Ostertagia ostertagi infection in the calf: effects of a trickle challenge on appetite, digestibility, rate of passage of digesta and liveweight gain

M, Fox; Gerrelli, Dianne; Pitt, S.R.; Jacobs, D. Ε.; Gill, M.; Gale, David

doi:10.1016/s0034-5288(18)31249-9

Cited by 64 publications

(23 citation statements)

References 11 publications

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“…protein) requirements. In addition to the endogenous protein loss and the increased resource requirements, a reduction in appetite and feed intake accompanies infection (Fox et al., 1989, Forbes et al., 2000, Kyriazakis, 2014). Although complex, the mechanism for inappetance in ostertagiosis was modelled as a function of the rate of immune acquisition, as it has been suggested that this reduction is associated with components of the immune response (e.g.…”

Section: Methodsmentioning

confidence: 99%

Modelling the consequences of targeted selective treatment strategies on performance and emergence of anthelmintic resistance amongst grazing calves

Berk

Laurenson

Forbes

et al. 2016

International Journal for Parasitology: Drugs and Drug Resistan

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The development of anthelmintic resistance by helminths can be slowed by maintaining refugia on pasture or in untreated hosts. Targeted selective treatments (TST) may achieve this through the treatment only of individuals that would benefit most from anthelmintic, according to certain criteria. However TST consequences on cattle are uncertain, mainly due to difficulties of comparison between alternative strategies. We developed a mathematical model to compare: 1) the most ‘beneficial’ indicator for treatment selection and 2) the method of selection of calves exposed to Ostertagia ostertagi, i.e. treating a fixed percentage of the population with the lowest (or highest) indicator values versus treating individuals who exceed (or are below) a given indicator threshold. The indicators evaluated were average daily gain (ADG), faecal egg counts (FEC), plasma pepsinogen, combined FEC and plasma pepsinogen, versus random selection of individuals. Treatment success was assessed in terms of benefit per R (BPR), the ratio of average benefit in weight gain to change in frequency of resistance alleles R (relative to an untreated population). The optimal indicator in terms of BPR for fixed percentages of calves treated was plasma pepsinogen and the worst ADG; in the latter case treatment was applied to some individuals who were not in need of treatment. The reverse was found when calves were treated according to threshold criteria, with ADG being the best target indicator for treatment. This was also the most beneficial strategy overall, with a significantly higher BPR value than any other strategy, but its degree of success depended on the chosen threshold of the indicator. The study shows strong support for TST, with all strategies showing improvements on calves treated selectively, compared with whole-herd treatment at 3, 8, 13 weeks post-turnout. The developed model appeared capable of assessing the consequences of other TST strategies on calf populations.

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Section: Methodsmentioning

confidence: 99%

Modelling the consequences of targeted selective treatment strategies on performance and emergence of anthelmintic resistance amongst grazing calves

Berk

Laurenson

Forbes

et al. 2016

International Journal for Parasitology: Drugs and Drug Resistan

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“…Experimental studies with mono-infections of O. ostertagi have demonstrated reductions in weight gain between insignificant (Taylor et al 1989) to high (Fox et al 1989) in animals exposed to different levels of infection. Fox et al (1989) infected 3-month-old male calves over a 45-day period with 450,000 L3 in total and found symptoms such as reduced appetite that resulted in a loss in live weights of the infected calves.…”

Section: Discussionmentioning

confidence: 99%

“…Fox et al (1989) infected 3-month-old male calves over a 45-day period with 450,000 L3 in total and found symptoms such as reduced appetite that resulted in a loss in live weights of the infected calves. Thus, severe symptoms are possible to induce with such high doses.…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies have shown that heavy gastrointestinal (GI) nematode infections due to overwintered larval exposure may result in a reduced weight gain of up to 65 kg in untreated calves during their first grazing season compared to animals kept worm-free under set stocked conditions (Dimander et al 2003a). Furthermore, experimental studies with different levels of O. ostertagi infections in young cattle have demonstrated reductions in weight gain ranging from insignificant (Taylor et al 1989) to considerable, combined with severe symptoms such as inappetence and diarrhoea (Fox et al 1989). Although O. ostertagi is regarded as more pathogenic than C. oncophora, experimental infections with C. oncophora have resulted in reduced weight gain in growing calves (Armour et al 1987;Coop et al 1979).…”

Section: Introductionmentioning

confidence: 99%

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Effects of single or concurrent infections with Eimeria alabamensis and gastrointestinal nematodes on the performance of calves on pasture

Larsson

Uggla

et al. 2006

Parasitol Res

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Twenty-four calves unexposed to pasture were allocated to four groups and inoculated with either two doses of 5 million Eimeria alabamensis oocysts at turn-out (E), 90,000 L3 of Ostertagia ostertagi and Cooperia oncophora divided on six occasions (N) or both oocysts and larvae as above (E + N). A control group was left uninoculated (C). For 10 weeks, the groups grazed in separate uniform paddocks not previously grazed by cattle. By day 5, most calves in groups E and E + N developed clinical coccidiosis that resulted in reduced weight gain compared to C and N. Mean trichostrongylid faecal egg counts in groups N and E + N never exceeded 300 eggs per gram of faeces, and average serum pepsinogen levels were less than 3.8 U tyrosine. This experiment demonstrates the potential impact of E. alabamensis on the performance of previously unexposed calves, whereas no aggravated effects were observed due to concurrent infections with gastrointestinal nematodes.

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“…cytokines, gastrin) are associated with inappetence causing a reduction in herbage intake (Fox et al, 1989;Greer et al, 2005), commonly known as (parasite-induced) anorexia (Kyriazakis, 2014). Reductions in desired herbage intake were modelled as a function of the rate of acquisition of immunity (Laurenson et al, 2011).…”

Section: Individual Lamb Modulementioning

confidence: 99%

Which is the best phenotypic trait for use in a targeted selective treatment strategy for growing lambs in temperate climates?

Laurenson

Kahn

Bishop

et al. 2016

Veterinary Parasitology

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Ostertagia ostertagi infection in the calf: effects of a trickle challenge on appetite, digestibility, rate of passage of digesta and liveweight gain

Cited by 64 publications

References 11 publications

Modelling the consequences of targeted selective treatment strategies on performance and emergence of anthelmintic resistance amongst grazing calves

Modelling the consequences of targeted selective treatment strategies on performance and emergence of anthelmintic resistance amongst grazing calves

Effects of single or concurrent infections with Eimeria alabamensis and gastrointestinal nematodes on the performance of calves on pasture

Which is the best phenotypic trait for use in a targeted selective treatment strategy for growing lambs in temperate climates?

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