Performance of second-season grazing cattle following different levels of parasite control in their first grazing season

The Economic Impact of Parasitism from Nematodes, Trematodes and Ticks on Beef Cattle Production

Global human population growth requires the consumption of more meat such as beef to meet human needs for protein intake. Cattle parasites are a constant and serious threat to the development of the beef cattle industry. Studies have shown that parasites not only reduce the performance of beef cattle, but also negatively affect the profitability of beef agriculture and have many other impacts, including contributing to the production of greenhouse gases. In addition, some zoonotic parasitic diseases may also threaten human health. Therefore, ongoing cattle parasite research is crucial for continual parasite control and the development of the beef cattle industry. Parasitism challenges profitable beef production by reducing feed efficiency, immune function, reproductive efficiency, liveweight, milk yield, calf yield and carcass weight, and leads to liver condemnations and disease transmission. Globally, beef cattle producers incur billions (US$) in losses due to parasitism annually, with gastrointestinal nematodes (GIN) and cattle ticks causing the greatest economic impact. The enormity of losses justifies parasitic control measures to protect profits and improve animal welfare. Geographical differences in production environment, management practices, climate, cattle age and genotype, parasite epidemiology and susceptibility to chemotherapies necessitate control methods customized for each farm. Appropriate use of anthelmintics, endectocides and acaricides have widely been shown to result in net positive return on investment. Implementing strategic parasite control measures, with thorough knowledge of parasite risk, prevalence, parasiticide resistance profiles and prices can result in positive economic returns for beef cattle farmers in all sectors.

Pasture rewetting in the context of nature conservation shows no long-term impact on endoparasite infections in sheep and cattle

BACKGROUND

Nature conservation with reduced drainage of pastures has been increasingly promoted in agriculture in recent years. However, moisture on pastures is a crucial factor for the development of free-living stages of many parasite species in ruminants. Hence, for the first time, we conducted a field study between 2015 and 2017 at the German North Sea coast to investigate the long-term effect of pasture rewetting (since 2004) on endoparasite infections in sheep and cattle.

METHODS

We examined faecal samples of 474 sheep and 646 cattle from five farms in spring, summer and autumn each year for the presence of endoparasite infections. Animals were kept on conventionally drained, undrained and rewetted pastures. The association between pasture rewetting and endoparasite infection probability was analysed in generalized linear mixed models and including further potential confounders.

RESULTS

Infection frequencies for gastrointestinal strongyles, Eimeria spp. and Strongyloides papillosus were significantly higher in sheep (62.9%, 31.7% and 16.7%) than in cattle (39.0%, 19.7% and 2.6%). Fasciola hepatica was detected with a frequency of 13.3% in sheep and 9.8% in cattle, while rumen fluke frequency was significantly higher in cattle (12.7%) than in sheep (3.8%). Nematodirus spp., lungworms (protostrongylids, Dictyocaulus viviparus), Moniezia spp., Trichuris spp. and Dicrocoelium dendriticum were identified in less than 7% of samples. Co-infection with more than three endoparasite taxa was present significantly more often in sheep than in cattle. We identified significant positive correlations above 0.2 for excretion intensities between S. papillosus with strongyles, Eimeria spp. and Nematodirus spp. in sheep and between strongyles and Nematodirus spp. in cattle. Pasture rewetting had no long-term effect on endoparasite infections, neither in sheep nor in cattle. Interestingly, F. hepatica infections decreased significantly in sheep and cattle from 2015 (10.9% and 13.9%) to 2017 (1.4% and 2.1%).

CONCLUSIONS

Pasture rewetting for nature conservation did not increase endoparasite infection probability in ruminants in the long term. This finding should be confirmed in ongoing studies aimed at further animal welfare parameters. The rapid decrease in F. hepatica infections over 3 years may suggest climatic impact or competition with rumen flukes in addition to potential anthelmintic treatment after feedback of the results to the farmers.

A systematic review and meta-analysis on the prevalence, distribution and nematode species diversity in small ruminants: a Nigerian perspective

Despite the global projections that agriculture will have to feed an additional 3 billion of the world's population in the nearest future, the global trends and negative impacts of nematodes on livestock productivity are still on the increase. Here, we reported the burden of gastrointestinal nematodes in small ruminants in Nigeria. Six thousand, five hundred and eighty one of the 13,259 small ruminants reported in 40 eligible studies across 18 Nigerian States were infected with at least one nematode species, yielding an overall pooled prevalence (PP) of 58.3% (95% CI 48.8, 67.2). Regional PP varied significantly (P < 0.001) and ranged between 19.5 (95% CI 5.8, 48.7) and 83.7% (95% CI 68.5, 92.3). Seasonal PP was higher in the dry (Prev: 56.5%, 95% CI 34.2, 76.4) than the rainy (Prev: 43.2%, 95% CI 26.7, 61.3) season. Haemonchus species were the most prevalent 21.3% while, Trichuris ovis and Strongyloides species had the widest geographic distribution. Several species of nematodes of small ruminants are highly prevalent in Nigeria. An all-inclusive approach involving public education and standardised management practices that involve adequate hygiene and sanitation, strategic and prophylactic use of anthelmintics, rotational grazing and the control of arthropod intermediate hosts will reduce the economic losses due to these parasites and curtail possible transmission to humans.

Parasite control in pasture-grazed dairy cattle: are we at the edge of a precipice?

Gastrointestinal nematode (GIN) parasites are one of the most production-limiting infections of pasture-based dairy cattle in Australasia. Intensification of dairy production systems in both countries has meant that farmers have come to rely heavily on anthelmintic drenches to control GIN parasitism. However, anthelmintic resistance is now widespread in New Zealand, particularly to the market-leading macrocyclic-lactones. Less work has been conducted on anthelmintic resistance in Australia but preliminary results of a study currently underway suggests that there are high levels of resistance on Victorian dairy farms. The identification and mitigation of risk factors for the development of resistance is crucial for long-term sustainability of control. These include the use of drenches with variable efficacy – particularly pour-on and injectable formulations. New Zealand studies suggest that this may be as a result of active not reaching parasites within the gut lumen as effectively as oral formulations. Also, the raising of young stock as monocultures is a risk factor for the development of resistance as it significantly reduces the numbers of unselected (and presumably susceptible) parasites on pasture. These risks can be mitigated: using effective drenches removes more resistant parasites. This often means the use of combination products containing more than one anthelmintic class. Combination products are more effective in the face of existing resistance, and can slow the development of resistance. Also, ensuring an adequate level of unselected parasites on pasture for ingestion by young stock will delay the development of resistance. While there are differences between dairying systems, both countries are likely to benefit from more active and collaborative research efforts to improving parasite control practices on dairy farms in their respective countries.

Nematode-coccidia parasite co-infections in African buffalo: Epidemiology and associations with host condition and pregnancy

Co-infections are common in natural populations and interactions among co-infecting parasites can significantly alter the transmission and host fitness costs of infection. Because both exposure and susceptibility vary over time, predicting the consequences of parasite interactions on host fitness and disease dynamics may require detailed information on their effects across different environmental (season) and host demographic (age, sex) conditions. This study examines five years of seasonal health and co-infection patterns in African buffalo (Syncerus caffer). We use data on two groups of gastrointestinal parasites, coccidia and nematodes, to test the hypothesis that co-infection and season interact to influence (1) parasite prevalence and intensity and (2) three proxies for host fitness: host pregnancy, host body condition, and parasite aggregation. Our results suggest that season-dependent interactions between nematodes and coccidia affect the distribution of infections. Coccidia prevalence, coccidia intensity and nematode prevalence were sensitive to factors that influence host immunity and exposure (age, sex, and season) but nematode intensity was most strongly predicted by co-infection with coccidia and its interaction with season. The influence of co-infection on host body condition and parasite aggregation occurred in season-dependent manner. Co-infected buffalo in the early wet season were in worse condition, had a less aggregated distribution of nematode parasites, and lower nematode infection intensity than buffalo infected with nematodes alone. We did not detect an effect of infection or co-infection on host pregnancy. These results suggest that demographic and seasonal variation may mediate the effects of parasites, and their interactions, on the distribution and fitness costs of infection.

Chasing helminths and their economic impact on farmed ruminants

Global agriculture will be required to intensify production from a shrinking natural resource base. Helminth infections of ruminants are a major constraint on efficient livestock production. The current challenge is to develop diagnostic methods that detect the production impact of helminth infections on farms in order to target control measures and contribute to the global challenge of preserving food security. We review here our understanding of the effects of helminth infections and control practices on productivity and the diagnostic tools that can inform on this. By combining advances in helminth laboratory diagnostics and animal health economics, sustainable management of helminth infections can be integrated into the whole-farm economic context.

Persistence of Eimeria bovis in soil

Eimeriosis is a disease that occurs globally and often affects cattle grazing on pastures contaminated with oocysts of the pathogenic species Eimeria bovis, Eimeria zuernii or Eimeria alabamensis, respectively. Nonetheless, little is understood regarding oocyst persistence on the pasture. The study was performed in the temperate climate zone. Soil samples were spiked with 100,000 E. bovis oocysts in July 2010 or with 50,000 oocysts in October 2010, respectively, both either with our without addition of cattle faeces. The soil samples were exposed to natural environmental conditions until April 2011. A subset of the samples was analysed immediately after spiking as positive control. The oocysts were recovered by a flotation method and counted in a reading chamber. On average, 23 % of the oocysts could be recovered from the positive control. The recovery of oocysts dropped to 0.30 % of the original level in the samples prepared in July independent of the addition of faeces, whereas the oocyst count was higher in the samples prepared in October, both without (2.05 %) and with (2.64 %) faecal material. No differences were observed between presence of oocysts or oocyst counts recovered in the presence or absence of faeces. Presence of faeces had a positive influence on oocyst integrity. During the winter season, the number of oocysts in the soil was lowered under the detection limit in most samples. On the other hand, the comparatively short 3-month summer period had a significant influence on the number of persisting oocysts too.