Regional heterogeneity and unexpectedly high abundance of Cooperia punctata in beef cattle at a northern latitude revealed by ITS-2 rDNA nemabiome metabarcoding.

BACKGROUND: The species composition of cattle gastrointestinal nematode (GIN) communities can vary greatly between regions. Despite this, there is remarkably little large-scale surveillance data for cattle GIN species which is due, at least in part, to a lack of scalable diagnostic tools. This lack of regional GIN species-level data represents a major knowledge gap for evidence-based parasite management and assessing the status and impact of factors such as climate change and anthelmintic drug resistance. METHODS: This paper presents a large-scale survey of GIN in beef herds across western Canada using ITS-2 rDNA nemabiome metabarcoding. Individual fecal samples were collected from 6 to 20 randomly selected heifers (n = 1665) from each of 85 herds between September 2016 and February 2017 and 10-25 first season calves (n = 824) from each of 42 herds between November 2016 and February 2017. RESULTS: Gastrointestinal nematode communities in heifers and calves were similar in Alberta and Saskatchewan, with Ostertagia ostertagi and Cooperia oncophora being the predominant GIN species in all herds consistent with previous studies. However, in Manitoba, Cooperia punctata was the predominant species overall and the most abundant GIN species in calves from 4/8 beef herds. CONCLUSIONS: This study revealed a marked regional heterogeneity of GIN species in grazing beef herds in western Canada. The predominance of C. punctata in Manitoba is unexpected, as although this parasite is often the predominant cattle GIN species in more southerly latitudes, it is generally only a minor component of cattle GIN communities in northern temperate regions. We hypothesize that the unexpected predominance of C. punctata at such a northerly latitude represents a range expansion, likely associated with changes in climate, anthelmintic use, management, and/or animal movement. Whatever the cause, these results are of practical concern since C. punctata is more pathogenic than C. oncophora, the Cooperia species that typically predominates in cooler temperate regions. Finally, this study illustrates the value of ITS-2 rDNA nemabiome metabarcoding as a surveillance tool for ruminant GIN parasites.

Simulation modelling to estimate the herd-sensitivity of various pool sizes to test beef herds for Johne's disease in Australia.

Johne's disease is a chronic intestinal disease affecting livestock. It leads to the shedding of Mycobacterium avium subspecies paratuberculosis (MAP) in the faeces, wasting and eventually death, with animal welfare, economic, and trade implications. The Johne's Beef Assurance Scheme, used in Australia to determine the risk of Johne's disease on beef properties and facilitate trade, is based on testing a subset of the herd with pooled faecal quantitative PCR. This study aimed to model the herd-sensitivity of pooled faecal testing under different Australian farming scenarios. Animals from simulated herds were randomly sampled and allocated into their respective pools. Each tested pool was provided a test outcome, with herd-sensitivity estimated as the probability of detecting a truly infected herd. The models simulated the test performance for the 'Sample' and 'Check' tests used in the assurance schemes (recommended sample sizes of 300 and 50, respectively) for a range of herd sizes, infection prevalence and MAP faecal shedding levels for the pool sizes of 5, 10, 15 and 20. Sensitivity and specificity input values of each pool size were obtained from a previous laboratory investigation. The herd-sensitivity estimate increased with herd size and infection prevalence levels, regardless of the pool size. Higher herd-sensitivity was also achieved for testing scenarios involving larger sample sizes. A pool size of 10 achieved similar herd-sensitivity to that of the current pool size for the majority of the Sample test and Check test scenarios. This was particularly evident when pool-specificity was assumed to be perfect. The overall herd-sensitivity of the Check test was very low for all infection prevalence levels and pool sizes, but it more than doubled, when the sample size increased from 50 to 100 animals (11% versus 26% for a herd size of 500 cattle with a 2% infection prevalence). The results show that the majority of beef producers participating in the assurance scheme can benefit from using a larger pool size for the pooled faecal quantitative PCR testing of their herd, in comparison to the pool size currently used.

Epidemiology and Management of BVDV in Rangeland Beef Breeding Herds in Northern Australia.

Approximately 60% of Australia's beef cattle are located in the vast rangelands of northern Australia. Despite the often low stocking densities and extensive management practices of the observed herd, animal prevalence of BVDV infection and typical rates of transmission are similar to those observed in intensively managed herds in southern Australia and elsewhere in the world. A recent large three- to four-year study of factors affecting the reproductive performance of breeding herds in this region found that where there was evidence of widespread and/or recent BVDV infection, the percentage of lactating cows that became pregnant within four months of calving was reduced by 23%, and calf wastage was increased by 9%. BVDV is now considered the second most important endemic disease affecting beef cattle in northern Australia, costing the industry an estimated AUD 50.9 million annually. Although an effective killed vaccine was released in Australia in 2003, the adoption of routine whole herd vaccination by commercial beef farmers has been slow. However, routine testing to identify persistently infected replacement breeding bulls and heifers has been more widely adopted.

Methane emissions of extensive grazing breeding herds in relation to the weaning and yearling stages in the Eastern Plains of Colombia / Emisiones de metano en hatos de carne en pastoreo extensivo relacionadas con los períodos de destete y levante en los Llanos

ABSTRACT A substantial proportion of beef production in Colombia originates in its extensive Eastern Plains. However, in this scenario and in a global context, demand for cattle production increasingly requests that it satisfies social and environmental expectations in addition to being economically efficient. A dataset containing five-year long records of cow-calf production systems collected at Carimagua Research Centre located in the Meta Department was retrospectively interrogated to understand the liveweight (LW)-derived flux matrix dynamics of methane (CH4) emissions. Estimated total CH4 (kg) emissions during the gestation period, were similar between conventional weaned (CW; 37.86 ± 0.506 kg) and early weaned (EW; 37.47 ± 0.476 kg) cows. However, averaged over two lactations, total CH4 emissions were larger (p < 0.0001) in CW cows (38.67 ± 0.456 kg) than in their EW (14.40 ± 0.435 kg) counterparts. Total gas emissions from birth to comparable commercial yearlings age were higher (p < 0.0001) for CW (43.11 ± 0.498 kg) calves than for EW (40.27 ± 0.472 kg) calves. It was concluded that mid and long-term pastoral datasets and new concerns are well suited to understand different contexts and adaptations to the contemporary weather conditions. Nevertheless, conventional farming systems will be less environmentally vulnerable if EW management practices involve the strategic and temporal use of improved pastures. The roles of veterinary medicine and animal sciences are briefly discussed in the context of unprecedented climate variability to provide a guide to the uncertain future.

RESUMEN Una proporción substancial de la producción de carne de res en Colombia se origina en sus Llanos Orientales. Sin embargo, allí, así como en un contexto global, dicha producción ganadera debe ser económicamente eficiente y satisfacer expectativas sociales y ambientales. Considerando algunos de esos intereses, se analizaron cinco años de eventos productivos y de manejo del destete implementados en el Centro de Investigaciones Carimagua, localizado en el departamento del Meta, para interpretar en vacas de carne y sus crías las dinámicas de peso vivo asociadas con emisiones derivadas de metano (CH4). Emisiones totales de CH4 (kg) durante la gestación fueron similares entre las vacas destetadas convencionalmente (CW; 37.86 ± 0.506 kg) y aquellas destetadas tempranamente (EW; 37.47 ± 0.476 kg). Sin embargo, el promedio de dos lactancias demostró mayores (p < 0.0001) emisiones en vacas CW (38.67 ± 0.456 kg) que en vacas EW (14.40 ± 0.435 kg). Emisiones acumuladas entre el nacimiento y el levante fueron mayores (p < 0.0001) en terneros CW (43.11 ± 0.498 kg) que en terneros EW (40.27 ± 0.472 kg). Se concluyó que nuevos cuestionamientos y datos de pastoreo de mediano y largo plazo son apropiados para entender contextos innovadores y adaptaciones a las condiciones climáticas actuales. Sin embargo, el manejo convencional en las fincas será menos vulnerable al medio ambiente si prácticas de destete temprano son introducidas considerando el uso estratégico y temporal de pastos mejorados. Los roles de la medicina veterinaria y las ciencias animales se discuten brevemente en el contexto de la variabilidad climática existente.