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1.
The susceptibility of lactating bovine udder quarters fitted with a polyethylene intramammary device to infection was investigated. Following experimental challenge with Streptococcus agalactiae or Staphylococcus aureus, the incidence of infection was significantly (p less than 0.05) lower in intramammary device-fitted quarters compared to control quarters. In general, total foremilk and strippings milk somatic cell counts for intramammary device-fitted and control quarters were not significantly (p less than 0.05) different. Differential foremilk and strippings milk somatic cell counts were significantly (p less than 0.05) higher in samples from intramammary device-fitted quarters compared to control quarters.  相似文献   

2.
Clinical mastitis in dairy cows is commonly treated with intramammary (IMM) antimicrobial agents. Pharmacokinetic data are used to design treatment regimens and determine withholding times. In some pharmacokinetic studies, investigators measure antimicrobial concentrations in foremilk, whereas in others, they use bucket milk or do not specify the milk fraction sampled. Our objective was to compare antimicrobial concentrations in foremilk, bucket milk, and strippings after IMM treatment of six healthy Holsteins. One mammary gland/cow was infused with 200 mg of cephapirin (CEPH) after each of the two milkings, using different milking frequencies and treatment intervals in a randomized crossover design. Treated glands were sampled at the first milking following each infusion. Antimicrobial concentrations in milk were measured using HPLC/MS/MS. CEPH concentration was higher in foremilk (geometric mean 44.2 μg/mL) than in bucket milk (15.7 μg/mL) or strippings (18.5 μg/mL), as it was true for desacetylcephapirin (DAC) (59.5, 23.0, and 30.2 μg/mL, respectively). This finding, which was based on milk samples collected at the first milking after IMM infusion, suggests that pharmacokinetic data based on drug concentrations in foremilk may be misleading. Strippings were more representative of bucket milk than foremilk. The relationship between milk fraction and antimicrobial concentration should be investigated for other IMM antimicrobial agents. Meanwhile, it is essential that pharmacokinetic and residue studies report the fraction of milk that was analyzed.  相似文献   

3.
A hand-held, commercially available instrument for measuring the electrical conductivity of milk (the Milk Checker) has been examined for its usefulness and accuracy in detecting subclinical and clinical mastitis. Foremilk from uninfected quarters had an electrical conductivity of 5.4 to 5.6 millisiemens (mS)/cm. Milk from cows with subclinical Staphylococcus aureus infections had a higher milk conductivity (7.1 to 7.5 mS/cm) but milk from cows with subclinical S uberis infections showed no increase in conductivity (5.3 to 5.6 mS/cm). However, experimental S uberis infections could be detected by a 50 per cent increase in the electrical conductivity of foremilk two milkings before visible signs of mastitis were apparent. The equipment could be a useful advisory/veterinary tool but is unlikely to be used routinely in the milking parlour.  相似文献   

4.
OBJECTIVE: To evaluate the elimination kinetics of chlorhexidine in milk when used as an intramammary infusion to stop lactation in cows. DESIGN: Prospective study. ANIMALS: 6 cows. PROCEDURE: The study was performed in 2 phases. Three cows were studied in each phase. All cows were treated with chlorhexidine suspension by infusion into a mastitic mammary gland quarter after 2 milkings 24 hours apart. Foremilk samples (100 mL) were collected from treated and untreated (controls) mammary gland quarters of each cow. Chlorhexidine was extracted from raw milk, and residue concentrations were quantified by use of high-performance liquid chromatography. Foremilk samples from days 2, 5, and 8 were analyzed in phase I, and samples from time 0 and days 3, 7, 14, 21, 28, 35, and 42 were analyzed in phase II. RESULTS: In phases I and II, there was no quantifiable transference of chlorhexidine to milk in untreated mammary gland quarters. Measurable chlorhexidine residues were found in milk from treated mammary gland quarters of 2 cows throughout the 42-day sample period in phase II. Estimated mean elimination half-life for chlorhexidine in milk was 11.5 days. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of the long elimination half-life of chlorhexidine in milk from treated mammary gland quarters, the lack of human dietary exposure data to suggest a food tolerance for chlorhexidine in food products, and the Food and Drug Administration's published zero tolerance for chlorhexidine in uncooked edible calf tissues, we do not recommend extralabel use of chlorhexidine suspension as a treatment to stop lactation in mastitic mammary gland quarters of cows.  相似文献   

5.
Intramammary devices (IMD) were abraded with medium-grade emery cloth or were left smooth. One IMD of each type was inserted into a mammary quarter of each of 5 lactating cows. The remaining 2 quarters served as controls. Quarter foremilk, bucket milk, and stripping milk samples were collected for 3 consecutive days at 2 weeks after IMD insertion, and milk somatic cell counts (SCC) were determined. Milk samples also were collected immediately after and 0.5, 1, 2, 4, 6, 8, and 11 hours after milking. All quarters were challenge exposed with 250 colony-forming units of Streptococcus uberis at 2 months after IMD insertion. Foremilk and stripping milk samples were collected for bacteriologic culture and SCC at the next 10 milkings. Mean foremilk, bucket milk, and stripping milk SCC (X 10(6) cells/ml) were 0.18, 0.07, and 0.91, respectively, for quarters with abraded IMD; 0.06, 0.05, and 0.43, respectively, for quarters with smooth IMD; and 0.03, 0.03, and 0.15, respectively, for control quarters. Mean SCC after milking (X 10(6) cells/ml) for the various intervals were 0.70, 1.29, 0.70, 0.97, 1.15, 1.17, 0.77, and 0.85 for quarters with abraded IMD; 0.43, 0.62, 0.61, 0.45, 0.64, 0.60, 0.31, and 0.26 for quarters with smooth IMD; and 0.15, 0.24, 0.15, 0.19, 0.15, 0.15, 0.14 and 0.06 for control quarters. After challenge exposure, 2 of 5 of the quarters with abraded IMD, 4 of 5 of the quarters with smooth IMD, and 8 of 9 control quarters became infected. Results indicated that abraded IMD increased SCC in stripping milk to concentrations that provided 60% protection against challenge exposure with S uberis.  相似文献   

6.
Treatments consisting of copper-impregnated polyethylene intramammary device (PIMD-Cu), PIMD-Cu which had been abraded to ensure exposure of surface copper (APIMD-Cu), PIMD which had been abraded in an identical manner (APIMD), and an untreated control were established in mammary quarters of 2 cows. Quarters selected were bacteria free and had milk somatic cell counts (MSCC) in strippings of less than 240 X 10(3) ml. Milk somatic cell counts were determined from strippings immediately after milking and 6 hours later. Cows were monitored for 4 weeks after devices were inserted. Milk samples (250 ml) were collected and analyzed for free fatty acids, a measure of hydrolytic rancidity, at 14 days. The devices were removed from mammary quarters after 4 weeks and examined with a scanning electron microscope. Surfaces of the devices were assessed for plaque buildup and presence of leukocytes. Immediately after and 6 hours later, geometric mean MSCC for APIMD, APIMD-Cu, PIMD-Cu, and control quarters average 946/1,556, 1,479/2,882, 512/1,148, and 161/190 X 10(3) ml, respectively. There was no difference in free fatty acid values of samples from treated and control quarters. Plaque formation was observed over the entire surface of APIMD. Numerous leukocytes were found associated with plaque and appeared to initiate development of plaque. Smaller amounts of plaque were found on APIMD-Cu, and minimal amounts were found on PIMD-Cu. Results indicate that modification of PIMD by abrading or addition of copper will increase MSCC to concentrations (greater than 900 X 10(3) ml) that should be protective against establishment of infection by mastitis pathogens.  相似文献   

7.
Quarter samples of foremilk and residual milk were taken approximately every second week from 2 days post partum (pp) throughout lactation month 9, from 5 dairy cows in their second lactation period. Bacteriologically positive milk samples were excluded. The aim was to study the variation in total and differential leukocyte counts, N-acetyl-ß-D-glucosaminidase (NAGase), antitrypsin (ATR) and serum albumin (BSA) in milk during the lactation period and different stages of oestrous cycle. Also the between milkings variation was studied from lactation month 4 to 9. At 2 days pp, each fraction of milk contained significantly higher numbers of leukocytes and had a higher activity of NAGase and ATR than later in the lactation period. In foremilk the highest content of BSA was also recorded at 2 days pp. From lactation month 2 to 9, stage of lactation had, in general, a slight effect on the variation in the variables measured. The total leukocyte count in residual milk tended to increase as lactation proceeded. The proportion of monocyte-macrophages in foremilk was significantly decreased during the last 4 months. NAGase and BSA in both fractions and ATR in residual milk increased significantly towards the end of the lactation period. From lactation month 4 to 9 the highest recorded ranges of variation between milkings, within quarter and stage of lactation, in the total leukocyte count, proportions of neutrophils, lymphocytes, monocyte-macrophages, NAGase, ATR and BSA in foremilk were 215 × 103ml, 42 %, 34 %, 54 %, 6.68 units, 0.36 units and 0.14 mg/ml respectively. The corresponding figures in residual milk were higher except for the variation in BSA which was slightly lower in residual milk than in foremilk. In residual milk there was a positive correlation between the proportion of neutrophils and the total leukocyte count, when calculated on data from all cows and the entire experimental period. During the oestrous periods, the proportion of neutrophils in residual milk was higher than during the dioestrous periods. Foremilk and residual milk differed in the total as well as the differential leukocyte counts in all the various stages of lactation, whereas the contents of NAGase, ATR and BSA were equal in both fractions. The exception was 2 days pp when the proportions of lymphocytes were equal in both fractions and BSA-significantly higher in foremilk than in residual milk.  相似文献   

8.
Experimental intramammary infections were induced in five post-parturient Holstein cows by inoculation of low numbers (5000 colony forming units) of virulent Salmonella dublin via the teat canal of mammary gland quarters. Rectal temperature, pulse and respiratory rates, milk yield, and milk quality as assessed by the California Mastitis Test (CMT) and somatic cell counts (SCC) were recorded every 12 hours at milking. Bacteriologic cultures of foremilk quarter samples and feces were obtained daily, as were complete blood counts. ELISA titers for IgG and IgM recognizing S. dublin lipopolysaccharide (LPS) were obtained weekly on serum and quarter milk samples. All cows excreted S. dublin intermittently from infected quarters, but no changes were detected in rectal temperature, appearance of the mammary gland or secretions, CBC, milk yield, and pulse and respiratory rates. Somatic cell counts were modestly increased in infected quarters as compared with uninfected quarters (P = .015, paired t test); however, CMT scores after infection remained low, and were not significantly different from pre-infection scores (P greater than .10, sign test). After infection, administration of dexamethasone resulted in signs of clinical mastitis and increased excretion of S. dublin from mammary quarters (P = .0004, paired t test). One cow had necrotizing mastitis and S. dublin septicemia and was euthanatized. In the four surviving cows, clinical improvement was observed after systemic gentamicin therapy and intramammary infusion with polymyxin B, but all cows continued to excrete S. dublin intermittently from one or more quarters and occasionally from feces for the remaining period of observation. All infected cows demonstrated a rise in IgG and IgM ELISA titers recognizing S. dublin LPS in serum and milk. At necropsy (13-25 weeks postinfection), S. dublin was recovered only from the mammary tissue or supramammary lymph nodes in three of four cows. In one cow, mammary gland and lymph-node samples were negative for S. dublin despite positive milk cultures. In all cows, histopathologic examination revealed multifocal areas of chronic active mastitis. These lesions were similar to histopathologic findings from mammary gland carriers with naturally acquired S. dublin infection.  相似文献   

9.
Quarter foremilk samples were taken at 2–3 weekly intervals for several years in a experimental herd comprising about 45 cows. The samples were submitted to bacteriological analysis and somatic cell counting. The most prevalent quarter infections from 1982 to 1988 were by coagulase-negative staphylococci (15–20% of all the quarters sampled). Most of these (75.6%) persisted until drying-off Dry cow therapy eliminated 86.5% of these infections. Comparison of udder quarters within cows, involving 775 samples from pairs of non-infected quarters and quarters infected by coagulase-negative staphylococci, yielded geometric means of somatic cell counts of 210 000 and 420 000 cells/ml, respectively. The correlation (r=0.87) between the herd bulk milk somatic cell count (SCC) and its estimation from the quarter milk somatic cell count performed on the same day allowed us to evaluate the contribution of the different categories of quarters, according to their infection status, to the herd bulk milk SCC. Quarters infected by a major pathogen (8.5% of samples) gave rise to 46.6% of the total number of cells, while quarters infected by coagulase-negative staphylococci (17.8% of samples) gave rise to 18.1%. Although coagulase-negative staphylococci represented only a secondary source of somatic cells as compared to major pathogens, they were not a negligible source considering the threshold of 300 000 somatic cells advocated for herd milk of good quality.  相似文献   

10.
Antibacterial factors act as innate immune components, which respond as soon as bacteria enter a living organism. To prevent and treat mastitis in cattle, understanding the concentrations of these substances inside the udder is important; however, they remain to be studied. In this investigation, the concentration of lingual antimicrobial peptide (LAP), S100 protein (S100A7), lactoferrin (LF), and immunoglobulin antibody were measured in the different fractions of foremilk. Lactating Holstein cows were examined, and 10 foremilk fractions were obtained from sequential samples up to 150 ml. The LAP concentrations in milk samples increased until 25 ml. The LF concentrations increased up to the 10 ml fraction, then stabilized at low level after the 50 ml fraction. For S100A7, some fractions had significantly higher (p < .05) concentrations than the 5 or 10 ml fractions. The IgA antibody concentration increased up to the 5 ml fraction, then after 50 ml fraction showed relatively low concentrations. This investigation determined the concentration patterns of LAP, LF, S100A7, and IgA antibody secreted in milk inside the udders of healthy lactating cows as baseline data. These distinct concentration patterns might indicate various protective responses.  相似文献   

11.
Subclinical mastitis caused by streptococcal infections affected 27 of 83 cows in a commercial dairy herd. Between three and six weeks after intramammary treatment of these cows with cloxacillin, 16 (59 per cent) of the treated cows developed acute clinical mastitis associated with Mycobacterium smegmatis. None of the untreated cows was affected. Infected quarters were moderately hypertrophied and fine clots were present in the milk for three to four weeks. No cows showed systemic signs of illness. Studies carried out over 12 months showed that infected cows shed M smegmatis for three to four months and affected quarters remained hypertrophied in all but one cow after 12 months. The mean milk cell count of affected quarters fell slowly from 4,850,000/ml in the acute stage to 810,000/ml five months later and 620,000/ml 12 months later, suggesting that the organism persisted in the udder. The estimated mean loss in lactation yield for cows with M smegmatis mastitis was 10.8 per cent. Losses were greatest when the hind quarters were involved (mean 28 per cent for cows with both hind quarters affected). Ten of the 16 affected cows were ultimately culled owing to serious reductions in yield.  相似文献   

12.
This study was conducted to investigate the normal somatic cell count (SCC) and to define subclinical mastitis in Murrah buffaloes. Data were collected from 60 clinically normal buffaloes stationed at five farms of Chitwan Nepal and Buffalo Research Center, Hissar, India. Somatic cell count was measured using the Newman-Lampert staining technique. The upper limit of SCC was determined >or=200 000/ml of milk based on the mean +/- 2SD of a total SCC. Abnormal data of the SCC was repeatedly removed, which lie beyond the values of more than mean + 2SD until all the data come to lie within (mean + 2SD). Averages of SCC of right front and right hind quarters were significantly higher than left front and left hind quarters. Nearly 94% of California mastitis test (CMT) negative quarters were having somatic cells >or=200 000/ml. The mean SCC of CMT positive quarter was significantly higher (P < 0.01) than CMT negative quarters. Subclinical mastitis was diagnosed on the basis of samples with SCCs >or=200 000/ml with positive bacterial cultures. Subclinical mastitis was found in 21.7% buffaloes and 8% of the quarter foremilk samples. Neutrophil counts were significantly higher in subclinical mastitis milk.  相似文献   

13.
Thirty cows were studied during the first six milkings after calving. Quarter foremilk samples were collected by the farmers at calving and at six subsequent milkings. Geometric-mean somatic cell count (SCC) decreased from 593,000 at calving to 126,000 cells/ml at the sixth milking after calving. In quarters infected with major pathogenic bacteria, geometric-mean SCC was 3,229,000 cells/ml at calving, and 1,257,000 cells/ml at the sixth milking after calving. In quarters infected with minor pathogenic bacteria, geometric-mean SCC was 1,000,000 cells/ml at calving, and 170,000 cells/ml at the sixth milking after calving. In culture-negative quarters, geometric-mean SCC decreased from 306,000 at calving to 42,000 cells/ml at the sixth milking after calving. Quarter SCC can be used early postpartum to give an indication of intra-mammary infection status.  相似文献   

14.
Intramammary infusion of Bifidobacterium breve (B. breve)-induced somatic cell (SC) counts, chemiluminescent response (CL), lactoferrin (LF) concentrations and mastitis-causing pathogens from quarters with subclinical mastitis were measured to evaluate innate immune response of mammary glands in dairy cows at 3 to 4 weeks before drying off. SC counts in 7 quarters of 7 control cows and 5 quarters of 6 cows with mastitis increased markedly on day 1 and SC values in control cows were significantly (P<0.05) increased and returned to pre-infusion levels on day 5 after B. breve-infusion. CL values in both groups increased markedly on day 1 and then decreased after B. breve-infusion; however, CL values in cows with mastitis did not return to normal levels on day 5 and at postpartum. The CL values were highly correlated with their SC counts in milk from both groups. LF concentrations increased toward day 3 after B. breve-infusion and were higher in cows with mastitis. B. breve-infusion eliminated 16.6% (1/6) of pathogens from 6 quarters with chronic subclinical mastitis. B. breve-induced SC responses in quarters from 3 cows with mastitis showed characteristic patterns of recovery, persistent and new infections. B. breve-induced SC counts in quarters from the cows in the pre-drying off were lower (25.7–70.6%) than those of the cows in mid-lactation. The intrinsic innate immune response in cows on pre-drying off may be decreased and appears to be insufficient to eliminate pathogens from mammary gland in the pre-drying off.  相似文献   

15.
OBJECTIVE: To determine whether half-udder intramammary infusion of cloxacillin results in transfer of cloxacillin from treated to untreated mammary gland quarters within nonlactating cows, and, if so, at what concentrations, and to determine whether selection of ipsilateral versus diagonal-contralateral quarters for treatment affects cloxacillin transfer among quarters. ANIMALS: 20 Holstein-Friesian cows from a dairy herd. PROCEDURES: A within-cow half-udder comparison trial was used in which 2 of 4 mammary gland quarters (ipsilaterally or diagonally) received an intramammary infusion of cloxacillin on day 1 of the nonlactating period. Three days later, milk samples were taken from all untreated quarters and high-pressure liquid chromatography was used to detect and quantify milk cloxacillin concentrations. RESULTS: Cloxacillin was detected in 25% of all untreated mammary gland quarters. Mean cloxacillin concentration in untreated quarters was below minimum inhibitory concentrations for targeted mastitis pathogens. No significant difference in cloxacillin concentrations was found in the ipsilateral or diagonal treatment groups. CONCLUSIONS AND CLINICAL RELEVANCE: Within-cow half-udder comparison trials are valid for antimicrobial trials in nonlactating cows, although transfer of antimicrobials does occur in trace concentrations. Ipsilateral or diagonal-contralateral treatment designs perform similarly. This type of design is economical for researchers, although care must be taken to account for within-cow clustering of mammary gland quarter data.  相似文献   

16.
To evaluate clinical effects of autogenous toxoid-bacterin treatment for Staphylococcus aureus subclinical mastitis in lactating cows, 22 cows which had at least one S. aureus infected quarter were selected from among cows at a S. aureus prevalent dairy farm. Eleven cows were injected with their own autogenous toxoid-bacterin and the others were maintained as non-injected control. In the toxoid-bacterin injected group, 27% of infected quarters were cured during the 12-week trial, compared to 5% in the control group. New intramammary infections with S. aureus were only detected in 3 quarters of the control group. Mean IgG antibody titer against S. aureus somatic antigens and alpha-toxin in serum and milk were significantly increased in the toxoid-bacterin injected group (p<0.05) and remained higher than those of the control group which showed no significant changes (p<0.05). In contrast to the control group, from 3 weeks after the second injection of the toxoid-bacterin injected group, mean S. aureus cfu/ml in milk samples from injected quarters with S. aureus was significantly decreased until the end of the study (p<0.05). In the toxoid-bacterin injected group, significant decreases of mean SCC were detected from milk samples from infected quarters with S. aureus from week 7 to week 10 (p<0.05). These data show that autogenous toxoid-bacterin treatment against S. aureus subclinical mastitis in lactating cows may increase the cure rate of the infections, reduce the severity of the infections and also prevent occurrence of the new infections.  相似文献   

17.
Experimental infections were produced in 78 quarters of 17 cows by the infusion of small numbers of a single strain of Staphylococcus aureus. In each single experiment three quarters in a cow were infected, with the fourth left as a control. At times varying from three to 60 days after the infusion of organisms, a standard intramammary antibiotic treatment was administered on a single occasion. A cure was arbitrarily defined as the absence of the organism in foremilk, from direct plating and replated incubated milk, together with return to normal somatic cell count levels as determined by an electronic counter.

With these standardized conditions the effects of a number of cow associated factors on the outcome of the therapy were determined.

Forty-three of the 78 quarters (55%) were cured by the standard treatment. Significant differences in percentages of quarters cured were found to be associated with the duration of infection before therapy, the lactation age of the cow, the length of time in lactation, somatic cell count in milk at time of treatment, the location of the quarter in the udder and individual cows. No significant effects on the outcome of the standard treatment were found associated with the number of bacteria in the secretion at the time of treatment, previous infection and cure in a quarter nor the season of the year in which treatment was given. Of the 35 quarters in which infection recurred following treatment, organisms were reisolated from 12 within four days, 18 between five and nine days, four between ten and 17 days and one after 28 days.

From these data it is apparent that if, as has been suggested, models such as described are to be used for efficacy trials, standardization of some parameters is essential.

  相似文献   

18.
To evaluate the clinical effects of bovine lactoferrin on staphylococcal mastitis in Holstein cows during the early non-lactating period, 41 mammary quarters were selected randomly from 36 cows on 3 dairy farms. Twelve quarters were infused intramammarily with bovine lactoferrin. Twenty-nine quarters were infused with antibiotic as a control. In the bovine lactoferrin-infused group, 91.7% of mastitic quarters were cured at 7 days after calving, compared with 48.3% in the control group. Furthermore, the changes in mammary secretion induced by the infusion of bovine lactoferrin were investigated. Mean numbers of staphylococci in mammary gland secretions were significantly decreased in both 5 bovine lactoferrin-infused quarters and 5 antibiotic-infused control quarters (p<0.05). Unlike in the control quarters, the mean total cell concentration in the mammary gland secretions increased in bovine lactoferrin-infused quarters. Similar results were obtained in 6 healthy quarters which were infused with bovine lactoferrin. In these quarters, the cell population contained mainly phagocytes such as polymorphonuclear leukocytes and cells positive for CD11b which is known as a complement receptor. The mean concentration of C3 in mammary gland secretions was significantly increased in 5 mastitic quarters infused with bovine lactoferrin (p<0.05), but showed no significant change in 5 mastitic control quarters. These results suggested that bovine lactoferrin treatment for staphylococcal mastitis in the early non-lactating period might increase the rate of cure through the induction of innate immunity in the host.  相似文献   

19.
Lactoferrin Concentration in Milk of Bovine Clinical Mastitis   总被引：4，自引：0，他引：4  
The lactoferrin (LF) concentration in the milk from dairy cows with clinical mastitis was determined to evaluate the relationship between the LF concentration (LFC) in milk and the non-specific defensive capability of the udder. The mean LFC in 368 milk samples from 319 cows with clinical mastitis was significantly higher (p<0.01) than that of normal cows. The mean LFC in milk from quarters infected with Mycoplasma bovis or Staphylococcus aureus was significantly higher (p<0.05) than that of quarters infected with coagulase-negative staphylococci (CNS). In Escherichia coli mastitis, the level of LFC in milk from cows with peracute mastitis was significantly lower (p<0.01) than that from cows with acute mastitis. In cases of mastitis due to E. coli, the mean LFC in milk from cows that needed more than 10 days to recover from the mastitis or were not cured was significantly lower (p<0.05) than that for cows which took less than 10 days to be cured. The mean LFC in milk from cows with peracute E. coli mastitis was significantly lower (p<0.05) than that for cows with mastitis associated with environmental streptococci or CNS, although these low LF levels were somewhat increased after 46 h from the occurrence of mastitis. These results suggest that the decreased levels of LF in peracute E. coli mastitis may be associated with the progress of inflammation in the early phase of mastitis.  相似文献   

20.
The objective of this study was to determine the effect of evaporative cooling and dietary supplemental Zn source on blood metabolites, insulin and mineral concentrations, and milk mineral concentrations following intramammary lipopolysaccharide (LPS) infusion. Seventy-two multiparous Holstein cows were assigned to one of four treatments with a 2 × 2 factorial arrangement. Treatments included two environments: with or without evaporative cooling using fans and misters over the freestall and feedbunk, and two dietary sources of supplemental Zn: 75 mg/kg of dry matter (DM) supplied by Zn hydroxychloride (inorganic Zn; IOZ) or Zn hydroxychloride (35 mg of Zn/kg of DM) + Zn–Met complex (ZMC; 40 mg of Zn/kg of DM). A subset of cows (n = 16; 263 ± 63 d in milk) was infused with 10 μg of LPS or a saline control in the left or right rear quarters on day 34 of the environmental treatment. Individual milk samples collected from LPS-infused quarters at −4, 0, 6, 12, 24, 48, 72, 96, and 144 h relative to infusion were analyzed for minerals. Blood samples were collected at the same time with an additional sample collected at 3 h post-infusion to analyze glucose, nonesterified fatty acids (NEFA), insulin, and minerals. Cooling by time interactions (P ≤ 0.07) were observed for plasma glucose, NEFA, and serum insulin. Compared with cooled cows, non-cooled cows had lower concentrations of plasma glucose except at 3 h following intramammary LPS infusion, greater serum insulin at 3 and 12 h, and lower plasma NEFA at 24 and 48 h after infusion. Relative to cooled cows, non-cooled cows tended (P = 0.07) to have lower serum K concentration and had lower (P < 0.01) serum Zn 6 h following infusion (cooling by time interaction: P < 0.01). Relative to ZMC cows, IOZ cows had greater (P ≤ 0.09) concentrations of plasma Se, skim milk Na and Se, and skim milk Na to K ratio. Regardless of treatment, intramammary LPS infusion reduced (P < 0.01) serum or plasma concentrations of Ca, Mg, Zn, Fe, and Se, but increased (P < 0.01) their concentration in skim milk. In conclusion, deprivation of cooling resulted in more rapid and prolonged insulin release and influenced the systemic and mammary mineral metabolism during mammary inflammation induced by LPS of lactating dairy cows. Dietary supplementation of Zn–Met complex reduced blood and milk Se concentrations compared with cows fed Zn from an inorganic source.  相似文献   

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