. Transcription of the fecA gene and of the inner membrane transport component fecB gene was upregulated in bacteria recovered from experimental intramammary infection. The presence of the fec system was shown to affect the ability of E. coli to grow in milk. While the rate of growth in milk of fec-positive (fec+) DFEC was similar to that of MPEC, it was significantly lower in DFEC lacking fec. Furthermore, deletion of fec reduced the rate of growth in milk of MPEC strain P4, whereas fec-transformed non-mammary gland-pathogenic DFEC strain K71 gained the phenotype of the level of growth in milk observed in MPEC. The role of fec in E. coli intramammary pathogenicity was investigated in vivo in cows, with results showing that an MPEC P4 mutant lacking fec lost its ability to induce mastitis, whereas the fec+ DFEC K71 mutant was able to trigger intramammary inflammation. For the first time, a single molecular locus was shown to be crucial in MPEC pathogenicity., IMPORTANCE Bovine mastitis is the major infectious disease in dairy cows and the leading cause of economic loss to the global dairy industry, directly contributing to the price of dairy products on supermarket shelves and the financial hardships suffered by dairy farmers. Mastitis is also the leading reason for the use of antibiotics in dairy farms. Good farm management practices in many countries have dramatically reduced the incidence of contagious mastitis; however, the problems associated with the incidence of environmental mastitis caused by bacteria such as Escherichia coli have proven intractable. E. coli bacteria cause acute mastitis, which affects the health and welfare of cows and in extreme cases may be fatal. Here we show for the first time that the pathogenicity of E. coli causing mastitis in cows is highly dependent on the fecIRABCDE ferric citrate uptake system that allows the bacterium to capture iron from citrate. The Fec system is highly expressed during infection in the bovine udder and is ubiquitous in and necessary for the E. coli bacteria that cause mammary infections in cattle. These results have far-reaching implications, raising the possibility that mastitis may be controllable by targeting this system.

The concentrations of glucose and glucose-derived carbons in milk reflect their concentrations in the mammary epithelial cell cytosol. We hypothesized that the sharp reduction in milk secretion observed during acute inflammation in the mammary gland is associated with conversion of the gland's metabolism to aerobic glycolysis and reduced extraction of glucose from the blood, in support to the innate immune system. Acute inflammation was induced by challenging one mammary gland in 5 cows with a single dose of 10 μg bacterial lipopolysaccharide. The glandular response was followed up to 96 h post-challenge. The challenge induced increases in polymorphonuclear leukocytes, milk malondialdehyde concentration and casein degradation. The response peaked at 24 h post-challenge and the inflammation began to decrease after 48 h, but at 96 h post-treatment, values had not yet returned to pre-treatment levels. Milk secretion, and milk lactose, glucose and citrate concentrations decreased sharply, reaching minimal levels at 24 h post-treatment. The correlations between these parameters and inflammation parameters were negative and statistically significant. The reduction of ∼50% in milk yield and lactose concentration in the treated gland indicated that extraction of glucose from the blood was reduced from a rate of ∼740 g d−1 to 190 g d−1 (i.e., by 550 g d−1) at the peak of response. The concentrations of glucose-6-phosphate, malate, oxaloacetate, lactate and pyruvate and the activities of the enzymes glucose-6-phosphate dehydrogenase, malate dehydrogenase and lactate dehydrogenase increased and, in general, were positively and significantly correlated to inflammation parameters. It was concluded that inflammation shifts the passage of glucose-derived carbons to the pentose phosphate pathway and shifts cell metabolism to glycolysis at the expense of mitochondrial activity.

Loss of milk quality caused by subclinical infection in dairy sheep has a negative effect on cheese manufacture. As milk from each single animal is not systematically evaluated for somatic cell count, milk from animals with undetected subclinical mastitis often reaches the refrigeration tanks, mixing with normal milk and reducing its technological suitability for cheese manufacture. This study was undertaken to investigate the effect of subclinical mastitis in the coagulation properties of ewe milk using a light backscatter fiber optic sensor. Manchego-type cheese was manufactured using milk from Lacaune and Manchega sheep. Milk from infected and non-infected udders was coagulated and monitored at laboratory scale using both a NIR fiber optic light backscatter sensor and a rheometer. Simultaneously, clotting and cutting time were visually evaluated by an experienced cheesemaker. Optical parameters t max , t 2max , and t 2min were highly correlated (0.914 r P Staphylococcus had longer coagulation and cutting time. Prediction models using light backscatter parameters alone or in combination with protein/solids concentration were successfully obtained for visually determined clotting and cutting time, rheologically derived gelation and cutting times and for tan δ at cutting with R 2 values ranging from 0.799 to 0.999. Our results suggest that early detection of subclinical mastitis and milk coagulation monitoring using light scatter can diminish the negative impact of mixing milk of infected animals, when milk is used for cheese manufacture.

Humans learned to exploit ruminants as a source of milk about 10,000 years ago. Since then, the use of domesticated ruminants as a source of milk and dairy products has expanded until today when the dairy industry has become one of the largest sectors in the modern food industry, including the spread at the present time to countries such as China and Japan. This review analyzes the reasons for this expansion and flourishing. As reviewed in detail, milk has numerous nutritional advantages, most important being almost an irreplaceable source of dietary calcium, hence justifying the effort required to increase its consumption. On the other hand, widespread lactose intolerance among the adult population is a considerable drawback to dairy-based foods consumption. Over the centuries, three factors allowed humans to overcome limitations imposed by lactose intolerance: (i) mutations, which occurred in particular populations, most notably in the north European Celtic societies and African nomads, in which carriers of the lactose intolerance gene converted from being lactose intolerant to lactose tolerant; (ii) the ability to develop low-lactose products such as cheese and yogurt; and (iii) colon microbiome adaptation, which allow lactose intolerant individuals to overcome its intolerance. However, in a few examples in the last decade, modern dairy products, such as the popular and widespread bio-cultured yogurts, were suspected to be unsuitable for lactose intolerant peoples. In addition, the use of lactose and milk-derived products containing lactose in non-dairy products has become widespread. For these reasons, it is concluded that it might be important and helpful to label food that may contain lactose because such information will allow lactose intolerant groups to control lactose intake within the physiological limitations of ~12 g per a single meal.

Manchego is a high-fat, long ripened hard cheese, which is produced by enzymatic coagulation of sheep milk. Manchego produced in the La Mancha region in Spain and has Protected Designation of Origin (PDO) status. The objective of the study was to evaluate the effects of intramammary infection (IMI) in Manchega and Lacaune dairy sheep with various coagulase negative staphylococci bacteria (CNS) on milk coagulation properties and cheese whey syneresis. The effect of the length of milk storage before processing on cheese yield and its quality was also evaluated. The study included 20 Manchega and 16 Lacaune dairy ewes. The half-udder model was applied: each of the selected animals had one gland free of infection, while the contra-lateral gland was infected with various CNS species. Pasteurized milk (10 L) from uninfected glands, and 50:50 and 75:25 milk blends from uninfected:CNS-infected glands was used for cheese production. Overall, 23 batches of cheese were made and ripened for 63 d. Cheeses were analyzed for organic components, physical and mechanical structure. The taste and sensual qualities of the cheese were evaluated by experts and consumers in two separate panels. Milk yield in the glands infected with CNS was significantly lower than in control glands. The milk of infected glands had higher somatic cell count and poorer coagulation properties in comparison to controls. Cheese made from infected milk had a significant effect on % fat, total fat, fat loss, total protein, protein loss and dry matter in both breeds. However, cheeses made of blends of 25% or 50% milk from infected glands had only minor losses of fat and protein content, which were not associated with noticeable changes in the final weight of the cheese; though, as discussed herein, further research in this line is warrant. The cheeses made of milk stored under refrigerated conditions were clearly perceived as different from the other cheeses because it had more intense attributes related with tangy taste (i.e., bitter, sharp, intense taste, acid) and soft texture (i.e., soft, pasty, not tough).

Recent findings have indicated that secreted phospholipases A2 (sPLA2s) have anti-inflammatory functions, including relief of symptoms in a mouse model of mastitis. This prompted us to investigate the therapeutic application of sPLA2, PLA2G1B, for bovine mastitis. Initial testing of PLA2G1B's effect on bovine mammary epithelial cell (bMEC) line PS revealed no changes in cell viability or cytokine-secretion pattern. However, when cells were first treated with lipopolysaccharide endotoxin (LPS) or live bacteria (Escherichia coli or Staphylococcus aureus), incubation with PLA2G1B significantly improved cell viability, suggesting involvement of sPLA2s in protecting membranes from lipid-peroxidation damage, rather than a bactericidal action. When PLA2G1B was applied simultaneously with LPS, a significant short-term reduction in interleukin-8 secretion was observed compared with bMECs treated only with LPS, supporting previous reports that PLA2G1B affects interleukin-8 signaling in similar cells. Following the favorable outcome of the in vitro experiments, we tested PLA2G1B in vivo by mammary infusion into infected glands. In one of a small sample (n = 4) of lactating cows chronically infected with Streptococcus dysgalactiae, a single PLA2G1B treatment completely cleared inflammation and bacteria, demonstrating its potential to cure subclinical mastitis. PLA2G1B treatment did not affect coagulase-negative staphylococci infection. These types of mastitis may involve formation of a resistant biofilm, and its elimination may relate to sPLA2s' characteristic ability to aggregate with cellular debris, facilitating their internalization by macrophages. In a bovine model of clinical mastitis based on introduction of E. coli via the streak canal, a single mammary infusion of PLA2G1B led to faster recovery to pre-infection milk-yield levels and decrease of somatic cell counts. In this case, all of sPLA2s' modes of resolving inflammation may apply, including competitive binding of the sPLA2s’ receptor, the inactivation of which confers resistance to endotoxic shock. Hence, this study strongly supports further research into PLA2G1B as a cure for bovine mastitis.

A hypothesis that the source of milk-serum derived vesicles (MSDVs) is the Golgi apparatus (GA) was examined. Using dynamic light scattering and electron microscopy, it was shown that MSDVs are composed of globular structures with hydrodynamic sizes of 70 ± 15 nm. More than 60% of the total protein content of MSDVs was associated with the MSDV lumen and 30% was associated with the MSDV membrane. Casein was the major protein found in the MSDV lumen. The conclusive markers of the GA, lactose synthase components (α-lactalbumin and galactosyltransferase) and activity (synthesis of lactose from glucose and UTP-galactose), the presence of casein in micellar form in the MSDV lumen, and a high luminal content of citric acid, were demonstrated in the lumen of MSDVs. Though MSDVs composed only 0.7% of the milk mass, they accounted for a high proportion of the total milk content of reactive (15% Cu and 18% Fe) and toxic minerals (60% Cd and 65% Pb), which strongly suggests that MSDVs serve as an avenue to protect mammary epithelial cells from the toxic effects of these minerals by storing them intraluminally and secreting them into milk. The presence of micellar casein in the MSDV lumen, along with the presence of metal transporters in their membranes, is responsible for this impressive capacity for storing reactive and toxic minerals. Exposing a single mammary gland to lipopolysaccharide challenge induced changes in regulatory proteins stored in the lumen of MSDVs (tissue plasminogen activators, plasminogen and plasmin) and in the activity of xanthine oxidase and alkaline phosphatase attached to the outer membrane of MSDVs. Thus, we have demonstrated that MSDVs are under the regulation of the nucleus and respond to extracellular signals.

This study establishes an experimental model for subclinical mastitis induced by Gram-positive (Gþ) exosecretions of Staphylococcus aureus origin or Gram-negative (G ) endo-toxin of Escherichia coli origin to examine its effects on follicular growth and steroidconcentrations in Holstein dairy cows. Cows were synchronized with the Ovsynch protocolfollowed by a series of follicular cycles that included GnRH and PGF 2 a doses administeredevery 8 days. Cows received small intramammary doses of either Gþ (10 m g, n ¼ 10) or G (0.5 m g, n ¼ 6) toxin, or saline (n ¼ 6; uninfected control) every 48 hours for 20 days.Follicular fluids were aspirated from preovulatory follicles before (aspiration one: control),at the end of (aspiration two: immediate effect), and 16 days after the end of (aspirationthree: carryover effect) toxin exposure. During the 3 weeks of subclinical mastitis inducedby Gþ or G , no local inflammatory signs were detected in the mammary gland and nosystemic symptoms were noted: body temperatures of the treated cows did not differ fromcontrols; plasma cortisol and haptoglobin concentrations were not elevated and did notdiffer among groups. Somatic cell count was higher in the treated groups than in controls,and higher in the G versus Gþ group. For analysis of reproductive responses, cows werefurther classified as nonaffected or affected based on an more than 20% decline in follicularandrostenedione concentration in aspiration two or three relative to the first, controlaspiration. Most G (5/6) and 40% of Gþ (4/10) cows were defined as affected by inducedmastitis. An immediate decrease in the number of medium-size follicles was recorded onDay 4 of the induced cycle, toward the end of the 20-day mastitis induction, in the affectedGþ compared with uninfected control group (1.0 0.5 vs. 3.0 0.4 follicles; P < 0.05); theaffected G and nonaffected Gþ subgroups exhibited a similar numerical decline in thenumber of follicles. A carryover (but not immediate) decrease to 51% and 62% in follicularestradiol concentrations in G affected group and Gþ affected group was detected relativeto controls (P < 0.05). The nonaffected Gþ subgroup did not differ from its controlcounterparts. Based on the current experimental model, subclinical IMI induced by Gþ orG toxin disrupts follicular functions, and it seems that the ovarian pool of early antralfollicles is susceptible to subclinical mastitis. 2014 Elsevier Inc. All rights reserved.

Bulk milk is the mixture of all the milked udders in a given herd. Nowadays, about 15–40% of the udders in most herds are intramammary infected by different bacteria species, mainly coagulase negative staphylococci. The presences of bacteria in the lumen of the mammary gland induce impairment of milk quality and increase the number of somatic cells. A positive relationship between % casein (casein/total protein) and curd firmness (CF) and negative relationship between lactose, or somatic cell count (SCC) and CF are associated with bacterial infection and with late lactation milk, and therefore with reduction in cheese yield and quality. On the other hand, in milk of goats with intramammary infection, the correlation between the levels of fat, protein, casein and curd yield is minor compared to milk of uninfected animals. Thus, gross milk composition is an insufficient predictor of milk quality for cheese production, since a high percent of the bulk milk originates from subclinically infected glands. Research carried out in the past few years highlighted the effectiveness of lactose as a predictor of milk quality. The correlation between lactose and CF was higher than that for % casein and SCC. Lactose concentration of ≤4% is associated with non-coagulating milk and therefore, such milk is unsuitable for making cheese, but still meets the criterion for consumption as pasteurized milk. A model that describes the simultaneous and close association between reduction in lactose concentration and milk yield on the one hand and reductions in lactose concentration and milk quality on the other hand is presented. The physiological and biochemical basis for deterioration of milk quality in subclinically infected and in late lactation animals is reviewed and suggestions to improve the quality of milk produced by farmers and acquired by dairies are presented.

Use of DNA-based methods, such as real-time PCR, has increased the sensitivity and shortened the time for bacterial identification, compared with traditional bacteriology; however, results should be interpreted carefully because a positive PCR result does not necessarily mean that an infection exists. One hundred eight lactating dairy ewes (56 Manchega and 52 Lacaune) and 24 Murciano-Granadina dairy goats were used for identifying the main bacteria causing intramammary infections (IMI) using traditional bacterial culturing and real-time PCR and their effects on milk performance. Udder-half milk samples were taken for bacterial culturing and somatic cell count (SCC) 3 times throughout lactation. Intramammary infections were assessed based on bacteria isolated in ≥2 samplings accompanied by increased SCC. Prevalence of subclinical IMI was 42.9% in Manchega and 50.0% in Lacaune ewes and 41.7% in goats, with the estimated milk yield loss being 13.1, 17.9, and 18.0%, respectively. According to bacteriology results, 87% of the identified single bacteria species (with more than 3 colonies/plate) or culture-negative growth were identical throughout samplings, which agreed 98.9% with the PCR results. Nevertheless, the study emphasized that 1 sampling may not be sufficient to determine IMI and, therefore, other inflammatory responses such as increased SCC should be monitored to identify true infections. Moreover, when PCR methodology is used, aseptic and precise milk sampling procedures are key for avoiding false-positive amplifications. In conclusion, both PCR and bacterial culture methods proved to have similar accuracy for identifying infective bacteria in sheep and goats. The final choice will depend on their response time and cost analysis, according to the requirements and farm management strategy.

The assumption, that metabolites derived from the activity of the mammary gland epithelial cells reflect changes in milk secretion and its coagulation properties, was tested in dairy cows. The experiment included cows with uninfected udders and cows with one of the glands infected by different bacteria specie. Analysis were carried at the cow level (including all four glands), or at the gland level. High and significant correlations among the concentrations of lactose, glucose, glucose-6-posphate, milk related respiratory index (the ratio between the concentrations of citrate/lactate+malate in milk) and milk-derived glycolytic index (the ratio between glucose-6-phosphate and glucose in milk) and milk clotting parameters were found. The physiological basis for these relations and their ability to predict the deterioration in milk quality in subclinically infected glands and in glands previously clinically infected with Escherichia coli are discussed.

Escherichia coli is one of the most frequently diagnosed causes of bovine mastitis, and is typically associated with acute, clinical mastitis. The objective of the present study was to evaluate the long term effects of intramammary infections by E. coli on milk yield and quality, especially milk coagulation. Twenty-four Israeli Holstein cows diagnosed with clinical mastitis due to intramammary infection by E. coli were used in this study. Mean lactation number, days in milk (DIM) and daily milk yield (DMY) at the time of infection was 3.3 ± 1.3, 131.7 days ± 78.6 and 45.7 L ± 8.4, respectively. DMY, milk constituents, somatic cells count (SCC), differential leukocytes count and coagulation parameters were subsequently assessed. Two patterns of inflammation were identified: 'short inflammation', characterized by15% decrease in DMY and30 days until return to normal (n = 5), and 'long inflammation', characterized by15% decrease in DMY and30 days to reach a new maximum DMY (n = 19). The estimated mean loss of marketable milk during the study was 200 L/cow for 'short inflammation' cases, and 1,500 L/cow for 'long inflammation' ones. Significant differences between 'short' and 'long inflammation' effects were found in almost all parameters studied. Long-term detrimental effects on milk quality were found regardless of clinical or bacteriological cure of affected glands.

The aim of this study was to verify the existence of a nitric oxide (NO) cycle in goat milk and to study how changes in it affect milk composition during subclinical mastitis. Fifteen lactating dairy goats in which one udder-half was free from bacterial infection and the contra-lateral one was naturally infected with various species of coagulase-negative staphylococci were used. In comparison to uninfected glands, subclinical mastitis was associated with a decrease in milk yield, lactose concentration, and curd yield and an increase in nitrite and nitrate concentrations and with measurements reflecting increased formation of NO-derived free-radical nitrogen dioxide. The occurrence of NO cycling in goat milk was largely confirmed. The increase in the NO-derived stress during subclinical infection was not associated with significant increase in oxidatively modified substances, 3-nitrotyrosine, and carbonyls on proteins, but with increased levels of peroxides on fat. However, the relatively modest nitrosative stress in subclinically infected glands was associated with significant reduction in total antioxidant capacity and vitamin C levels in milk. We concluded that subclinical mastitis in goats caused by coagulase-negative staphylococci imposes negative changes in milk yield, milk quality for cheese production, and negatively affects the nutritional value of milk as food. Thus, subclinical mastitis in goats should be considered as a serious economic burden both by farmers and by the dairy industry.

The current study measured the influence of milk of subclinically infected glands by different bacteria species on the cow's milk. The effects of bacterial infection or inflammation on gland milk yield were related to the bacteria species that caused the infection. The volume of milk of the inflamed gland from the cow's milk yield was significantly lower (P

This review focuses on recent evidence showing that various types of udder inflammation (mastitis) are associated with increased concentration of NO˙-derived metabolites, nitrite and nitrate, and oxidatively modified organic components under commercial farming and experimental conditions. In milk, NO˙ constantly cycles through: (i) auto oxidation to nitrite; (ii) hydrogen peroxide-dependent conversion of nitrite into NO2˙ by lactoperoxidase; (iii) interaction of NO2˙ with thiyl (RS˙) radicals on proteins formed by NO˙ to generate S-nitrosothiols; and (iv) disintegration of NO˙ from S-nitrosothiols, which completes the cycle. The main mechanism which restrains this cycle is conversion of nitrite to nitrate by catalase in a hydrogen peroxide dependent manner. The main source of hydrogen peroxide in milk derives from the oxidation of secreted hypoxanthine and xanthine by xanthine oxidoreductase. Formation of NO2˙ has an important role in the glandular innate defense system because it has bactericidal effects towards major pathogens that infect the mammary gland. However, increased formation of NO2˙ that occurs during mastitis and extended storage of milk for more than three days, even when kept in cold, dark conditions, induce nitrosative stress on milk organic components. Nitrosative stress in milk is reflected by a marked increase in the concentration of 3-nitrotyrosine, carbonyl and lipid peroxides. Thus, it is possible that current criteria for dairy plants acceptance of milk overlook important information on milk safety for consumption by humans. The literature regarding the presence of nitrite and nitrate in milk under experimental, farm and marketed milk is reviewed and the potential implications discussed. Relevant conclusions to improve safety of milk for human consumption are derived, and the particular importance in applying such recommendations for milk designated for the manufacturing of infant formulas is outlined.

The recent burst of duplication and divergence of the bovine PLA2G2D genes is considered typical of immune response genes, and it was recently shown that PLA2G2D is abundantly expressed in mouse leukocytes and acts as an immunosuppressive phospholipase. Analysis of 1,143 Holstein bulls indicated that the four common haplotypes spanning PLA2G2D display copy number variation ranging from 1 to 4 per haploid genome. Association of the fourth haplotype with negative total merit remained significant (P

Previously it was shown that a low molecular mass fraction isolated from the proteoseepeptone preparation of milk, fraction E, inhibited milk coagulation. Here, the composition and molecular mass of fraction E, and its effect on milk clotting parameters, was investigated to better understand its mechanism of action. Fraction E comprised casein-derived peptides of 1e3 kDa rich in phosphorus residues. Fraction E content increased substantially in milk from glands infected with Escherichia coli and Streptococcus dysgalactiae, and during storage of the milk. However, the specific activity of fraction E on milk clotting parameters was the same whether sampled from healthy, infected or stored milk. The inhibitory effect was reversible on adding 0.75 mM CaCl2, suggesting that chelation of Ca by fraction E was involved in the inhibitory mechanism. However, only partial recovery was achieved and an excess of Ca was required, suggesting the involvement of additional pathways in the process.

Escherichia coli is a major agent of bovine mastitis worldwide. However, specific E. coli virulence factors associated to pathogenicity during intra-mammary infections are yet unknown and this pathotype remains uncharacterized. The objectives of the present work were to assess the presence of a wide range of known virulence factors in a large set of E. coli strains isolated from bovine mastitis (mastitis set) and to study the genotypic distribution of strains in the mastitis set in comparison to a set of strains isolated from cows’ environment in dairy farms (environmental set). Virulence factors were assessed by DNA hybridization microarray. The three most prevalent virulence factors found in the mastitis set were lpfA (long polar fimbriae), iss (increased serum resistance) and astA (enteroaggregative E. coli heat-stable enterotoxin 1). None, however, characterized the majority of these strains. Genotyping was assessed by ECOR phylogenetic grouping, multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Strains in the mastitis and environmental sets were differentially distributed into ECOR phylogenetic groups; groups A and B1 being the most prevalent ones. Multiple MLST strain types were found in the two sets of strains, but only a few were common to both, and diversity was higher in the environmental set. A variety of PFGE patterns were found in the mastitis and environmental sets. Two clusters comprising mostly highly similar mastitis strains were identified. The results confirm that mastitis E. coli strains mostly lack known E. coli virulence factors. In addition, it is shown that the genotypic diversity of mastitis strains does not reflect the diversity found in the environmental E. coli population.

Passive vaccination is used to treat a wide range of infections and cancer. However, this approach has some limitations. An immune complex termed Y-complex was developed to intensify the effect of the passive vaccine. The complex is composed of a microbead that carries specific antibodies and an inducer. It enables targeting of pathogen or abnormal cells, and stimulation of a desired response by innate immune cells, depending on the inducer. The production and efficacy of Y-complex as a passive immune prophylaxis is demonstrated in this study by its use in treating cow mastitis. In an in vitro assay, Y-complex inhibited propagation and induced phagocytosis of bacteria. In challenge experiments, cows were inoculated through the udder with Escherichia coli or Streptococcus dysgalactiae. Following treatment with Y-complex, no bacteria were isolated in the milk and N-acetyl-ß-D-glucosaminidase activity had returned to normal levels. Thus the Y-complex approach can be used as an effective treatment for mastitis. Due to its modularity, this approach may serve as a treatment for a variety of disease agents.

Real-time analysis of milk coagulation properties as performed by the AfiLab™ milk spectrometer introduces new opportunities for the dairy industry. The study evaluated the performance of the AfiLab™ in a milking parlor of a commercial farm to provide real-time analysis of milk-clotting parameters –Afi-CF for cheese manufacture and determine its repeatability in time for individual cows. The AfiLab™ in a parlor, equipped with two parallel milk lines, enables to divert the milk on-line into two bulk milk tanks (A and B). Three commercial dairy herds of 220 to 320 Israeli Holstein cows producing ∼11 500 l during 305 days were selected for the study. The Afi-CF repeatability during time was found significant (P < 0.001) for cows. The statistic model succeeded in explaining 83.5% of the variance between Afi-CF and cows, and no significant variance was found between the mean weekly repeated recordings. Days in milk and log somatic cell count (SCC) had no significant effect. Fat, protein and lactose significantly affected Afi-CF and the empirical van Slyke equation. Real-time simulations were performed for different cutoff levels of coagulation properties where the milk of high Afi-CF cutoff value was channeled to tank A and the lower into tank B. The simulations showed that milk coagulation properties of an individual cow are not uniform, as most cows contributed milk to both tanks. Proportions of the individual cow's milk in each tank depended on the selected Afi-CF cutoff. The assessment of the major causative factors of a cow producing low-quality milk for cheese production was evaluated for the group that produced the low 10% quality milk. The largest number of cows in those groups at the three farms was found to be cows with post-intramammary infection with Escherichia coli and subclinical infections with streptococci or coagulase-negative staphylococci (∼30%), although the SCC of these cows was not significantly different. Early time in lactation together with high milk yield >50 l/day, and late in lactation together with low milk yield

The economical profitability of the dairy industry is based on the quality of the bulk milk collected in the farms, therefore it was based on the herd level rather than on the individual animals at real time. Udder infection and stage of lactation are directly related to the quality of milk produced on the herd level. However, improvement of milk quality requires testing each animal’s milk separately and continuously. Recently, it was postulated that online equipment can estimate milk quality according to its clotting parameters, and thus result in better economical return for cheese making. This study further investigated the potential application of the AfiLab TM equipment to provide real-time analysis of milk-clotting parameters for cheese manufacture and cheese yield on quarter (1018) and individual cow (277) levels. Days in milk, lactose, log SCC and udder infection were found to have a significant effect on curd firmness and cheese properties and yield. The results clearly indicate that: (a) the parameter Afi-CF determined with the AfiLab TM is suitable for assessing milk quality for its clotting parameters, a value which is not provided by merely measuring fat and protein content on the gland and the cow levels; (b) bacterial type is the single major cause of reduced milk quality, with variations depending on the bacterial species; and (c) early and late lactation also had negative effects on milk-clotting parameters. Cheese made from the various milk samples that were determined by the Afilab TM to be of higher quality for cheese making resulted in higher yield and better texture, which were related mainly to the bacterial species and stage of lactation.

This study compared immediate and carryover effects of mastitis induced by Gram-negative endotoxin (E. coli LPS) and Gram-positive exosecretions (Staph. aureus ex.) on preovulatory follicle function. Synchronized, uninfected cyclic lactating Holstein cows were treated with PGF(2α) on day 6 of the cycle and 36 h later, a dose of either E. coli LPS (n = 8), S. aureus ex. (n = 10), or saline (n = 9) was administered into the mammary gland. Follicular fluids and granulosa cells were aspirated 6 h later from the preovulatory follicles and cows were treated with GnRH. This (cycle 1; immediate effect) was repeated three times (excluding the mammary injections) to induce three 7 d cycles (cycles 2, 3, and 4; carryover effect). E. coli LPS increased body temperature, plasma cortisol concentration, and somatic cell count (SCC), whereas S. aureus ex. induced a minor, subclinical elevation of SCC and slight rise (NS) in body temperature and cortisol concentration. Follicular estradiol, androstenedione, and progesterone concentrations in the E. coli LPS group decreased (P0.05) in cycle 1 to about 40%, 13%, and 35%, respectively, of control levels, whereas in the S. aureus ex. group, only estradiol decreased (P0.05), to 56% of control concentrations. In cycles 3 and 4, follicular steroids in the E. coli LPS group returned to control concentrations, whereas in the S. aureus ex. group, follicular concentrations of estradiol and androstenedione were lower (P0.10) than in controls. In the control group, the concentrations of all follicular and circulating steroids remained stable (P0.05) throughout the study. Follicle size was similar in all groups, but the S. aureus ex. treatment caused a decrease (P0.02) in the number of follicles developed in cycles 3 and 4. The mRNA expression of steroidogenic genes and LHCGR in the granulosa cells was not affected (P0.05) by either treatment during the study, except for a tendency toward lower (P0.1) expression in cycle 1 and lower (P0.05) expression in cycle 4 of the latter in the S. aureus ex. group. Strain levels, such as SCC and body temperature, following toxin injection correlated well with the magnitude of the immediate decline in follicular steroids. As is typical for Gram-negative clinical events, E. coli LPS-induced acute mastitis caused immediate, short-term, but not long-term impairment of follicular responses, whereas the Gram-positive S. aureus ex.-induced subclinical mastitis exhibited both immediate and carryover disruptive effects on preovulatory follicle function.

Effects of glandular bacterial infection and stage of lactation on milk quality were compared among cows, goats and sheep. These parameters affected milk quality in all three species: sheep were most affected by bacterial infection and goats by stage (particularly end) of lactation. The study highlighted the effectiveness of lactose level as a predictor of milk quality; in all three species, the correlation between lactose level and curd firmness (CF) was higher than those between casein as a percentage of total protein and CF, or between somatic cell count and CF. In all three species, lactose concentrations ≤4% were associated with non-clotting milk. A model that describes the simultaneous and close association between reductions in lactose concentration and milk yield, on the one hand, and reductions in lactose concentration and milk quality on the other hand, is presented.

The objective of the present study of the goat mammary-gland defense system was to characterize and compare the immune responses – locally in the mammary gland and systemically in the blood – to intramammary infection with various staphylococci. In all cases the SCC and total leukocyte counts were significantly higher in the infected than in uninfected glands, the highest being in milk from glands infected with Staphylococcus aureus . Leukocyte distributions in the milk showed significant differences among groups, only in the percentage of PMN, with no differences in percentages of T (CD4 + and CD8 + ) lymphocytes and macrophages. The numbers of B cells bearing CD21 were negligible in all milk samples. In blood, no differences were found in numbers and distributions of erythrocytes and white blood cells. All infected goats were seropositive to homologous bacteria, with high mutual cross-reactivity whereas uninfected goats were seronegative. In vitro bacterial phagocytosis of cells from blood of uninfected goats found differing dynamics among the various staphylococci, and addition of bacterial exosecretions had no effect. In contrast, when the same assays were conducted with blood cells from infected goats, phagocytosis was faster in homologues than in heterologues and exhibited different dynamics. Bacterial exosecretions, both homologous and heterologous, decreased the rate and percentage of active PMN in contrast to cells from uninfected goats. The present results suggest that the host immunity to the various staphylococci is similar, and that it involves systemic immunity, but does not eradicate the bacteria. This suggests that during evolution, similar IMI-causing bacteria attained a balance with the host, through which the host maintained its overall performance while allowing the bacteria to survive.

Goat milk production is a dynamic and growing industry that is fundamental to the wellbe- ing of hundreds of millions of people worldwide and is an important part of the economy in many countries. The aim of the present review is to provide an integrated and critical analysis of the major aspects in this field to highlight unexploited nutritional potential of goat milk and the need for improvements, particularly in food safety. First, it should be kept in mind that goat milk like cow milk delivers many nutrients with relatively low energy content, and is relevant to the health of consumers throughout the life cycle. In addition, the review presents data suggesting that goat milk possesses many advantages over cow milk, for use as a nutritional source for infants and children and as a medicinal food. Fur- thermore, goats, by consuming large amounts of natural browsing plants all year around, are a potentially overlooked "treasure trove", with respect to health promoting compo- nents. The survey suggests that total bacterial count that is currently used as the major quality measure to prevent pathogen-related food toxicity is not sufficiently effective. The proposal is to include somatic cell count as a routine criterion to qualify the hygienic status of goat milk in terms of the relevant physiology and biochemistry. The paper presents a novel mechanism controlling milk secretion, and demonstrates the use of this knowledge in making decisions for two major managerial tasks that farmers face, namely milking fre- quency that dictates to a large extent the milk yield and workload on the farm, and helping to deal with subclinical mastitis that is the single major cause for economical losses in dairy farms worldwide. © 2010 Published by Elsevier B.V.

The effects of naturally occurring subclinical chronic or clinical short-term mastitis on time of ovulation, plasma steroid and gonadotropin concentrations, and follicular and luteal dynamics were examined in 73 lactating Holstein cows. Cows were sorted by milk somatic cell count and bacteriological examination into an uninfected group (n=22), a clinical mastitis group (n=9; events occurring 20+/-7 d before the study), and a subclinical chronic mastitis group (n=42). In addition, uninfected and mastitic cows were further sorted by their estrus to ovulation (E-O) interval. About 30% of mastitic cows (mainly subclinical) manifested an extended E-O interval of 56+/-9.2h compared with 28+/-0.8h in uninfected cows and 29+/-0.5h in the other 70% of mastitic cows. In mastitic cows with extended E-O interval, the concentration of plasma estradiol at onset of estrus was lower than that of uninfected cows or mastitic cows that exhibited normal E-O intervals (3.1+/-0.4, 5.8+/-0.5, and 5.5+/-0.5 pg/mL, respectively). The disruptive effect of mastitis on follicular estradiol probably does not involve alterations in gonadotropin secretion because any depressive effects of mastitis on pulsatile LH concentrations were not detected. Cortisol concentrations did not differ among groups. The preovulatory LH surge in mastitic cows with delayed ovulation varied among individuals, being lower, delayed, or with no surge noted compared with the normal LH surge exhibited by uninfected cows or mastitic cows with normal E-O interval (6.8+/-0.7 ng/mL). The diameter of the second-wave dominant follicle was larger and the number of medium follicles was smaller in uninfected and subclinical cows with normal intervals compared with subclinical cows with extended intervals (13.4+/-0.5 vs. 10.9+/-0.9mm, and 3.8+/-0.2 vs. 6.7+/-0.14 follicles, respectively). Mid-luteal progesterone concentrations were similar in uninfected and mastitic cows. These results indicate for the first time that around 30% of cows with subclinical chronic mastitis exhibit delayed ovulation that is associated with low plasma concentrations of estradiol and a low or delayed preovulatory LH surge.

The enzyme catalase is well-known to catalyze the disintegration of hydrogen peroxide to water and oxygen; however, this study shows that its main function in bovine milk is oxidation of nitrite to nitrate. This process depends on hydrogen peroxide, of which the main source appears to be hydrogen peroxide formation that is coupled to the conversion of purines--xanthine in the present study--to uric acid by milk xanthine oxidase. However, additional secondary sources of hydrogen peroxide appear to be important during the relatively long storage of milk in the gland cistern. This paper demonstrates that the oxidation of nitrite to nitrate is necessary to prevent accumulation of free radicals and oxidative products during storage of milk in the gland and during the unavoidable delay between milking and pasteurization in dairy plants. Recommendations for minimizing the deterioration in milk quality during commercial storage are presented.

Staphylococcus haemolyticusis a pathogen frequently isolated from dairy cows and small ruminants. However, it always appears in only a few animals and not as a major pathogen. Recently, in a dairy goat herd of approximately 250 milking animals, 25·6% (46/180 goats) had milk cultures with atypical highly mucoid colonies accompanied by elevated somatic cell counts. The isolates were identified asStaph. haemolyticus. The present study describes the steps used in an attempt to identify the bacterium and to compare it with other coagulase-negative staphylococci (CNS) includingStaph. haemolyticus. Species identification performed with the API STAPH-IDENT 32 kit showed >99·4% identity confirmed by 16S rDNA sequencing tests. Microscopically the atypicalStaph. haemolyticusstrains showed unique cuboidal tetrad clusters reminiscent of those of the genusSarcina. The outbreak caused by an atypical CNS underlines the need for accurate biochemical and genetic methods for ultimate identification of CNS to the species level.

The effect of intramammary (IMM) or intravenous (IV) administration of E. coli endotoxin (LPS), at the onset of estrus, at the time of ovulation was examined. Steroid and gonadotropin concentrations around ovulation were also determined. Lactating Holstein cows (n=33) were assigned to saline-controls (n=12) and treated with LPS-IV (0.5 microg/kg; n=13) or LPS-IMM (10 microg; n=8). Synchronized cows were observed continuously for estrus. LPS (or saline) was injected within 30 min from the onset of standing estrus, at peak estradiol concentrations. The typical rise of body temperature, somatic cell count, cortisol, and NAGase activity was noted. One-third of both LPS-IV- and LPS-IMM-treated cows were manifested by an extended estrus to ovulation (E-O) interval of around 75 h or did not ovulate, compared with about 30 h in the other 2/3 of LPS cows and all controls. Estradiol concentrations 24 h before and after LPS did not differ between groups. However, LPS-IV cows with extended intervals exhibited another estrus and an additional rise of estradiol followed by delayed ovulation. LPS-treated cows with a delayed E-O interval had low or delayed LH surge; two LPS-treated cows did not exhibit LH surge and did not ovulate. All control cows exhibited normal hormone levels. Delayed ovulation was associated with a delayed rise of luteal progesterone. The results indicated that exposing cows to endotoxin during estrus induced a decreased and delayed LH surge in one-third of the cows. This was associated with delayed ovulation, which reduces the chances of successful fertilization.

Subclinical mastitis, caused by different bacteria with similar milk composition and somatic cell count, impairs milk quality and its products differently through increased release of deteriorative enzymes into the milk. Milk from glands infected with Streptococcus dysgalactiae was almost identical in gross composition to milk from uninfected glands. However, yogurt and cheese made from commingled milk from the infected quarters exhibited inferior texture compared to yogurt and cheese made from uninfected ones. Proteose peptone was size-fractionated by gel filtration and the various fractions of milk from the infected glands were added to uninfected milk. This study demonstrated for the first time that addition of certain fractions to milk from uninfected glands resulted in altered milk coagulation properties. It is hypothesized that the infecting bacteria influence the immune system of the udder, which then impairs the qualities of the milk from infected quarters that is conventionally used for manufacturing dairy products.

Refrigerated storage of good-quality milk from a single cow resulted in moderate deterioration of its quality, low level of bacterial growth (standard plate and psychrotroph counts), and low small losses of curd yield. When milk was collected from farm bulk milk tanks and from dairy silos, its quality deteriorated faster than that of single-cow milk, resulting in high bacteria counts and high loss of curd yield, most of which was already apparent for the farm bulk milk tank. Statistical analyses did not reveal any significant interaction between bacterial growth, milk composition, somatic cell count, and curd yield loss, indicating that other mechanisms such as enzymatic activity might be responsible. From the comparison between the high-quality milk from an uninfected cow's udder and the commingled milk on the farm and in the dairy silos, it appears that introduction of milk coming from infected udders might cause curd yield loss such as that noted in the present study.

Equations for predicting milk and curd loss due to intramammary infection in sheep and goat herds were derived. The empirical equations were derived from previously published studies conducted by this team with Assaf sheep and crossbreeds of goats in Israel. From these equations, it appears that infection of 25, 50 and 75% of the udders in a given herd was associated with loss of 4.1–12.2.5% milk in sheep and 0.8–2.3% in goats; whereas curd loss was 5.2–15.5% in sheep and 3.3–9.8.9% in goats. Based on percent of udder infection and projected SCC, the following categories are suggested for classification of sheep and goat milk: i. High-quality milk 1,500,000 SCC/mL, associated with infection rate above 50%; iv. Milk containing >3,500,000 SCC/mL should not be accepted for human consumption.