Serological Investigation of Granulocytic Ehrlichia Infection in Sheep in Norway

Serum samples of 749 sheep from 75 sheep flocks in Norway, i.e. 361 lambs (6 to 7 months old) and 388 adults (>1.5 year), were analysed for antibodies to Ehrlichia equi. Ten animals from each flock were examined. Seropositive animals were found along the coast of southern Norway from Vestfold to S?r-Tr?ndelag (as far north as 63°38'N). Seropositive sheep were not found in southeast, east or northern Norway. Thirty-two flocks were seropositive, although tick-borne fever had only been diagnosed earlier in half of these. In 78% of the seropositive flocks, more than 80% of the sheep were seropositive. A total of 35.7 % and 36.3 % of lambs and adults were found seropositive, respectively. However, the overall seroprevalence among animals that had been grazing on Ixodes pastures were 0.80 for the lambs and 0.84 for the adults. Mean antibody titres (± SD) (log₁₀) in seropositive lambs and adults were 2.59 (± 0.449) and 2.70 (± 0.481), respectively. No significant differences in either seroprevalence or mean antibody titre between sheep of different ages were obtained in this study. Based on antibodies 94% of sheep flocks on Ixodes pastures were infected with a granulocytic Ehrlichia infection. The association between seropositive flocks and Ixodes infested pasture shows a very high degree of agreement (p < 0.00001). The present study indicates that granulocytic Ehrlichia infection in sheep is underdiagnosed in Norway.     

The Effect of Two Different Oxytetracycline Treatments in Experimental Ehrlichia phagocytophila Infected Lambs

The effect of 2 different oxytetracycline treatments in acute E. phagocytophila infected lambs was investigated. Twenty 5-month-old lambs of the Dala and Rygja breeds were used. Ten lambs were inoculated intravenously with a stabilate of an ovine E. phagocytophila strain. On the third day of fever, 4 lambs were given long-acting oxytetracycline (Terramycin prolongatum vet^?, Pfizer) (20 mg/kg) intramuscularly and another 4 lambs were given short-acting oxytetracycline (Terramycin vet^?, Pfizer) (10 mg/kg) intravenously for 5 consecutive days. The lambs were examined for the presence of Ehrlichia infection by blood smear evaluation, polymerase chain reaction (PCR) and antibody titre against E. equi. One month after the last antibiotic treatment, 250 ml citrate blood from each of these lambs were inoculated into each of 10 susceptible lambs, which were observed during the following 6 weeks. The results indicate that oxytetracycline given in the acute stage of the infection may effectively teminate the development of fever, rickettsemia and weight reduction in E. phagocytophila infected lambs. No difference was observed between the 2 treatment groups. However, at least 3 of 8 antibiotic treated lambs (37.5%) were still infected with granulocytic Ehrlichia 3 months after treatment.     

Reduced Weight Gain Due to Subclinical Anaplasma phagocytophilum (Formerly Ehrlichia phagocytophila) Infection

Tick-borne fever (TBF) is caused by the rickettsia Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila) and is a common disease in sheep in areas of Norway infested by Ixodes ricinus ticks. TBF can cause both direct and indirect losses to sheep kept on tick-infested pastures. In the present work we studied a sheep flock of 26 ewes and 50 lambs on pasture from May until September. No cases of TBF had earlier been observed on this pasture. Blood samples from lambs with a reduced weekly weight gain were collected and analysed for A. phagocytophilum infection by blood smear examination. In addition, at the end of the study, sera from all lambs were analysed by an indirect fluorescent antibody assay (IFA) to determine the antibody titre to E. equi. No clinical signs of tick-borne infections were observed, except in one lamb. However, 30 (60%) of the lambs grazing on this pasture became infected with A. phagocytophilum, and the infected lambs had a reduced weight gain (mean) of 3.8 kg compared with the uninfected lambs. The present study indicates that A. phagocytophilum infection may be widespread and contribute to considerable productivity losses even on pastures with no apparent tick infestation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Epidemiological Characteristics of Classical Scrapie Outbreaks in 30 Sheep Flocks in the United Kingdom

Background

Most previous analyses of scrapie outbreaks have focused on flocks run by research institutes, which may not reflect the field situation. Within this study, we attempt to rectify this deficit by describing the epidemiological characteristics of 30 sheep flocks naturally-infected with classical scrapie, and by exploring possible underlying causes of variation in the characteristics between flocks, including flock-level prion protein (PrP) genotype profile. In total, the study involved PrP genotype data for nearly 8600 animals and over 400 scrapie cases.

Methodology/Principal Findings

We found that most scrapie cases were restricted to just two PrP genotypes (ARQ/VRQ and VRQ/VRQ), though two flocks had markedly different affected genotypes, despite having similar underlying genotype profiles to other flocks of the same breed; we identified differences amongst flocks in the age of cases of certain PrP genotypes; we found that the age-at-onset of clinical signs depended on peak incidence and flock type; we found evidence that purchasing infected animals is an important means of introducing scrapie to a flock; we found some evidence that flock-level PrP genotype profile and flock size account for variation in outbreak characteristics; identified seasonality in cases associated with lambing time in certain flocks; and we identified one case that was homozygous for phenylalanine at codon 141, a polymorphism associated with a very high risk of atypical scrapie, and 28 cases that were heterozygous at this codon.

Conclusions/Significance

This paper presents the largest study to date on commercially-run sheep flocks naturally-infected with classical scrapie, involving 30 study flocks, more than 400 scrapie cases and over 8500 PrP genotypes. We show that some of the observed variation in epidemiological characteristics between farms is related to differences in their PrP genotype profile; although much remains unexplained and may instead be attributed to the stochastic nature of scrapie dynamics.     

Assessment of DNA fingerprinting for determining genetic diversity in sheep populations

Genomic DNA, prepared from 12 animals from four sheep flocks, was digested with either HaeIII or Hin fI and probed with three DNA fingerprinting probes. Mean DNA fingerprint band sharing and band frequency calculated for each flock were used to estimate genetic diversity. Each of the DNA fingerprinting systems showed the same trend in diversity within the sampled flocks, and greater diversity between the flocks than within the flocks. DNA fingerprinting therefore provides a useful measure of genetic diversity in sheep.     

Variation of serum selenium concentrations in German sheep flocks and implications for herd health management consultancy

Background

This study was performed to demonstrate the widespread distribution and severity of selenium (Se) deficiency in sheep flocks and to evaluate the impact of influencing factors. In 150 flocks, ten serum samples of adult ewes were analysed for Se concentration. The farmers were interviewed concerning flock size, provision of mineral supplement, predominant form of husbandry (stationary fenced pasture/transhumance), predominant form of water provision (tap water/well/surface water) and predominant soil (sandy, silty/loamy, clay) in the area. The location of the flock was recorded as well as the production stage/season at the time of sampling. Intra-group variation and the validity to analyse pooled samples were tested.

Results

Pools of five samples correlated well with the mean of individually analysed samples. The intra-group range of serum Se concentration varied enormously (mean 45.4?±?18.8 μg Se/l). About 60% of the flocks showed mean serum Se concentrations below 80 μg/l, 37.4% were below 60 μg Se/l, representing a Se deficient stage. Using mineral supplement in general was no key factor for Se status. Stationary flocks on fenced pasture had constantly higher mean serum Se concentrations during breeding (outdoors, August-November), lambing (mainly indoors, December-March) and lactation (outdoors, April-July), whereas flocks practising transhumance had significantly lower Se status, except during lambing. There was no significant correlation between the soil type and the Se status, but flocks in Southern Germany tend to show a lower Se status compared to Central and Northern Germany. Increasing flock size was associated with lower mean serum Se concentrations. In stationary flocks only, the use of surface water was accompanied by significantly lower Se status.

Conclusion

Se deficiency is widespread in German sheep flocks. More than one third of the flocks showed Se deficiency, indicating the need to optimise the nutritional management. Factors raising suspicion of Se deficiency are large flocks, transhumance during lactation and the breeding season as well as surface water provision in stationary flocks.

     

Freemartinism and FecX allele determination in replacement ewes of the Rasa Aragonesa sheep breed by duplex PCR

A new naturally occurring mutation in the fecundity gene BMP15 in the Rasa Aragonesa sheep breed (Ovis aries) has been found to affect prolificacy. This mutation (FecX^R allele) is a deletion of 17 base pairs that leads to an altered amino acid sequence, and this alteration increases prolificacy in heterozygous ewes but causes sterility in homozygous ewes. Selection of repository lambs with the FecX^R allele increases rates of twins and multiple lambing and thereby also increases the probability of lambing freemartins that will become sterile. In this sense, an accurate, reliable, and quick method was developed by duplex polymerase chain reaction (PCR) for sex, amplifying an ovine-specific Y chromosome repetitive fragment, and BMP15 genotype determination in replacement ewe lambs. The BMP15 fragment served as an internal control of the amplification and detected the FecX^R allele, avoiding a false negative and then a mistake in freemartin detection. This assay uncovered 6 freemartin females among 195 replacement ewes from 7 different commercial flocks and 1 experimental flock. Furthermore, 1554 rams from 64 commercial flocks were also analyzed to identify FecX^R rams. This analysis identified 103 rams hemizygous for the FecX^R allele and 1 heterozygous ram. Because this gene is located on the X chromosome, this heterozygous animal is a freemartin ram that is co-amplifying the DNA from XX and XY lymphocytes. These results confirm the usefulness of this multiplex PCR assay for detecting phenotypically sexed females, freemartins, and the BMP15 genotype to detect highly prolific ewes in commercial flocks and to assist breeders in selection of repository lambs.     

Reproductive response and LH secretion in ewes treated with melatonin implants and induced to ovulate with the ram effect

Two experiments were conducted to examine the effects of treating seasonally anoestrous ewes with melatonin before ram introduction on reproductive response, and on LH secretion in anoestrous ewes induced to ovulate by rams.In Experiment 1, a total of 667 ewes from three flocks involving Merino (Flock 1, N = 149), Merino entrefino (Flock 2, N = 325) and Rasa Aragonesa (Flock 3, N = 203) breeds were used. Within each flock, ewes isolated from rams since the previous lambing were assigned at random to receive melatonin implants of Regulin (75, 175 and 105 in Merino, Merino entrefino and Rasa Aragonesa flocks, respectively) or to serve as untreated controls (74 in Merino, 150 in Merino entrefino and 98 in Rasa Aragonesa flocks). Fertile rams were introduced into all flocks 5 weeks after implantation in March (Flocks 1 and 2) or April (Flock 3), and remained with the ewes for a 50 day mating period. Percentage of ewes with luteal activity at ram introduction did not differ between melatonin treated and control ewes in any flock. There were no significant differences in either the mean interval from ram introduction to lambing or the distribution of lambing. Implantation with melatonin resulted in an improvement of prolificacy in all three flocks, although this only reached statistical significance in the Merino flock (1.15 vs. 1.03 in treated and control ewes, respectively, P < 0.05). Fertility was increased significantly (P < 0.05) in the Merino entrefino flock (64.5% in treated vs. 51.3% in control ewes).In Experiment 2, two trials were undertaken utilizing a total of 63 ewes. Trial 1 involved 24 mature Manchega ewes and Trial 2 involved 39 Merino ewe lambs. Half of the animals in each trial received a Regulin implant on 28 February (Trial 1) or 12 March (Trial 2) and the remaining half acted as controls. Rams were introduced 5 weeks after implantation and remained with the ewes for a 25 day period. In both trials, anoestrous ewes at ram introduction were bled at 20 min intervals for 3 h before and 5 h after ram introduction and then at 3 h intervals over the next 24 h for assessment of plasma concentrations of LH. Secretion of LH before or following introduction of rams was not affected by melatonin. Both treated and control anoestrous ewes in each trial responded to introduction of rams with an increase in the frequency of the LH pulses (P < 0.05), but no significant changes were detected in pulse amplitude or mean levels of LH. A preovulatory surge of LH was detected between 8 and 26 h after ram introduction, but neither mean interval from ram introduction to the peak of LH surge, nor the magnitude of the LH peak, was influenced by melatonin treatment.Results from this study show that: (1) melatonin implants administered during early seasonal anoestrus have the potential to improve reproductive performance in Spanish breeds of sheep, but the response is conditioned by breed, management system and environmental factors; (2) melatonin did not modify the secretion of LH in anoestrous ewes induced to ovulate by the ram effect under our experimental conditions.     

Ovine Toxoplasmosis in Sweden

Sera from 155 ewes representing 21 different sheep flocks from the central parts of Sweden were examined for the presence of antibodies to Toxoplasma gondii by the indirect fluorescent-antibody test. Seropositive animals were found in 14 flocks, which corresponded to 55 % of the tested sera. Animals from the same flock were with few exceptions either all positive or all negative. Some ewes with a history of abortion a few months before blood sampling showed high titers indicating causative correlation with toxoplasmosis. These are the first verified cases of ovine toxoplasmal abortions in Sweden.     

<Emphasis Type="Italic">Anaplasma phagocytophilum</Emphasis> in Danish sheep: confirmation by DNA sequencing

Background  

The presence of Anaplasma phagocytophilum, an Ixodes ricinus transmitted bacterium, was investigated in two flocks of Danish grazing lambs. Direct PCR detection was performed on DNA extracted from blood and serum with subsequent confirmation by DNA sequencing.     

Bio-economic modelling of sheep meat production systems with varying flock litter size using field data

Sheep meat producers derive the majority of income from sales of weaned lambs, determined by flock conception rates, litter size, and lamb survival. Field data from commercial flocks can inform sensitivity analyses of the effect of litter size on flock productivity, feed demand, and gross margin. This study adapted an established bio-economic model of a flock of breeding ewes informed by statistical relationships (from linear models) between flock litter size (lambs born per ewe lambing) and production factors (such as flock barren rate, litter birth type and lamb birth weight) identified using 156 145 animal records from the Irish national sheep breeding database. Sensitivity analyses were undertaken to investigate the effects of flock litter size on flock production, feed demand, and gross margin. Results showed that as flock litter size increased, the proportion of lambs born as multiples increased, with 14 % of lambs born as singles when flock litter size was 2.2 lambs born per ewe lambing. Flock gross margin increased from €2 205 to €7 730 as litter size increased from 1.0 to 2.0 lambs born per ewe lambing. As litter size increased from 1.0 to 2.2 lambs born per ewe lambing, flock gross margin increased linearly by, on average, €52 per 0.01 increase in litter size. At a litter size of > 2.2 lambs born per ewe lambing, flock gross margin increased on average €12 per 0.01 increase in litter size. At a litter size of 2.2 lambs born per ewe lambing, flock efficiency (at 65.0 kg of lamb weaned per ewe presented for breeding), weaning rate (at 1.5 lambs weaned per ewe presented for breeding; not including excess lambs from large litters sold within a week after birth and thus not weaned on-farm), and gross margin (at €8 500) began to plateau. The results indicate lower marginal returns in gross margin at very high flock litter size, due to the lower value of additional lambs born as triplets and quadruplets compared with single- and twin-born lambs. However, the diminishing economic returns occurred at higher flock litter size than are currently biologically achieved in most flocks. Quantification from this analysis demonstrates how the value of increasing the number of lambs born changes at very high flock litter size, which can inform the priorities and performance benchmarking for international sheep meat production industries.     

The Dynamics, Prevalence and Impact of Nematode Infections in Organically Raised Sheep in Sweden

A three-year survey (1997–99) was carried out on organically reared sheep flocks throughout Sweden. The aim was to determine the prevalence and intensity of nematode infections and to establish relationships between sheep management practices and parasite infections. Faecal samples from ewes and lambs were collected from 152 organic flocks around lambing-time and during the grazing-period for analysis. Results were compared with the different management practices that farmers use to prevent parasitism in their flocks. A high proportion of the flocks was infected with nematodes. The most prevalent species were Haemonchus contortus, Teladorsagia circumeincta, Trichostrongylus axei, T. colubriformis and Chabertia ovina and infections progressively increased during summer in lambs grazing on permanent pastures. Severity of parasitic infection in lambs was highly dependent on egg output from the ewes. H. contortus was found in 37% of the flocks, even at latitudes approximating the Polar Circle. Nematodirus battus was recorded for the first time in Sweden during the course of this study. Lambs turned out onto permanent pasture showed higher nematode faecal egg counts (epg) than lambs that had grazed on pastures, which had not carried sheep the previous year. This beneficial effect of lambs grazing non-infected pastures persisted if the ewes were treated with an anthelmintic before turn-out and if the lambs were kept on pastures of low infectivity after weaning. In lambs, the prevalence and the magnitude of their egg counts were higher during autumn in flocks where lambs were slaughtered after 8 months of age, compared with flocks where all lambs were slaughtered before this age. These results will be used in providing advice to farmers of ways to modify their flock management in order to minimise the use of anthelmintics, but at the same time efficiently produce prime lambs.     

Seroprevalence of ovine paratuberculosis infection in the Northeast of Portugal

A survey to estimate the prevalence of ovine paratuberculosis in sheep flocks was conducted in the Northeast of Portugal. In total, 3900 samples of sheep older than 2 years belonging to 150 sheep flocks from 12 different territorial Livestock Farmers Organizations (OPP) were investigated for the presence of antibodies against Mycobacterium avium subspecies paratuberculosis using a commercial enzyme-linked immunosorbent assay (ELISA) test. Seventy (46.7%) flocks had one or more serologically positive animals. The individual paratuberculosis prevalence was 3.7% (144/3900), with values ranging from 0.0 to 10.3% per flock. Statistically significant differences between OPP, herd size and the presence of clinical signs was observed. According to the test sensitivity and specificity claimed by the manufacturer, the true prevalence in the Northeast of Portugal was calculated as 6.4%. In summary, a small percentage of animals and a high percentage of flocks in the Northeast of Portugal were serologically positive.     

Epidemiological studies on foot and mouth disease and paratuberculosis in small ruminants in Tafelah and Ma’an,Jordan

A cross-sectional study was performed to investigate some epidemiological aspects of foot and mouth disease (FMD) and paratuberculosis in small ruminant flocks located in two governorates in Southern Jordan. A total of 320 sheep and 300 goats from 38 and 24, sheep and goat flocks, respectively, were randomly sampled and assayed for presence of antibodies against FMD virus and Mycobacterium paratuberculosis using commercially available kits. A structured pre-tested questionnaire was administered to collect information on flocks’ health and management. A multivariable logistic regression model was constructed to investigate risk factors associated with seropositivity to the two studied diseases. The individual prevalence of FMD and paratuberculosis in sheep was 10.4 and 22.1%, respectively. The sheep flock level seroprevalence for FMD and paratuberculosis was 44.7 and 50%, respectively. In goats, the individual prevalence of FMD and paratuberculosis was 6.3 and 18.1%, respectively. The goat flock level seroprevalence for FMD and paratuberculosis was 33.3 and 45.8%, respectively. The logistic regression model revealed mixed farming as a common risk factor for both FMD and paratuberculosis. Grazing in communal areas and addition of new animals were identified as risk factors for paratuberculosis.     

Road-Based Surveys for Estimating Wild Turkey Density in the Texas Rolling Plains

Abstract: Line-transect-based distance sampling has been used to estimate density of several wild bird species including wild turkeys (Meleagris gallopavo). We used inflatable turkey decoys during autumn (Aug-Nov) and winter (Dec-Mar) 2003-2005 at study sites in the Texas Rolling Plains, USA, to simulate Rio Grande wild turkey (M. g. intermedia) flocks. We evaluated detectability of flocks using logistic regression models. Our modeling effort suggested that distance to a flock and flock size played important roles in flock detectability. We also conducted surveys from roads for wild turkeys during November 2004-January 2006. The detection probability of decoy flocks was similar to wild turkey flocks during winter (decoy flock, 69.3 ± 6.2% [x̄ ± 95% CI]; wild turkey flock, 62.2 ± 18.3%) and autumn (decoy flock, 44.1 ± 5.1%; wild turkey flock, 44.7 ± 25.6%), which suggested that using decoys was appropriate for evaluating detectability of wild turkey flocks from roads. We conducted computer simulations to evaluate the performance of line-transect-based distance sampling and examined the power to detect trends in population change. Simulations suggested that population density may be underestimated by 12% during inter and 29% during autumn. Such bias occurred because of incomplete detectability of flocks near roads. Winter surveys tended to have less bias, lower relative variability, and greater power than did autumn surveys. During winter surveys, power was sufficient (≥0.80) to detect a 10-25% change in population density in 8-12 years using ≥100 16-km transects or ≥80 32-km transects. We concluded line-transect-based distance sampling from roads is an efficient, effective, and inexpensive technique for monitoring Rio Grande wild turkey populations across large scales.     

Rickettsial agents in Egyptian ticks collected from domestic animals

To assess the presence of rickettsial pathogens in ticks from Egypt, we collected ticks from domestic and peridomestic animals between June 2002 and July 2003. DNA extracts from 1019 ticks were tested, using PCR and sequencing, for Anaplasma spp., Bartonella spp., Coxiella burnetii, Ehrlichia spp., and Rickettsia spp. Ticks included: 29 Argas persicus, 10 Hyalomma anatolicum anatolicum, 55 Hyalomma anatolicum excavatum, 174 Hyalomma dromedarii, 2 Hyalomma impeltatum, 3 Hyalomma marginatum rufipes, 55 unidentified nymphal Hyalomma, 625 Rhipicephalus (Boophilus) annulatus, 49 Rhipicephalus sanguineus, and 17 Rhipicephalus turanicus. Ticks were collected predominantly (>80%) from buffalo, cattle, and camels, with smaller numbers from chicken and rabbit sheds, sheep, foxes, a domestic dog, a hedgehog, and a black rat. We detected Anaplasma marginale, Coxiella burnetii, Rickettsia aeschlimannii, and four novel genotypes similar to: “Anaplasma platys,” Ehrlichia canis, Ehrlichia spp. reported from Asian ticks, and a Rickettsiales endosymbiont of Ixodes ricinus.     

Allele frequency of the spider lamb syndrome in Brazilian Hampshire Down and Suffolk flocks

The spider lamb syndrome (SLS) is an autosomal recessive condition of sheep, characterized by severe bone lesions. The disease is caused by a mutation at codon 700 of the gene fibroblast growth factor receptor 3 (FGFR3), resulting in a valine (V) to glutamate (E) substitution, and leading to an abnormal bone growth. Congenital diseases as SLS may have an important impact on animal production. The objective of this work was to detect the frequency of E allele on Suffolk and H. Down breeds in three flocks from the southern region of Brazil. A total of 256 samples, 146 from two Suffolk flocks and 110 from one H. Down flocks were evaluated. The genomic DNA extracted from peripheral blood was PCR amplified and cleaved with XhoI restriction enzyme. Allele E frequency varied among the different herds: Suffolk, 6% in one flock and 3% in the other, and H. Down 6%, corresponding to 6–12% of heterozygotes for the condition. These results emphasize the need for preventive measures to minimize the birth of affected lambs. Also, the culling of animals, mainly rams, carrying the E allele will bring more efficiency to the sheep industry. These data are important also for sheep breeders, as the genotyping of the breed stock will afford more security to breeding programs and stop the spread of this undesirable allele, reducing economic losses. It is important to note that, in Brazil, the DNA test for SLS is not a routine procedure.     

Parasites of the feral sheep of Pitt Island,Chatham group

Abstract

Samples from the feral and domestic sheep on Pitt Island were examined for parasites. The feral sheep had never been treated against parasites, and most were due for extermination. The domestic sheep were examined by way of comparison. The sheep ked (Melophagus ovinus) and the chorioptic mange mite (Chorioptes bovis) were found on feral but not domestic sheep. The sheep body louse (Damalinia ovis) was found on domestic but not feral sheep. Lung nodules and liver lesions, presumed to be caused by parasites, were significantly more prevalent in domestic than in feral sheep. The prevalence of Cysticercus tenuicollis cysts and Sarcocystis spp. macrocysts was similar in feral and domestic sheep. The species of intestinal nematode and their relative abundance in feral sheep were similar to those in mainland sheep. Fewer feral sheep were found to have antibodies to Toxoplasma gondii when compared with other breeds; the proportion with antibodies to Sarcocystis ovicanis differed little from that in the mainland flocks, however. The data are compared with information from the Campbell Island feral sheep flock.     

Mutations in Ovis aries TMEM154 are associated with lower small ruminant lentivirus proviral concentration in one sheep flock

Small ruminant lentivirus (SRLV), also called ovine progressive pneumonia virus or maedi‐visna, is present in 24% of US sheep. Like human immunodeficiency virus, SRLV is a macrophage‐tropic lentivirus that causes lifelong infection. The production impacts from SRLV are due to a range of disease symptoms, including pneumonia, arthritis, mastitis, body condition wasting and encephalitis. There is no cure and no effective vaccine for preventing SRLV infection. However, breed differences in prevalence and proviral concentration indicate a genetic basis for susceptibility to SRLV. Animals with high blood proviral concentration show increased tissue lesion severity, so proviral concentration represents a live animal test for control post‐infection in terms of proviral replication and disease severity. Recently, it was found that sheep with two copies of TMEM154 haplotype 1 (encoding lysine at position 35) had lower odds of SRLV infection. In this study, we examined the relationship between SRLV control post‐infection and variants in two genes, TMEM154 and CCR5, in four flocks containing 1403 SRLV‐positive sheep. We found two copies of TMEM154 haplotype 1 were associated with lower SRLV proviral concentration in one flock (P < 0.02). This identified the same favorable diplotype for SRLV control post‐infection as for odds of infection. However, frequencies of haplotypes 2 and 3 were too low in the other three flocks to test. The CCR5 promoter deletion did not have consistent association with SRLV proviral concentration. Future work in flocks with more balanced allele frequencies is needed to confirm or refute TMEM154 association with control of SRLV post‐infection.