A longitudinal study of gastrointestinal parasites in English dairy farms. Practices and factors associated with first lactation heifer exposure to Ostertagia ostertagi on pasture

Abstract

The gastrointestinal nematode Ostertagia ostertagi is an important cause of lost production, health, and welfare in cattle. Detailed records were obtained over a 5-yr period (2010-2015) by questionnaires and qualitative interviews to investigate the practices adopted by dairy farmers to control cattle helminth infections and the factors associated with heifer exposure to O. ostertagi on pasture. In total, 1,454 heifers' individual milk samples were collected over a 1-yr period (2014-2015) in 43 dairy farms in England and tested for O. ostertagi antibody by ELISA. Multilevel linear regression models were used to investigate the association between individual milk optical density ratio (ODR) against O. ostertagi and heifer management from birth to time of sampling. Farm and heifer median ODR against O. ostertagi were 0.98 (interquartile range = 0.76-1.02) and 0.64 (interquartile range = 0.42-0.84), respectively. The majority of heifers (88%) received an anthelmintic treatment before sampling in this study. After controlling for the effect of anthelmintic treatments, heifer individual milk ODR against O. ostertagi significantly increased with high stocking rate at first grazing and co-grazing with adult cows before calving. Conversely, heifer individual milk ODR against O. ostertagi significantly decreased when heifers had co-grazed with sheep and pasture grass had frequently been mowed. Overall, these results provide evidence to support targeting grazing management toward limiting the use of anthelmintics in dairy young stock to enable sustainable control of cattle helminth infections in England. However, to be accepted and adopted by farmers, these best practices would need to take into account farmers' perspectives and contextual challenges.

Occurrence of internal parasites in cattle in various management systems in South-East Poland

“…Również w Anglii inwazja jest powszechnie występującą. Metodami serologicznymi stwierdzono jej występowanie we wszystkich badanych stadach (2). W każdym z wymienionych krajów w tej grupie pasożytów wykazano dominację rodzaju Ostertagia.…”

“…Taki wynik badania jest prawdopodobnie odzwierciedleniem faktu, iż bydło mięsne częściej korzysta z pastwisk, co sprzyja zarażeniu ww. pasożytami (2,6,25). Odnosi się to również do tasiemców z rodzaju Moniezia i nicieni z rodzaju Dictiocaulus, dla których mimo wyższych wartości bezwzględnych prewalencji nie wykazano istotności statystycznej.…”

Short- and long-term association between individual levels of milk antibody against Ostertagia ostertagi and first-lactation heifer’s production performances

“…1,500/43) regularly sampled throughout the seasons on each farm and tested for O. ostertagi antibodies. A more detailed description of the heifer samples 117 selection criteria and the sampling process is available in Bellet et al (2018).…”

“…Cow samples that 145 had been tested for O. ostertagi antibodies in 2012 and then stored at QMMS at -20°C, were tested again under similar laboratory conditions in March 2014. No significant differences were obtained between the results of the two years (Bellet et al, 2018). After collection on farm, heifer IM samples were preserved using bronopol/natamycin and kept at ambient temperature until arrival at the laboratory.…”

“…Data were collated and initially analysed using STATA 12.1 (STATA Inc., Texas, USA). Due to the nature and the complexity of individual information on grazing management, 173 a systematic process of data entry was performed for each heifer included in the study (Bellet et al, 2018). Data were collated and initially analyzed using Stata 12.1 (Stata Inc., College Station, TX).…”