Eradication of Chorioptes bovis mange in a dairy herd with turn-out to graze by Eprinex Pour-On

The possibility to control or even eradicate chorioptes manage by a single herd treatment with EPRINEX Pour-On (dosage: 0.5 mg Eprinomection/kg bodyweight) during pasture season was investigated in a dairy herd of 320 dairy cows. A further aim of the study was to evaluate whether such mid-summer treatment with EPRINEX Pour-On due to its endo-ectocide action would at the same time also result in a metaphylaxis of gastro-intestinal and lung worms and in a reduction of fly infestation. Due to clinical symptoms manage prevalence in the herd prior to treatment was 11 percent. After treatment, clinical symptoms disappeared within 2 months completely and did not re-occur during the subsequent housing period. Chorioptes mites during the entire trial period no longer were detected. The final clinical and parasitological investigation shortly before turn-out the next year (April 1999) demonstrated chorioptes mange to be eradicated clinically and parasitologically. Due to the mid-summer treatment infestation with gastrointestinal helminths also was eliminated and clinical symptoms of helminth infestations during the pasture season no longer were observed. However, at housing in November, low numbers of eggs of gastrointestinal nematodes were detected in 6% of dairy cows, 32% of second-season and 63% of first-season heifers, respectively. Milk yield per cow and day on average increased by 1 litre after treatment with EPRINEX Pour-On. This increase in production is likely a result of the reduction in total parasite burden of lactating cows.     

Field trials in New Zealand confirming the efficacy of eprinomectin applied topically to cattle

The efficacy and acceptability of eprinomectin in a topical formulation against gastro-intestinal nematodes in cattle was assessed under field conditions. Seven similar commercial dairy farms in the North and South Islands of New Zealand were included in the studies, involving 247 Holstein-Friesian, Jersey or Jersey-cross cattle. Cattle were confirmed by positive faecal nematode egg counts to have natural infections of gastro-intestinal nematodes and were held in separate treatment groups. In each replicate, four animals received eprinomectin (500 microg/kg body weight) and one animal received vehicle solution, all applied topically at 1 ml/10 kg body weight. Faecal samples were collected before, and 14 days after treatment, for faecal trongylid egg counts. Animals treated with eprinomectin had significantly lower (p < 0.05) Day 14 faecal strongylid egg counts than the controls. There were no significant differences (p > 0.10) between treated and control groups for pretreatment strongylid egg counts. No formulation runoff or adverse reactions were observed. These studies showed eprinomectin to be effective against gastro-intestinal nematode infections and safe for use in dairy cattle under natural field conditions.     

欧洲不同良种肉牛杂交利用青海黄牛后代生长发育试验研究

为了研究青海省肉牛杂交改良效果,筛选适应高寒地区肉牛最佳杂交组合,从而为今后开展肉牛杂交工作提供有力的依据,通过6年的试验研究,测定分析了蓝本、皮本、利本、夏本、德本F1牛和青海黄牛的初生,3月龄,6月龄,12月龄,18月龄体重及体尺指标及杂交后代对青海高原高寒气候的适应性观察。结果显示:五个杂交组合F1代不同年龄的生长速度和体尺指标均明显优于青海黄牛(P<0.01)说明良种肉牛改良效果显著,在不同杂交组合后代的比较中,蓝本F1牛生长发育最快,各阶段体重及体尺指标显著高于青海黄牛,比皮本、利本、夏本、德本F1牛也有明显提高。     

Increase in milk yield following eprinomectin treatment at calving in pastured dairy cattle

Gastrointestinal nematodes rarely cause signs of clinical disease in adult cattle. However, they have been shown to exert a negative impact on production in lactating animals, as seen by improved production following elimination of the worms using anthelmintics. A double blind, randomized clinical trial was performed in 28 dairy herds in Canada. The objective of the study was to evaluate the effect of treatment with eprinomectin pour-on solution (IVOMEC EPRINEX) at calving on production, in cattle that have had some exposure to pasture. Cows were randomly allocated to treatment or placebo in blocks of 10, based on calving date, and treated with eprinomectin or placebo on the day of calving.Information on milk production was obtained from all animals, as well as recorded cases of selected diseases. Milk production results from the Canadian dairy herd management system database were analysed using a mixed model with herd as a random effect and test within-cow as a repeated measurement. Test day milk yields from the first six tests after treatment were included in the model, representing a period of between 180 and 200 days in milk (dim). Treated cows produced an additional 0.94 kg of milk per day when compared to the controls over this period. The production effect was independent of calving season, age of the animal and geographical location. No effect of treatment was seen on milk composition, somatic cell count (scc) or on the selected health parameters that were recorded for all included animals.Monthly fecal egg counts (FEC) were performed for eight randomly selected animals in each herd. The observed FEC were low in this study, with a range from 0 to 419 trichostrongyle type eggs per 5g (ep5g) of feces in animals not yet treated with the anthelmintic. The average count was 9.8 and the median was 1.0. FECs dropped immediately after calving and stayed lower for at least 100 days in treated animals when compared to controls.In conclusion, gastrointestinal nematodes appear to have an effect on milk production in Canadian dairy cows that have had some degree of pasture exposure. Eliminating the present subclinical parasite burdens produced a consistent increase in milk production that can yield economic benefits for the dairy producer.     

BOOK REVIEWS

Book reviewed in this article:
John McFadyean, Founder of Modern Veterinary Research. Iain Pattison. J. A. Allen.
Proceedings of XII Seminar, Sheep and Beef Cattle Society of the New Zealand Veterinary Association.
Pictorial Anatomy of the Cat. S. G. Ginbert.
Grazing Animals. Editor F. H. W. Morley.
Equine Medicine and Surgery. Editors R. A. Mansman and E. S. McAllister.
Applied Veterinary Anatomy. R. E. Habel.
Beef Production from Different Dairy Breeds and Dairy Beef Crosses. Editors C. J. More and O'Per rail.
Animal Health. David Sainsbury.     

Anthelmintic efficacy of febantel paste in naturally infected calves

The purpose of the present study was to verify results of the lowest dose (5 mg kg-1) of febantel evaluated in an earlier trial in which there were no differences in efficacies of three dose rates (5, 7.5 and 10 mg kg-1 body weight) against natural gastrointestinal nematode infections of cattle. Fourteen Angus calves (mean weight and age of 155 kg and 525 days, respectively), from the same farm, with relatively heavy (mean of 448 eggs g-1 feces (epg] parasite burdens were selected. After an adjustment period of 8 days in drylot, beginning on 25 July, seven calves were treated with a 45.5% paste formulation of febantel. On Day 7 post-treatment, calves were necropsied for determination of residual worms. Rectal fecal samples were obtained prior to adjustment, at treatment, 5 days post-treatment and at necropsy. On both Day 5 post-treatment and at necropsy a mean of less than 1 epg was recovered from treated calves compared with 765 and 1566 epg, respectively, in control calves. Worms counts at necropsy revealed an efficacy of 98.5% against all adult abomasal worms (Haemonchus placei, 100%, P less than 0.02; Trichostrongylus axei, 99.4%, P less than 0.0001; Ostertagia ostertagi, 90.5%, P less than 0.0002). Treatment was 100% efficacious against adult small and large intestinal worms. However, numbers of Bunostomum phlebotomum, O. radiatum and Trichuris spp. recovered in the control calves were too low to enable a reliable test of drug efficacy. Treatment was not effective against either mucosal or luminal fourth stage larvae of abomasal O. ostertagi.(ABSTRACT TRUNCATED AT 250 WORDS)     

BMY和婆罗门牛早期生长性状遗传力研究

本文采用云南省肉牛与牧草研究中心杂交选育的热带亚热带肉牛BMY和纯种婆罗门(Brahman,简称B)2000至2003年的资料,配合动物模型应用MTDFREML软件进行初生重和6月龄体重两个性状的遗传力估计,结果为BMY的初生重、6月龄体重、B的初生重,6月龄体重遗传力分别是:0.34、0.16、0.36、0.13。     

Emory milkvetch (Astragalus emoryanus var emoryanus) poisoning in chicks, sheep, and cattle.

A severe outbreak of Emory milkvetch poisoning in cattle and sheep occurred near Roswell, New Mexico, in the spring of 1975. Mortality averaged 2% to 3% and morbidity averaged 15% to 20%. Emory milkvetch collected from the infested area contained miserotoxin measured as 5 to 9 mg of NO2/g of plant (dry weight). Chicks fed extracts of Emory milkvetch showed toxic signs when fed one dose as 300 mg of NO2/kg of body weight, and died within 5 to 8 hours when fed milkvetch as 400 mg of NO2/kg. A sheep fed Emory milkvetch for 7 days in the form of 38 mg of NO2/kg/day developed signs of nitro poisoning on the 7th day. Cattle were poisoned or died when fed Emory milkvetch as 12 to 20 mg of NO2/ig for several days. The toxic signs observed in the field and under experimental conditions were similar.     

Trends in mortality ratios among cattle in US feedlots.

OBJECTIVE: To evaluate trends in feedlot cattle mortality ratios over time, by primary body system affected, and by type of animal. DESIGN: Retrospective cohort study. ANIMALS: Approximately 21.8 million cattle entering 121 feedlots in the United States during 1994 through 1999. PROCEDURES: Yearly and monthly mortality ratios were calculated. Numbers of deaths were modeled by use of Poisson regression methods for repeated measures. Relative risks of death over time and by animal type were estimated. RESULTS: Averaged over time, the mortality ratio was 12.6 deaths/1,000 cattle entering the feedlots. The mortality ratio increased from 10.3 deaths/1,000 cattle in 1994 to 14.2 deaths/1,000 cattle in 1999, but this difference was not statistically significant (P = 0.09). Cattle entering the feedlots during 1999 had a significantly increased risk (relative risk, 1.46) of dying of respiratory tract disorders, compared with cattle that entered during 1994, and respiratory tract disorders accounted for 57.1% of all deaths. Dairy cattle had a significantly increased risk of death of any cause, compared with beef steers. Beef heifers had a significantly increased risk of dying of respiratory tract disorders, compared with beef steers. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that although overall yearly mortality ratio did not significantly increase during the study, the risk of death attributable to respiratory tract disorders was increased during most years, compared with risk of death during 1994. The increased rates of fatal respiratory tract disorders may also reflect increased rates of non-fatal respiratory tract disorders, which would be expected to have adverse production effects in surviving animals.     

不同肉用品种牛与新疆褐牛最佳杂交组合筛选试验

新疆褐牛是我国自主培育的乳肉兼用品种,具有耐寒、耐粗饲、适应性和抗逆性强、适宜草原放牧等特性。试验选择新疆褐牛（BD）与肉用品种牛——南德温牛（ND）、红安格斯牛（AG）、肉用西门塔尔牛（XM）进行经济杂交,以确定其是否可以表现出明显的杂种优势和很好的配合力。结果表明,ND×BD组出生重较其他2组高,AG×BD组出生重最低;随着月龄的增加,AG×BD组的体重迅速增加,表现为生长早期强势发育,但随着月龄的不断增加,从6月龄开始,AG×BD组与其他2组体重逐渐接近;到12月龄时,AG×BD组胸宽显著高于其他2组,但其他指标没有差异。试验显示,最佳杂交组合为ND×BD组,其次为AG×BD组,最后为XM×BD组。     

Efficacy of moxidectin against an ivermectin-resistant strain of Haemonchus contortus in sheep.

The efficacy of moxidectin was determined against ivermectin-susceptible and resistant strains of Haemonchus contortus. At the onset of the trial, 40 lambs were each infected with 5000 third stage larvae of one of two strains of Haemonchus contortus. The lambs were randomly sorted into eight treatment groups 28 days post-infection and were treated as follows: Group 1, susceptible strain with no treatment; Group 2, resistant strain with no treatment; Group 3, susceptible strain treated with 0.2 mg moxidectin kg-1 body weight; Group 4, resistant strain treated with 0.2 mg moxidectin kg-1; Group 5, resistant strain treated with 0.4 mg moxidectin kg-1; Group 6, susceptible strain treated with 0.2 mg ivermectin kg-1; Group 7, resistant strain treated with 0.4 mg ivermectin kg-1; Group 8, resistant strain treated with 0.8 mg ivermectin kg-1. The lambs were killed 1 week post-treatment. Comparisons were made among groups based on the number of eggs per gram of feces on the day of treatment and the numbers of worms recovered from each lamb. Both moxidectin and ivermectin were effective in removing susceptible Haemonchus with efficacies of 100% and 99.7%, respectively. The efficacy of moxidectin against the resistant strain was 99.9% and 100% at 0.2 mg kg-1 and 0.4 mg kg-1, respectively, whereas there were only 38.8% and 53.1% efficacies in the lambs treated with 0.4 mg ivermectin kg-1 and 0.8 mg kg-1 body weight, respectively.     

A stochastic partial-budget analysis of an experimental Pasteurella haemolytica feedlot vaccine trial

A field trial compared a modified Pasteurella haemolytica biotype A serotype 1 leukotoxin vaccine to a commercial vaccine during March-July 1995 in a Natal Midlands, South African, feedlot. Weaners/long weaners purchased by the feedlot were allocated systematically into test vaccine and control vaccine groups of 1241 and 1240 head, respectively, and fed in groups of approximately 200 head. Morbidity and mortality were monitored until the animals were marketed. Details of pleuritis and pneumonia at veterinary meat inspection were recorded for 409 test-vaccinated and 424 control-vaccinated cattle. An increase in morbidity but not mortality risk of respiratory disease was shown between test (13.8% morbidity) and control (11.4% morbidity) groups. Cattle with a processing weight <245 kg were 1.4 times more likely to develop respiratory diseases than cattle with a processing weight > or =245 kg. Cattle bought on auction were 1.6 times more likely to develop respiratory disease than cattle bought at private sales. A partial farm budget incorporating Latin Hypercube sampling of uncertain variables was done to obtain the distribution of possible financial outcomes if the test vaccine were used. Impact (sensitivity) analyses indicated that median weight of carcass cut away had the greatest impact on the profit margin. The partial farm budget highlighted the importance of reducing sub-clinical lesions in a feedlot.     

不同肉牛育肥的牛肉产品生产对饲料粮消耗比较分析

在对繁殖母牛、哺乳犊牛和架子牛进行饲养试验及调查的基础上,结合所进行的架子牛育肥试验和犊牛直线育肥试验,参考肉牛饲养标准和已发表的肉牛育肥试验数据,并根据目前我国牛肉产品提供状况和肉用牛育肥的饲料资源情况,分别比较不同肉牛育肥牛肉产品生产所需要的粮食。结果表明,为获得等同重量的肉牛产品,直线育肥技术比后期集中育肥要消耗较少的粮食,而高档牛肉生产（高端肉产品生产）需要消耗更多的饲料粮。     

The efficacy of eprinomectin extended-release injection against Hypoderma spp. (Diptera: Oestridae) in cattle

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was determined in cattle harboring naturally acquired infestations of first- or second- and third-stage larvae of Hypoderma spp. in three studies conducted according to the same protocol in the USA (two studies) and Germany (one study). Thirty cattle sourced from herds with a history of Hypoderma infestation were included in each study. Cattle were formed into replicates of three animals each on the basis of pre-treatment anti-Hypoderma antibody titers. Within replicates each animal was randomly allocated to one of the following treatments: ERI vehicle (control) at 1 mL/50 kg bodyweight, administered once on Day 0; Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once on Day 0 (when larvae were expected to be first instars); or Eprinomectin 5% ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg), administered once when larvae were second or third instars (study dependent, Day 73, 119, or 140). Treatments were administered by subcutaneous injection in front of the shoulder. In all studies, emerging and/or expressed Hypoderma larvae were recovered, speciated, and counted and viability was determined. Eprinomectin LAI treatment was 100% (p < 0.05) efficacious against first- and second- or third-stage larvae of Hypoderma bovis (two studies) and Hypoderma lineatum (one study). All animals accepted the treatment well. No adverse reaction to treatments was observed in any animal in any study.     

Clinical and parasitological evaluations of levamisole as a treatment for bovine stephanofilariasis

Field trials were carried out with two formulations of levamisole for treatment of chronic inflammatory lesions on the muzzle and teats of cattle, caused by Stephanofilaria okinawaensis in the enzootic area of the disease, Ishigaki Island, Okinawa Prefecture, Japan.Cattle were treated orally with levamisole hydrochloride (10% powder) at a dose of 7.5 g/100 kg of body weight once (64 cattle) or twice with an interval of 3 or 4 weeks (five cattle each). Lesions on the muzzle and tests disappeared or were reduced within 4 weeks of the first medication. In some cattle a sign of recurrence was observed 8 weeks after medication.Parasitological and histological examinations were carried out 1 week carried out 1 week (10 cattle), 4 weeks (12 cattle), and 8 weeks (13 cattle) after single oral administration of levamisole hydrochloride. No Stephanofilaria worms were detected at 1 week after medication. A small number of worms were detected at 4 weeks and more were observed 8 weeks after medication.A levamisole phosphate solution (18.2%) was injected subcutaneously once into one teat of each of three cattle, or twice into the neck with a 4-week interval between treatments (five cattle). The dose was 2 ml/teat (364 mg of active ingredient) or 2 ml/45 kg of body weight for the side of the neck. There was marked improvement as with oral medication with levamisole hydrochloride powder.     

Pasteurella haemolytica cytotoxin neutralizing activity in sera from Ontario beef cattle.

A random sample of sera obtained from cattle necropsied as part of the Bruce County Beef Project in 1980-81 was assayed for the ability to neutralize the cytotoxin of Pasteurella haemolytica A1. Cattle dying of fibrinous pneumonia had significantly lower neutralizing activity in serum than cattle which died for reasons other than pneumonia. Activity in pneumonic cattle was also lower than the mean of twelve samples randomly chosen from sera of cattle bled on entry to feedlots in the fall of 1979. A role for the toxin neutralizing response in resistance to pneumonic pasteurellosis is proposed.     

郏县红牛的分子育种研究与高效选育

本文围绕郏县红牛肉用性状的高效选育,分析了郏县红牛种质资源特性与现状,综述了郏县红牛分子育种研究进展与成就,在此基础上,提出了郏县红牛高效选育的实施和措施。首先必须坚持进行郏县红牛的本品种选育,其次是利用已取得的在分子育种方面的研究成果,开展高效选育。在选育和扩群的基础上提出了郏县红牛遗传利用的原则和方法。     

西藏日喀则市黄牛改良现状与对策

为提高西藏黄牛生产性能,使其成为当地的优良品种,利用优秀奶牛冻精使用胚胎移植的方法,或引进优质的种公牛对西藏黄牛进行改良.结果表明,改良后的黄牛经济效益显著,相当于两头以上当地母牛的产奶量,每头改良母牛增加收入1 755元,而且提前一年半投产.     

中国荷斯坦后备奶牛生长发育规律的研究

通过对西安现代化农业开发公司草滩农场170头荷斯坦牛后备牛初生,4月龄至16月龄体高、体长、胸围及体重进行测定,统计各月龄体高、体长、胸围及体重的累积生长的平均值、绝对生长值、相对生长值,对应绘制出四项指标的累计生长、相对生长曲线;分析了西安地区中国荷斯坦牛的早期生长发育状况,为制定后备牛的培育方案奠定了基础。     

Pharmacokinetics of Eprinomectin in Plasma and Milk following Subcutaneous Administration to Lactating Dairy Cattle

Eprinomectin is only available as a topically applied anthelmintic for dairy cattle. To determine whether eprinomectin can be applied as an injectable formulation in dairy cattle, a novel injectable formulation was developed and was subcutaneously delivered to four lactating dairy cattle at a dose rate of 0.2 mg/ kg. Plasma and milk samples were collected. The concentrations of eprinomectin in all samples were determined by HPLC. The peak plasma concentration (C_max)of 44.0±24.2 ng/ml occurred 39±19.3 h after subcutaneous administration, equivalent to the C_max (43.76±18.23 ng/ml) previously reported for dairy cattle after a pour-on administration of 0.5 mg/kg eprinomectin. The area under the plasma concentration–time curve (AUC) after subcutaneous administration was 7354±1861 (ng h)/ml, higher than that obtained after pour-on delivery (5737.68±412.80 (ng h)/ml). The mean residence time (MRT) of the drug in plasma was 211±55.2 h. Eprinomectin was detected in the milk at the second sampling time. The concentration of drug in milk was parallel to that in plasma, with a milk to plasma ratio of 0.16±0.01. The highest detected concentration of eprinomectin in milk was 9.0 ng/ml, below the maximum residue limit (MRL) of eprinomectin in milk established by the Joint FAO/WHO Expert Committee on Food Additives in 2000. The amount of eprinomectin recovered in the milk during this trial was 0.39%±0.08% of the total administered dose. This study demonstrates that subcutaneous administration of eprinomectin led to higher bioavailability and a lower dose than a pour-on application, and that an injectable formulation of eprinomectin may be applied in dairy cattle with a zero withdrawal period.