2019年呼伦贝尔地区奶牛产奶量及质量指标不同月份变化分析

旨在探讨内蒙古自治区呼伦贝尔地区不同月份荷斯坦奶牛乳成分、体细胞数和菌落总数的变化情况。试验共采集2019年1-12月14 354批次样本进行分析,以探索不同月份对奶牛产奶量、乳成分、体细胞数和菌落总数的影响。结果表明：呼伦贝尔地区荷斯坦奶牛产奶量在不同月份有变化,4-5月达到最高值,11月到次年2月最低,建议在该阶段做好奶牛冷应激防护;体细胞数在1-3月比较高,建议加强奶牛饲养管理,注意乳房炎防控;乳成分和菌落总数基本不受月份变化影响。     

Coagulase-negative staphylococci and mammary gland infections in cows

Coagulase-negative staphylococci (CNS) are the most frequently isolated bacteria from bovine mammary gland milk samples. The objective of this study was to determine the type of inflammation evoked by CNS in the mammary gland of cows during their first lactation. Twenty-four Israeli-Holstein heifers in their first lactation were tested for bacteriological status, somatic cell count (SCC) and differential leucocyte count in milk 60-120 days postparturition and every 50-60 days after until drying off. Following the first testing, the 96 quarters of the 24 heifers were classified as follows: 69.8% as no bacterial growth (NBG), 27.1% infected with CNS and 3.1% infected with Staphylococcus aureus. During lactation, 84.5% quarters had no change in their classification, 6.2% were newly infected with other pathogens, 3.1% were classified as self-cured and in 6.2% sporadic bacteria were isolated. Among the CNS, S. intermedius, S. chromogenes and S. haemolyticus were the most frequently isolated. Milk from CNS-infected quarters had significantly higher SCC than milk from NBG quarters. An analysis of the leucocyte pattern in milk from CNS vs. NBG quarters revealed a significant increase in polymorphonuclears and a significant decrease in the percentage of total lymphocytes and lymphocytes bearing CD4+ or CD8+. The high percentage of CNS-infected quarters that remained unchanged in their bacterial status during the first lactation, indicates that those CNS have the ability to elude the immune system and persist in the mammary gland for a long time. The persisting infection, resulting to some extent from an increase of SCC by some CNS strains, suggests that in the near future control steps will have to be taken into consideration, in order to enhance the improvement of milk quality.     

Seasonal variation of bulk milk somatic cell counts in UK dairy herds: investigations of the summer rise

Individual cow somatic cell count (SCC) patterns were explored over a one year period in 33 dairy herds to investigate the reason for a summer rise in bulk milk somatic cell counts (BMSCC). Cow test day somatic cell counts were categorised according to the magnitude of change since the previous test day reading, to examine which categories were responsible for the summer increase. Multilevel models using Markov chain Monte Carlo methods were specified to estimate the number of somatic cells/ml produced by different cell count categories. Stage of lactation and parity were accounted for in the models. There was an increase in the proportion of cows that remained above 200,000 cells/ml for two consecutive recordings in summer and this group of cows were responsible for 70.8% of the increase in somatic cells/ml produced from May to September compared with October to March. There was no evidence that a greater new infection rate (somatic cell counts moving from below 100,000 cells/ml to over 200,000 cells/ml) contributed to the increased summer bulk milk somatic cell counts. There was no indication that a general small increase in all somatic cell counts played an important role in the increased summer somatic cell counts. Markov chain Monte Carlo methods provided a valuable and flexible platform for parameter estimation in reasonably complex multilevel models.     

Studies on induced Klebsiella mastitis with relationships among N-acetyl-beta-D-glucosaminidase, bacterial and somatic cell counts

Mastitis was induced by infusion of 3,000-7,000 colony-forming units of Klebsiella pneumoniae into the left rear quarter of four primiparous Holstein-Freisians. Greater than 100 organisms were recovered from a quarter milk sample within 2 hr and in 87.5% of the hourly cultures taken after 8 hr. Bacteria, California Mastitis Tests, somatic cell counts and N-acetyl-beta-D-glucosaminidase levels differed significantly from that of control quarters in infused cows after hr 6, 8, 9 and 9 respectively. High correlations were obtained between somatic cell count and N-acetyl-beta-D-glucosaminidase (r = .97) and N-acetyl-beta-D-glucosaminidase and natural log bacterial count (r. = .88). N-acetyl-beta-D-glucosaminidase was related to natural log bacterial counts of samples taken 1, 2, 3, and 4 hr prior to the test (rN-acetyl-beta-D-glucosaminidase and natural log bacterial count (r = .91, .92, .93, and .95).     

Effects of intramammary infection and parity on calf weaning weight and milk quality in beef cows

The objectives of this study were to determine 1) the effect of intramammary infection on calf weaning weight, milk somatic cell count, and milk composition, and 2) the effect of parity on percentages of infected cows, infected quarters, and blind quarters. The number of infected quarters, milk somatic cell counts, milk components, and intramammary infection were studied at weaning in 164 beef cows. The percentage of infected cows ranged from 61.9% at first parity to 66.7% at fifth to ninth parities. Cows with three or four infected quarters had higher (P < .01) milk somatic cell counts than cows with zero, one, or two infected quarters. Among bacterial isolates, Staphylococcus aureus-infected quarters had the highest (P < .01) milk somatic cell count. Percentages of butterfat and lactose were lower (P < .01) in milk from infected quarters than from uninfected quarters. Infections by S. aureus and coagulase-negative staphylococci were the most common and accounted for 67 to 78% of the infections. Percentages of infected quarters and infections caused by S. aureus increased with parity (P < .01). Intramammary infections did not affect (P > .10) calf weaning weight. In conclusion, intramammary infection had no effect on calf weaning weight but increased milk somatic cell count and decreased the percentage of protein, lactose, solids-not-fat, and butterfat. The number of infected and blind mammary quarters increased with parity.     

Effect of premilking teat disinfection on mastitis incidence, total bacterial count, cell count and milk yield in three dairy herds.

An iodophor teat disinfectant was applied before milking by dip or spray to 50 cows and 50 cows were left untreated in each of three commercial herds. The mean incidence of clinical mastitis was reduced by 57 per cent, the total bacterial count by 70 per cent and the count of thermoduric organisms by 32 per cent. These results were not statistically significant, except that one herd showed a significant decrease in total bacterial count. There was no effect on somatic cell count, milk production or milk iodine residues. Atmospheric iodine concentrations increased in the two herds which applied the treatment as a spray, but the levels attained were not likely to be detrimental to human health.     

牛奶质量安全主要风险因子分析Ⅶ.体细胞数和菌落总数

体细胞数和菌落总数是衡量奶牛乳房健康状况和乳品质量的一项重要指标。作者对主要国家牛乳中体细胞数和菌落总数的限量进行了比较,分析了中国与主要国家限量的异同及原因,介绍了体细胞数和菌落总数的检测方法,对体细胞数的变化规律、风险评估进行综合分析阐述。     

Somatic cells count in cow's bulk tank milk

The objective of this study was therefore to present factors affecting somatic cell counts in bovine bulk milk as a result of intramammary infections as well as non-infectious factors. The paper presents also the impact of on-farm management practices on the level of bulk milk somatic cell counts and presents quality indicators in bulk tank milk. At the farm level bulk milk bacterial infection takes place through three main sources: bacterial contamination from the external surface of the udder and teats, from the surface of the milking equipment, and from mastitis microorganisms within the udder. The threshold of 200,000 cells/ml identifies bacteriological negative quarters of the udder. The counts of mammary pathogens in bulk tank milk are relatively low, on average not exceeding 1,000 cfu/ml. Environmental pathogens predominate in bulk tank milk samples with somatic cells count <300 × 10(3) ml.     

Staphylococcus aureus exosecretions and bovine mastitis

The role of Staphylococcus aureus and coagulase-negative staphylococcal exosecretions in bovine udder infection was tested by monitoring the cows' response to in vivo inoculation of bacterial exosecretions into udder quarters. Twenty Israeli-Holstein dairy cows were included in the study; two or three of the udder quarters of each cow were intracisternally inoculated with 0.04-0.05 mg/quarter (total proteins) of the various sterile bacterial exosecretions in a sterile pyrogen-free saline. Each udder was inoculated with two or three different bacterial exosecretions or placebo (Columbia Broth). Cows were monitored for 96 h post-inoculation for rectal temperature, heart and respiratory rates, alimentary tract activity (rumen contraction), udder temperature, pain, oedema and udder size. Milk samples were examined bacteriologically and for somatic cell count, N-acetyl-D-glucosaminidase (NAGase) activity and somatic cell differentiation. No enterotoxins (beta-G) or toxic shock syndrome toxin-1 were detected in response to any of the bacteria tested. Control quarters or those inoculated with Columbia Broth, showed similar NAGase and somatic cell count values throughout the experiment. Twelve of the 18 strains tested, induced inflammation in the inoculated quarters while six did not. Of the 12 strains causing local inflammation, only six were found significantly different from the control and were considered as high response (group 1). The other six that caused a local inflammation did not differ significantly from the control, and were considered to be moderate response (group 2). The six S. aureus isolates that did not cause an inflammatory response were considered to have low response (group 3). In all quarters inoculated with S. aureus bacterial exosecretions belonging to groups 1 and 2, the polymorphonuclear cells and macrophages were proportionally increased while CD4+ and CD8+ T-lymphocyte populations decreased. One-dimensional NuPAGE (7%) Tris-acetate gel electrophoresisof the bacterial exosecretions revealed four different bands appearing between 36 and 31 kDa, marked from top to bottom as A, B, C and D. An association was found between the combinations of expressed bands and the cow responses: the majority of the cases could be linked to the expression of bands B and C.     

Relationships between infection with caprine arthritis encephalitis virus, intramammary bacterial infection and somatic cell counts in dairy goats.

Somatic cell counts, the bacteriological condition of the milk and antibodies against caprine arthritis encephalitis virus (CAEV) were measured monthly throughout lactation in 121 lactating goats of the Murcia-Granada breed in four commercial dairy goat herds. The prevalence of bacterial intramammary infection was 5.6 per cent and the prevalence of CAEV infection was 20.6 per cent. An analysis of variance revealed a significant effect of herd, intramammary infection and the interaction between intramammary infection and CAEV on the somatic cell count. In udder halves free of intramammary infection, the somatic cell counts were significantly lower in seronegative goats than in seropositive goats (P<0.05), but the difference was not significant in udder halves persistently infected by bacteria. There was a significant increase in somatic cell counts due to bacterial intramammary infection (P<0.01) in the seronegative goats, but this effect was not present in the seropositive animals.     

原料奶生产良好卫生规范(GMP)的实施效果

随着乳品工业的迅速发展,长效奶、学生奶等的兴起,乳品企业对原料奶的卫生要求也随之提高。而原料奶中的细菌数和体细胞数的含量又取决于牧场的卫生条件、牛体的健康状况、挤奶方式、储藏条件、储藏时间以及运输条件。本试验对实施牧场GMP(Good Manufacturing Practice)前后原料奶的卫生质量进行了比较。结果发现,GMP规范的实施有效地降低了原料奶中的细菌总数和体细胞数。     

Milk leucocyte populations in heifers free of udder infection

Improvement of udder health through a process of genetic selection is related to heritability and the role of the specific trait in the probability of an individual cow developing an infection. It was suggested that different patterns of leucocyte population of the healthy gland are a significant factor in mastitis. Thus, in order to analyse the heritability of a trait and its correlation with udder health, the present study examined the leucocyte populations of uninfected mammary glands, their variability among quarters in a particular cow, and the changes that occur during lactation. Each one of the 20 cows examined was tested on average 3.06 times during lactation. The somatic cell count (SCC)/ml ranged from 12,000 to 151,000, the coefficients of determination (R2) were higher than 0.5 for SCC. No significant differences were found in the dependent variables between the sampled times (test) nor any interaction between the slopes calculated for the cows over time. No significant differences were found among quarters within a cow for any of the dependent variables including SCC. The effect of the cow trait was found to be significant for polymorphonuclear (PMN), macrophage (MO), and T-lymphocyte-bearing CD4+. The number of lymphocytes labelled with the anti-B monoclonal antibodies was negligible. In conclusion the patterns of leucocyte populations in milk together with the variance among cows should enable an analysis of the heritability of this trait and its correlation with udder health in a future study.     

Potential of differential somatic cell counts as indicators of mastitis in quarter milk samples from dairy cows

Bacteriological status, somatic cell counts and proportions of lymphocytes, granulocytes and monocytes were determined in 1,659 quarter milk samples from 39 dairy cows. Discriminant analysis was performed in order to assess the ability of total and differential somatic cell counts and combinations of total somatic cell count and each of the differential cell counts, to discriminate between infected and pathogen-free quarters, as well as between quarters infected with minor pathogens and quarters infected with major pathogens. Total somatic cell count classified 82.9% of all quarters correctly with respect to bacteriological status. Differential somatic cell count was less effective than total somatic cell count in discriminating between infected and pathogen-free quarters, as well as between quarters infected with minor vs. major pathogens. Combination of total and differential somatic cell counts did not improve the rate of correctly classified quarters. Inclusion of demographic data into the discriminant function increased the number of quarters correctly classified, mainly through an increase in the proportion of correctly classified infected quarters.     

A clinical trial to evaluate the effectiveness of antibiotic treatment of lactating cows with high somatic cell counts in their milk

OBJECTIVE: To determine the effectiveness of treatment of lactating cows with high somatic cell counts in milk. DESIGN: Randomised clinical trial. METHODS: Single pooled quarter samples of milk were obtained from cows with somatic cell counts above 500,000 cells/mL on fifty farms. Milk samples were cultured for known mastitis bacterial pathogens. Cows were randomly allocated to treated and untreated groups. Treated cows received both intramammary cloxacillin and parenteral erythromycin. Single pooled quarter milk samples were obtained at 6 weeks after treatment and were cultured for the presence of pathogenic bacteria. The percentage of samples with no growth at the post-treatment culture was used as an estimate of the bacteriological cures for each pathogen type and for each treatment group. Somatic cell counts of cows were compared between treatment groups and within pathogen group. The number of cows that completed a full lactation were compared between each treatment group and within each pathogen group. RESULTS: Treatment had no effect upon bacteriological cures, irrespective of pathogen present or the presence of bacteria during the previous lactation. There was no effect of treatment upon somatic cell count except for cows infected with Streptococcus dysgalactiae in which treatment caused a significant lowering of cell counts. This effect was not present in the subsequent lactation. Treatment of chronically infected cows did not alter the probability of a cow completing a full lactation but did improve the probability of newly infected cows being retained for the next lactation. Twenty-eight of 214 treated cows developed clinical mastitis in more than one quarter after treatment, thus indicating a poor technique by farmers for the insertion of intramammary antibiotics. CONCLUSIONS: Treatment during lactation of cows with high somatic cell counts in milk is ineffective in reducing bacterial infections and in reducing somatic cell counts to acceptable numbers.     

Milk leucocyte population patterns in bovine udder infection of different aetiology

This study compared the different leucocyte populations in milk from udders infected with different mastitic pathogens and in different stages of infection. Milk samples were collected from quarters free of intramammary infection, acutely infected with Escherichia coli or Staphylococcus aureus and chronically infected with S. aureus, coagulase-negative staphylococci (CNS) or Streptococcus dysgalactiae. Udder bacteriological status was confirmed after three consecutive bacteriological examinations from weekly quarter milk samples. At the time of the trial, milk samples were tested for somatic cell count (SCC) and differential cell count by both light microscopy (LM) and flow cytometry. Monoclonal antibody (mAb) CD11a/CD18 was used in order to differentiate between leucocytes and epithelial cells when tested by flow cytometry. Udder quarters free of intramammary infection had a mean SCC lower than 107 x 10(3) cells/ml in which the epithelial cells were the main cell type followed by polymorphonuclear cells (PMNs), while macrophages and lymphocytes had a lower concentration. Only 56% of the cells were labelled with the mAb anti-CD11a/CD18. In either acute E. coli- or S. aureus-infected quarters, SCC were significantly higher (P < 0.0001) than in samples from the time of inoculation, with over 90% of the cells labelled with the mAb anti-CD11a/CD18. The main cell type was neutrophils. In chronically infected cows, differences in SCC and in leucocyte patterns were found between infecting pathogens as well as between quarters harbouring the same pathogen. In all the chronically infected quarters, SCC was significantly higher (P < 0.05) than in uninfected ones. The distribution of the leucocyte patterns in the quarters infected with S. dysgalactiae did not differ from that in quarters with acute infection with both E. coli and S. aureus. In the cows chronically infected with S. aureus or CNS, the proportion of PMN was higher but not significantly different from quarters free of intramammary infection, while epithelial cells were significantly lower (P < 0.05). The T lymphocytes bearing CD4+ or CD8+ were significantly higher in quarters chronically infected with S. aureus than in quarters free of intramammary infection and in quarters acutely infected with either E. coli or S. aureus. In all samples B cells were negligible.     

牛奶体细胞生成与乳品质量和安全的关系

牛奶体细胞数是反映奶牛乳房健康状况的重要指标之一,该指标偏高意味着奶牛可能处于亚健康或疾病状态。在奶牛正常生理状态下,牛奶体细胞的组成和数量都是基本稳定的,而当乳房外伤或疾病(如乳房炎等)发生时,牛奶体细胞数增多,产奶量降低,乳品质量下降。牛奶的品质关系到消费者的健康,因此,确保生鲜乳的质量安全是奶牛养殖工作者必须着手解决的首要问题。因此,本文围绕牛奶体细胞生成与产奶量和乳品质之间的关系展开综述,为提高乳品质量安全提供理论指导。     

Bacterial growth during the early phase of infection determines the severity of experimental Escherichia coli mastitis in dairy cows

The aim of this study was to investigate the importance of bacterial growth for the severity of experimental Escherichia coli mastitis, indirectly expressed as the area under the curve of bacterial counts in milk over time. The association of pre-infusion somatic cell count and post-infusion influx of inflammatory cells in milk with severity of infection was also examined. Bacterial growth was studied through culture in milk samples (in vitro) and through monitoring of bacterial counts in milk during the early phase of infection (in vivo) in 36 cows. Individual variation in bacterial counts was more than 2 x 10(2)-fold after 6 h of in vitro incubation, and more than 8 x 10(2)-fold 6 h after intramammary infusion. In vitro growth in milk was not associated with in vivo growth during the early phase of infection, nor with severity of E. coli mastitis. Somatic cell count before experimental E. coli mastitis was negatively associated with in vivo bacterial growth during the early phase of infection (R2 = 0.28), but was not associated with severity of E. coli mastitis (R2 = 0.06). In vivo bacterial growth during the early phase of infection (positive association; R2 = 0.41), together with influx of inflammatory cells in milk, expressed as mean hourly increase of somatic cell count between 6 and 12 h post-infusion (negative association; R2 = 0.11), are major determinants for the severity of experimental E. coli mastitis (R2 = 0.56).     

The contribution of mammary infections by coagulase-negative staphylococci to the herd bulk milk somatic cell count

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.     

Observations on intramammary infection and somatic cell counts in cows treated with recombinant bovine somatotropin.

Data were collected on udder health variables as part of a study of the effects of recombinant bovine somatotropin on production in lactating dairy cows. Milk samples, obtained at three intervals during the study, were assessed for their somatic cell count and bacteriological culture result. There was an increase in the prevalence of infection at mid-lactation in the 20.6 and 41.2 mg per day treatment groups as compared to the controls. There was no difference detected in the mean cell count between groups from the samples collected pretrial, mid-lactation, or late lactation. However, analysis of the individual cow Dairy Herd Improvement somatic cell count data showed a difference between groups which was most evident in mid-lactation.     

Efficacy of two antibiotic treatments in curing clinical and subclinical mastitis in lactating dairy cows

AIM: To compare the bacteriological and clinical cure rates for clinical and subclinical mastitis in New Zealand dairy cows following treatment with either an intramammary penicillin-dihydrosptreptomycin preparation or a subcutaneous injection of penethamate hydriodide. METHODS: Milk samples were collected from clinical and subclinical cases of mastitis before and 14 and 21 days after initiation of treatment for bacteriological culture, somatic cell count determination and conductivity testing. RESULTS: No significant differences in the bacteriological cure rate of major Gram-positive pathogens, clinical cure rate, somatic cell count or conductivity were found between treatments. However, the bacteriological cure rate of coagulase-negative staphylococcus infections and the overall bacteriological cure rate was lower for quarters treated with penethamate than with penicillin-dihydrosptreptomycin. CONCLUSIONS: The bacteriological cure rate of mastitis caused by major Gram-positive pathogens, the clinical cure rate, somatic cell count and conductivity did not differ between the two antibiotic treatments. .