***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The persistent efficacy of doramectin and ivermectin injectable against moderate and high infection levels of Ostertagia ostertagi and Cooperia oncophora were evaluated in cattle . Calves were allocated to six groups of six animals . On Day 0 animals of Groups I1/I2 and D1/D2 were treated with 0.2mg/kg ivermectin and doramectin injectable , respectively . Animals of the C1 , I1 and D1 groups received a daily ( moderate ) infection of 1000 L3 of O. ostertagi and 1000 L3 of C. oncophora , and animals of the C2 , I2 and D2 groups received a daily ( high ) infection of 10,000 L3 of each species . The animals were infected for 21 days with both species , the infections with C. oncophora and O. ostertagi started from Days 8 and 15 post treatment , respectively . Animals were necropsied on Day 40 . The calculation of the persistent activity of ivermectin and doramectin was based on the efficacy against the different developmental and adult stages of both parasites . The present study confirmed that infection levels may influence the duration of persistent efficacy of an anthelmintic . Doramectin had at the moderate infection level a persistent efficacy of at least 35 days against O. ostertagi and at least 28 days against C. oncophora ; at the high infection dose persistent efficacy was somewhat shorter i.e. up to 33 days and approximately 28 days , respectively . The duration of persistent efficacy of ivermectin against O. ostertagi at the moderate infection level was between 14 and 25 days , at the high dose level up to 25 days . Persistent efficacy of ivermectin  against C. oncophora could , at both infection doses , not be measured , with the present experimental design The persistent activity of moxidectin topically administered at the dose rate of 0.5 mg kg-1 bodyweight was evaluated against experimental nematode infection in 30 calves r and omly allocated to six groups . Five groups were treated on days -42 , -35 , -28 , -21 and -14 . The 6th group remained untreated as a control . On Day 0 , the calves were infected experimentally with 1000 Dictyocaulus viviparus and 50,000 Ostertagia ostertagi larvae and killed 3 weeks later . The formulation of moxidectin showed excellent activity against both parasites for up to 5 weeks ( > 99 % ) . Six weeks after treatment the reduction in the number of D. viviparus was still high ( > 90 % ) . No adverse reactions to moxidectin were observed in any of the animals Abstract Six studies were conducted to evaluate the persistent efficacy of eprinomectin pour-on against experimental challenges with infective nematode larvae in calves . In each study , calves were r and omly assigned to one untreated group and up to four test groups , which were treated with eprinomectin at 500 μg/kg body weight at weekly intervals before single bolus challenge . The calves were necropsied approximately 4 weeks after challenge infection for nematode recovery . Eprinomectin pour-on provided ≥90 % efficacy against challenge with Haemonchus placei , Trichostrongylus axei and T. colubriformis at 21 days after treatment and against Cooperia oncophora , C. punctata , C. surnabada , Dictyocaulus viviparus , Nematodirus helvetianus , Oesophagostomum radiatum and Ostertagia ostertagi at 28 days after treatment The persistence of the efficacy of  doramectin injectable against Ostertagia ostertagi and Cooperia oncophora was evaluated in two studies in calves . In both , the calves were allocated to six groups of six . Calves in the first control group ( c1 ) and first treated group ( Ti ) received a daily infection of 200 L3 of O ostertagi and 200 L3 of C oncophora ; the calves in groups C2 and T2 received a daily infection of 1000 L3 of each species , and groups C3 and T3 received 10,000 L3 of each species per day . The calves in the three treated groups each received 0.2 mg/kg doramectin injectable on day 0 . In the first study , the calves were infected for 21 days with Cooperia and for 28 days with Ostertagia , and they were slaughtered on day 33 . In the second study , the calves were infected for 21 days with both species , the infections with Cooperia and Ostertagia starting from eight and 15 days , respectively , after the treatment , and the animals were slaughtered on day 40 . The calculation of the persistence of the activity of doramectin  was based on its efficacy against the different developmental and adult stages of the two parasites . The data from both studies indicated that the efficacy of doramectin against Ostertagia persisted for at least five weeks , but no conclusions could be drawn about the effect of the size of the infective doses on the persistence of the activity . In contrast , the Cooperia worm counts from the second study suggested that the efficacy of doramectin against Cooperia persisted for at least four weeks when the calves were exposed to a low or moderate infection level , whereas at the highest infection level it persisted for between three and four weeks Eight neonatal , Holstein bull calves were paired by birth date and birth weight and r and omly assigned to either a finely ground or unground control diet ( chopped hay and rolled grain ) to study the effects of the physical form of the diet on anatomical , microbial , and fermentative development of the rumen . The diets varied in particle size but were identical in composition ( 25 % alfalfa hay and 75 % grain mix ) . Calves were fed milk at 8 % of birth weight daily until weaning . Feed intake was equalized for each pair of calves . Ruminal fluid sample s were collected from ruminal cannulas to determine pH , fermentation products , and buffering capacity and to enumerate bacteria .  Calves were slaughtered at 10 wk of age , and weights of the full and empty reticulorumen , abomasum , and omasum were recorded . Ruminal tissue sample s were taken to assess papillary development by morphometric measurements . Calves had similar body weights at wk 10 . Ruminal pH was affected by age and was lower for calves fed the ground diet . Total anaerobic bacterial counts were not affected by the physical form of the diet ; however , calves fed the ground diet had lower numbers of cellulolytic bacteria and higher numbers of amylolytic bacteria than did calves fed the unground diet . Physical form of the diet did not affect the weights of the reticulorumen whether full or empty . However , calves fed the ground diet had heavier omasum weights , both full and empty . Physical form of the diet affected papillary size and shape but did not influence the muscle thickness of rumen . Results indicated that the physical form of the diet had a significant influence on the anatomical and microbial development of the forestomac and , therefore , might influence future performance Intramuscular immunization of calves with an excretory-secretory antigen fraction enriched for cysteine proteinase activity ( ES-thiol ) and QuilA as adjuvant induces a protective immune response against the abomasal nematode Ostertagia ostertagi . The objectives of the present study were to confirm the protective capacity of ES-thiol in combination with QuilA , to test Al(OH)(3 ) as adjuvant for vaccination against O. ostertagi and to look for correlations between protection and immunological effector responses . Calves(seven animals/group ) were vaccinated three times intramuscularly with 100 micro g antigen and /or adjuvant ( ES-thiol with QuilA , ES-thiol with Al(OH)(3 ) , QuilA alone and Al(OH)(3 ) alone ) and subsequently challenged with a trickled oral infection of 25 000 infective larvae in total over 25 days . Faecal egg counts in the ES-thiol QuilA group were reduced by 56 % during the two-month period of the trial compared to the QuilA control group ( P < 0.002 ) . Calves immunized with ES-thiol QuilA had significantly smaller adult worms ( P < 0.002 ) and less eggs/female worm ( P < 0.05 ) compared to the QuilA control group . No differences in egg output , worm counts or parameters of worm fitness were observed in the ES-thiol Al(OH)(3 ) group compared to the Al(OH)(3 ) control group . Although the protective immune mechanism against O. ostertagi remains unknown , protection in the ES-thiol QuilA group was associated with high levels of parasite-specific antibodies in the abomasal mucosa The objective of this study was to evaluate the effect of different infection levels of Ostertagia ostertagi and Cooperia oncophora in a simulated ' first grazing season ' on the resistance of calves to an artificial challenge infection . The infection levels were determined by the infection schedules and the chemoprophylaxis used . Thirty six 7 - 11-month old Holstein-Friesian bull calves were r and omly divided into four groups . The animals of group B received an ivermectin sustained release bolus ( ISRB ) on day 0 . The calves of group D were treated on days 0 and 56 with a subcutaneous injection of doramectin ( 0.2 mg kg(-1 ) BW ) . Group C was the untreated control group . The calves of group N were used as helminth-naive controls , while the animals of groups B , C and D were trickle infected for 24 weeks . The infection schedules were design ed to simulate the expected infection pattern for each treatment group under set-stocked conditions in temperate climate areas . After the last infection , all animals were treated with oxfendazole . One week later , all animals received a challenge infection of 50,000 O. ostertagi L3 and 100,000 C. oncophora L3 , spread over 10 consecutive days . During the primary infection period the faecal egg output and the serum pepsinogen and antibody levels reflected the different levels of host-parasite contact between the groups ( group C > group D > group B > group N ) . After the challenge infection , faecal egg counts , total Ostertagia burden , size of the adult worms and abomasal globule leucocyte counts all indicated a positive relationship between the level of Ostertagia infection during the primary infection period and the level of acquired resistance . A reduction of host-parasite contact during the primary infection period , as a consequence of the infection schedule and the chemoprophylaxis used , result ed in a diminished level of resistance to the artificial challenge infection with O. ostertagi . Faecal cultures and small intestine worm counts indicated that all previously infected groups had acquired a high degree of resistance to the Cooperia challenge infection Dr Dorny is also at the Department of Veterinary Medicine , Prince Leopold Institute of Tropical Medicine , Nationalestraat 155 , 2000 Antwerp , Belgium DORAMECTIN and eprinomectin are macrocyclic lactones with a high efficacy against cattle strongyle nematodes ( Shoop and others 1996 , Conder and others 1998 ) . They also show a persistence of activity of several weeks , which makes them particularly attractive for the strategic control of gastrointestinal nematodes in calves ( Eagleson and Langholff 1997 , Molento and others 1999 ) . Both compounds are available as pour-on formulations for easier administration . Doramectin pour-on is licensed in some countries for use in a chemoprophylactic system for nematode control in first grazing season calves given at turnout and again eight weeks later ( Vercruysse and others 1998 ) ; the same chemoprophylactic design was used with eprinomectin pour-on in some field experiments ( Epe and others 1999 , Dorny and others 2000 ) . The duration of persistent activity of doramectin pour-on has been reported to be 28 days and 35 days against Cooperia oncophora and Ostertagia ostertagi , respectively ( Molento and others 1999 ) ; for eprinomectin it has been reported to be 21 days and 28 days , respectively , against the same nematode species ( Eagleson and Langholff 1997 ) . However , it has been demonstrated that trial design , parasite and /or host factors may affect the length of activity of macrocyclic lactones ( Deroover and others 1997 , Vercruysse and others 2000 ) and this may be the reason for the wide range of persistent efficacy described in literature for injectable formulations of these drugs . The aim of this study was to compare , under the same experimental conditions , the persistent efficacy of doramectin and eprinomectin pour-on formulations against C oncophora and 0 ostertagi infections in cattle . The study was performed under pen conditions at the experimental farm of Ghent University . On day -5 of the study , 35 helminth-naive , Holstein cross bull calves , eight to nine months of age , were r and omly allocated to one of five groups ( TI to T5 ) , each containing seven animals . Animals in the T1 group served as negative controls and received no treatment . On day 0 , the calves in groups T2 and T4 were given either doramectin pour-on ( group T2 ) or eprinomectin pour-on ( group T4 ) , both at a dose rate of 500 rig/kg bodyweight . On day 7 , the calves in groups T3 and T5 were topically treated with either doramectin ( group T3 ) or eprinomectin ( group T5 ) at the same dosage . All The persistence of the efficacy of mox 
    Output:
    
Adult mortality was positively correlated with infection dose .
In conclusion , this meta- analysis provides novel estimates for the parameterization of life cycle-based transmission models , explicitly reports measures of variance around these estimates , gives evidence for density dependence of larval establishment and adult mortality , shows that host age affects larval establishment and , to our knowledge , provides the first evidence for O. ostertagi of a female-biased sex ratio