Economic evaluation of the method of gradual formation of groups of dairy cows from primiparae free of infectious mastitis]

Employing the turnover of a dairy-cow herd with primiparas to control infectious mastitis is beneficial because young dairy cows, as a rule free of inflammations of the mammary gland, are not included among dairy cows already infected or suspected of being infected and so it is possible to form groups of dairy cows free of mastitis. For this intention an agricultural enterprise was chosen in potato production region I. In the given period 316 to 336 dairy cows of Bohemian Spotted breed were followed. To express the impact of the infection on the milk efficiency and to draw economic conclusions on the efficiency of treating infectious mastitis we observed the total milk yield of the different dairy cows in one lactation. In the given enterprise unsuccessful treatment of an infected dairy cow in three lactations resulted in a total loss of 4,648 Kcs. Therefore from the economic aspect it appears to be profitable to replace productive, but ill, older dairy cows by healthy first-calvers because the negative effect of the mastitis on the production of milk increases with every successive lactation.     

河北保定部分奶牛场临床型乳房炎发病情况调查研究

为探索奶牛临床型乳房炎的发病情况与泌乳量、泌乳期、季节之间的联系,以河北保定地区5个奶牛场为例进行调查研究。通过对调查结果的统计分析,结果显示：奶牛乳房炎多发生在泌乳90~150 d,泌乳天数越长发病头数越多;从产奶量来看,泌乳量越高发病牛比例越高;从发病季节来看,奶牛乳房炎在秋季发病率高,春季、夏季和冬季发病率低。     

Estimation of milk production losses due to sub-clinical mastitis in dairy cattle in Costa Rica

Five dairy farms, situated on the slopes of the volcano Poás in the pre-mountain cloud forest ecological zone, Alajuela and Heredia Provinces, Costa Rica, provided data for estimation of the production losses due to sub-clinical mastitis. Within the same farm, cows with proven sub-clinical mastitis were matched with cows without signs of sub-clinical mastitis, according to breed, lactation number and days in lactation. A total of 529 cows were detected with sub-clinical mastitis, of which only 200 could be paired with control cows free of mastitis; each pair was used only once.

Crude milk production losses per cow with sub-clinical mastitis were estimated at 1.56 kg day⁻¹for daily milk yield. Milk production loss per affected quarter due to sub-clinical mastitis was estimated to be 17.6% on average. The decrease in milk production in heifers with sub-clinical mastitis did not differ significantly from the decrease in production in older cows. No significant difference in milk production loss was detected when the data were stratified on parity or the number of quarters affected.     

Risk factors associated with the incidence rate of clinical mastitis in smallholder dairy cows in the Dar es Salaam region of Tanzania

Smallholder dairy herds around the Dar es Salaam region of Tanzania supply 86% of raw milk consumed by the city dwellers. Previous studies have indicated that clinical mastitis is an important disease affecting smallholder dairy cows and an 18-month questionnaire-based longitudinal field-study was conducted between July 2003 and March 2005 to elucidate risk factors associated with the incidence. A total of 6057 quarter-level observations from 317 lactating cows on 87 randomly selected smallholder dairy herds were analysed at the quarter and cow level using logistic and Poisson regression models, respectively. At the quarter level, the average incidence rate of clinical mastitis was 38.4 cases per 100 quarter-years at risk whereas at the cow level the incidence rate was 43.3 cases per 100 cow-years at risk. The incidence was significantly (P< or =0.001) associated with cow factors (body condition score, parity, stage of lactation, and udder consistency), housing (floor type) conditions and milking (cow and udder preparation) practices. It was concluded that the extrapolation of the classic ten-point mastitis control plan into smallholder dairy herds should be undertaken cautiously. An integrated approach to dairy extension should focus more on the creation of mastitis awareness among smallholder producers and on the improvement of animal nutrition and reproduction indices-factors that may also have a direct impact on milk yield.     

Prevalence and associations between bacterial isolates from dry mammary glands of dairy cows

To assess the prevalence and patterns of bacterial isolates, cultures were made from the dry mammary glands of dairy cows in six commercial dairy herds in the UK. Milk samples were taken from all four quarters of 480 cows at drying off and at weekly intervals from 14 days before to seven days after calving. A major mastitis pathogen was isolated from at least one quarter of 220 (45.8 per cent) of the cows and from more than one quarter of 90 (18.8 per cent) of them. During the late dry to calving period, of the 957 quarters with three culture results, a major mastitis pathogen was cultured from 236 (24.7 per cent) quarters of 186 (38.8 [corrected] per cent) cows. The most commonly isolated major pathogen was Escherichia coli, followed by Streptococcus uberis and coagulase-positive staphylococci. There were significant differences between the patterns of isolates from different farms and in different calving months, suggesting that the rate of infection was partially dependent on external conditions. The isolation of E. coli, S. uberis or coagulase-positive staphylococci from a cow during the late dry/periparturient period was associated with an increased risk of that cow being culled in the next lactation. Bayesian general linear mixed models were used to assess the associations between the different bacterial species. The probability of isolating either E. coli or S. uberis was significantly greater when the other organism was cultured in a milk sample; this was also true of coagulase-positive staphylococci and S. uberis. When Corynebacterium species were isolated from a milk sample, the probability of isolating coagulase-positive staphylococci or S. uberis decreased significantly, and when coagulase-negative staphylococci were isolated the probability of isolating coagulase-positive staphylococci was reduced.     

我国规模牛场奶牛个体生鲜乳体细胞数水平及影响因素探析

本研究旨在探析我国规模奶牛场奶牛个体生鲜乳体细胞数（SCC）的水平、分布和影响因素。利用SAS9.0的GLM模型,统计分析覆盖16个省（市、区）,33个规模奶牛场,23 351头中国荷斯坦牛,从2007年至2009年连续3年的225 775条奶牛个体生鲜乳SCC检测记录。结果表明：奶牛个体生鲜乳SCC的总体均值为48×104cell/mL,标准差为117×104cell/mL,个体生鲜乳SCC波动范围较大;其中,77.9%的奶牛个体,其生鲜乳SCC小于50×104cell/mL,对群体混合样生鲜乳SCC的影响系数为0.26;11.3%的奶牛个体,其生鲜乳SCC介于50×104～100×104cell/mL之间,乳房处于隐性感染状态,对群体混合样生鲜乳SCC的影响系数为0.16;10.8%的奶牛个体,生鲜乳SCC大于100×104cell/mL,理论上乳房处于临床感染状态,对群体混合样生鲜乳SCC的影响系数为0.58。奶牛个体生鲜乳体细胞数评分（SCS）呈正态分布,与奶牛个体因素（产奶量、乳脂率、乳蛋白含量、胎次和泌乳阶段）和环境因素（泌乳月份、泌乳季节）差异极显著（P〈0.01）,与奶牛养殖区域、奶牛场差异不显著（P〉0.05）。我国规模奶牛场奶牛个体生鲜乳SCC主要在50×104cell/mL以下,依据影响参数能实现对生鲜乳SCC水平的调控。     

Induced staphylococcal infections in the bovine mammary gland

In a study to develop and define a practical model of bovine mastitis caused by Staphylococcus aureus, induced infections were attempted in 203 bovine mammary glands of 41 cows, using 12 strains of S aureus. Approximately 100 colony-forming units of S aureus in saline solution were injected after milking, and milk samples were collected daily from test glands for 14 days to monitor the progress of infections and inflammatory responses. Relationships were examined for cow-related factors and for various characteristics of the strains of S aureus used to the development of a persistent intramammary infection. A dairy cow that was useful in this model was defined as follows: (1) the 2nd to 7th month in the 1st to 5th lactation; (2) producing milk from all mammary glands that contained less than 6 x 10(5) somatic cells/ml; and (3) having mammary glands that were free of any primary mastitis pathogen, as well as micrococci and Corynebacterium bovis. From the present study, it was not possible to define clearly a strain of S aureus which would be useful in the model, but 5 strains of S aureus were identified as being capable of producing persistent subacute infections with a high degree of repeatability.     

大连地区奶牛隐性乳房炎主要病原菌的分离鉴定及药敏试验

为了明确引起大连地区奶牛隐性乳房炎的主要病原菌及其发病情况,对大连市不同地区的256头黑白花泌乳奶牛进行调查研究,对奶牛隐性乳房炎奶样进行病原菌的分离鉴定及药敏试验。结果表明,检出奶牛隐性乳房炎阳性率为65.63%、乳区阳性率为51.95%;病原菌以金黄色葡萄球菌(Staphylococcus aureus)、链球菌(Streptococcus)和大肠杆菌(Escherichia coli)为主,占检出细菌总数的83.33%;体外药敏试验筛选出了对主要病原菌高度敏感的药物,能有效地治疗奶牛隐性乳房炎。     

An investigation of mastitis due to S agalactiae, S uberis and M smegmatis in a dairy herd

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.     

Costs associated with selected preventive practices and with episodes of clinical mastitis in nine herds with low somatic cell counts

Nine dairy herds (mean size, 149 cows) with bulk-tank milk somatic cell counts of less than 300,000 cells/ml and greater than 80% of cows with Dairy Herd Improvement Association linear somatic cell counts less than or equal to 4 were selected for study. Each herd was monitored for 12 consecutive months. Duplicate quarter-milk specimens were collected from each cow for bacteriologic culturing at beginning of lactation, cessation of lactation, and at the time of each clinical episode of mastitis. Streptococcus agalactiae was never isolated and Staphylococcus aureus was isolated from less than 1% of all quarters. There were 554 episodes of clinical mastitis. During the year of study, the incidence rate of clinical mastitis varied from 15.6 to 63.7% of cows among the 9 herds. Mean costs per cow per year in herd for mastitis prevention were: $10 for paper towels, $3 for nonlactating cow treatment, and $10 for teat disinfectants. Mean cost associated with clinical mastitis was $107/episode. Approximately 84% ($90) of the costs attributed to a clinical episode were associated with decreased milk production and nonsalable milk. Costs of medication and professional veterinary fees per clinical episode varied significantly among the 9 herds. Three of the herds did not have a veterinarian treat a clinical episode of mastitis during the year of study even though 2 of these herds had the first and third highest incidence rates of clinical mastitis. When calculated on a per cow in herd basis, mean costs of $40/cow/year were attributed to clinical mastitis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Test-day somatic cell score, fat-to-protein ratio and milk yield as indicator traits for sub-clinical mastitis in dairy cattle

Test-day (TD) records of milk, fat-to-protein ratio (F:P) and somatic cell score (SCS) of first-lactation Canadian Holstein cows were analysed by a three-trait finite mixture random regression model, with the purpose of revealing hidden structures in the data owing to putative, sub-clinical mastitis. Different distributions of the data were allowed in 30 intervals of days in milk (DIM), covering the lactation from 5 to 305 days. Bayesian analysis with Gibbs sampling was used for model inferences. Estimated proportion of TD records originated from cows infected with mastitis was 0.66 in DIM from 5 to 15 and averaged 0.2 in the remaining part of lactation. Data from healthy and mastitic cows exhibited markedly different distributions, with respect to both average value and the variance, across all parts of lactation. Heterogeneity of distributions for infected cows was also apparent in different DIM intervals. Cows with mastitis were characterized by smaller milk yield (down to -5 kg) and larger F:P (up to 0.13) and SCS (up to 1.3) compared with healthy contemporaries. Differences in averages between healthy and infected cows for F:P were the most profound at the beginning of lactation, when a dairy cow suffers the strongest energy deficit and is therefore more prone to mammary infection. Residual variances for data from infected cows were substantially larger than for the other mixture components. Fat-to-protein ratio had a significant genetic component, with estimates of heritability that were larger or comparable with milk yield, and was not strongly correlated with milk and SCS on both genetic and environmental scales. Daily milk, F:P and SCS are easily available from milk-recording data for most breeding schemes in dairy cattle. Fat-to-protein ratio can potentially be a valuable addition to SCS and milk yield as an indicator trait for selection against mastitis.     

Intramammary treatment of clinical mastitis of dairy cows with a combination of lincomycin and neomycin, or penicillin and dihydrostreptomycin

AIM: To compare clinical and bacteriological cure rates of clinical mastitis following treatment with intramammary preparations containing either lincomycin and neomycin or penicillin and dihydrostreptomycin. METHODS: Cases of clinical mastitis were sourced from four seasonal-calving dairy herds in the central Waikato region of New Zealand during the first 120 days of lactation. Affected quarters were infused three times at 12 h intervals with either 333 mg lincomycin plus 100 mg neomycin (lin/neo; 197 glands),or 1,000 mg penicillin plus 500 mg dihydrostreptomycin (pen/DHS; 207 glands). Milk samples were collected for bacteriology from each quarter immediately before and approximately 21 days after initiation of treatment. Additionally, a composite milk sample from each cow was collected, on average, 54 days after enrolment for assessment of milk yield, composition and somatic cell count (SCC). The probability of bacterial cure was initially analysed using Chi-squared analysis, and factors that were associated (p<0.2) were offered to a reverse stepwise logistic regression model. Continuous variables (e.g. milk solids production and log10 SCC) were analysed using general linear models. RESULTS: A total of 404 quarters diagnosed with clinical mastitis, from 282 cows in the first 120 days of lactation, were included. Streptococcus uberis, coagulase-negative staphylococci and Staphylococcus aureus were isolated from 56.5%, 18.8% and 10.0% of the bacteriologically positive quarters. There was no difference in the bacteriological cure rate (76.7% vs 76.7%, OR=0.94; p>0.8), the log10 SCC (2.1, SE 0.1, vs 2.0, SE 0.1; p>0.3) or milk production (1.2, SE 0.1, vs 1.2, SE 0.1, kg milksolids/cow/day; p>0.7) between lin/neo vs pen/DHS treatments, respectively. However, the proportion of cows re-treated following initial treatment was higher for the lin/neo compared to pen/DHS-treated group (16.3% vs 5.2%, OR=3.46; p<0.05). CONCLUSIONS: No difference in bacteriological cure rate, milk production or SCC was evident between lin/neo and pen/DHS intramammary treatments for clinical mastitis in dairy cows during the first 120 days of lactation. KEYWORDS: Dairy cow, mastitis, intramammary, antibiotic, treatment, somatic cell count.     

Natural and experimental bovine intramammary infection with Prototheca zopfii

A naturally occurring case of chronic mastitis caused by Prototheca zopfii was detected in a dairy cow. The cow was observed for 12 weeks, and milk samples were cultured each week. Milk production was decreased, and high numbers (greater than 10(3)/ml) of the organism were detected in the milk. Six glands of 2 cows were inoculated with small numbers of P zopfii. All 3 cows were euthanatized, and at postmortem, a progressive pyogranulomatous inflammation was observed in all infected mammary glands. The organism was recovered from tissue and secretions from all inoculated glands and from lymph nodes draining these glands but not from other tissues.     

Study of clinical mastitis in British dairy herds with bulk milk somatic cell counts less than 150,000 cells/ml

A 12-month prospective study of clinical mastitis was conducted in 482 British dairy herds with a bulk milk somatic cell count (BMSCC) of less than 150,000 cells/ml. The mean proportion of cows in the herd with clinical mastitis was 23.1 per cent (range 0 to 80), with a mean of 1.50 quarter cases per cow. The mean incidence rate of clinical mastitis was 36.7 quarter cases per 100 cow years (range 0 to 208.2). Twelve per cent of the quarter cases showed systemic signs, including inappetence and severe lethargy. Over 22 per cent of quarter cases occurred in the first seven days of lactation and over 50 per cent occurred in the first 90 days of lactation. Cluster analysis indicated that the main difference between herds with a low and average incidence of mastitis was the proportion of clinical cases occurring in the first seven days of lactation, 14 per cent compared with 44 per cent, respectively. The risk of severe clinical mastitis compared with mild clinical mastitis decreased significantly as the individual cow somatic cell count (SCC) in the month before clinical mastitis was diagnosed increased.     

酶菌复合制剂对奶牛生产性能和体细胞数的影响

本试验旨在研究酶菌复合制剂对奶牛生产性能和体细胞数的影响。选取年龄、胎次、泌乳天数及生理性状相近的荷斯坦奶牛240头,随机为成4组,每组6个重复,每个重复10头牛。对照组饲喂基础日粮,试验Ⅰ、Ⅱ和Ⅲ组分别在基础日粮中添加0.5、1.0和1.5 kg/t的酶菌复合制剂,预试期10 d,正试期40 d,分别于试验第10、20、30、40天采集牛粪便,利用粪便分析筛对牛粪便组成进行分析。分别在试验第1、20、40天采集乳样,采用乳汁分析仪测定各组乳样中乳脂率、乳蛋白率、非脂固形物和奶中体细胞数（SCC）,试验期间记录每头牛平均日产奶量（ADMY）及平均日采食量（ADFI）。试验结果表明,添加酶菌复合制剂能够显著增加奶牛平均日产奶量（P<0.05）,提高牛乳中乳蛋白和乳脂肪含量（P<0.05）,降低体细胞数（P<0.05）,改善粪便结构。综合试验结果,酶菌复合制剂应用于奶牛养殖的最优添加量为1.0 kg/t,可以提高奶牛产奶量,降低牛体细胞数。     

奶牛日粮添加"NPN"补充料试验研究

[目的]为了解"NPN"的饲喂效果.[方法]选取年龄、体重、胎次、泌乳阶段、日产奶量相近的中低产奶牛24头,随机区组为试验组和对照组,每组12头.对山西省现代农业研究中心和山西省农业科学院畜牧兽医研究所联合开发的专利产品"反刍动物'NPN'补充料"进行了为期70 d的应用试验.[结果]表明:试验组12头奶牛70 d总产...     

The economic benefit of treating subclinical Streptococcus agalactiae mastitis in lactating cows

The economic benefits of treating lactating cows for Streptococcus agalactiae mastitis were studied at a large (689 milking cows) central California dairy. Postcure milk production of case cows (infected, treated, and cured) was compared with production of paired control cows (uninfected) and was matched for yield, days in milk, days in gestation, and parity. A simulation was used to plot expected lactation curves for mastitic cows (infected, not treated) with characteristics similar to those of each control cow, and these curves were compared with actual case-cow lactation curves. The difference in actual and expected production was used to calculate net economic benefits of treatment. Comparison of expected with actual production indicated a net benefit from treatment of $396/cow for cows treated in early lactation and $237 for cows treated in midlactation, but a net loss of $55 for cows treated in late lactation. Lactation number did not have a significant impact on economic benefits of treatment. In contrast to other studies indicating no economic benefit from treating mastitis during lactation, this study's positive results may have been attributable to the high cure rate (98%) and the subclinical form of mastitis being treated. Streptococcus agalactiae mastitis treatment during early and midlactation would appear to be an economically justifiable option for dairy managers.     

硒与奶牛隐性乳房炎相关性的研究进展

奶牛乳房炎是我国奶牛疾病中发病率最高的疾病之一,严重影响奶牛产奶量和乳制品质量,给奶牛养殖业造成巨大经济损失。有证据表明,多种营养物质的缺乏都会增加奶牛隐性乳房炎的发病率。其中,微量元素硒能改善奶牛乳腺免疫功能,对奶牛乳腺健康和降低隐性乳房炎发病率具有重要意义。主要阐述硒与奶牛隐性乳房炎的相关性,以期为通过调控乳腺免疫功能和防控乳腺炎提供依据。     

Aetiology of clinical mastitis in six Somerset dairy herds.

Clinical mastitis was monitored in six Somerset dairy herds for one year. The herds all had three-month geometric mean bulk milk somatic cell counts of less than 250,000 cells/ml. Escherichia coli was the predominant pathogen isolated on all the farms and in all months of the year. Environmental pathogens accounted for 61.4 per cent of all cases of clinical mastitis and for 79.3 per cent of the mastitis cases in which an aetiological agent was identified. The mean annual incidence was 41.6 cases per 100 cows (range 14 to 75). Affected cows suffered a mean of 1.5 cases and 16.4 per cent of quarters suffered at least one repeat case. Mastitis due to E. coli was more severe than mastitis due to other causes and it tended to be more severe in early lactation and during the housing period. Mastitis was significantly more severe (grades 2 and 3) in the herd with the lowest bulk milk somatic cell count and in the herd which was kept indoors throughout the year than in the other four herds. Mastitis was fatal in 2.2 per cent of cases and resulted in the death of 0.6 per cent of the lactating cows.     

Factors prior to dry period associated with high and low levels of cow milk somatic cell counts in next lactation

Data from a randomized controlled field study of selective dry cow therapy were used in which 686 cows had been allocated to 2 control groups (sampling only or placebo) or 2 therapy groups. Possible factors from previous lactation were assessed in determining their association with the probability of 'failure', designated as a cow milk somatic cell count (CMSCC) of greater than 399,000 per ml in geometric mean of several measurements during subsequent lactation. Success cows were those with a CMSCC of less than 200,000 per ml. For our analyses, this targeted 187 success cows and 186 failure cows. Therapy was given as a total dose of 400,000 IU penicillin and 100 mg neomycin per infected quarter as dry cow preparation once, or as a lactation formula with a total dose of 1.2 million IU penicillin and 1,200 mg dihydrostreptomycin per infected quarter during a 1-week period. Significant factors in the predictive model for success included therapy, low level of CMSCC (geometric mean of the 3 last tests) in previous lactation, low level of CMSCC (weighted by daily milk yield mean) in the herd, young cows, and not having had a case of treatment for chronic clinical mastitis. Additional information on the probability of failure in treated and untreated cows can be predicted by number of quarters infected with Staphylococcus aureus approximately 1.5 months before drying off. The models derived are considered for use as tools in selective treatment and culling decisions.