Dioxin residues in the edible tissue of finishing pigs after dioxin feeding

The aim of this study was to determine the contamination of finishing pigs with polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) after feeding either uncontaminated feed or feed contaminated with 0.75, 2 or 4 ng/kg toxic equivalents (TEQ; calculated by multiplying individual congener concentrations by congener-specific toxicity equivalency factors). The feed was mixed with pure substances of PCDD/Fs to get the intended contamination. Five groups of six piglets each were fed contaminated feed, one group of five piglets served as control. One group was fed contaminated feed (4 ng TEQ/kg) only for the rearing period (6 weeks), and another group for the first 8 weeks of the fattening period (4 ng TEQ/kg feed). The other groups received the contaminated feed during the 12-weeks fattening period. After slaughtering, the edible parts of the belly, loin and fore-end were collected and homogenized. The samples of group 2 and 4a were investigated uncooked as well as roasted. Fattening yield and feed conversion (kg feed/kg weight gain) of the animals of all groups were in the normal range (final weight 109.7 kg; feed conversion 2.55-2.69 kg). The PCDD/F-content in 1 kg fat of the belly, loin and fore-end in relation to the intake was between 0.016 (4 ng TEQ/kg feed for a 6-weeks rearing period) and 1.39% (fore-end; 2 ng TEQ/kg feed for 12-weeks fattening period). There was a decrease in dioxin residues after a 12-weeks period but not after a 4-weeks period of feeding an uncontaminated feed. When feed contaminated with 0.75, 2 and 4 ng TEQ/kg was given for a 12-weeks fattening period, the residue concentrations of PCDD/F-TEQ in 1 kg belly was 0.455, 1.07 and 1.55 ng, in 1 kg fore-end 0.04 ng, 0.32 ng and 0.34 ng and in 1 kg loin 0.015 ng, 0.07 ng and 0.30 ng respectively. Roasting had no influence on the dioxin-residues. The residues per g belly fat exceed the maximum limits for dioxin in food of 0.6 pg WHO-PCDD/F-TEQ/g fat (EC Recommendations 2002/201/EC), when feed containing 0.75 ng PCDD/F-TEQ/kg is given for 12 weeks. When feed containing 0.4 ng TEQ (maximum content; EC recommendations 2002/201/EC) is given for 12 weeks, approximately 0.55 pg TEQ/g fat can be expected in the food. This value is within the action level of 0.6 pg/g fat of porks. In conclusion, the results of the study allow prediction of dioxin residues in the edible tissue of pork, if the feed contamination is known and the amount of feed intake can be estimated.     

Management of land and livestock contaminated with polychlorinated biphenyls

Investigations were conducted on several small neighbouring beef cattle and sheep farms that were found to be contaminated with polychlorinated biphenyls (PCBs). The residues detected contained about 62% w/w chlorine and soil concentrations ranged from 0.35 to 1.9 mg/kg. Beef cattle and sheep grazing the contaminated land had PCB concentrations in their fat of 0.3 to 1.7 mg/kg and 0.19 to 0.45 mg/kg, respectively. The concentration of PCBs in the caudal fat of cattle was 0.3 to 2 times the concentration of PCBs in the land they were grazing and was positively related to stocking rates. PCBs were present in milk fat from cattle at about the same concentration as in caudal fat, and lactation appeared to contribute to decontamination. Wool grease from sheep contained about 1 to 2 times the concentration of PCBs in subcutaneous fat. Calves of contaminated cows also became contaminated. The half-life for decontamination of PCBs in a group of 8 young female beef cattle was calculated at 13 months. PCBs were detected in pasture samples at concentrations ranging from less than 0.01 mg/kg to 0.12 mg/kg. However, PCBs were not detected in any sample of hay cut from these paddocks. In 4 sheep fed a sole ration of this hay, traces of PCBs were detected in their fat following 89 days of feeding. Grazing livestock for meat production on land contaminated with PCBs is not recommended because livestock readily acquire residues, and PCBs persist in soil and livestock for long periods. Grazing sheep for wool production on land contaminated with PCBs may be an option.     

Use of polychlorinated biphenyl congener analysis for monitoring food and raw material of animal origin]

Occurrence of individual polychlorinated biphenyl (PCB) congeners in the environment, foodstuffs and other biological materials was assessed. Analysis of specific PCB congeners (28, 52, 101, 138, 153, 180), occurring in animal raw materials and foodstuffs most frequently, has been implemented. Sample processing, isolation of fat from milk, meat, organs, fat tissue and eggs, and separation of PCB from fats using the sorbents Florisil or Ekosorb (a new Czechoslovak sorbent based on modified silica gel, Kavalier Glassworks, Votice) are described in detail. Individual PCB congeners were determined by capillary gas chromatography (gas chromatograph Varian VISTA 6,000, equipped with a 63Ni ECD; silica capillary column SPB-5, 30 m x 0.32 mm I.D., 0.25 micron film; column temperature programme: 60 degrees C for 2 min, then to 250 degrees C at 20 degrees C/min and held for 13 min; splitless injection). Chromatograms of commercial chemicals Delor 103 and Delor 106 (corresponding to Aroclor 1242 and 1260, respectively), of a mixture of six specific PCB congener standards and of a PCB--containing milk sample are presented in Fig. 1-3. Methods of PCBs estimation, currently used in Czechoslovakia, and benefits of congeneric analysis of PCBs (reproducibility of results, quantification of individual congeners) are discussed. Analysis of specific PCB congeners is used for the assay of PCBs in foodstuffs and investigations of PCBs dynamics in food chains and distribution and accumulation of PCBs in animal organisms. Contents of specific PCB congeners in milk, pork and pig liver and kidney samples are given in Tab. II.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dioxin residues in the edible tissue of broiler chicken

The aim of this study was to determine the contamination of broiler chicken with polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) after feeding either uncontaminated feed or feed contaminated with 1, 2 or 4 ng/kg toxic equivalents (TEQ). The feed was mixed with pure substances of PCDD/Fs to get the intended contamination. Ten groups of seven 1-day-old chickens each were housed in special cages for broiler fattening. The fattening period lasted for 6 weeks. The contaminated feed was given for either 2, 4, or 6 weeks, one group received uncontaminated feed (control group). After slaughtering the edible parts of the chickens breast and leg including the skin were homogenized. Body weight gain and feed conversion (kg feed/kg body weight gain) were in the normal range (final weight 1.98+/-0.07 kg; feed conversion 1.74+/-0.03). One kilogram edible tissue contained an average of 21.2+/-4.1% of the total TEQ-intake in all groups. The PCDD/Fs residues in the edible tissues significantly correlated with the amount of PCDD/Fs-intake (r=0.99; Pearson correlation). There was no decrease in dioxin residues (% of total PCDD/Fs intake) after a 2 or 4 weeks withdrawal period. The results of this trial predict that a threshold value of 2 pg/g chicken fat can be met if the PCDD/Fs content in chicken feed is not higher than 0.4 ng/kg.     

Concentrations of oestrone sulphate during pregnancy in milk from Jersey and Friesian dairy cows differing in milk yields and composition

Oestrone sulphate concentrations were measured by radioimmunoassay in milk samples obtained weekly during pregnancy from Jersey and Friesian cows, with each breed grazed at two different stocking rates. Mean milk yields differed significantly (P<0.05) between the four herds, while mean percentage milk fat and protein values differed significantly (P<0.05) between the two breeds. In all four herds, oestrone sulphate concentrations in milk rose progressively during pregnancy from a mean value of approximately 80-100 pg/ml at 60-80 days of pregnancy to a plateau value of approximately 1 ng/ml at 181-200 days. In non-pregnant cows, oestrone sulphate concentrations in milk ranged from non-detectable to 110 pg/ml, with a mean +/- s.e.m. value of 59 +/- 4 pg/ml. There was considerable variation in milk oestrone sulphate concentrations between cows in each herd, and oestrone sulphate concentrations could also fluctuate markedly within cows from week to week. Despite this variation, the concentration of oestrone sulphate in 98% of milk samples obtained after 120 days of pregnancy was greater than the highest concentration found in milk from non-pregnant cows. Measurement of oestrone sulphate concentrations in milk samples taken at least 120 days after mating or insemination may provide an alternative, non-invasive means of determining or confirming pregnancy in New Zealand dairy cows.     

Tissue deposition of polychlorinated biphenyls in cats fed Atlantic Ocean bluefish.

Bluefish (Pomatomus saltatrix), a very popular marine sport fish caught in Atlantic coastal waters, contain significant levels of polychlorinated biphenyls (PCBs). Since fish can be an appreciable portion of human and feline diets, a feeding study was conducted with cats fed exclusively bluefish for 86 days with determination of tissue concentrations of PCBs. The concentrations of PCBs in brain, liver, and fat were significantly higher (p = 0.01) in the fish-fed cats than in the control group using the Wilcoxon rank sum test. The highest PCB levels were in fat, the median concentrations being 48 and 0.61 ppm (dry weight) in the fish-fed and control cats, respectively. The significance of the results is discussed.     

Dioxin concentration in milk and tissues of cows and sheep related to feed and soil contamination

If cows or sheep are grazing on areas known for a higher dioxin level of the soil, respectively, dry cows are fed with feedstuffs produced on such areas, the dioxin concentration in food, in this case in cows' milk and livers of sheep could reach or exceed maximum levels. Furthermore large amounts of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzo-p-furans (PCDD/F) can be excreted with the faeces. But there are chances for farmers to prevent or at least to minimize the dioxin load of feed and with it of food (including the harvesting technique and the feeding strategy).     

Improving the sensitivity of the IBR-gE ELISA for testing IBR marker vaccinated cows from bulk milk

The low sensitivity of the IBR-gE ELISA compared to other diagnostic ELISA tests for IBR is a major disadvantage of IBR control programmes based on IBR marker vaccination. Therefore the IBR-gE ELISA is not generally recommended for testing pooled or bulk milk samples.The aim of this study was to determine the performance of a commercially available kit for concentrating and purifying antibodies in milk in order to improve the sensitivity of detecting IBR-gE antibody positive cows from pooled and bulk milk samples. A single IBR-gE positive cow is likely to remain undetected in a pool of 49 negative milk samples without concentration. By contrast, the bulk milk concentration procedure improved sensitivity from 5.4% to 75.7% in a positive herd. Milk samples with a high or moderate positive signal are more likely to be detected after pool milk concentration compared to weak positive samples. Whereas a follow up study involving a monthly testing of bulk milk samples from three marker vaccinated IBR-gE negative herds over a period of seven months yielded negative results each month, bulk milk from a herd containing <5% IBR-gE positive cows always detected positive after concentration. Although the milk concentration procedure had no impact on specificity, it significantly enhanced the sensitivity of the detection of IBR-gE positive milk in pooled and bulk milk samples. After further evaluation this procedure could allow a cost efficient and reliable method of monitoring IBR marker-vaccinated herds for IBR-gE antibodies.     

Concentration of conjugated linoleic acid in grazing sheep and goat milk fat

The conjugated linoleic acid (CLA) content of grazing sheep and goat milk fat, throughout their lactation period, was examined. Six sheep and six goat representative farms were selected at random and milk samples were taken at monthly intervals for fatty acids profile determination. Sheep and goat nutrition was based on natural grazing and on supplementary feeding during the winter months. From April onwards, grazing native pastures was the only source of feed for sheep and goats. The University farm whose sheep are kept indoors all year round without any grazing, was also used as reference. Fifteen individual milk samples were also taken in April from a sheep and goat farm respectively, in order to see the variability of CLA inside the farm. The results showed that: a. the CLA content of grazing sheep and goat milk fat increased significantly in April–May (early growth stage of grass) and then declined while that of indoors kept sheep was more or less constant during the same period, b. the isomers cis-9, trans-11 and trans-10, cis-12 of CLA were found in grazing sheep milk fat, while in indoors kept sheep and goats' milk fat only the cis-9, trans-11 isomer was found, c. the CLA content of sheep milk fat was much higher than that of goats, d. a negative correlation between sheep milk fat and CLA content was found and e. there was considerable variation in milk fat CLA content between sheep and goat farms and inside the farms.     

中国荷斯坦奶牛RPL23A、ACACB基因3个SNPs检测及其与产奶性状的关联分析

旨在开展奶牛群体高乳成分功能基因的验证与筛选,利用微流控芯片自主选育技术分析北京地区母牛群体高乳蛋白、高乳脂基因频率,同时分析基因多态性及其与产奶性状的相关性。本研究对北京地区8个大型奶牛场1 596头中国荷斯坦奶牛RPL23A、ACACB基因的多态性进行了检测,所有个体均为3胎以内的泌乳牛,收集每头牛所有测定日的产奶量、乳脂率、乳蛋白率等数据,同时对3个多态位点不同基因型与产奶性状进行了关联分析。RPL23A基因的SNP位点g.20146771G>A,在第一泌乳期,与产奶量、乳脂量、乳脂率和乳蛋白量均达到极显著关联（P<0.01）,第二泌乳期,g.20146771G>A与5个产奶性状均呈极显著关联（P<0.01）。ACACB基因的SNP位点g.63962768C>T,在第一泌乳期,与产奶量、乳脂量、乳脂率和乳蛋白量均呈极显著关联（P<0.01）,在第二泌乳期,与产奶量、乳脂量、乳脂率和乳蛋白率呈极显著关联（P<0.01）。结果表明,RPL23A、ACACB基因可以作为影响中国荷斯坦奶牛产奶性状的候选基因用于标记辅助选择,以上基因位点可能通过直接或间接的途径影响奶牛的乳脂或乳蛋白性状,对产奶性状起到重要调控作用。本研究为荷斯坦奶牛后续的标记辅助选择奠定了良好基础。     

氯化胆碱和维生素K3饲料添加剂中二噁英类化合物浓度及其单体分布特征

本试验旨在调查2种常用饲料添加剂氯化胆碱和维生素K3中二噁英类化合物浓度及其单体分布特征。共检测17个氯化胆碱和29个维生素K3样品,二噁英化合物分别采用加速溶剂萃取仪和自动纯化系统进行提取和净化,并采用同位素稀释-高分辨气相色谱/高分辨双聚焦磁式质谱联用技术(HRGC/HRMS)进行准确定量分析检测。结果表明:氯化胆碱与维生素K3中二噁英类化合物浓度分别为4.370和13.871 pg/g,它们的毒性当量平均浓度分别是0.184和0.379 pg WHO-TEQ/g,其中有1个氯化胆碱样品和5个维生素K3样品中毒性当量浓度超过欧盟限量标准值(0.75 pg WHO-TEQ/g)。2种饲料添加剂均以八氯二苯并呋喃(OCDF)为最主要的污染同系物,毒性当量的主要贡献均以2,3,4,7,8-五氯二苯并呋喃(2,3,4,7,8-PeCDF)和1,2,3,4,7,8-六氯二苯并呋喃(1,2,3,4,7,8-HxCDF)为主,分别为42%和55%。污染同系物分布特征以氯化二苯并呋喃(PCDFs)为主要优势污染物。PCDFs在氯化胆碱和维生素K3中的贡献率分别占总浓度的88%和97%。     

Phosphorus Intake and Excretion on South Carolina Dairy Farms

The objective of this study was to survey dairy farmers to determine P levels in feed and manure. Feed and manure samples were collected from 19 Holstein, six Jersey, and two Guernsey farms in South Carolina. Samples from the Jersey and Guernsey herds were pooled. Samples were dried and analyzed for N and P. Amounts of all feeds were recorded; then, nutrient intake was determined. Dairy Herd Improvement records were used to determine the milk yield and fat content and, subsequently, the P requirement. Nineteen of 27 herds (70%) were fed more P than required according to nutrient requirements established by the NRC. The average P intake was 94.9 g (0.48% of diet DM) compared with the average requirement of 78.3 g (0.41% of diet DM). There were correlations between dietary and fecal P (R² = 0.46) and between CP and P intake (R² = 0.62). There was not a significant correlation between excess P intake and milk yield. In summary, many dairy producers overfeed P. Feeding dietary P at recommended levels will optimize milk yield and reduce P excretion on dairy farms.     

Transfer of chlortetracycline from contaminated feedingstuff to cows' milk

Three groups of four Friesian cows in mid-lactation were fed a compound feedingstuff contaminated with 2, 10 or 300 mg chlortetracycline/kg for 21 days, and were then fed an uncontaminated diet for seven days. A fourth group of four cows was fed an uncontaminated diet throughout the study. Daily pooled milk samples from each cow were analysed by high performance liquid chromatography (HPLC) with a detection limit of 50 microg chlortetracycline/litre. Chlortetracycline was detected in only two milk samples taken from one of the animals fed feed containing 300 mg 300 mg chlortetracycline/kg, and both contained less than the maximum residue limit (MRL) specified by the European Union (100 microg/litre). All the milk samples were also analysed by the Delvotest SP microbiological assay, which has a detection limit of 300 microg chlortetracycline/litre. During the treatment period, this method gave four presumptive false-positive results, because they were not confirmed by HPLC. Selected daily pooled samples from each treatment group were also analysed by the semi-quantitative Charm II radioreceptor assay with a detection limit of 10 microg chlortetracycline/litre. Immunoreactive chlortetracycline was detected only in the animals fed feed containing 300 mg chlortetracycline/kg and several of the results exceeded the EU MRL during the treatment period. No significant treatment effects on animal performance were observed. However, there was a trend towards a higher milk fat concentration (P<0.09) and a lower milk protein concentration (P<0.07) with increasing concentration of chlortetracycline in the diet.     

Converting to organic dairy farming: Consequences for production, somatic cell scores and calving interval of first parity Holstein cows

This paper aims to describe the changes prompted by conversion to organic farming for milk production and fertility of first parity Holstein cows.

Data was collected for Dutch organic farms, with a distinction made between long-standing-organic farms, converted organic farms and a reference group of conventional farms. The percentage Holstein blood in the herds, milk production (kg milk, % milk fat, % milk protein), somatic cell scores (SCS), calving interval (CI) and age at first calving (AFC) were described over time. An animal model was used to estimate the effects of conversion on different traits based on data from converted organic farms.

Milk production was lower and somatic cell counts were higher on long-standing-organic farms than on conventional and converted organic farms. Interestingly, at pre-organic farms, i.e. before their conversion, the milk production level was already lower than at conventional farms.

The estimates from our statistical analysis showed a highly significant decrease in milk yield and protein percentage due to conversion. Also fat content decreased, SCS increased and AFC increased significantly.

It can be concluded that the conversion to organic farming is a gradual process over years. Dutch farmers who decided during the late 1990s to convert to organic farming, represented a specific group of farmers distinct from conventional farmers, which was reflected by lower milk yields, milk fat percentage and protein percentage before conversion as compared to conventional farms. During conversion, significant changes in milk production, protein and fat contents and somatic cell scores took place. Age of first calving is an important difference between organic and conventional farming.     

PCB concentrations in hair, blood, tissues and secretions of chronically-exposed dairy cows, fattening bulls and calves. 1. Course and relation of some polychlorinated biphenyls in hair, milk and tissues in exposed nursing cows and conventionally raised dairy cows]

20 cows contaminated chronically with PCB were kept as nurse cows or in a tie-stall. The contamination in different substrates (hair, milk, blood, feces) was examined for a period up to 8 months. The distribution of PCB in the carcass of some animals was registered in addition. The system of keeping nurse cows turned out to be useful in order to overcome a contamination situation. Drying off gravid animals in the first step helps solving problems of handling contaminated milk. With low contaminated animals a short dry off period is sufficient, so that the milk--after calving--is marketable (report II, in preparation). In case of nurse cows with two calves post partum a continuous decline of PCB-concentrations in the milk can be observed. With biological half life periods of 2-4 months, milk with PCB 153-concentrations of 0.15-0.20 mg/kg fat will be marketable within this period. Cows milked by milking-machines show a decline of PCB in the milk similar to nurse cows. Two animals had a limited increase p.p., probably caused by mobilization of fat in the high lactation stage. Over longer periods, the biological half-life-periods were comparable to nursing cows. Hair is easy to sample and store; it is useful as a diagnostic substrate beside the milk in order to estimate the degree of contamination in individual animals. The ratio of PCB-concentrations between perirenal fat and hair is 1:0.95 (s = +/-0.192); the ratio of PCB-concentrations between perirenal fat and milk is 1:0.77 (s = +/- 0.122).(ABSTRACT TRUNCATED AT 250 WORDS)     

Variability of acetone in milk in a large low-production dairy herd: a longitudinal case study

The objective of this study was to relate acetone in milk with cow and management factors in one low producing dairy herd (5260 kg milk per 305-day lactation). Milk acetone was measured in regular monthly milk samples one to three times within 100 days of lactation in 4433 lactations (2639 cows, 7800 measurements) from one herd over a period of 32 months (1988-91). Associations between milk acetone and cow factors and surrogate measures of management were evaluated by variance components of multiple fixed effect models. Lactation stage, calendar month of study, production groups and milk yield were strong, and percentage milk fat and parity were weak predictors of milk acetone. There was a trend of increasing body weight loss from the first to the second month of lactation with increasing milk acetone level. A substantial increase in milk production in 1991 was accompanied by an almost twofold rise in milk acetone. It was concluded that environmental parameters had strong relationships with milk acetone even in this low-producing herd.     

Development of cell content and shedding of Prototheca spp. in milk from infected udder quarters of cows

It was the objective of this study to analyse shedding patterns and somatic cell counts in cows and quarters infected with Prototheca spp. and to evaluate two approaches to identify infected animals by somatic cell count (SCC) or by bacteriological analysis of pooled milk samples. Five lactating dairy cows, chronically infected with Prototheca spp. in at least one quarter were studied over 11 weeks to 13 months. Quarter milk samples and a pooled milk sample from 4 quarters were collected aseptically from all quarters of the cows on a weekly basis. Culture results of quarter milk and pooled samples were compared using cross tabulation. SCC of quarter milk samples and of pooled samples were related to the probability of detection in the infected quarters and cows, respectively. Shedding of Prototheca spp. was continuous in 2 of 8 quarters. In the other quarters negative samples were obtained sporadically or over a longer period (1 quarter). Overall, Prototheca spp. were isolated from 83.6% of quarter milk samples and 77.0% of pooled milk samples of infected quarters and cows. Somatic cell counts were higher in those samples from infected quarters that contained the algae than in negative samples (p < 0.0001). The same applied for composite samples from infected cows. Positive samples had higher SCC than negative samples. However, Prototheca spp. were also isolated from quarter milk and pooled samples with physiological SCC (i.e. < 10(5)/ml). Infected quarters that were dried off did not develop acute mastitis. However, drying off had no effect on the infection, i.e. samples collected at calving or 8 weeks after dry off still contained Prototheca spp. Results indicate that pre-selection of cows to be sampled for Prototheca spp. by SCC and the use of composite samples are probably inadequate in attempts to eradicate the disease. However, due to intermittent shedding of the algae in some cows, single herd sampling using quarter milk samples probably also fails to detect all infected cases. Therefore, continuous monitoring of problem cows with clinical mastitis or increased SCC in herds during eradication programs is recommended.     

Factors influencing pregnancy rate and late embryonic loss in dairy cattle.

This trial was conducted on three Hungarian dairy farms between March 2003 and April 2004. The aims of this study were to examine the effect of milk production and milk contents, the day after calving (DAC) and the sire for the pregnancy rate (PR) and late embryonic loss (LEL) in dairies. Five thousand three hundred and eighty insemination was carried out in this period. Pregnancies (n = 1969) were detected by BioPryn test from 3919 blood samples between 30-36 days post insemination (PI). Retention of pregnancy was determined by rectal palpation on Day 60. LEL has been determined by the optical density (OD) of blood samples/cutoff ratio and the serum progesterone (P4) concentration 30-36 days PI. According to serum progesterone concentration the authors predicted a presumed or possible embryonic loss or maintenance of the pregnancy. The efficiency of the artificial inseminations (AI) was significantly lower 60 days within post-partum. Significant positive correlation was found between the result of early and late PR and DAC and the milk protein/fat ratio. Significant negative correlation was detected between the early and late PR the milk protein and fat content. A later stage (60 days PI) of pregnancy the milk production has a negative effect for retaining of pregnancy. More data would be necessary to state that sires can influence the reproduction ability of their progenies. This is a really important issue, because the AI bulls have a great impact on the herds and the one-way selection may cause decreased fertility on breed level as well.     

The associations between milk production, milk composition and Salmonella in the bulk milk supplies of dairy farms in Ontario.

The purpose of this study was to assess changes in dairy herd milk production and milk composition associated with changes in Salmonella contamination of bulk milk on dairy farms in southwestern Ontario. Twenty-three dairy farms that had submitted milk filters for culture from which Salmonella were isolated (cases) and 23 farms that submitted Salmonella-negative milk filters (controls) were included in the study. The rolling herd averages for milk and fat of case and control farms for the months of December 1985, December 1986 and April 1987 were compared and no significant differences were detected. Case and control farms were divided into three groups (A,B,C) on the basis of Salmonella culture results of milk filters submitted at various time periods throughout the study. Daily and monthly changes in milk production and composition parameters that reflected the time periods of milk filter culture were compared. The following unconditional associations between a changing Salmonella infection status on dairy farms and changes in milk production or composition variables were significant (p less than or equal to 0.05): group A: case farms had higher plate loop counts than control farms; group B: case farms had younger cows than control farms; group C: case farms had cows with longer average days in lactation than control farms. After analytical control of confounding variables, the disappearance of Salmonella from bulk milk supplies of dairy farms was associated with a decrease in percent fat and in somatic cell count.     

Evaluation of the contamination degree of roe-deer with cadmium and polychlorinated biphenyls in Warmia and Mazury district

The results of investigations concerning degree the contamination degree with cadmium and polychlorinated biphenyls (PCB's) of roe-deer organs hunt in seven selected areas of Warmia and Mazury voivodship are presented. The highest mean cadmium content in the organs investigated was found in the samples from G?ebock area (liver - 0.0576 mg/kg, kidney - 3.351 mg/kg) and the lowest one was observed in the samples from Pisz area (liver - 0.181 mg/kg, kidneys - 1.653 mg/kg). Mean level of polychlorinated biphenyls residues in the roe-deer fat from Warmia and Mazury district was 0.004 mg/kg. The highest PCB's mean concentration was found in the roe-deer fat samples from Milomlyn area (0.008 mg/kg), and the lowest one in those from G?ebock area (0.002 mg/kg). Presented levels of investigated xenobiotics do not make at present (except cadmium in kidney) any toxicological threats for venison consumers in Warmia and Mazury district.