Industrial Dairy Farms Research Articles

The first study of bovine immunodeficiency virus (BIV) and brucellosis co-infection in west-central Iran

Background: BIV is a well-known bovine immunosuppressive cause, but its pathogenesis has not been well characterized. In recent years, it has been hypothesized that infection with BIV might predispose cattle to be infected by other agents. OBJECTIVE: This study was performed to investigate of BIV and Brucella co-infection so that in the future more studies will be done on the issue of predisposing cattle to other microorganisms like Brucella after BIV infection. METHODS: Blood samples were collected from a total of 2290 cattle in Iran (490 and 1800 cattle in non-industrial and industrial dairy farms, respectively from Isfahan and Chaharmahal and Bakhtiari provinces). The BIV-positive animals were detected by Lab-ELISA and nested PCR tests. RESULTS: In this study, the overall prevalence of BIV in Iran was 1.61% (4.5% and 0.83% in non-industrial and industrial dairy farms, respectively). CONCLUSIONS: There was a statistically significant relationship between BIV status and Brucella infection using Chi square and Pearson’s correlation coefficient test for all of the samples (p=0.0001, r=0.24), samples from Chaharmahal and Bakhtiari (p=0.044, r=0.13) and from industrial farms in Isfahan (p=0.001, r=0.074).

Mycoflora and chemotype characterization of Fusarium graminearum isolatesobtained from corn and barley used as feedstuffs in the northeast of Iran

This study aimed to investigate the mycoflora and chemotyping of Fusarium graminearum isolates in corn and barley used in industrial dairy farms in Khorasan-Razavi Province, northeastern Iran. For this purpose, a total of 128 corn and barley samples were collected from 16 different large industrial dairy farms. Mean moisture of the samples collected in different seasons of the year was significantly different (P < 0.05). The most prevalent fungi isolated from corn samples were Penicillium spp. (90.62%) and Aspergillus spp. (82.81%), and that of barley samples was Penicillium spp. (89.06%). Frequency of Fusarium spp. in corn and barley samples was 85.93% and 26.56%, respectively. All isolates (100%) were confirmed as Fusarium using an ITS primer. Eight (11.11%) out of 72 Fusarium spp. isolates were confirmed as F. graminearum using species-specific primers. Five out of 8 F. graminearum isolates were positive in terms of the presence of the trichothecene-producing gene using a Tri5-specific primer. Three and 2 out of 5 toxin-producing F. graminearum isolates were positive using Tri13DON- and Tri13NIV-specific primers, respectively. In conclusion, the presence of toxigenic Fusarium in corn and barley samples used in feedstuffs in Iran is a potential risk to animal and human health.

Levels of Some Heavy Metals in Raw Cow's Milk from Selected Milk Production Sites in Iran: Is There any Health Concern?

Background: The aim of this study was to evaluate the content of mercury (Hg), arsenic (As), nickel (Ni) and tin (Sn) in raw cow’s milk of traditional and industrial sites from 8 different sites in Arak City, Markazi Province, Iran. Methods: In this cross sectional study, a total of 32 samples were collected from sub-cities of Arak, Iran via subjective sampling method. Both industrial and traditional dairy farms were selected for sampling. Twenty-five gram of each sample was turned to ash in ovens for metal analyses including Hg, As, Ni and Sn by anatomic absorption spectrometer. Results: The residue amounts of Hg and As were lower than permissible limit suggested by Codex Alimentarius, but for Ni and Sn it was higher only in one of the collection sites. The average concentra­tion of Hg was significantly higher (P<0.05) in traditional farms as compared to industrial farms. Be­sides, amounts of Sn was significantly high in the traditional farms (P<0.05). Further, a high contents Ni was detected in industrial farms (P<0.05). Conclusion: High Sn and Ni contents of some milk samples from this region might be potentially hazardous to consumers. Further, none of the other metals tested crossed permissible levels.

Study on serum glucose, insulin, NEFA, BHBA and lipid profile in different productive status of high producing Holstein dairy cows

Background: Metabolic profiles have been used in efforts to predict pre parturient problems and fertility, to diagnose metabolic diseases, and to assess nutritional status in dairy cows. These profiles may help to confirm the diagnosis of sub clinical diseases, to be aware of possible causes of infertility in the herds, or to monitor improvement in herd animals. OBJECTIVES: This study investigated changes in the metabolic profile of high producing Holstein dairy cows from early lactation to close-up dry periods. The results of the current research can provide useful guidelines for management strategies during different physiological phases of high producing Holstein dairy cows. METHODS: Twenty-five multiparous high producing Holstein dairy cows were selected from a high producing industrial dairy farm. Cattle were divided into 5 equal groups of early, mid and late lactation and far-off and close-up dry cows. Blood samples were collected from all cows and sera were separated to evaluate glucose, insulin, β-hydroxybutyric acid (BHBA), non-esterified fatty acid (NEFA), cholesterol, triglyceride (TG), high, low and very low density lipoproteins (HDL-cholesterol, LDL-cholesterol and VLDL-cholesterol). RESULTS: The highest levels of insulin were detected in mid lactation and close-up dry periods. The changing patterns of BHBA and NEFA were significant and the highest levels of these biomarkers were detected in the early lactation group. The decreasing pattern of BHBA and NEFA were seen from early lactation to far-off dry cows. Significant elevations were seen in these biomarkers from far-off to close-up dry cows. CONCLUSIONS: The results of the present study show that metabolic biomarkers change in high producing Holstein dairy cows, under different physiological states. These changes are induced commonly by negative energy balance, lactogenesis and fetal growth in each state.

Characterization of aflatoxigenic Aspergillus flavus and A. parasiticus strain isolates from animal feedstuffs in northeastern Iran.

Aflatoxins are secondary toxic metabolites produced by some Aspergillus spp. particularly, Aspergillus flavus and A. parasiticus that contaminate food and feed. The objective of this study was to evaluate the contamination of feedstuffs with Aspergillus spp. and detect genes involved in the aflatoxin biosynthesis pathway of A. flavus and A. parasiticus isolates. A total of 110 cow feed samples (comprised of silage, concentrate, hay and total mixed ration) from 30 industrial and semi-industrial dairy farms of Khorasan Razavi province, northeastern Iran, were examined using cultural and PCR methods. 68 (61.82%) Aspergillus spp. were isolated from 110 samples of feedstuff. The predominant Aspergillus isolates were A. fumigates (21.81%), followed by A. flavus (17.27%), A. niger (10%), A. parasiticus (8.18%), and A. oryzae (4.54%). Fungal contamination levels of industrial and semi-industrial dairy farm samples were not significantly different (P>0.05). Using four sets of primers, a quadruplex PCR was developed to detect genes (nor1, ver1, omtA and aflR) at different loci coding enzymes in the aflatoxin biosynthesis pathway of A. flavus and A. parasiticus strains. Out of 28 strains of A. flavus and A. parasiticus, 10 isolates (35.71%) showed a quadruplet pattern indicating the important genes involved in the aflatoxin biosynthesis pathway, encoded for functional products. These isolates were confirmed to be aflatoxigenic by Thin Layer Chromatography. 18 isolates (64.29%) had three, two and single molecular patterns. The results obtained by this study show that rapid and specific detection of aflatoxigenic molds is important to ensure the microbiological safety of feedstuffs.

Association between serum copper concentration and the risk of bovine leptospirosis

Leptospirosis is a zoonotic disease found in nearly all parts of the world. This disease is exacerbated by a weakened immune system. Copper is an important component of the immune system. The aim of this study was to investigate the effect of copper deficiency on leptospirosis occurrence. A total of 260 serum samples were randomly collected from eight industrial and semi-industrial dairy farms from center and southeast of Iran. Microscopic agglutination test to check leptospirosis was performed. Serum copper level was analyzed using an atomic absorption spectrometer. Fifty-eight serum samples had detectable antibodies against at least one serovar of Leptospira interrogans at a dilution of ≥1:100, and among the positive cows, 55 samples were copper deficient. In contrast, there were 202 serologically negative subjects, 29 of these samples had copper deficiency. Copper deficiency can weaken immunity and thus exacerbate the incidence of leptospirosis.

Isolation, identification and molecular characterization of Mycobacterium bovis from tuberculin-positive cattle in Hamedan province of Iran

IntroductionTuberculosis (TB) remains a major cause of death in many countries. Bovine tuberculosis caused by Mycobacterium bovis is one of the key members of the Mycobacterium tuberculosis complex. Current methods need long incubation times, which is in contrast to the necessity for rapid and accurate identification and isolation. Molecular techniques, such as RFLP fingerprinting, for accurate identification and differentiation of M. tuberculosis isolates are a more desirable approach. Materials and methodsIn a 12-month study plan, which began in November 2011, lymph nodes obtained from 92 samples of dairy cattle yielded tuberculin-positive marks that were collected from 10 different regions of the province; 43 isolates were identified by acid-fast culture. Using biochemical tests along with IS6110 specific fragment search, colonies were proved to belong to M. tuberculosis complex and more precisely M. bovis strains. PVUII enzymatic digestion of their DNA was followed by Southern blotting and hybridization with DR and PGRS markers. Finally, RFLP fragment hybridized with substrate BCIP and NBT was carried out, and their results were evaluated by GelproAnalyser software. ResultsAll 43 isolates out of the 92 samples that were analyzed by RFLP with two probes of DR and PGRS, interestingly, proved the circulation of an identical strain of M. bovis throughout the whole province. Discussion and conclusionAssessing the genomic patterns of all the strains and comparing the results with previous studies conducted in the area revealed that, while they represent the circulation of a common ancestral clone, as a preliminary successful achievement in industrial and semi-industrial dairy farms located in the zone of the tuberculosis control program, they still have a long way to go to meet the ultimate eradication goals.

Greenhouse gas emissions of packaged fluid milk production in Tehran

The main purpose of this study was first to estimate the carbon footprint (CF) of packaged fluid milk through life cycle assessment (LCA), using regional data in Tehran, and then to identify opportunities for lower greenhouse gas (GHG) emissions. The system boundary for cradle to gate assessment was divided into three life cycle stages: agronomy, animal farm and dairy plant, and data were gathered from multiple sources, e.g. questionnaire, published studies and dairy plant database in 2011–2012. Through the study, the IPCC 2006 methodology and the International Dairy Federation (IDF) Carbon Footprint Guide were used to calculate the CF of milk. The functional unit (FU) was one litre of pasteurized milk packaged in a plastic pouch. The average CF for 1 kg of fat-protein corrected milk (FPCM) at the farm gate was 1.57 kg CO2-eq, however, for the FU, it was 1.73 kg CO2-eq. The main contributors to overall CF of milk product were enteric methane 30%, electricity 14%, diesel 8.9%, manure emissions 8.8% and transportations 8.6%. The average CF of FPCM at farm gate was higher than the previous European reports, but lower than the previous estimate of 3–5 kg CO2-eq/kg milk. Developing the infrastructure to utilize renewable energy sources, such as solar energy, may be a solution for high share of energy-related emissions from the dairy sector. We call for more research on CF and other environmental impacts like eutrophication, and impacts from water consumption in different regions of the country both in traditional and industrial dairy farm systems.

Serological study of bovine herpesvirus type 1 and parainfluenza type 3 in cow farms of Qazvin province based on different ages and seasons

The main objective of this study was to estimate the seroprevalence of Bovine herpes virus type 1 and parainfluenza type 3 in a non-vaccinated population cattle in the livestock region of Qazvin province. Totally 504 sera were randomly collected and tested from 8 industrial dairy farms in Qazvin province during March 2010-March 2011. The result of one way analysis of variance was used for the analysis data. Also Tukey Method was employed to detect pair wise differences among the ages determined that there were a significant differences among the average titer in 1 to 3, 1 to 4, 2 to 3 and 2 to 4 year cows (P<0.005, P<0.001, P<0.041, P<0.001). Due to the significance at the different titers, and comparing pair wise among different seasons Tukey,s method had been used and showed significant difference in summer with autumn (P<0.038 ) and winter (P<0.001). A chi-square test showed the significant differences among ages (P=0.001). The sero- prevalence of BHV-1 was estimated to be 7.1% with 1.2% standard error (SE). The result of PI3 showed the significance at the different titers comparing with the different seasons. Therefore Tukey,s method had been used and showed significant difference among seasons (P<0.001). The seroprevalence of PI3 was estimated to be 95% with 1% SE.

Becoming bovine: Mechanics and metamorphosis in Hokkaido's animal-human-machine

The fieldwork for my doctoral degree was carried out over nineteen months, a year of which was spent working on an industrial dairy farm in Hokkaido, Japan's northernmost Island. As in much of the industrialised world, dairy farming in Japan is rapidly changing. Many farmers are forced by neo-liberal agricultural policies to shift from small family operated farms to high-tech, high-speed, and high overhead industrial operations. This paper focuses on the history of dairy farming in the Tokachi region; more specifically one farm and the shift over a generation to a rotary parlour milking system. It addresses the linkages this mode of production has cultivated amongst humans, dairy cows and industrialized space.The parlour system at Great Hopes Farm allows five workers (aided by three more stall staff) to milk over 1000 cows, fifty at a time, three times a day. The impetus behind moving to parlour technology is that it increases productivity through mechanically enhanced observation and control. However this recent mechanical separation of human and cow during the milking process has led to affectively shared interspecies and inter-human alienation. The technology of the parlour system sets daily rhythms for bovine and human alike, and separates both from a process formerly dependent upon, specialized knowledge, affective empathy, and embodied knowledge. Human and bovine experience the systemic violence of the machine and what remains is a complex bio-politics of interspecies affect and the separation of “bare” and “political” life.

Extending Social Theory to Farm Animals: Addressing Alienation in the Dairy Sector

AbstractWe extend social theory to farm animals in an attempt to illustrate how non‐human animals embedded in social systems can be examined using sociological concepts. Inspired by efforts to include the freedom to express natural behaviour in farm animal welfare standards, we apply Marx's conception of alienation to dairy cows. We first examine industrial dairy farm conditions and find that these systems result in the distortion of life and the suppression of physical and social needs. We then explore alienation in an alternative production system where cows graze on pasture and choose when to be milked by robotic milking machines. Based on farm visits and interviews with farmers, we find that this alternative system addresses several aspects of alienation found in industrial dairy farms. However, despite the benefits associated with alternative production systems, forms of alienation will persist in all systems where maximising profits remains prioritised over life and wellbeing.

Molecular typing of group A bovine rotavirus of calves in the provinces of Tehran, Alborz and Qazvin

BACKGROUND: Group A bovine rotavirus (BRV-A) is one of the most important causes of gastroenteritis and diarrhea in newborn calves. OBJECTIVES: Major types of BRV-A in Tehran, Alborz and Qazvin were detected in this study. METHODS: A total 125 fecal samples of calves showing clinical signs of diarrhea were collected from 26 industrial dairy farms located in the provinces of Tehran, Alborz and Qazvin, during two years. RESULTS: BRV-A was detected in 39.2 % (49/125) of total samples using a commercial ELISA kit. Thirty five positive samples were analyzed by seminested multiplex RT-PCR for P and G genotyping. G10 was the most prevalent genotype, accounting for 57.1% of samples, G6 accounted for 22.9% of samples and in 5.7% of samples (2/35), mixed infection of both genotypes G6 and G10 were detected. Also, the detected P types were P[11] and P[5], accounting for 71.4% and 14.2%, respectively. In our study, none of the genotypes G8 and P[1] were detected. The incidence of genotype combinations cor-responded to the B223-like strains (G10P[11]), UK-like strains (G6P[5]) and KN4-like strains (G6P[11]) were 51.4%,14.3% and 8.6%, respectively. Mixed infections G6/G10P[11] were detected in 2.85% of all samples analyzed with RT-PCR. CONCLUSIONS: To the best of our knowledge, this is the first report about the determination of P genotypes of BRV-A and distribution of the most common BRV-A strains circulating in Iran. Our study also indicated that the incidence of the G genotypes of BRV-A in the provinces of Tehran, Alborz and Qazvin, which is one of the greatest husbandry centers in Iran, has changed in the past years. Furthermore, this finding could be valuable in rotavirus vaccine design.

A Case-Control Study of Association between Diarrhea in Newborn Calves and Infection with Rotavirus and Coronavirus in Some Industrial Dairy Herds of Mashhad Aarea, Iran in 2008

A 1:1 matched case-control study of calves under 1 month of age was carried out by weekly visits to 7 dairy farms in Mashhad from May 2008 to October 2008. Fecal samples were collected from a total of 112 calves with clinical signs of diarrhea and from 112 matched animals without clinical signs of diarrhea as assessed by a scoring system. The samples were investigated for the presence of Rotavirus and Coronavirus by a commercial antigen capture ELISA test. Rotavirus antigen was detected in 29.5% and 17% of diarrheic and non-diarrheic calves, respectively and Coronavirus antigen was detected in 2.7% and 1.8% of diarrheic and non-diarrheic calves, respectively. Among diarrheic calves Rotavirus was the most common in the third week of life and Coronavirus was detected only in some cases of second week of life. The excretion of Rotavirus in the feces of scouring calves was significantly higher than in non-diarrheic calves (P value =0.03, odds ratio = 1.9 (1.05 – 3.76)), but there was not any significant association between shedding of Coronavirus in the feces and diarrhea (P value =0.66, odds ratio = 1.4 (0.24 –9.05)). These results indicate that in these industrial dairy farms in Mashhad, infections by Rotavirus can be considered as an important cause for newborn calf diarrhea.

A serological survey on leptospirosis in aborted dairy cattle in industrial farms of Hamedan suburb, Iran

Summary Leptospirosis is a zoonosis of worldwide distribution, caused by Leptospira interrogans. It is a well known cause of bovine reproductive losses such as abortion, infertility, stillbirth and birth of weak calves. In this research, the relationship between the seroprevalence rate of Leptospira spp. infection and abortion in industrial dairy farms of Hamedan province, Iran was studied. A total of 80 blood samples were taken from aborted cows in six dairy farms. Sera were tested for antibodies against 6 serovars of Leptospira interrogans (hardjo, pomona, canicola, grippotyphosa, icterohaemorrhagiae and ballum) using microscopic agglutination test (MAT). Antibodies were detected in 18 (22.5%) of the aborted cows, including 17 (21.25%) against L. canicola and 1 (1.25%) against L. pomona. It is concluded that dogs (shepherd and stray) and wild carnivores may have an important role to maintain and transmit the L. canicola infection to the cattle population in this region, therefore, vaccination of cattle and shepherd dogs should be applied.

Serum copper, zinc and iron status of various bovine categories on Holstein dairy cattle farms

The aim of this study was to evaluate the blood serum concentrations of copper (Cu), zinc (Zn) and iron (Fe) in various bovine categories reared on industrial Holstein dairy farms. The study was carried out on 12 industrial Holstein dairy cattle farms in various region of Isfahan province, central Iran. Blood samples were collected from 240 dairy cows, 120 dry cows, 120 heifers and 120 calves. The Cu, Fe, and Zn contents were assessed in samples using atomic absorption spectrophotometer. Dry cows and heifers showed the lower Cu concentrations in comparison with dairy cows and calves (P < 0.05). Heifers and calves showed the higher Zn concentrations in comparison with dairy cows (P < 0.05). The serum Fe concentrations were significantly higher in heifers than those in dairy and dry cows (P < 0.05). Dairy cows showed higher Cu and lower Zn and Fe concentrations in comparison with the other categories (P < 0.05). Cu deficiency was diagnosed in 68% of the examined dairy cows (67% herds), 82% dry cows (92% herds), 75% heifers (92% herds) and 61% calves (58% herds). Only a small number of cattle were Zn- and Fe-deficient while on all farms, Cu deficiency was diagnosed in at least one of the bovine categories. In conclusion, because of the different physiological states of various bovine categories reared on Holstein dairy farms, mineral supplements (Cu, Zn and Fe) should be provided based on physiological requirements of individual bovine categories and the results of those diet analyses.

Geographic Distribution of Stomoxyine Flies (Diptera: Muscidae) and Diurnal Activity of &lt;I&gt;Stomoxys calcitrans&lt;/I&gt; in Thailand

Stomoxyine flies (Stomoxys spp.) were collected in 10 localities of Thailand using the Vavoua traps. These localities represented four major ecological settings, as follows: small local dairy farms, large industrial dairy farms, a national park, and one elephant conservation area. Three species of stable flies were identified in the following proportions: Stomoxys calcitrans (91.5%), Stomoxys indicus (7.9%), and Stomoxys sitiens (0.6%). The number of flies collected differed significantly among collection sites (chi2 = 360.15, df=3, P < 0.05). The greatest number of stomoxyine flies was captured in dairy farms. Seasonal and daily activity of S. calcitrans was observed during a 1-yr period at two selected locations (Dairy Farming Promotion Organization of Thailand and Khao Kheow Open Zoo). S. calcitrans was more abundant during the rainy season (March-September), but was not associated with the total rainfall (r2 = 0.0002, P > 0.05). Peak of daily flight activity of males S. calcitrans was at 1000 and 1600 h, whereas females showed an increase of activity all along the day until 1600 h. A better understanding of stomoxyine fly behavior related to patterns of daily activity will facilitate and improve the efficiency of fly control measures in private and government sectors.

Prevalence of Cryptosporidium spp. infection in some dairy herds of Mashhad (Iran) and its association with diarrhea in newborn calves

A 1:1 matched case-control study of calves less than 1 month of age was carried out by weekly visits to some dairy farms in Mashhad, Iran. Fecal samples were collected over a 6-month period from a total of 112 calves with clinical signs of diarrhea and from 112 matched animals without clinical signs of diarrhea as assessed by a scoring system. The samples were investigated for the presence of Cryptosporidium spp. oocysts by modified Ziehl–Neelson staining method. Cryptosporidium spp. oocysts were present in 51.8% of calves with diarrhea and in 21.4% of the controls. Among diarrheic calves, the highest prevalence of Cryptosporidium oocyst shedding was in age group 8–14 days (74.5%), and the lowest prevalence of Cryptosporidium oocyst shedding was in age group 22–30 days (23.8%). The McNemar test in all sampled calves showed significant differences in odds ratio for the presence of Cryptosporidium spp. in fecal samples, and the excretion of parasite in the feces of scouring calves was significantly higher (odds ratio 6.1) than in healthy calves. Differences between animals with and without diarrhea were statistically significant for age groups 1–7 and also 8–14 day-old calves. These results indicate that in these industrial dairy farms in Mashhad, infections by Cryptosporidium should be considered as a potential cause for newborn calf.

Serological study of bovine viral respiratory diseases in dairy herds in Kerman province, Iran

Summary Respiratory disorders are major concern for dairy cattle industry. Viruses and bacteria in combination with stress play a key role in triggering acute respiratory infections. The most important viral agents are bovine viral diarrhoea virus (BVDV), bovine herpes virus type 1 (BHV-1), bovine respiratory syncytial virus (BRSV), parainfluenza virus type 3 (PIV-3) and bovine adenovirus (BAV). This cross-sectional study was conducted to evaluate the serological status of BVDV, BHV-1, BRSV, PIV-3 and BAV in dairy herds in Kerman province, Iran. From June to November 2007, 181 serum samples were collected from 1–3-year-old cattle from 15 industrial dairy farms in Kerman province using cluster sampling. The samples were tested by commercial indirect ELISA kits. Antibodies were detected against BVDV, BHV-1, BRSV, PIV-3 and BAV in 77.90, 30.39, 100, 100 and 100% of serum samples, respectively. All farms were positive at least for one of these viruses and antibodies against all the 5 viruses were detected in 4 (26.66%) herds among 15 dairy farms. According to the present study, BVDV, BRSV, PIV-3 and BAV are common viruses in dairy herds in Kerman province.

Serologic and bacteriologic diagnosis of bovine leptospirosis in Tehran suburb dairy farms

Summary Leptospirosis is a worldwide zoonosis caused by Leptospira interrogans. This study was conducted to evaluate serologic and bacteriologic findings of leptospirosis in clinically-suspected cows. 380 sera and 33 urine samples were collected from 6 industrial dairy farms in Tehran suburb, from December 2004 to June 2005. The prevalence of disease was determined by microscopic agglutination test (MAT), enzyme-linked immunosorbent assay (ELISA), direct dark-field microscopic (DFM) examination, indirect fluorescent antibody test (IFAT), microbiologic cultural isolation technique and polymerase chain reaction (PCR). Antibodies were detected by MAT at least against one serovar of L. interrogans in 55 sera (14.5%) among 380 samples at a dilution of ≥ 1:100. L. interrogans serovar icterohaemorrhagiae was the most prevalent serovar. Leptospiral antibodies were detected by ELISA in 85 sera (22.4%) among 380 samples. Four (12.1%) of 33 urine samples were suspected by DFM examination and no positive sample by IFAT was observed. Leptospires could be isolated from none of the 33 samples taken from industrial farms. In this study, positive controls were detected at a dilution of ≥ 2000 leptospires per each ml of urine sample by PCR. Therefore, no DNA from serum and urine samples were collected from 6 industrial dairy farms could be detected by this method. It seems that, to increase the accuracy in the diagnosis of the disease, using a range of reliable techniques and comparing the results is important in reaching final conclusion.

Aflatoxin M 1 contamination in winter and summer milk in 14 states in Iran

During February and August 2004, 319 raw milk samples were collected from dairy farms and milk collecting centers of 15 dairy plants in 14 Iranian states in winter and summer. Samples were analyzed for aflatoxin M 1 with a validated high performance liquid chromatography (HPLC) method. The recovery at 0.05 μg/kg was 68% and coefficient of variation (CV) was 15%. The recovery at 0.5 μg/kg was 81% and CV was 25%. Aflatoxin M 1 contamination was detected in 54% of the field samples. The sample-mean concentration of aflatoxin M 1 was 0.057 μg/kg with 0.014 standard deviation and sample median 0.039; 44% of the samples had levels <0.01 μg/kg and 77% were <0.05 μg/kg. The levels of contamination in industrial and traditional dairy farms were equal, but the season had an indirect effect ( α ⩽ 0.05) on the levels of contamination on the farms. The level of contamination in winter was significantly ( α ⩽ 0.1) higher than in summer.