呼和浩特地区牛乳及其乳制品中兽药残留现状调查

旨在了解呼和浩特地区牛乳及其乳制品中兽药残留现状。采用现场调查、问卷调查等方法,调查了65家经销奶产品超市及60家奶产品特产经销店乳制品的销售情况,调查了139名呼和浩特市市民对牛乳及其乳制品的食用情况;调查了35个牛场驻场兽医及10名相关专家在临床上的兽药使用现状。采用回顾性调查方法,调查了2014—2015年内蒙古有关权威部门采用LC-MS-MS、ELISA等方法对呼和浩特地区370份牛乳进行兽药残留检测的结果。采用HPLC方法,检测了呼和浩特地区74份牛乳制品样本中的兽药残留。调查结果显示,呼和浩特市被调查的对象中96.41%的消费者食用牛乳及其乳制品,56.11%的消费者关注乳制品中兽药残留问题;呼和浩特地区牛乳总销量的94.46%来自于呼和浩特地区奶牛场,5.54%来自于其他地区;94.44%的牛场有专职兽医;20%的被调查牛场有超量使用兽药的情况,85.71%的被调查牛场有用药记录,94.29%的被调查牛场严格执行兽药休药期;100%的牛场对所产牛乳进行抗菌药物检测;目前呼和浩特地区兽医临床最常用的4种抗菌药物分别为青霉素、氨苄西林、阿莫西林及头孢噻呋,其他有庆大霉素、甲硝唑等。实验室检测结果显示,呼和浩特地区2014—2015年生产的牛乳中兽药残留均为阴性,市售乳制品样本中亦未检出残留。呼和浩特各辖区生产、流通的牛乳及其乳制品均符合动物性食品中兽药最高残留限量要求。     

乳酸菌防治奶牛乳房炎的作用效果及前景展望

乳房炎是奶牛常见的疾病之一,患病奶牛因其废弃奶的产生,以及治疗和淘汰等相关费用的增加,给奶牛养殖业带来了巨大的经济损失。目前,对于奶牛临床性乳房炎的治疗主要依赖于抗生素,而抗生素的长期大量使用会导致耐药性病原菌的产生和牛奶中的药物残留等问题。作为抗生素的潜在替代品,乳酸菌在防治病原微生物方面很有潜力,现综述了乳酸菌防治奶牛乳房炎的作用效果、潜在机制及前景展望,以期为奶牛乳房炎的临床实践与科研提供参考。     

Ivermectin use and resulting milk residues on 4 Canadian dairy herds

The Canadian gFARAD was contacted for milk withdrawal recommendations after multiple cases of topical ivermectin use in lactating dairy cows. The following 4 cases included pertinent milk residue information and illustrate the challenges faced by producers, veterinarians, and regulatory authorities when ivermectin use occurs in dairy cows.     

Comparison of postvaccinal milk drop in dairy cattle vaccinated with one of two different commercial vaccines

Several veterinarians and dairy producers elect to vaccinate dairy herds with killed combination products in the fall or spring. Postvaccinal milk drop has been reported following the use of some killed vaccines, making it important to identify vaccines that can cause milk drop and evaluate the magnitude of postvaccinal milk drop. This study compared the pre- and postvaccinal milk production levels of dairy cows vaccinated with two commercial vaccines or injected with a saline placebo. Dairy cows receiving vaccine C (Cattlemaster Gold FP5; Pfizer Animal Health, Montreal, Canada) experienced a statistically significant difference in mean postvaccinal milk drop (-1.83 kg/cow/day) compared with cows receiving vaccine T (Triangle 4+Type 2 BVD, Wyeth Animal Health, Guelph, Ontario, Canada; -0.63 kg/cow/day) or saline (-0.02 kg/cow/day).     

Mastitis control services and utilization of milk somatic cell count data by veterinarians in Ohio

A telephone survey was conducted of 50 randomly selected Ohio-licensed veterinarians engaged in dairy practice. The survey's purpose was to determine the extent of mastitis control services offered by practitioners and to assess their utilization of milk somatic cell count (SCC) data on individual cows available from the Dairy Herd Improvement Association (DHIA). During the preceding year, 96% (48/50) of practitioners surveyed had performed bacteriologic culture of milk samples. Practitioners were twice as likely to have performed culture on milk from mastitic cows that failed to respond to treatment as they were to have performed culture for purposes of identifying pathogen trends within a herd. Veterinarians in predominantly dairy practices were more likely to have completed bacteriologic examination of milk in their own laboratories than were veterinarians who were engaged in less than 50% dairy practice (P = 0.016). Most veterinarians (83%) reported that coagulase test results were available or that Staphylococcus aureus was differentiated from other staphylococcal species. Streptococcus agalactiae was not differentiated from other streptococcal species by 35% of practitioners surveyed. For veterinarians with clients enrolled in the DHIA, 91% (43/47) reported looking at, discussing, or otherwise using the DHIA records. Eighty-one percent (35/43) of veterinarians who had clients using services from the DHIA reported that clients also received individual cow milk SCC results. Veterinarians engaged in predominantly, dairy practice expressed a greater familiarity with the linear score method of SCC reporting than did veterinarians whose practices were less than 50% dairy (P = 0.085); however, both groups reported a preference for raw SCC data.(ABSTRACT TRUNCATED AT 250 WORDS)     

Paratuberculosis sero-status and milk production,SCC and calving interval in Irish dairy herds

The objective of this study was to investigate the impact of paratuberculosis sero-status on milk yield, fat, protein, somatic cell count and calving interval in Irish dairy herds. Serum from all animals over 12 months of age (n = 2,602) in 34 dairy herds was tested for antibodies to Mycobacterium avium subsp. paratuberculosis using an ELISA. Herds were categorised by sero-status into positive, non-negative and negative, where a positive herd contained two or more positive cows, a non-negative herd contained only one positive cow and a negative herd contained no positive cows. Data at animal, parity and herd-level were analysed by multiple regression using general linear models. Positive herds (mean herd size = 129 cows) and non-negative herds (81 cows) were larger than negative herds (72 cows) (P < 0.01). Negative herds had the highest economic breeding index (EBI), while positive herds had the highest estimated breeding value (EBV) for milk yield. There was no significant effect of paratuberculosis sero-status at animal, parity or herd-level on milk yield, milk fat or protein production, somatic cell count score (SCCS) or calving interval. Negative herds tended to have a lower SCCS than positive and nonnegative herds (P = 0.087). This study only examined the effects of paratuberculosis sero-status but did not examine the clinical effects of Johne's disease at the farm or dairy industry levels.     

Dexamethasone and flumethasone residues in milk of intramuscularly dosed cows

A field study was performed to assess the level of drug residues in milk after therapeutic application of highly potent synthetic glucocorticoids. Dexamethasone was tested either as a crystalline suspension or as a combination of sodium phosphate and phenylpropionate esters. Intramuscular injection of these preparations in lactating dairy cows (60 μg dexamethasone/kg body wt) yielded drug residues in milk of up to 8.4 ng/mL 12 h after treatment. These dexamethasone residues fell to below 1.0 ng/mL within 3 days after treatment. Intramuscular injection of an aqueous flumethasone preparation (13.5 μg/kg body wt) produced drug residues in milk in the range of 0.7-1.2 ng/mL 12 h after treatment, whereas flumethasone was below the detection limit of 0.23 ng/mL 2 days after administration. These results indicate that toxicologically significant residues may arise transiently in the milk during the first 2-3 days after intramuscular injection of synthetic glucocorticoids. Urine from the same animals contained 5- to 50-fold higher glucocorticoid concentrations than the corresponding milk samples. Thus, urine analysis appears to be an effective method to monitor the use of synthetic glucocorticoids in food producing animals.     

Bovine spongiform encephalopathy and the safety of milk from Canadian dairy cattle

The detection of bovine spongiform encephalopathy (BSE) in beef cattle closed Canadian beef export markets to 30 countries, including the USA, with devastating financial losses. The detection and confirmation of the fifth and seventh BSE-infected animals but first infected dairy cows extended the problem of risk management to Canadian dairy farmers. As the public are concerned about the safety not only of beef but also of milk and milk products that may contain disease-causing prions, this review examines the evidence for the safety of milk from studies on prions in milk or colostrum and their vertical and lateral transmission in various animal systems. The evidence indicates that the risk of contracting new variant Creutzfeldt-Jakob disease through the consumption of milk is negligible.     

Record keeping,genetic selection,educational experience and farm management effects on average milk yield per cow,milk fat percentage,bacterial score and bulk tank somatic cell count of dairy farms in the Central region of Thailand

A study was conducted to estimate the record keeping, genetic selection, educational, and farm management effects on average milk yield per cow (AYC), milk fat percentage, bacterial score, and bulk tank somatic cell count (BTSCC) of dairy farms in the central region of Thailand. Farms were located in the provinces of Saraburi and Nakhon Ratchisima and were members of the Muaklek dairy cooperative. Records from individual animals were unavailable. Thus, farm records of milk yield, milk fat percentage, bacterial score, and BTCCC were collected from July 1, 2003 through June 30, 2006. Additional record keeping, genetic selection, education, and farm management information was collected through a questionnaire in May of 2006. Data from the Muaklek dairy cooperative and the questionnaire were then merged by a farm identification number. A single trait mixed model was used to analyze AYC, milk fat percentage, and BTSCC, while a log linear model was used to analyze bacterial score. Results showed that farms that kept records on individual animals had higher (P < 0.05) milk fat percentages and lower bacterial scores than farms that did not. Farms that used genetic information (EBV) and phenotypes when selecting sires were higher (P < 0.05) for milk fat percentage than farms that used only phenotypes and personal opinion. Farms milking cows with a single unit milking machine and by hand, had higher (P < 0.05) bacterial scores and BTSCC than farms using only a single or multi unit machine. Overall farms that kept individual animal records, used EBV when selecting sires, used a single method for collecting milk, and used family labor achieved higher performance from their herds than farms that did not.     

Licking induced changes to the pattern of moxidectin milk elimination after topical treatment in dairy cows

Pour-on administration of the macrocyclic lactones anti-parasitic compounds in beef and dairy cattle is now worldwide accepted. However, the information available on their milk excretion pattern, after topical administration is rather limited. Additionally, the cattle licking behaviour has been proven to affect the kinetics of these anti-parasitic compounds. The purpose of this study was to investigate the influence of the natural licking behaviour on the plasma and milk disposition of moxidectin (MXD), topically administered (500 μg/kg) in lactating dairy cows. Ten lactating Holstein dairy cows (705 kg body weight) were allocated into two experimental groups ( n  = 5). The licking was prevented during 5 days postadministration in animals in group I, and the remaining cows (group II) were allowed to lick freely. MXD concentrations profiles were measured in plasma and milk over 15 days posttreatment. The licking restriction period caused marked changes in MXD disposition kinetics both in plasma and milk. Both plasma and milk MXD concentrations (partial AUC 0–5 days) were significantly lower ( P  < 0.05) in licking-restricted cows. After the 5-day of restriction period, the animals were allowed to lick freely, which permitted the oral ingestion of MXD, situation clearly reflected both in plasma profile and milk excretion pattern. Despite the enhanced MXD milk concentrations measured in free-licking cows, drug concentrations did not reach the maximum MXD residues limit.     

Effect of supplementing a high-protein ram press sunflower cake concentrate on smallholder milk production in Zimbabwe

Ram press sunflower cake protein concentrate was formulated locally and its effect on the performance of dairy cows was compared with that of a commercial dairy concentrate. The effects of concentrate on roughage dry matter intake, milk yield and milk composition, live weight and calving intervals were similar for all concentrates, which indicated that the home grown dairy concentrates were as effective as the dairy commercial concentrate. The lack of significant differences in the concentrations of rumen NH₃-N, pH, VFAs and total AA in all the cows between concentrate types supported this. The results indicated that in the low-resource and low-input production systems, crossbreds were as productive as Jersey and Red Dane cows. The exotic cows were more susceptible to tick-borne diseases and mastitis, and showed higher incidences of calving problems and retained placenta compared with crossbred cows. The economics of feeding ram press sunflower concentrate were compared with those of a commercial dairy concentrate on the performance of crossbred, Red Dane and Jersey cows. The gross margin was higher when feeding sunflower cake than when feeding commercial dairy concentrate (p < 0.05).     

Antibiotic residues (bacterial inhibitory substances) in the milk of cows treated under label and extra-label conditions

The objectives of this study were to describe the depletion pattern of antibiotic residues (microbial inhibitory substances) from the milk of cows treated under field conditions of clinical disease and antibiotic administration, including both label and extra-label use, and to determine if the type of extra-label use, the route of administration, and the drug used were factors associated with prolonged shedding of residues in milk.

Milk samples from 138 cows, treated with a variety of antibiotic products on farms in southwestern Ontario in 1989 and 1990, were collected before treatment and for six days after cessation of treatment. Samples were tested for antibiotic residues with the Brilliant Black reduction test (BR-test) and the Bacillus stearothermophilus var calidolactis disc assay. In 13/138 (9.4%) of cow treatments, at least one milk sample was positive on both antibiotic residue tests after the label milk withholding time for the drug(s) used. In ten of these instances, the antibiotics were administered in extra-label fashion and in three the drugs were reportedly used according to label instructions. Extra-label use of antibiotics was significantly associated with increased risk of antibiotic residues in milk beyond the label withholding time. No significant differences in risk were observed among the various antibiotic products used in the study.

The farms involved in this study were selected on the basis of their proximity to our laboratory; therefore, the frequency of antibiotic residue detection after withholding times may not be indicative of the provincial or national situation. If farmers and veterinarians find themselves in a situation where extra-label use of an antibiotic is necessary, use of an alternative antibiotic that can be used at label dose and with a known withdrawal time may avoid a problem with residues.

     

Drug and chemical residues in livestock

The problem of drug and chemical residues in foods of animal origin has become increasingly important to the entire livestock industry as growing consumer health concerns continue to erode the demand for these products. Although nearly 90 per cent of all drugs approved for use in livestock are available for over-the-counter sales, in the public's view, it is only the veterinarian who administers drugs to animals and who, therefore, is responsible for all drug residues in food. Congress has responded to these consumer concerns by applying increased pressure on the FDA to restrict the extra-label use of drugs by veterinarians. The veterinary profession now finds itself in a position in which it must reexamine its current drug-use policies and strive to develop policies that are more responsible to the consumer, both in appearance and substance.     

益生菌治疗奶牛乳腺炎的研究进展

乳腺炎是影响奶牛生产性能及健康最常见、最严重的疾病之一,可以导致奶牛淘汰、养殖场（户）经济损失。该病常用抗生素治疗,但易产生耐药性,畜产品存在抗生素残留,不利于奶牛养殖业绿色健康发展。益生菌具有增强奶牛免疫力、降低发病率和改善生产性能的优势,可替代抗生素,有良好的应用价值。本文对奶牛乳腺炎危害、益生菌有益作用和替代抗生素治疗的潜质进行综述,推动奶牛养殖业绿色、健康发展。     

畜禽产品兽药残留危害现状与分析

近20年来,随着养殖业的集约化、规模化发展,各种动物疫病不断暴发,养殖场为预防和控制动物疫病,大量使用各种兽药。然而,滥用兽药和非法使用违禁药物的现象时有发生,严重影响了畜禽产品的质量和食品安全。因此,开展兽药残留的检测与调查,对于提高人民健康水平,加强畜禽产品的市场竞争力有着重要意义,也为兽药残留的科学研究提供了基础性资料。     

Use of the Food Animal Residue Avoidance Databank (FARAD)

OBJECTIVES: To report the results of 3 surveys evaluating the extent that the Food Animal Residue Avoidance Databank (FARAD) is used by veterinarians, the profession's perception of the need for the program, barriers that prevent veterinarians from fully using the service, and the perceptions that animal production industry groups have regarding FARAD. DESIGN: Telephone and mail surveys were used to collect information using cross-sectional, case-control, and directed sample studies. SAMPLE POPULATION: Food animal veterinarians and veterinarians and nonveterinarians in allied animal industries or with special interest in production animal medicine. RESULTS: The use of FARAD was high among dairy and general practitioners, but low among beef practitioners and veterinarians with minor commitment to food animal medicine. Solo practitioners and veterinarians with less than 13 years in practice were less likely to use FARAD. Dairy practitioners who had not used FARAD were most likely to prescribe extralabel products. CLINICAL IMPLICATIONS: Results imply that dairy and general food animal practitioners have either greater need or access through educational networks and are more aware of FARAD than practitioners who work with beef and those with a minor component of their practice involving food animals. The difference in familiarity and use of FARAD between practice type is an important finding, but the root of the difference is not clear; it may be attributable to a difference in the effectiveness of knowledge transfer for the groups, or the message is ignored because the issue of drug residues is less compelling for veterinarians and their clients in the beef sector.     

Association between milk production, somatic cell count and bacterial dermatoses in three dairy cattle herds

OBJECTIVE: To determine the correlations between three bacterial dermatoses in cattle, milk production and bulk-milk somatic cell count (BMSCC). DESIGN: Field observations in three dairy cattle herds. METHODS: Milk production, BMSCC, fertility and all herd diseases were recorded by computerised dairy management systems. Each herd was visited twice weekly and the clinical signs, course of diseases and morbidity and culling rates were noted. Bulk-tank milk was sampled twice monthly and analysed for somatic cell count. Bacteriological and histological examinations were carried out from samples collected from affected animals in the respective herds. RESULTS: The acute exudative form of dermatophilosis was diagnosed only in first-calving cows. The morbidity rate was 53% and the culling rate was 16% of the affected animals. The BMSCC increased by a factor of 2.4 times, and there was an average loss of milk production of 30%/cow/day in affected animals. Ulcerative lymphangitis was diagnosed in first-calving cows (22%) and older cows (15%). The culling rate was 28%. The BMSCC increased by a factor of 17.3 times, and the average loss of milk production was 5.5%/affected animal/day. Papillomatous digital dermatitis (PDD) was diagnosed in first-calving cows (25%) and in older cows (18%). The culling rate was 8%. The BMSCC increased by a factor of two times, and the average loss of milk production was 1.7%/affected animal/day. CONCLUSIONS: The correlations between three skin diseases (ulcerative lymphangitis, dermatophilosis, papillomatous digital dermatitis), milk production and BMSCC have been found to be unfavourable.     

Fenbendazole-related drug residues in milk from treated dairy cows

Oral administration of [¹⁴C] fenbendazole (FBZ) at a dose of 5.Omg/kg leads to the presence of radiolabel in the milk of lactating dairy cows. However, the maximum mean concentration of total FBZ equivalents quantitated to one-third of the recommended safe concentration in milk (1.67 μg/mL). The label is equally distributed to the fat and aqueous portions of the milk. The maximum level, in general, is attained approximately 24-36 h after drug administration, with the highest levels ranging from 24 to 48 h after administration. The residues rapidly deplete, attaining levels of 10-20ng/mL by day 5, and are essentially undetectable by radiolabel monitoring by day 6. Extraction of the milk by matrix solid phase dispersion indicated that the label was distributed between traces of the parent drug, FBZ, and predominantly, the FBZ sulphoxide (SO) and sulphone (SO₂) metabolites. No other radiolabelled peaks were observed. Based on these data the metabolites of FBZ, FBZ-sulphone and FBZ-sulphoxide, could be used as marker residues for monitoring the administration of FBZ to lactating dairy cows.     

The benefits of animal identification for food safety

The Center for Veterinary Medicine supports the effort to have a practical, workable form of mandatory animal identification. An animal identification system will make tracing of the source of animals with drug or chemical residues quicker and more effective. One of the best means of addressing and solving the problem of residues is through mandatory livestock identification. A successful traceback benefits both the producer and the industry. The U.S. Department of Agriculture (USDA) has proposed a mandatory nationwide system to require that all swine in interstate commerce be identified. Under the proposal several means of identification are listed and could be used. Additional methods or devices could be requested in writing to USDA. Persons required to keep records under the system would maintain the documents at their place of business for 2 yr. Records would be available to authorized USDA employees during ordinary business hours. FDA has had difficulty tracing tissue residue violations, particularly those involving sulfamethazine residues in swine. Investigations involving culled dairy cows and veal calves also have been closed due to lack of producer identification. The ability for FDA to determine the source of residues is vitally important in a coordinated government program to eliminate illegal tissue residues.     

我国部分地区乳房炎奶样中大肠杆菌的分离鉴定及耐药性分析

为了解我国部分地区奶牛乳房炎奶样中大肠杆菌的耐药情况,以指导牛场合理使用抗生素,提高治疗效果和畜产品质量,从全国六个省市自治区采取158例奶牛乳房炎的奶样,对奶样中的大肠杆菌进行分离纯化与鉴定,并进行药敏试验。结果显示,158份奶样中,共分离出38株大肠杆菌,其中黑龙江18株(分离率为36.0%)、上海3株(分离率6.0%)、北京3株(分离率27.2%)、新疆10株(分离率33.3%)、山东4株(分离率26.7%)、陕西0株(分离率0)。药敏试验显示,磺胺异噁唑耐药率最高,为73.7%;环丙沙星、诺氟沙星、四环素、链霉素药物的敏感率最高,为100%。分离菌株最多耐13种药物,最少耐4种药物,呈现多重耐药性。不同种类的抗生素中,上海和山东对β-内酰胺类药物和氯霉素类药物以及黑龙江、上海和新疆对磺胺类药物的耐药情况比较严重,耐药率高达50%以上。结果表明,各地区分离株对多种抗菌药物产生了不同程度耐药性和多重耐药,临床兽医在治疗时应注意合理用药,提高疗效和畜产品质量,减少耐药性的产生。