Evaluation of allergenicity of cow milk treated with enzymatic hydrolysis through a mouse model of allergy

Cow milk (CM) allergy is a worldwide concern. Currently, few studies have been performed on the immunoreactivity of CM and fewer still on the antigenicity of CM in vivo and in vitro. In this study, we assessed the potential allergenicity of enzymatically hydrolyzed CM using in vitro ELISA and oral sensitization and challenge of BALB/c mice. Alcalase-, Protamex-, and Flavourzyme-treated CM (all from Novozymes) diminished IgE binding capacity, with greatest reductions of 56.31%, 50.62%, and 56.45%, respectively. Allergic symptoms and levels of total IgG₁ were reduced, and allergic inflammation of the lung, jejunum, and spleen was relieved. Moreover, the numbers of CD8⁺ T and B220⁺ cells decreased, and the balance of CD4⁺ T/CD8⁺ T cells was effectively regulated. These findings suggest that the potential allergenicity of CM was reduced by enzymatic hydrolysis, and our research will lay a solid foundation for developing high-quality hypoallergenic CM products.     

Yogurt starter cultures of Streptococcus thermophilus and Lactobacillus bulgaricus ameliorate symptoms and modulate the immune response in a mouse model of dextran sulfate sodium-induced colitis

We investigated the yogurt starter cultures of Lactobacillus bulgaricus 151 and Streptococcus thermophilus MK-10 for their effect on the severity of experimental colitis, lymphocyte profile, and regulatory T-cell response. Colitis was induced in BALB/c mice via the administration of 3.5% dextran sulfate sodium salt (DSS) in drinking water for 6 d. Next, the mice were gavaged intragastrically with an active yogurt cultures (YC) mixture (～5 × 10⁹ cfu/mouse per day) or saline (vehicle) for 8 d. Mice receiving DSS or saline alone served as positive and negative controls, respectively. The length of the colon, disease activity index, histological scores, myeloperoxidase activity, epithelium-associated microbes, short-chain fatty acid profile, total IgA antibody-forming cells, CD3⁺CD8⁺, CD3⁺CD4⁺, CD3⁺CD4⁺CD25⁺, CD3⁺CD4⁺CD25⁺Foxp3⁺ T-cell subsets, and cytokine profiles (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-γ, and tumor necrosis factor) were examined after termination of the mice. Feeding mice with YC mixture reduced disease symptoms and modified intestinal microbiota and host inflammatory responsiveness to DSS. We observed limited weight loss and a decreased disease activity index score, lowered myeloperoxidase activity, and somewhat reduced damage of the intestine. The YC mixture upregulated the colon length, increased the amount and diversity of mucosa-associated microbes (enterobacteria, enterococci, and yeast), and decreased the concentration of putrefactive short-chain fatty acids in the cecal contents. It downregulated the input of cytotoxic CD3⁺CD8⁺ T cells and CD3⁺CD4⁺CD25⁺FoxP3⁺ regulatory T cells in Peyer's patches and enhanced CD3⁺CD4⁺CD25⁺ T cells in spleens and CD3⁺CD4⁺CD25⁺FoxP3⁺ cells in peripheral blood mononuclear cells. Simultaneously, IgA antibody-forming cells were downregulated in mesenteric lymph nodes (MLN) and enhanced in spleens (SPL). The cultures mostly enhanced the production of cytokines tested in MLN and SPL, except for IL-6, which was downregulated in MLN. Interleukin-2 and IL-4 were the most upregulated in MLN, whereas IL-10, IL-4, IL-2, IFN-γ, and tumor necrosis factor were most upregulated in SPL. In serum, the YC mixture downregulated IFN-γ and clearly increased IL-2. Based on these results, we recognize the high anti-inflammatory and immunomodulatory potential of the L. bulgaricus 151 and S. thermophilus MK-10 set. The strains possess the ability to modulate the intestinal mucosal and systemic immune system toward both IgA production and induction of regulatory T cells, shifting Th1/Th2 balance.     

Milk basic protein supplementation exerts an anti-inflammatory effect in a food-allergic enteropathy model mouse

To examine novel functions of milk basic protein (MBP) in T-cell-related inflammatory diseases, such as autoimmune diseases and allergies, we evaluated the effects of MBP on the causative responses of ovalbumin (OVA)-specific T cells in a food-allergic enteropathy model, OVA23–3 mice, which express an OVA-specific T-cell receptor gene. The OVA-specific CD4⁺ T cells of the mesenteric lymph nodes (MLN) from OVA23–3 mice were cultured with CD11c⁺ dendritic cells of MLN from BALB/cA mice in the absence or presence of MBP following stimulation with OVA; then the levels of CD69 expression and the levels of cytokine production by CD4⁺ T cells were measured to evaluate activation. The effects of MBP supplementation of OVA 23–3 mice were assessed by feeding a diet containing OVA (OVA diet) with or without MBP for 28 d. Intestinal inflammation, together with activation and cytokine production of CD4⁺ T cells by MLN, as well as femoral bone mineral density, were measured. In in vitro culture, MBP inhibited excess activation and IL-4 production by CD4⁺ T cells. The supplementation of MBP to the OVA diet attenuated OVA-specific IgE production in OVA-diet-fed OVA23–3 mice and slightly resolved developing enteropathy caused by excess IL-4 production by CD4⁺ T cells. Feeding OVA diet to OVA23–3 mice exhibited bone loss accompanied with enteropathy, whereas MBP supplementation prevented bone loss and increased osteoprotegerin, an osteoclastogenesis inhibitory factor, in the mice. The inhibition of T-cell-activation in both MLN and bone marrow by MBP supplementation may help prevent increased IgE levels caused by excessive IL-4 production and bone loss accompanied by enteropathy. Our findings show that MBP may help attenuate both T-cell-related inflammation and bone loss.     

Strain-specific pathogenicity of putative host-adapted and nonadapted strains of Streptococcus uberis in dairy cattle

Streptococcus uberis is an important cause of intramammary infection in dairy cattle. Strains of Strep. uberis appear to differ in their ability to cause disease based on previous epidemiological studies. We explored the pathogenicity of 2 strains of Strep. uberis, where one strain represented a putatively host-adapted type based on its ability to cause persistent infection and to spread from cow to cow in a lactating herd. This type was part of a clonal complex that is commonly associated with bovine mastitis. The other strain, which was isolated from a transient infection in a single animal in the same herd and did not belong to any known clonal complex, was selected as putatively nonadapted type. Cows (6 per strain) were experimentally challenged in a single hind quarter and the adjacent hind quarter was used as mock challenged control quarter. Both strains showed an equal ability to grow in the milk of challenge animals in vitro. All cows that were challenged with the putatively host-adapted strain developed clinical signs of mastitis, including fever and milk yield depression as well as elevated somatic cell count due to influx of polymorphonuclear leucocytes and lymphocytes. The cytokine response followed a specific order, with an increase in IL-1β, IL-6, and IL-8 levels at the time of first SCC elevation, followed by an increase in IL-10, IL-12p40, and tumor necrosis factor-α levels approximately 6 h later. In 4 of 6 animals, IL-17A was detected in milk between 57 and 168 h postchallenge. The increase in IL-17A levels coincided with inversion of the prechallenge CD4⁺-to-CD8⁺ T lymphocyte ratio, which was observed from 96 h postchallenge. This was followed by normalization of the CD4⁺-to-CD8⁺ ratio due to continued increase of the CD8⁺ concentration up to 312 h postchallenge. Spontaneous resolution of infection was observed in 5 animals and coincided with a measurable IL-17A response in 4 animals, suggesting that IL-17 may be involved in the resolution of intramammary infection. With the exception of minor elevation of IL-8 levels, no clinical, cytological, or immunological response was detected in quarters challenged with the nonadapted strain. The observed strain-specific pathogenicity was consistent across animals, implying that it is determined by pathogen factors rather than host factors.     

Cow-specific treatment of clinical mastitis: an economic approach

Under Dutch circumstances, most clinical mastitis (CM) cases of cows on dairy farms are treated with a standard intramammary antimicrobial treatment. Several antimicrobial treatments are available for CM, differing in antimicrobial compound, route of application, duration, and cost. Because cow factors (e.g., parity, stage of lactation, and somatic cell count history) and the causal pathogen influence the probability of cure, cow-specific treatment of CM is often recommended. The objective of this study was to determine if cow-specific treatment of CM is economically beneficial. Using a stochastic Monte Carlo simulation model, 20,000 CM cases were simulated. These CM cases were caused by Streptococcus uberis and Streptococcus dysgalactiae (40%), Staphylococcus aureus (30%), or Escherichia coli (30%). For each simulated CM case, the consequences of using different antimicrobial treatment regimens (standard 3-d intramammary, extended 5-d intramammary, combination 3-d intramammary + systemic, combination 3-d intramammary + systemic + 1-d nonsteroidal antiinflammatory drugs, and combination extended 5-d intramammary + systemic) were simulated simultaneously. Finally, total costs of the 5 antimicrobial treatment regimens were compared. Some inputs for the model were based on literature information and assumptions made by the authors were used if no information was available. Bacteriological cure for each individual cow depended on the antimicrobial treatment regimen, the causal pathogen, and the cow factors parity, stage of lactation, somatic cell count history, CM history, and whether the cow was systemically ill. Total costs for each case depended on treatment costs for the initial CM case (including costs for antibiotics, milk withdrawal, and labor), treatment costs for follow-up CM cases, costs for milk production losses, and costs for culling. Average total costs for CM using the 5 treatments were (US) $224, $247, $253, $260, and $275, respectively. Average probabilities of bacteriological cure for the 5 treatments were 0.53, 0.65, 0.65, 0.68, and 0.75, respectively. For all different simulated CM cases, the standard 3-d intramammary antimicrobial treatment had the lowest total costs. The benefits of lower costs for milk production losses and culling for cases treated with the intensive treatments did not outweigh the higher treatment costs. The stochastic model was developed using information from the literature and assumptions made by the authors. Using these information sources resulted in a difference in effectiveness of different antimicrobial treatments for CM. Based on our assumptions, cow-specific treatment of CM was not economically beneficial.     

Dielectric spectroscopy-based characterisation of different types of Paneer (Indian cottage cheese) in terms of texture,microstructure and functional groups

Different variants of Paneer were prepared with cow milk (CM), buffalo milk (BM), skimmed milk powder (SMP) and blends (40:60, 50:50, 60:40) of SMP with CM/BM. The Paneer composition, texture, microstructure and spread of functional groups were correlated with the dielectric capacitance values. Results depicted a strong correlation (R² > 0.95) between milk used for Paneer making and its proximate composition in terms of the capacitance value, and it was highest for CM followed by BM; 100% SMP Paneer recorded lowest values. Paneer made from blends of SMP and liquid milk had the lowest transmittance value, indicating higher total protein content.     

Comparison of the immunogenicity of yak milk and cow milk

This is a comparison of potential allergenicity in a mouse model. Balb/C mice were sensitized by intraperitoneal injections (administered in three doses) of skimmed milk, casein, and whey protein from cow or yak milk. After 4 weeks, the mice were challenged and killed, sera were collected, and the spleens removed for analysis. An enzyme-linked immunosorbent assay was used to determine the specific antibodies (IgG and IgE) and cytokine. The number of mice with diarrhea was higher in the cow milk protein-sensitized group than in the yak milk protein-sensitized group. Serum (IgG, IgE) antibodies and histamine levels were also higher in cow milk protein-sensitized mice. Cytokine production by spleen-derived T cells showed high levels of interleukin-4 and interleukin-5 production and low levels of interferon-γ in cow milk protein and yak milk protein-sensitized mice. Lymphocyte proliferation ratio induced by yak milk protein was lower than cow milk protein. All results indicated that Maiwa yak milk protein may less allergenic than cow milk protein in mice.     

Factors associated with concentrations of select cytokine and acute phase proteins in dairy cows with naturally occurring clinical mastitis

The objective of the current observational study was to determine the potential associations between cow factors, clinical mastitis (CM) etiology, and concentrations of select acute phase proteins and cytokines in milk from affected quarters of cows with CM. Cows with CM (n = 197) were grouped based on systemic disease severity, milk culture result, parity, days in milk (DIM), previous CM occurrence, and season of the year when CM occurred. Concentrations of lipopolysaccharide-binding protein (LBP), haptoglobin (Hp), BSA, IFN-γ, tumor necrosis factor-α (TNF-α), IL-1β, IL-8, IL-10, IL-12, transforming growth factor (TGF)-α, and TGF-β and activity of lactate dehydrogenase (LDH) were evaluated. Differences in the least squares means log₁₀ transformed concentrations of these proteins were compared using multiple linear regression mixed models. The milk concentrations of LBP, Hp, IL-1β, IL-10, and IL-12, and activity of LDH in milk were higher in cows with moderate to severe versus mild systemic disease. The concentrations of Hp, BSA, IL-1β, and IL-10 in milk were higher in cows with a gram-negative versus gram-positive milk culture result. Season of the year when CM occurred was associated with the concentration of all proteins evaluated except for IL-1β and IL-12. Concentrations were higher in the winter versus summer except for Hp and TGF-β, for which the opposite was true. Concentrations of LBP, IL-10, and IL-12, and LDH activity in milk were associated with DIM group. Except for LBP, these proteins were lower in cows with CM during the first 60 DIM versus those in mid or later lactation. Interferon-γ, TNF-α, and IL-8 were undetectable in 67, 31, and 20% of samples, respectively. Detection of IFN-γ and IL-8 was associated with season, and detection of TNF-α and IL-8 was associated with systemic disease severity. The current study provides the most comprehensive report of milk concentrations of innate immune response proteins in cows with naturally occurring CM and identifies factors that potentially influence those concentrations. Further investigation into the seasonal variation of cytokine production and its potential effect on the outcome of CM is warranted. Furthermore, the results of this study provide useful data for planning future studies examining the role of the innate immune response in CM.     

Relationship between cortisol response to stress and behavior, immune profile, and production performance of dairy ewes

The existence of a relationship between cortisol levels, after an acute stress, and behavioral activities, immunological profile, and production performance in sheep was studied. An initial flock of 30 Comisana ewes was involved in the experiment, and each of the 30 ewes was individually subjected to an isolation test in a novel environment. Subsequently, from the initial flock, 2 groups of 8 Comisana ewes were each retrospectively selected, and the animals were divided, according to their cortisol concentration 10 min after the isolation test, into high cortisol (HC) ewes, having a peak of cortisol concentration >90 ng/mL (average: 119.3 ng/mL ± 11.8), and low cortisol (LC) ewes having a peak of cortisol concentration <80 ng/mL (average: 52.4 ± 11.8). During the isolation test, the behavior of each animal was video-recorded and behavioral activities were registered. Blood samples were collected before the isolation test, immediately after the test (10 min), and at 60, 120, 300 min, 24 h, and 48 h after the test to evaluate percentages of T-helper (CD4⁺) and T-cytotoxic (CD8⁺) cells, CD4⁺/CD8⁺ ratio, and IL-1β and IL-6 levels. The ewes were milked for 3 d after the isolation test to determine cortisol levels and IL-1β and IL-6 concentrations in whey. Milk yield was recorded at each milking, and milk samples were analyzed for pH, nutritional parameters, renneting properties, and somatic cell count. During the isolation test, HC ewes exhibited a shorter duration of movement and fewer bleats than LC ewes. The average plasma IL-1β concentration was higher in HC than in LC ewes. The average whey IL-1β and IL-6 concentrations were higher in whey from HC ewes than in LC ewes. A positive correlation emerged between plasma and whey IL-1β concentrations. The average CD4⁺/CD8⁺ ratio in blood was lower in HC than in LC ewes. Time from isolation affected the CD4⁺/CD8⁺ ratio: at 120 min, the CD4⁺/CD8⁺ ratio increased compared with that at 10 min after isolation and then decreased until 300 min after isolation. On average, ewes with low cortisol concentrations showed higher milk production and lower SCC than ewes with high cortisol concentrations. Results suggest that plasma cortisol concentration is connected to the behavioral response and immune competence of dairy ewes and cytokine concentrations. Both whey IL-1β and IL-6 can be considered reliable indicators of the magnitude of hypothalamic-pituitary-adrenal axis activation. The stress-induced changes in CD4⁺/CD8⁺ ratio are critical for controlling disease incidence and planning appropriate vaccination programs. High reactivity of the hypothalamic-pituitary-adrenal axis is also associated with a reduction in milk production and an increased predisposition to develop intramammary inflammatory processes.     

Anti-allergic effect of strawberry extract

We examined the anti-allergic effect of strawberry extract on human peripheral blood mononuclear cells (PBMCs) and atopic dermatitis model mice NC/NgaTndCrlj. The addition of strawberry extract suppressed total IgE production in the cedar pollen antigen Cry j 1-stimulated PBMCs. Flow cytometric analysis showed that strawberry extract decreased the rate of CD3⁺CD4⁺ helper T cells by 17.3% and increased the rate of CD3⁺CD8⁺ cytotoxic T cells by 19.7% in PBMCs. Moreover, the extract inhibited the expression level of GATA3 that is the master regulator of type 2 helper T cells (Th2) in human primary pan T cells isolated from PBMCs. Oral administration of strawberry extract lowered dermatitis scores and serum IgE levels in mice. In addition, it also decreased the GATA3 expression level in mouse blood cells. These results revealed that strawberry extract suppressed the severity of atopic dermatitis through the down-regulation of serum IgE by inhibition of Th2 differentiation.     

Effects of age and nutrition on expression of CD25, CD44, and L-selectin (CD62L) on T-cells from neonatal calves

Effects of the plane of nutrition and age on the proliferation and activation of lymphocyte subsets from milk replacer-fed calves were investigated in vitro. Holstein calves were fed a standard (0.45 kg/d of a 20% crude protein, 20% fat milk replacer, n = 4) or intensified (1.14 kg/d of a 28% crude protein, 20% fat milk replacer, n = 4) diet from 1 to 8 wk of age. Average daily weight gain of intensified-diet (0.66 kg/d) calves was greater than that of standard-diet (0.27 kg/d) calves. Relative to the pokeweed mitogen-induced responses of CD4⁺ cells from steers (5 to 6 mo of age), CD4⁺ cells from 1-wk-old calves showed decreased proliferative activity, delayed increase in CD25 expression, and no demonstrable increase in CD44 expression or decrease in CD62L expression. Calf CD8⁺ and γδT-cell receptor⁺ cells, unlike T-cells from the older animals, did not demonstrate decreased expression of CD62L after stimulation with mitogen. The increased expression of CD44 by mitogen-stimulated γδT-cell receptor⁺ cells from older animals was not seen in γδT-cell receptor⁺ cells from 1-wk-old calves. At wk 8 of age, mitogen-induced proliferation and expression of activation antigens by T-cells from standard-fed calves were similar to responses of T-cells from steers indicating rapid maturation of T-cell function during the neonatal period. Feeding calves an intensified milk replacer was associated with decreased proliferation of mitogen-stimulated CD4⁺, CD8⁺, and γδT-cell receptor⁺ cells; decreased CD25 expression by mitogen-stimulated CD4⁺ and CD8⁺ cells; and decreased CD44 expression by mitogen-stimulated CD8⁺ cells. These results indicate that the functional capacity of the calf's T-cell population becomes more adult-like during the first weeks of life and suggest that nutrition modulates T-cell function during this period of immune maturation.     

Immune regulation of epithelial cell function: Implications for GI pathologies

The mammalian immune system is a complex and dynamic network that recognizes, responds, and adapts to numerous foreign and self-molecules. CD4⁺ T cells orchestrate adaptive immune responses and upon stimulation by antigen, naïve CD4⁺ T cells proliferate and differentiate into various T cell subsets including T helper (Th) 1, Th2, and Th17 effector cells, and T regulatory cells (Treg). Each of the T cell subsets is characterized by distinct profiles of cytokines and carries out distinct and sometimes opposing activities. Initiated by IL-12 released from dendritic cells, the development of Th1 cells is the typical host response against the invasion of intracellular pathogens such as bacteria or viruses. Th1 cells deliver cell-mediated immunity through their secreted cytokines such as IFN-γ, TNF-α, IL-1β, IL-2, and IL-12, and are responsible for the clearance of intracellular pathogens. Th2 cells are initiated by IL-4 and develop in response to allergens or the invasion of extracellular pathogens. Th2 cytokines include IL-4, IL-5, and IL-13, and are particularly important for allergic responses and the clearance of parasites.     

Immunomodulatory and hypoallergenic properties of milk protein hydrolysates in ICR mice

Approximately 2.5% of young children are allergic to cow milk. In this study, milk protein hydrolysates made from full-cream milk via enzymatic hydrolysis played a positive role in regulating the immune system of ICR mice. Milk protein hydrolysates enhanced immunity in mice by stimulating host immunity, probably by increasing the weight of certain immune system organs, improving the level of hemolysin in serum, and enhancing the phagocytosis of macrophages. Milk protein hydrolysates have the capability to reduce type I hypersensitivity by decreasing IgE levels, IL-4 in serum, and the release of histamine and bicarbonate in peritoneal mast cells, as well as enhancing transforming growth factor-β levels in the serum of ovalbumin-sensitized mice.     

Immunomodulatory effects of marine oligopeptide preparation from Chum Salmon (Oncorhynchus keta) in mice

To observe the immunomodulatory effects of marine oligopeptide preparation (MOP) from Chum Salmon (Oncorhynchus keta) by the method of enzymatic hydrolysis, female ICR mice (6–8 weeks old) were administered the MOP for four weeks with the dose of 0, 0.22, 0.45 and 1.35 g/kg/body weight. In comparison with the control group, the MOP could significantly enhance the capacity of lymphocyte proliferation induced by the mitogen concanavalin A, the number of plaque-forming cells, natural killer cell activity, the percentage of CD4⁺ T helper (Th) cells in spleen and the secretion of Th1 (IL-2, IFN-γ) and Th2 (IL-5, IL-6) type cell cytokines. Nevertheless, no significant differences in weight gain, lymphoid organ indices and phagocytosis capacity were observed in our study. These results suggest that MOP is a possible immune stimulant and may strengthen the immune response of its host.     

Camel milk regulates T-cell proliferation to alleviate dextran sodium sulphate-induced colitis in mice

The incidence of inflammatory bowel disease (IBD) is increasing in China. Current clinical methods of treatment for IBD are accompanied by side effects, and thus, the search for effective therapeutic drugs with minimal adverse effects is necessary. In the present study, the effects of camel milk (CM) on dextran sodium sulphate (DSS)-induced acute and chronic colitis in a mouse model were investigated. The results showed CM effectively alleviated the injury induced by DSS to the colon mucosa and imbalance of immune cells in mice. However, treatment with CM significantly increased the body weight of mice and decreased the disease activity index (DAI), histopathological score, proliferation of Th17 cells and concentration of inflammatory cytokine IL-17. The results from the present study indicate CM possesses intestinal protective effects.     

Effect of pregrazing herbage mass and pasture allowance on the lactation performance of Holstein-Friesian dairy cows

The objective of this study was to investigate the effect of pregrazing herbage mass (HM) and pasture allowance (PA) on the grazing management and lactation performance of spring-calving dairy cows. Sixty-eight Holstein-Friesian dairy cows (mean calving date, February 6) were randomly assigned across 4 treatments (n = 17) in a 2 × 2 factorial arrangement. The 4 treatments consisted of 2 pregrazing HM (>4 cm) and 2 PA (>4 cm): 1,700 kg of dry matter (DM)/ha (medium, M) or 2,200 kg of DM/ha (high, H), and 16 or 20 kg of pasture DM/cow per day. The experimental period lasted 30 wk. The experimental area was divided into 4 farmlets, with 1 farmlet per treatment. Mean HM throughout the experimental period was 1,767 kg of DM/ha (M HM) compared with 2,358 kg of DM/ha (H HM). Offering an M HM sward resulted in significantly greater milk protein yield (+31.7 g/d) and lower mean body weight (−12.8 kg). The body condition score change was significantly smaller (−0.21) with the M HM treatments compared with the H HM treatment (−0.34). Milk solids output per hectare was 6% greater on the M HM treatments compared with the H HM treatments. Increasing PA significantly increased milk (+0.9 kg/d), solids-corrected milk (+0.7 kg/d), protein (+43.9 g/d), and lactose (+52.7 g/d) yields. Mean body weight was also significantly greater for cows offered 20 kg of PA (+11.4 kg/cow). It was concluded that in rotational grazing systems, adapting the concept of grazing M HM pastures (1,700 kg of DM/ha) will result in increased sward quality and increased milk solids output per hectare. At medium levels of pregrazing HM, offering animals 20 kg of DM PA will result in increased milk yield per cow.     

Feed and nitrogen efficiency are affected differently but milk lactose production is stimulated equally when isoenergetic protein and fat is supplemented in lactating dairy cow diets

Fifty-six Holstein-Friesian cows were used in a randomized complete block design to test the effects of supplemental energy from protein (PT) and fat (FT) on lactation performance and nutrient digestibility in a 2 × 2 factorial arrangement. During the control period, cows were adapted for 28 d to a basal total mixed ration consisting of 34% grass silage, 33% corn silage, 5% grass hay, and 28% concentrate on a dry matter (DM) basis. Experimental rations were fed for 28 d immediately following the control period and consisted of (1) low protein, low fat (LP/LF), (2) high protein, low fat (HP/LF), (3) low protein, high fat (LP/HF), or (4) high protein and high fat (HP/HF). To obtain the HP and HF diets, intake of the basal ration was restricted and supplemented isoenergetically (net energy basis) with 2.0 kg/d of rumen-protected protein (soybean + rapeseed, 50:50 mixture on DM basis) and 0.68 kg/d of hydrogenated palm fatty acids (FA) on a DM basis. Milk production and composition, nutrient intake, and apparent digestibility were measured during the final 7 d of the control and experimental periods. No interaction was found between PT and FT on milk production and composition. Yields of milk, fat- and protein-corrected milk, and lactose increased in response to PT and FT and lactose concentration was unaffected by treatment. Milk protein concentration and yield increased in response to PT, and protein yield tended to increase in response to FT. Milk fat concentration and yield increased in response to FT and were unaffected by PT. Milk urea concentration increased and nitrogen efficiency decreased in response to PT. Feed and nitrogen efficiency were highest on the LP/HF diet and both parameters increased in response to FT, whereas milk urea concentration was not affected by FT. Energy from fat increased the concentration and yield of ≥16-carbon FA in milk and decreased the concentration of FA synthesized de novo, but had no effect on their yield. Concentration and yield of de novo-synthesized FA increased in response to PT. Concentration and yield of polyunsaturated FA increased and decreased in response to PT and FT, respectively. Apparent total-tract digestibility of crude fat decreased in response to PT, and FT increased crude protein digestibility. Energy supplementation through rumen-inert hydrogenated palm FA appears to be an efficient feeding strategy to stimulate milk production with regard to feed and nitrogen efficiency compared with supplementing an isoenergetic level of rumen-protected protein.     

Increase in Escherichia coli inoculum dose accelerates CD8+ T-cell trafficking in the primiparous bovine mammary gland

Although migration of leukocytes into the mammary gland is pivotal for a cow's response against intramammary invading pathogens, the contribution of lymphocyte subsets to this response remains unclear. To investigate the dynamics of lymphocyte populations during Escherichia coli mastitis, T-lymphocyte subsets, CD4⁺/CD8⁺ ratio, CD21⁺ cells, and lymphoproliferation were studied in blood and milk of primiparous cows exposed to different quantities of bacteria. The cows were intramammarily inoculated with 10⁴ cfu of E. coli (group A) and 10⁶ cfu (group B). Compared with group A, a much greater number of lymphocytes migrated into the infected quarters at postinfection hour (PIH) 6 to 24 in group B, and the CD8⁺ cells were the first-recruited T cells in the milk. There was a significant decline in the CD4⁺/CD8⁺ ratios at PIH 6 to 24 in group B. The decrease of CD4⁺/CD8⁺ ratios at PIH 6 to 24 resulted mainly from greater CD8⁺ cell concentrations in milk. In contrast, at PIH 72, CD4⁺/CD8⁺ ratios increased about 2-fold in both groups. This increase was mainly due to the increase in CD4⁺ cell concentration. The increased concentration of CD4⁺ cells coincided with an increase in the CD21⁺ cell population in the milk. In blood, the increase of CD8⁺ cells appeared much faster in group B (PIH 6 and 12) than in group A. The results from lymphoproliferation also indicated a greater increase in the proliferative response in both blood and milk lymphocytes of group B. Our study demonstrates for the first time that an increase of E. coli inoculum dose accelerates the trafficking of CD8+ cells during initiation of E. coli mastitis, and these cells are the predominant T cells in milk during the early hours of bovine E. coli mastitis.     

Description of herd level criteria for good and poor udder health in Norwegian dairy cows

Data from the Norwegian dairy herd recording system were used to evaluate herd level criteria for good and poor udder health in dairy cows. All dairy herds with at least 10 cow-years were included (n = 12,780). The association between bulk milk somatic cell count (BMSCC) and clinical mastitis rate (CM) was weak (R2 = 0.002), indicating that studies based on BMSCC provide different information regarding udder health than studies based on CM. The strongest correlations were found between average cow milk somatic cell count (CMSCC) and BMSCC and between percentage of individual cow milk sample >200,000 cells/mL and the variables BMSCC and CMSCC. A new variable called new infection rate (NEWINF) based on individual cow somatic cell count measurements and CM was evaluated. The NEWINF is influenced by the frequency of individual cow milk samplings, and, to compare herds, it is necessary to adjust for the frequency of cow milk samplings on each farm. The NEWINF was found to be a useful tool for describing overall udder health status at the farm level, as it combines both CM and somatic cell count.