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Coccidiosis at rose veal starter farms is often diagnosed however, this was the first study performed considering this topic on this type of rearing unit. The objective of this study was to identify Eimeria species faecal shedding patterns at ten Dutch rose veal starter farms during rearing. Further objectives were to investigate associations with (gut) health, production and management decisions. Faecal samples from twelve randomly selected calves per farm were collected weekly during 9 consecutive weeks. Thereafter samples were pooled in a predetermined composition of six. These calves were clinically evaluated every sample visit and weighed at the first and last visit. Laboratory tests included a flotation test of the samples. If this yielded Eimeria oocysts, both oocysts per gram feces (OPG) and species differentiation were established using a modified McMaster method. Management parameters and technical herd results were identified after finalizing the study period using a questionnaire. Studied patterns in oocyst shedding included the pool's cumulated OPG, maximum OPG level and the number of sample days (SD) that OPG exceeded a confirmed level. Statistical analysis included univariate and multivariate analysis. Associated (p < 0.10) OPG patterns considering rumen fill, faecal consistency and average daily weight gain (ADG) were tested using a model with herd included as random effect. RESULTS: on all ten farms E. alabamensis, E.bovis and E. zuernii besides non-pathogenic species were identified, often as mixed infections. Peak OPG occurred predominately at SD 21 and 28 (E. alabamensis and E. bovis), and at SD 42 (E. zuernii). In 16 pools, OPG levels ≥500 for E. bovis or E. zuernii, were found. Significant correlation (p < 0.0001) showed between the log 10 OPG of pathogenic Eimeria and of all Eimeria species. Multivariate analysis showed significant correlation between cumulative faecal consistency scores and cumulative log 10 OPG of pathogenic Eimeria species (β = 0.16; p = 0.008). Pools exceeding 750 OPG for E. bovis showed 93 g lower ADG and pools experiencing ≥2 SD with >1000 OPG for E. alabamensis 141 g lower ADG. From the questionnaire we identified lower cumulated OPG of all Eimeria species except for E. bovis at farms where the units were cleaned before arrival of the calves. CONCLUSION: As a rule, on Dutch rose veal starter farms, mixed Eimeria infections occur, but shedding patterns differ between farms. Clinical and growth performance is related to OPG patterns found. Cleaning units before arrival of calves lowers oocyst shedding during the rearing period., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Faecal egg counts (FEC) and the FEC reduction test (FECRT) for assessing gastrointestinal nematode (GIN) infection and efficacy of anthelmintics are rarely carried out on ruminant farms because of the cost of individual analyses. The use of pooled faecal samples is a promising method to reduce time and costs, but few studies are available for cattle, especially on the evaluation of different pool sizes and FECRT application., Methods: A study was conducted to assess FEC strategies based on pooled faecal samples using different pool sizes and to evaluate the pen-side use of a portable FEC-kit for the assessment of FEC on cattle farms. A total of 19 farms representing 29 groups of cattle were investigated in Italy and France. On each farm, individual faecal samples from heifers were collected before (D0) and two weeks after (D14) anthelmintic treatment with ivermectin or benzimidazoles. FEC were determined individually and as pooled samples using the Mini-FLOTAC technique. Four different pool sizes were used: 5 individual samples, 10 individual samples, global and global on-farm. Correlations and agreements between individual and pooled results were estimated with Spearman's correlation coefficient and Lin's concordance correlation coefficients, respectively., Results: High correlation and agreement coefficients were found between the mean of individual FEC and the mean of FEC of the different pool sizes when considering all FEC obtained at D0 and D14. However, these parameters were lower for FECR calculation due to a poorer estimate of FEC at D14 from the faecal pools. When using FEC from pooled samples only at D0, higher correlation and agreement coefficients were found between FECR data, the better results being obtained with pools of 5 samples. Interestingly, FEC obtained on pooled samples by the portable FEC-kit on-farm showed high correlation and agreement with FEC obtained on individual samples in the laboratory. This field approach has to be validated on a larger scale to assess its feasibility and reliability., Conclusions: The present study highlights that the pooling strategy and the use of portable FEC-kits on-farm are rapid and cost-effective procedures for the assessment of GIN egg excretion and can be used cautiously for FECR calculation following the administration of anthelmintics in cattle.