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.     

Transfer of fat-soluble pesticides from contaminated feed to poultry tissues and eggs

1. Implementation of Good Manufacturing Practice and HACCP (Hazard Analysis Critical Control Points) in the production of poultry feed requires efficient tools for profiling risks associated with pesticide use in the production of crops for feed. 2. This paper describes a simple model that may be of use in the first tiers of risk profiling of feeds. 3. The model adequately reproduced the pattern of residues in fat and eggs of laying hens dosed with a selection of lipophilic pesticides that may be used in the production of crops for poultry feeds: deltamethrin, diflubenzuron, fipronil, lindane, piperonyl butoxide and spinosad. 4. Simulations suggest results derived from studies on laying chickens can be extrapolated to other laying birds. 5. Poultry meat production systems focus on maximising growth of birds giving rise to significant potential for dilution of residues that transfer to fat from feed. 6. Simulations of residues in fat of chickens, ducks, geese and turkeys exposed to a lipophilic pesticide with an elimination half-life of one day at 10 mg/kg body weight/d from hatching to typical market ages suggest residues in fat that are highest in turkeys > chickens > geese > ducks. 7. The model is of use in interpreting published dosing studies and predicting likely residues in birds at times after last exposure/dosing.     

Type C botulism in dairy cattle from feed contaminated with a dead cat.

Four hundred twenty-seven of 441 adult Holstein dairy cattle from a 1,200-cow dairy died over a 1-week period during early spring 1998. Affected animals were from 4 late lactation pens, one of which included the bull string. Signs included weakness, recumbency, watery diarrhea, and death. Eighty animals from the 4 pens were dead approximately 8 hours after the first ill cows were noted. Affected cows would collapse on stimulation and extend all 4 limbs with moderate rigidity. Several lacked lingual tonus and had abdominal breathing patterns. The animals had been fed a load of total mixed ration that included a rotten bale of oat hay containing a dead cat. No common toxicants were identified, and pathologic examination revealed no consistent lesions. Testing of tissue from the cat carcass found in the feed sample using mouse protection bioassay identified the presence of type C botulinum toxin. Samples of feed, tissue from affected animals, cat tissue from feed, milk, and serum were also tested using an enzyme-linked immunosorbent assay (ELISA) specific for type C botulinum. Two samples of rumen contents were tested and found to be positive for botulism by ELISA, and 1 of 3 liver samples had a weak positive finding. No botulinum toxin was found in milk or sera using the ELISA.     

Effect of experimental feed additives on aflatoxin in milk of dairy cows fed aflatoxin‐contaminated diets

Three studies were conducted to determine the potential of experimental feed additives (EFAs), clays or non‐digestible yeast oligosaccharides, to reduce milk aflatoxin (AFM₁) concentrations in lactating Holstein cows consuming aflatoxin‐contaminated diets. All studies included a pre‐treatment period and a 2‐week experimental period in a randomized block design. During the pre‐treatment period, cows received a total mixed ration (TMR) with no aflatoxin contamination. During both experimental weeks, all cows were fed a TMR containing aflatoxin‐contaminated corn. During experimental week 1, cows received no EFA’s in the TMR, but EFA’s were included in the TMR for the second experimental week. In studies 1 and 2, the experimental period consisted of 2 weeks each lasting 7 days with 12 cows per treatment. Aflatoxin M₁ concentrations were analysed by HPLC for milk samples collected on days 5–7 and days 11–14. In various experiments, treatments included control (no EFA), 100 g/cow daily of experimental Lallemand^® product, 10 g/cow daily of MTB‐100^®‐2004, (Alltech, Inc.), 10 g/cow daily of MTB‐100^®‐2006, (Alltech, Inc.), 10 g/cow daily of experimental Alltech^® product (Alltech, Inc.) and 227 g/cow daily of Astra‐Ben 20^® (AB‐20^®; Prince Agri Products, Inc.). In study 3, the experimental period of 2 weeks each lasting 8 days and milk samples were collected from day 4 to 8 and day 11 to 16. Milk samples from study 3 were analysed for AFM₁ concentrations by ELISA. For all experiments, changes in AFM₁ concentrations because of the addition of EFA’s were calculated. Four of the five EFAs tested in this study had no significant effect on AFM₁ concentrations. However, the addition of AB‐20^® resulted in a significant decrease in AFM₁ concentrations (60.4%). In summary, the addition of AB‐20^® to the diet of cattle appears to be effective for significantly reducing AFM₁ concentrations in the milk of cows fed an aflatoxin‐contaminated diet.     

Effect of mycotoxin contaminated feed on production parameters of dairy cows

Based on a feeding trial using 27 lactating "Simmental-cows" the effect of naturally contaminated feed with deoxynivalenol (DON) as well as zearalenone (ZON) regarding production parameters was examined. 3 groups of cows according to lactation number, milk yield (kg ECM) and body mass were used. The average daily intake of DON in group K was 12.4 mg, in group T 14.1 mg and in group M 14.3 mg and ZON in group K was 12.4 mg, in group T 0.67 mg and in group M 0.68 mg respectively. The feed of animals of group M was supplemented with "Mycofix Plus" as mycotoxin inactivator. The red and white blood picture including the thrombocytes were in all groups within the normal range. Concerning enzymes (GGT, AP) and metabolites (GLUC, TBIL, UREA, CREA) the mean values of the 3 groups were in the normal range. Slightly increased were the mean values of all groups in respect to the AST- and GLDH-activities. Volatile fatty acids of the rumen content were significantly highest in group M, also the number of dead rumen infusoria was significantly decreased, but the counts of small sized infusoria increased. The study has shown that "Mycofix Plus" might be able to enhance the activity of rumen flora concerning detoxification of mycotoxins in feed of dairy cows.     

中国荷斯坦牛乳尿素氮浓度昼夜变化规律研究

随机收集了8头处于泌乳期的中国荷斯坦奶牛24h内乳样,对乳中尿素氮浓度的昼夜变化情况进行研究。结果发现,同一奶牛个体在不同的时间点乳尿素氮浓度差异较大。因此,单个时间点的乳液尿素氮浓度代表性较差,有必要收集全天乳样。     

Mixed feed containing dextran improves milk production of holstein dairy cows

Total 37 Holstein daily cows (body weight: 631.76 +/- 18.45 kg, age: 5.47 +/- 1.94 years, parturition: 3.71 +/- 1.76 times) which became pregnant and gave birth to calves in the same season and lactated continuously were selected for this study. They were randomly divided into two groups: Group A-control, Group B-fed with 30 g/head/day of mixed feed containing supplemental dextran for one year from October 2001. After supplementation of the mixed feed, milk yields and components (fat, protein and solid non-fat) of Group B were compared with those of Group A in the 8th, 10th and 11th months (May, July and August of 2002). Milk yields of Group B were greater than the yields of Group A. In particular, there was a significant difference (p<0.001) between these groups in the July and August values. Milk components of Group B slightly differed from those of Group A before the supplementation, but after the supplementation, concentrations and total amounts of fat, protein and solid non-fat significantly increased more in Group B than in Group A. Thus mixed feed containing dextran can increase the milk production of Holstein dairy cows in the hot season.     

乳中早孕因子的分离纯化及性质鉴定

早孕因子(early pregnancy factor, EPF)于1974年首次被澳大利亚学者Morton[1]等人发现的.EPF在动物受精后数小时至数天内即可检出,并在胎儿死亡或排出后很短时间即消失,以此对孕畜进行是否已受孕的超早期诊断,减少空怀率等,亦可作为监测胎儿发育情况的一个有效指标;同时还可用于胚胎移植过程中活胚胎的选择及判定移植是否成功.     

Mycobacterium bovis cultured from commercially pasteurized cows' milk: laboratory cross-contamination

The ability of Mycobacterium paratuberculosis to survive the commercial pasteurization process of raw milk remains controversial. In a study undertaken in Venezuela to culture M. paratuberculosis from commercially pasteurized cows' milk, 83-200 ml containers of milk were processed and cultured on Herrold's egg yolk slants. No M. paratuberculosis was cultured but a total of six colonies of Mycobacterium bovis were isolated from one container each from two different milk providers. Because laboratory cross-contamination was suspected, the laboratory records were reviewed and spoligotyping was carried out on the isolated individual colonies. On the day before these milk specimens were processed, the biological safety cabinet had been used for the isolation of M. bovis from lymph nodes from infected cattle. Spoligotyping showed that that the colonies isolated from the milk all had the same pattern as the strains isolated from the lymph nodes that were processed the previous day. As far as we know, this is the first report of cross-contamination in a veterinary mycobacterial laboratory. False-positive cultures in the mycobacterial laboratory are not rare. In this setting M. bovis was isolated because it is the most common manipulated organism in this laboratory. We believe that reports on the isolation of M. paratuberculosis from commercially pasteurized milk should exclude cross-contamination before reporting, especially when this organism is routinely isolated from animal material in the same lab.     

Effect of feed restriction on dairy cow milk production: a review

In the dairy cow, negative energy balance affects milk yield and composition as well as animal health. Studying the effects of negative energy balance on dairy cow milk production is thus essential. Feed restriction (FR) experiments attempting to reproduce negative energy balance by reducing the quantity or quality of the diet were conducted in order to better describe the animal physiology changes. The study of FR is also of interest since with climate change issues, cows may be increasingly faced with periods of drought leading to a shortage of forages. The aim of this article is to review the effects of FR during lactation in dairy cows to obtain a better understanding of metabolism changes and how it affects mammary gland activity and milk production and composition. A total of 41 papers studying FR in lactating cows were used to investigate physiological changes induced by these protocols. FR protocols affect the entire animal metabolism as indicated by changes in blood metabolites such as a decrease in glucose concentration and an increase in non-esterified fatty acid or β-hydroxybutyrate concentrations; hormonal regulations such as a decrease in insulin and insulin-like growth factor I or an increase in growth hormone concentrations. These variations indicated a mobilization of body reserve in most studies. FR also affects mammary gland activity through changes in gene expression and could affect mammary cell turnover through cell apoptosis, cell proliferation, and exfoliation of mammary epithelial cells into milk. Because of modifications of the mammary gland and general metabolism, FR decreases milk production and can affect milk composition with decreased lactose and protein concentrations and increased fat concentration. These effects, however, can vary widely depending on the type of restriction, its duration and intensity, or the stage of lactation in which it takes place. Finally, to avoid yield loss and metabolic disorders, it is important to identify reliable biomarkers to monitor energy balance.     

不同预混料及缓冲剂对奶牛泌乳性能的影响

选择6头荷斯坦奶牛研究添加预混料和复合缓冲剂对奶牛产奶量和乳脂成分的影响。试验采用3×3重复拉丁方设计,分3组处理:(Ⅰ)基础日粮+1%市售商品预混料(对照组);(Ⅱ)基础日粮+1%新型预混料;(Ⅲ)基础日粮+1%新型预混料+复合缓冲剂。结果表明:1)试验Ⅲ组的粗蛋白质、粗脂肪、中性洗涤纤维和酸性洗涤纤维的表观消化率均高于其他两组,但差异不显著(P>0.05)。2)试验Ⅲ组产奶量为23.98kg/d,比试验Ⅰ组和试验Ⅱ组分别提高5.78%和3.67%,且差异极显著(P>0.05);试验Ⅲ组的乳脂率、乳蛋白、乳糖和非脂固形物均显著高于试验Ⅰ组和试验Ⅱ组。3)试验Ⅲ组奶牛血糖含量为86.83mg/dL,极显著高于试验Ⅰ组和试验Ⅱ组;试验各组血清尿素氮含量无显著差异(P>0.05)。     

镰刀菌及玉米赤霉烯酮毒素对饲料的污染与控制

1　镰刀菌的特点镰刀菌 (Ｆｕｓａｒｉｕｍ)属霉菌的一个种属 ,它和青霉、曲霉一样分布极广 ,种类繁多 ,比较常见的有禾谷镰刀菌、三线镰刀菌、木贼镰刀菌、雪腐镰刀菌、粉红镰刀菌、燕麦镰刀菌、串珠镰刀菌、尖孢镰刀菌、拟枝镰刀菌、茄病镰刀菌等。镰刀菌菌落一般呈白色绒毛状 ,菌丝发达 ,内含大量分生孢子 ,常产生可溶性色素。分生孢子有大、小两种类型 ,大型分生孢子大多呈镰刀形、多隔 ;小型分生孢子有卵形、梨形、圆形、柱形等。镰刀菌的主要代谢产物为玉米赤霉烯酮 (ＺＥＮ)、单端孢霉烯族化合物和丁烯酸内酯等。镰刀菌是一种所谓的…     

饲料中添加烟酸对夏季奶牛产奶性能的影响

试验选取9头泌乳早期处于热应激的荷斯坦牛,采用3×3拉丁方设计,分别饲喂基础日粮(对照组)和在基础日粮中添加5g/d和10g/d烟酸日粮,研究添加烟酸对奶牛生产性能影响。结果表明:添加5g/d和10g/d烟酸可使奶牛产奶量分别提高13.20%和9.39%(P<0.05);而4%标准乳量无显著差异(P>0.05);添加烟酸对乳蛋白和乳脂率无显著影响(P>0.05)。     

Nationwide survey of antibodies to bovine coronavirus in bulk milk from Swedish dairy herds.

Bulk milk samples from 2236 dairy herds randomly selected throughout Sweden in proportion to region and herd size were analysed for antibodies to bovine coronavirus (BCV) in an ELISA. The results were expressed as optical density (OD) values and an OD > 0.04 was considered positive. Eighty-nine per cent of the samples were antibody-positive and 52 per cent had high levels of antibodies to BCV (an OD > 0.70). There were significantly higher OD values (P < 0.001) and fewer antibody-negative samples (P < 0.001) from larger herds than from smaller herds. There were also significantly higher OD values and fewer antibody-negative samples from herds in southern Sweden than from herds in northern Sweden (P < 0.001 and P < 0.001, respectively). These results indicate a higher frequency of BCV infections in larger herds and in herds in southern Sweden.