Targeted application of anthelmintics to control trichostrongylosis in dairy goats: result from a 2-year survey in farms

The targeted application of anthelmintic treatments represents one of the current available solutions to slow down the development of anthelmintic resistance within worm populations. Within an experimental flock of dairy goats, control of gastrointestinal parasitism by such selective treatments, targeting the most receptive animals within a flock, was previously found to be effective and to have no detrimental consequences on milk production. The objectives of the current study were to verify the validity of this method in farm conditions. Eleven dairy goat farms from three main areas of production in France were surveyed for 2 years. In six farms, the survey was prolonged for a third year. During year 1, systematic treatments were applied during the grazing season whereas in year 2 and or year 3, treatments were given exclusively to the goats in first lactation and to the multiparous ones with the highest potential of milk production. The level of nematode infection was measured four times per year through individual coproscopical examinations and the mean annual production of milk was recorded. No significant changes in egg excretion nor in milk production were noticed in any farm during years 2 or 3 after switching from the systematic to the selective mode of treatments. These results confirmed that targeted application of anthelmintics might represent a way to combine the control of trichostrongyles and the prevention of anthelmintic resistance.     

Distribution and repeatability of faecal egg counts and blood parameters in dairy goats naturally infected with gastrointestinal nematodes

The frequency, distribution and repeatability of measurements related to infection with gastrointestinal nematodes have been estimated in dairy goats. Monthly faecal and blood samples were taken over two grazing seasons from a flock of 120 naturally infected goats. The frequency distribution of egg excretion was positively skewed at each sampling date, suggesting an aggregative distribution of parasites. Overdispersed distributions were also apparent for pepsinogen and inorganic phosphate values. Repeatabilities for each parameter were estimated within each year. The values ranged between 0.23 to 0.43 and were relatively similar during the 2 years, with the highest coefficients recorded for pepsinogen. For each parameter, moderate to high repeatabilities were also estimated between the 2 years. Overall, the data suggest that, in dairy goats, the distribution of worms is overdispersed with a few individuals repeatedly harbouring large worm populations. These results have practical implications for genetic selection for resistance to worm infection and for selective administration of anthelmintics.     

Control of gastrointestinal parasitism with nematodes in dairy goats by treating the host category at risk

Infections of the gastrointestinal tract with parasitic nematodes remain one of the main limiting factors in grazing dairy goats. The usual mode of control of these parasitic diseases has up to now been based on the repeated use of anthelmintics. However, the prevalence rates of anthelmintic resistances, in particular to benzimidazoles, are now particularly high in the French dairy goat production. This situation makes it mandatory to reconsider the usual mode of control of these nematodes and to look for short term, alternative solutions which combine the control of gastrointestinal infections and management of anthelmintic resistances. One of the possible options is to leave a part of the flock without treatment during the grazing season in order to maintain alleles of susceptibility to anthelmintics within the worm populations. Previous epidemiological observations identifying the categories of host populations at risk are presented which provide the rationale for targeted applications of treatments. The results of assays on experimental flocks and from farm surveys examining the advantages and drawbacks of selective treatments are presented. The value of these results in combination with other alternative solutions of control are discussed in order to use minimum treatments with maximum benefits.     

High perinatal mortality associated with triple anthelmintic resistance in a German sheep flock

High perinatal mortality, low milk yields and occasional ewe deaths were investigated in a Dorper sheep flock in Southern Germany. Parasitic gastroenteritis due to Trichostrongylus spp. associated with severe weight loss despite regular anthelmintic treatments of the flock was identified as the underlying cause. A faecal egg count reduction (FECR) test revealed zero reduction after treatment with ivermectin or albendazole, respectively, and a FECR of 57.9% following treatment with levamisole. These results indicate a lack of, or considerably reduced efficacy of substances from all three classical groups of anthelmintics and demonstrate that triple anthelmintic resistance is also present in Germany. The introduction of resistant worm populations with imported livestock, excessive use of anthelmintic drugs and under-dosing of goats have possibly led to the problem in the flock described. Veterinary advice on anthelmintic treatments and responsible parasite control programmes are therefore crucial in small ruminant flocks.     

Distribution and repeatability of nematode faecal egg counts in dairy goats: a farm survey and implications for worm control

The aims of this study were to characterise trichostrongyle egg excretion in dairy goat flocks under various epidemiological conditions, and to assess the relative importance of animals in their first lactation and goats with high levels of milk production on the total egg output of the flock. The repeatability of egg excretion was estimated on 4 different dates in 14 dairy goat farms in France. Egg outputs were positively skewed on most farms suggesting an aggregated distribution of parasites. Within-year repeatability coefficients ranged from 0.29 to 0.82 suggesting that, on most farms, animals with high egg excretion on one occasion are likely to show high rates of excretion on other occasions. Comparisons of egg outputs from the selected subgroups showed that the high producing goats contributed prominently to egg excretion, particularly at times of peak parasitism. Results from goats in their first lactation were more equivocal. These results provide a rationale for anthelmintic strategies in dairy goats based on phenotypic characters.     

Effects of the initial level of milk production and of the dietary protein intake on the course of natural nematode infection in dairy goats

The level of dietary protein is known to alter the establishment and the pathophysiology of gastrointestinal nematodes in sheep. On the other hand, high-producing dairy goats are less resistant and/or resilient than low-producing ones to experimental nematode infection. During a 2-year study, we have investigated the course of a natural nematode infection (mainly T. colubriformis) in a high-producing dairy goat flock. In year 1, 50 grazing goats divided in high (HP) or low producer (LP) were compared from April to October for parasitological and milk parameters. In year 2, the 25 HP goats were only considered and were allocated to two levels of dietary protein, high level (HPr) with a protein coverage of 125% or normal level (NPr) with a protein coverage of 106%. They were monitored as above. In year 1, HP goats showed a greater nematode egg output (1856 vs. 1000epg) associated with higher values in T. colubriformis IgG in autumn than LP ones whereas the decrease in serum phosphate concentration was similar in both groups. In year 2, HPr goats exhibited lower egg output in autumn (2219 vs. 2817) vs. NPr ones. Moreover, milk yield and fat content were significantly higher in HPr vs. NPr in the 2nd part of the study. HP goats are less resistant to nematode infection in natural conditions. Resistance and resilience of HP goats may partially be improved by a protein supplementation in the diet.     

Targeted selective treatment for worm management-How do we sell rational programs to farmers?

Seriously escalating global anthelmintic resistance in gastrointestinal nematodes of small ruminants has spawned a variety of alternatives to anthelmintics for worm management, based on the need for sustainable Integrated Parasite Management (sIPM). Pivotal to the sIPM approach is the concept of refugia, the proportion of a given parasite population that escapes exposure to control measures. By balancing drug applications with the maintenance of refugia, the accumulation of anthelmintic resistance alleles in worm populations can be considerably delayed, while still providing good levels of control. The over-dispersed nature of parasitic infections provides an opportunity to achieve this balance, by targeting treatments to the members of a flock or herd that are least tolerant to nematode infection. However, implementation of this strategy has only recently become feasible, with the development of the FAMACHA((c)) system for clinical evaluation of anaemia due to haemonchosis. Subsequently, the use of milk yields has proven an effective indicator in dairy goats infected predominantly with nematodes other than Haemonchus contortus. In addition, short-term weight changes and perhaps also body condition scoring may provide indices of parasitism, permitting the rapid identification of animals likely to benefit from treatment. However, sIPM and refugia-based approaches are more complex than whole-flock treatments in conventional programs, and adoption by farmers is most likely where the theoretical basis is understood. As close communication with informed advisors is generally limited, there is a danger that sIPM will remain a theoretical concept without alternative modes of communication. The development of computer-based decision support programs, which use epidemiological, seasonal and clinical information to provide recommendations for specific situations, should be accorded high priority in the future development of worm management systems.     

Effects of the repeated distribution of sainfoin hay on the resistance and the resilience of goats naturally infected with gastrointestinal nematodes

Due to the high prevalence of anthelmintic resistance in goats, the need to explore novel approaches to control nematodes and to reduce the exclusive reliance on chemotherapy is strongly demanded in this host species. In sheep, several studies have shown that the consumption of tannin-rich legume forages was associated with positive effects on host resilience and resistance to parasite infection. In goats, studies on such interactions between tanniferous plants and nematode infections remain few. The objectives of the current study were to examine under natural conditions the effects of consumption of sainfoin hay by goats on the parasite populations and on host resilience. Eighteen adult cull goats naturally infected with Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus colubriformis were used in the study. At the start of the assay, the goats were allocated into two groups, balanced according to weight and the levels of egg excretion. The two groups grazed separate pastures for 3 months with similar stocking rates. Goats from group S received each month indoors, for 7 days, sainfoin hay and control goats (group C) received hay of ryegrass. The diets in both groups were made isoenergetic and isoproteic and the refusals measured. Individual parasitological and pathophysiological measurements were performed fortnightly in order to compare host resistance and resilience. At the end of the study, five goats per group were necropsied. The distribution of sainfoin was associated with: (1) a higher consumption of hay; (2) significant, lower levels of nematode egg excretion which was associated with a decrease in worm fertility but no change in worm population; however, the number of intestinal worms was reduced by 50% in group S; (3) a better host resilience. In particular, after 2 months of grazing, two control goats died and half of the remaining animals needed to be treated whereas this was not the case in group S. These differences were related to significant changes in pepsinogen and phosphate values (PCV) but not in pepsinogen and phosphate concentrations. These results demonstrate that a repeated distribution of sainfoin hay to grazing goats might be beneficial in regard of pasture contamination and host resilience. They suggest that administration of sainfoin hay might represent a valuable alternative and adjunct to reduce nematode infections in dairy goat flock.     

不同能量水平日粮对西农萨能奶山羊产奶量及乳成分的影响

 为了筛选西农萨能奶山羊泌乳期全价料最适能量水平,选取体重（50.56±0.76) kg、胎次（2~3）、产奶量（2.12±0.10) kg/d相近及分娩日期与体况一致,并处于泌乳高峰期的健康西农萨能奶山羊36只,采用单因子随机区组试验设计,随机分为A、B、C、D四组,每组9只,分别饲喂能量（指净能水平,下同）水平为12.53 MJ/(d·只)、12.80 MJ/(d·只)、13.07 MJ/(d·只)和13.19  MJ/(d·只)。试验期为63 d,预试期7 d;正试期56 d,共分为4个阶段,每阶段2周。结果表明,随着日粮能量水平的提高,各阶段试验羊采食量及产奶量均呈先上升后下降的趋势,饲喂12.8  MJ/(d·只)能量日粮山羊可获得最大平均采食量;饲喂能量水平为13.07  MJ/(d·只)的日粮山羊可获得最大产奶量;不同能量水平对山羊乳成分及血液生化指标没有显著影响。     

日粮中不同马齿苋青贮添加量对奶山羊泌乳性能的影响

本试验旨在研究添加不同剂量马齿苋青贮对奶山羊泌乳性能的影响。选取体重（62±3）kg、1~2胎次、产奶量（1.90±0.15）kg/d、泌乳期相近（产后0~60 d）的健康奶山羊12只，随机分为4组，每组3个重复，每个重复1只羊。在奶山羊全混合日粮（TMR）中分别添加0（CK组）、10（A组）、20（B组）和30 g/d DM（C组）马齿苋青贮添加剂，试验期共75 d，其中预试期15 d，正试期60 d。试验期间测定每组奶山羊干物质采食量、产奶量、乳品质及血液生化指标。结果显示：随马齿苋青贮添加量的增加，奶山羊干物质采食量随之增加；添加马齿苋青贮的试验组奶山羊泌乳量均高于对照组；羊乳的pH呈弱碱性（7.10~7.24），并随马齿苋青贮添加量增加而降低，其中CK组最高，C组最低；羊乳中乳糖、总多酚（TPC）、总黄酮（TFC）和β胡萝卜素的含量均随着马齿苋青贮添加量增加而增多；血液中总胆固醇含量则相反。综上所述，日粮中添加马齿苋青贮对奶山羊无不良影响，可一定程度上提高奶山羊干物质采食量、泌乳量及乳品质，降低血液中总胆固醇含量。     

饲粮磷水平对崂山奶山羊泌乳性能和血清生化指标的影响

本试验旨在研究饲粮磷水平对崂山奶山羊泌乳性能和血清生化指标的影响。选择体重(56.55±1.17)kg、产奶量(2.20±0.07)kg/d、泌乳中期的2胎健康崂山奶山羊30只,采用单因素随机分组设计,随机分成3组,每组10只,每只羊为1个重复。各组饲喂能量和蛋白质水平基本一致,磷水平分别为0.26%、0.36%及0.46%的饲粮。预试期15 d,正试期60 d。结果表明:1)饲粮磷水平对干物质采食量均无显著影响(P0.05)。2)0.36%组产奶量全期平均值较高,极显著高于0.26%组、0.46%组(P0.01),0.26%组与0.46%组差异不显著(P0.05);干物质采食量/产奶量、干物质采食量/4%标准乳产量均以0.36%组较低,极显著低于0.46%组(P0.01)。3)饲粮磷水平对乳脂率、乳蛋白率、乳糖率、乳非脂固形物率、乳磷含量、乳钙含量均无显著影响(P0.05)。4)饲粮磷水平对血清中钙、磷、尿素氮含量及碱性磷酸酶活性均无显著影响(P0.05)。由此可见,泌乳期崂山奶山羊饲粮磷水平以0.36%为宜。     

基于Meta分析的母羊泌乳模型构建及泌乳性能预测

母羊泌乳量不仅关乎母羊自身营养需求,也是影响羔羊生长发育的重要因素,准确预测母羊泌乳量在母羊和羔羊精准饲养中具有现实意义.本文利用方差倒数Meta分析方法研究母羊泌乳曲线模型及泌乳参数,并对其泌乳性能进行预测.分别在Web of Science、CNKI等文献数据库中检索母羊泌乳曲线及影响因素的相关文献,依据纳入标准筛...     

Control of gastrointestinal nematodes in goats on pastures in South Africa using nematophagous fungi Duddingtonia flagrans and selective anthelmintic treatments

The effectiveness of selective anthelmintic treatments and use of nematophagous fungi Duddingtonia flagrans in reducing levels of gastrointestinal nematodes in goats was investigated at Onderstepoort, South Africa. Nineteen (19) naturally infected indigenous male goats, aged 10 months, were separated into four groups and grazed in separate previously ungrazed paddocks for two worm seasons (February 2002-March 2003). Two groups of goats were fed D. flagrans chlamydospores daily and two groups did not receive fungi. The FAMACHA system was used to determine which goats required anthelmintic treatments. Twice as many goats in the no-fungi fed group required treatments as compared with the fungi fed group. Mean FAMACHA scores in the no-fungi fed group were higher during most of the sampling occasions compared to the group fed fungi, but the difference was not significant. The group-mean faecal egg counts and PCV% were comparable between the two treatment groups throughout the study. Haemonchus was the predominant parasite genus in composite group faecal cultures. Group-mean body weights and body condition scores were higher for the no-fungi fed group from May 2002 up to the end of the study, though statistical differences were not significant. Mean worm burdens indicated that the most abundant species infecting animals were Haemonchus contortus and Trichostrongylus spp. and were higher in the fungi fed group. More animals required individual anthelmintic treatments in the no-fungi fed group. The requirement for extra treatments in the no-fungi fed group must, however, be considered against the financial cost of the fungi, the requirement of daily feeding of the fungi, the lower performance and higher worm burdens in the fungi fed group.     

Comparison of three methods for gastrointestinal nematode diagnosis determination in grazing dairy cattle in relation to milk production

Development of resistance to anthelmintic drugs has motivated the search for diagnostic methods to identify animals for targeted selective treatments. We compared three methods for the diagnosis of nematode infection in relation to milk production in a fully grazing dairy herd of 150 cows in the humid Pampa (Argentina). Animals had feces, blood and milk sampled during the first postpartum month for EPG, pepsinogen and anti-Ostertagia antibody determination, respectively. With the results obtained two groups of cows, divided in high and low parasite burden, were conformed for each method, and milk production was then compared between groups. When cows were separated by the EPG method (EPG=0 (N=106) vs. EPG>0 (N=44)) a difference of nearly 800 l of milk per cow per lactation was found (P<0.05). On the other hand, milk production between groups separated by Pepsinogen (mUtyr ≤ 1000 vs. mUtyr > 1000) or by anti-Ostertagia (ODR ≤ 0.5 vs. ODR > 0.5) results did not differ. Interestingly, proportion of cows in each group differed between methods (P<0.0001), and the anti-Ostertagia method yielded significantly more cows in the high index group compared to results using the EPG or Pepsinogen method. No correlations were found between parasite indexes determined by the different methods. High parasite burden estimation found may be ascribed to the production system, fully grazing all year round, and to the sampling time, at the beginning of lactation with cows in negative energy balance and depressed immunity. The fact that the cows were born and reared outside, on pasture with continuous nematode larvae exposure, may also account for the results obtained. In conclusion, EPG counting during the first postpartum month may be a useful tool for the diagnosis of production impairment induced by high nematode burden in adult grazing dairy cows. The anthelmintic treatment of only the EPG-positive recently calved cows would improve milk production, while reducing selective pressure on nematode population for the development of resistance.     

不同能量和蛋白水平日粮对西农萨能奶山羊泌乳性能的影响

为筛选西农萨能奶山羊泌乳期全价料最适能量和蛋白水平,选取体重(50.56±0.76)kg、胎次(2～3)、产奶量(2.12±0.10)kg/d相近和分娩日期与体况一致,并处于泌乳高峰期的健康西农萨能奶山羊36只,随机分为6组,每组6只。采用3×2因子随机区组试验设计6种日粮,NE水平为12.64、13.08和13.52MJ/d,CP水平为16.13%和17.82%。试验期84d,共分4个阶段,每阶段21d。结果表明:日粮NE和CP水平对奶山羊DMI和血液生化指标没有显著影响,但存在交互作用,NE 13.52MJ/d和CP16.13%处理组的DMI最高。随日粮NE和CP水平升高泌乳量增加,其中CP提高可显著增加泌乳量(P=0.041);而乳脂肪、乳蛋白、乳糖、干物质和非脂乳固体等乳成分指标则降低,其中CP提高可显著降低乳蛋白(P=0.013)和非脂乳固体(P=0.031);日粮NE和CP水平对奶山羊泌乳性能的影响存在交互作用,NE 13.52MJ/d和CP17.82%时泌乳量最高,而NE 13.08MJ/d和CP16.13%时乳品质最好。综合各项指标并考虑生产实际,得出西农萨能奶山羊泌乳期日粮适宜的NE和CP水平分别为13.08MJ/d和CP16.13%。     

影响西农萨能奶山羊产奶性状的非遗传因素分析

本试验旨在探究母羊出生年度、季节、胎次、泌乳阶段4个固定效应对西农萨能奶山羊产奶性状的影响。以西北农林科技大学萨能羊原种场2006-2018年的645只泌乳母羊为研究对象,每月采集乳样1次,采样日早、晚各采集1次,将两次乳样等比例混合后,采用乳成分分析仪测定乳脂率、乳蛋白率、乳糖率、总脂固形物、非脂固形物、密度、冰点和酸度共8个指标,结合羊场产奶量记录,采用固定效应模型,通过SAS 9.4软件进行表型的描述性统计分析,再采用GLM模型进行固定效应对产奶性状的影响分析。结果表明,西农萨能奶山羊平均300 d产奶量为507.67 kg,乳脂率为3.58%,乳蛋白率为3.20%,乳糖率为4.19%;总固形物含量为12.21%,非脂固形物含量为8.46%;出生年度、胎次对产奶量影响极显著（P<0.01）,出生季节对产奶量影响不显著（P>0.05）;泌乳阶段、出生年度对乳脂率等8个乳成分性状均有极显著影响（P<0.01）,胎次对除乳蛋白率和总固形物的其他6个乳成分指标均存在极显著影响（P<0.01）。综合以上试验结果,胎次及泌乳阶段是影响西农萨能奶山羊产奶性状的两种主要非遗传因素,第3、4胎母羊产奶性能最佳,泌乳早期的乳品质更优,揭示了对种群进行良种选育工作和羊饲养管理的重要性,也为后期进行奶山羊经济性状遗传评估和群体遗传改良提供理论基础。     

Efficacy of ivermectin in reducing gastrointestinal nematode fecal egg counts in goats in Burundi

Cross-bred goats in Burundi infested with gastrointestinal nematodes were submitted to fecal investigations and injected subcutaneously with ivermectin. In Experiment 1, goats were treated with 200 μg kg⁻¹ bw ivermectin. In Experiment 2, animals were administered twice that dose. In Experiment 3, goats suspected to be resistant to other anthelmintics were treated with 200 μg kg⁻¹ bw ivermectin. In Experiment 4, two doses of the same strength were injected with an interval of 7 days. Results demonstrate that 200 μg kg⁻¹ bw ivermectin is effective for the control of gastrointestinal nematodes of goats in Burundi; this dosage is also effective against nematodes suspected to be resistant to other anthelmintics. The administration of 400 μg kg⁻¹ bw did not induce greater or more prolonged effectiveness percentages. The supposed decrease of ivermectin's residual activity on Day 28 might be avoided by administering two doses with an interval of 7 days. No adverse effects were observed in treated animals.     

Effects of strategic anthelmintic treatments on the milk production of dairy sheep naturally infected by gastrointestinal strongyles

The present paper was aimed at assessing the benefit of strategic anthelmintic treatments on milk production in four commercial dairy sheep farms in Southern Italy whose animals were naturally infected by gastrointestinal (GI) strongyles and Dicrocoelium dendriticum. The scheme was based on two treatments timed in relationship to parturition, i.e. the first with moxidectin in the periparturient period and the second with netobimin at the mid/end of lactation. On each farm, two similar groups (20 animals each) were formed, one untreated control group and one group treated according to the above-mentioned scheme. Faecal egg counts (FEC) were performed on each study animal at the start of the trial and then monthly until the end of the study; in addition, milk production was recorded for each animal fortnightly in each farm for the lactation period. The results showed a significant increase in milk yield across all four farms that ranged from 19% to 44% improvement in milk yield. The benefit in milk yield in addition to considerably reduced egg output of the treated animals provide clear evidence that the two main aims of prophylactic parasite control, i.e. to maintain or improve animal performance and to reduce pasture contamination, can be achieved using strategic anthelmintic treatments.     

西农萨能奶山羊泌乳期产奶量、乳成分及血液生理生化指标变化规律研究

旨在探索西农萨能奶山羊泌乳期生产性能、乳成分、血液生理生化指标和营养物质摄入量等变化规律及其相互关系.本研究选取15只体重、胎次、产奶量、分娩日期相近,体况健康的西农萨能奶山羊.单圈饲喂54周,试验期内准确测定个体生产性能、乳成分、血液生理生化指标和营养物质摄入量等,建立各项指标随泌乳期变化规律模型及泌乳期内指标间的相...     

A Questionnaire Survey on the Practices Adopted to Control Gastrointestinal Nematode Parasitism in Dairy Goat Farms in France

To evaluate the efficacy with which recommendations of means to avoid the spread of anthelmintic resistance in parasitic nematode populations are communicated to farmers on dairy goat farms in France, a questionnaire survey was undertaken on their use of antiparasitic drugs. Information was collected from 73 farms in two main areas of dairy goat production. The data referred to three years. Anthelmintics were used in 69 farms, the mean number of treatments per year being 2.74. Changing the drug from one year to another was not practised. Moreover, of the 58 farms using two or more treatments per year, only 37% used anthelmintics from different classes in the lactation and drying-off periods. Benzimidazoles and probenzimidazoles were given in all except two farms and these substances represented more than 80% of all the treatments. Levamisole/pyrantel or avermectins were used in 15% and 27% of the farms, respectively. Double the ovine dose, as recommended in goats to ensure efficacy of benzimidazoles, was applied in 55% of the farms. In addition, in all the flocks, the substances were given on the basis of a mean estimated live weight and not by reference to the heaviest animal. These results indicate that errors in the use of anthelmintics are still frequent in dairy goat farms in France, with probable consequences for the spread of anthelmintic resistance in the populations of parasites.