14In this study, 96 faecal samples were collected from pregnant Merino ewes, at two broad-15 acre, commercial sheep farms in southern Western Australia, on two separate occasions 16 (16 and 2 weeks prior to lambing). Following lambing, 111 (Farm A) and 124 (Farm B) 17 female crossbred lambs (2 -6 weeks old), were individually identified using ear tags (a 18 numbered tag and a radio-frequency tag). A total of 1,155 faecal samples were collected 19 only from these individually identified lambs on five separate sampling occasions. All 20 samples were screened using PCR to detect Cryptosporidium (18S rRNA and actin loci) 21and Giardia duodenalis (glutamate dehydrogenase and triosephosphate isomerise loci). 22The overall prevalences (lambs positive for a parasite on at least one of the five 23 samplings) at Farm A and B were 81.3% and 71.4%, respectively for Cryptosporidium and 24 similarly 67.3% and 60.5% for Giardia, respectively. Cryptosporidium and Giardia 25 prevalences at individual samplings ranged between 18.5 -42.6% in lambs and were 26 <10% in the ewes. Cryptosporidium xiaoi was the most prevalent species detected at all 27 five samplings and was also isolated from lamb dam water on Farm B. Cryptosporidium 28 ubiquitum was most commonly detected in younger lambs and C. parvum was detected in 29 lambs at all five samplings, typically in older lambs and as part of a mixed species infection 30 with C. xiaoi. A novel, possibly new genotype (sheep genotype I), was identified in six 31Cryptosporidium isolates from Farm B. Giardia duodenalis assemblage E was the most 32 common genotype detected at all five samplings, with greater proportions of assemblage A 33 and mixed assemblage A and E infections identified in older lambs. This longitudinal study 34 identified high overall prevalences of Cryptosporidium and Giardia in lambs grazed 35 extensively on pastures, whilst reinforcing that sampling a random selection of animals 36 from a flock/herd on one occasion (point prevalence), underestimates the overall 37 prevalence of these parasites in the flock/herd across an extended time period. Based on 38 these findings, grazing lambs were identified as a low risk source of zoonotic 39Page 3 of 36 Cryptosporidium and Giardia species/genotypes, with these protozoa detected at all five 40 samplings in some lambs, indicating that these individuals were either unable to clear the 41 naturally acquired protozoan infections or were repeatedly re-infected from their 42 environment or other flock members. 43

Live weight, growth rate and BCS were inconsistently associated with protozoa detection 37 across different samplings and farms. Adjusted WEC was correlated positively with FCS 38 and negatively with faecal DM%, differing between sampling occasions and farms. 39Campylobacter jejuni prevalence was very low (<1%). Adjusted WEC were not correlated 40 with carcase attributes, growth rates or live weights. This study is the first to quantify 41 productivity consequences of naturally acquired protozoa infections in lambs managed 42 under extensive farming conditions. 43

No abstract

Please cite this article as: Sweeny, J.P.A., Robertson, I.D., Ryan, U.M., Jacobson, C., Woodgate, R.G., Impacts of naturally acquired protozoa and strongylid nematode infections on growth and faecal attributes in lambs, Veterinary Parasitology (2010Parasitology ( ), doi:10.1016Parasitology ( /j.vetpar.2011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Page 1 of 39 A c c e p t e d M a n u s c r i p t with an increased risk of non-pelleted faeces (FCS≥3.0) for both flocks. Cryptosporidium-27 positive lambs were 2.8-11.6 times more likely to have non-pelleted faeces and Giardia 28 positive lambs were 2.4-14.0 times more likely to have non-pelleted faeces compared to 29 lambs negative for each respective parasite. Lambs positive for both Cryptosporidium and 30 Giardia were 2.9-11.8 times more likely to have non-pelleted faeces than lambs positive 31 for only one or neither of these parasites. Mixed internal parasite infections were found to 32 have greater impacts on FCS and BCS than single infections. A higher number of internal 33 parasites detected per lamb was associated with lower BCS and more loose faeces. The 34 relationship between parasite detection and live weight or growth rate were inconsistent for 35 both flocks. Adjusted WEC was correlated with FCS and faecal DM% for one flock only, 36 although little or no correlation was found with live weight and growth rate for both flocks. 37Cryptosporidium ubiquitum and C. parvum were the most prevalent Cryptosporidium 38Page 3 of 39 A c c e p t e d M a n u s c r i p t Page 3 of 3 species isolated in the two flocks. Giardia assemblage E was the most commonly isolated 39 genotype assemblage from both flocks, while assemblage A was isolated almost as 40 frequently as assemblage E in the one flock. One flock was a potential source of zoonotic 41Cryptosporidium and the other flock was a potential source of zoonotic Giardia. 42

No abstract