Melophagus ovinus (Pupipara: Hippoboscidae): Confirmation of the nonpathogenicity of Trypanosoma melophagium for sheep keds

Data are presented to show that Trypanosoma melophagium is not pathogenic to the sheep ked, Melophagus ovinus. During each normal cycle of the ked population on sheep, death of variable numbers of keds occurs that cannot be attributed to host resistance. Pathological signs include abdominal swelling, reddening of the hemolymph, cessation of peristalsis, and desquamation of the epithelium of the posterior midgut. These pathological developments are attributed to hypoxia in the gut wall resulting from occlusion of abdominal spiracles with debris. They occur alike in keds infected with T. melophagium and in keds that have been made flagellate free experimentally.     

Parasitism of the deer ked,Lipoptena cervi,on the moose,Alces alces,in eastern Finland

The deer ked, Lipoptena cervi L. (Diptera: Hippoboscidae), is an ectoparasitic fly that spread to Finland in the early 1960s from the southeast across the Soviet border. It is currently a common parasite of the moose, Alces alces (Artiodactyla: Cervidae), in the southern part of the country and its area of distribution is gradually spreading to Finnish Lapland, where it will come into contact with another potential cervid host, the semi‐domesticated reindeer, Rangifer tarandus tarandus. The aim of this study was to determine the intensity of deer ked parasitism on the moose in eastern Finland. Whole skins of 23 moose were examined for the presence of deer keds, which were extracted and their total numbers estimated. The intensity of deer ked parasitism was correlated to the age, sex, skin area and anatomical region of the host. Bulls had the highest total number of keds (10616 ± 1375) and the highest deer ked density (35.7 ± 4.4 keds/dm² of skin). Cows had a higher total number of keds than calves (3549 ± 587 vs. 1730 ± 191), but ked densities on cows and calves were roughly equal (11.8 ± 1.7 vs. 9.4 ± 1.1 keds/dm² of skin). The density of keds was highest on the anterior back, followed by the posterior back, front limbs, abdomen, head and hind limbs. The sex ratio of deer keds was close to equal (male : female, 1.0 : 1.1). After they had consumed blood, male keds were heavier than females. As the total numbers and densities of deer keds were higher than reported previously on moose or for any other louse fly species, the effects of parasitism on the health of the host species should be determined.     

Never too late? Consequences of late birthdate for mass and survival of bighorn lambs

In strongly seasonal environments, the timing of birth can have important fitness consequences. We investigated which factors affect parturition date and how birthdate interacts with sex, maternal characteristics and environmental variables to affect the growth and survival of bighorn sheep (Ovis canadensis) lambs in a marked population in Alberta. Over 14 years, the estimated birthdate of 216 lambs ranged from 21 May to 18 July. Parturition date was heritable and genetically correlated with maternal mass the previous fall. Weaning a lamb delayed parturition the following year by about 7 days. Birthdate did not affect summer growth rate, but late-born lambs were lighter in mid September (the approximate time of weaning) than early-born ones. Birthdate did not affect survival to weaning, but late birth decreased survival to 1 year for male lambs. Forage quality, measured by fecal crude protein, did not affect survival to 1 year. Once we accounted for lamb mass in mid September, birthdate no longer affected the probability of survival, suggesting that late birth decreased survival by shortening a lamb's growing season. Because there was no compensatory summer growth, late-born lambs were smaller than early-born ones at the onset of winter. Our data highlight the importance of birthdate on life history traits and suggest that resource scarcity had more severe consequences for juvenile males than for females.     

Dynamics of Pneumonia in a Bighorn Sheep Metapopulation

Abstract: We investigated the dynamics of 8 populations of a bighorn sheep (Ovis canadensis) metapopulation in Hells Canyon, USA from 1997 to 2003. Pneumonia was the most common cause (43%) of adult mortality and the primary factor limiting population growth. Cougar (Puma concolor) predation was the second most-frequent source (27%) of adult mortality but did not reduce the rate of population growth significantly. Most pneumonia-caused mortality occurred in fall and early winter and most cougar predation occurred in late winter and early spring. Average annual survival of adult males (0.84) was lower than females (0.91). Pneumonia was the most common known cause of lamb mortality (86%), and pneumonia-related mortality was detected whenever summer lamb survival was <50%. Pneumonia-caused mortality rates in lambs were high from 21 days to 91 days of age and peaked at 42 days to 70 days. Summer pneumonia epizootics in lambs were independent of pneumonia-caused mortality in adults. Pneumonia-caused mortality occurred at the population level and was not synchronized geographically or temporally among populations. Although catastrophic all-age pneumonia-epizootics have previously been described in bighorn sheep, we found that chronic, although sporadic, pneumonia-caused mortality in adults and lambs can also have important effects on the dynamics of bighorn sheep populations.     

Behavioural patterns in ewe–lamb pairs and vulnerability to predation by wolverines

In Norway domestic sheep Ovis aries range unattended in mountainous areas during the summer season. Wolverines Gulo gulo re-established in the alpine regions of southern Norway during recent decades and are viewed as a substantial predator on lambs. Reducing predation on sheep by wolverines would not only reduce the economic loss to farmers but also promote the acceptance of wolverines in their summer ranges. We hypothesized that male lambs would be more prone to wolverine predation, because of higher locomotor activity, lower behavioural ewe–lamb synchrony and larger ewe–lamb distance. We studied ewe and lamb behavioural patterns, synchrony and ewe–lamb distance on a summer range in Knutshøi, south-central Norway. Although no differences were found in ewe–lamb distance or locomotor activity in gender, female lambs synchronized their behaviour more with their mother than males. Only for female lambs, increased synchrony resulted in closer ewe–lamb distances. Overall losses to wolverines based on long-term data indicate that male lambs are more prone to predation than females later in the season. These sex-specific behavioural differences in lambs affect the spatial and social relationships between ewe and lamb, and are likely to increase with age eventually leading to sexual segregation. Male lambs can therefore be expected to be more prone to wolverine predation towards the end of the season, when lambs become independent from the ewe.     

Serum and skin surface antibodies and their associations with sheep biting lice, Bovicola ovis, on experimentally infested sheep

The sheep biting louse ( Bovicola ovis ) feeds superficially on the skin of sheep but appears to stimulate an immune response. In this study we examined the association between louse infestation and serum and skin surface antibodies. Louse numbers were monitored on experimentally infested Polypay and Columbia ewes for two years and on their lambs in the second year. Serum and skin wash samples were tested for antibodies to soluble extracts of B. ovis , Stomoxys calcitrans and Musca autumnali s by enzyme linked immunosorbent assay (ELISA). In addition, the effects of skin wash extracts on B. ovis were examined in vitro .
The titre of anti- B. ovis antibodies in the serum did not differ significantly between infested and naive ewes. However, there was an increase in serum antibody titre which coincided with periods of high louse density in ewes with high louse counts. Infested lambs had higher serum antibody levels than naive lambs. Substantial cross reactivity was evident among extracts of the different insects.
Densities of lice on the ewes during population decline were negatively related to the titre of skin surface antibodies. Skin washings collected from sheep during B. ovis population decline reduced the number of louse progeny when incorporated into louse diet. These results indicate that B. ovis stimulates an immune response in sheep and suggest that compounds on the skin surface may play a role in the regulation of louse populations.     

Quantitative trait loci (QTL) mapping of resistance to strongyles and coccidia in the free-living Soay sheep (Ovis aries)

A genome-wide scan was performed to detect quantitative trait loci (QTL) for resistance to gastrointestinal parasites and ectoparasitic keds segregating in the free-living Soay sheep population on St. Kilda (UK). The mapping panel consisted of a single pedigree of 882 individuals of which 588 were genotyped. The Soay linkage map used for the scans comprised 251 markers covering the whole genome at average spacing of 15cM. The traits here investigated were the strongyle faecal egg count (FEC), the coccidia faecal oocyst count (FOC) and a count of keds (Melophagus ovinus). QTL mapping was performed by means of variance component analysis so that the genetic parameters of the study traits were also estimated and compared with previous studies in Soay and domestic sheep. Strongyle FEC and coccidia FOC showed moderate heritability (h(2)=0.26 and 0.22, respectively) in lambs but low heritability in adults (h(2)<0.10). Ked count appeared to have very low h(2) in both lambs and adults. Genome scans were performed for the traits with moderate heritability and two genomic regions reached the level of suggestive linkage for coccidia FOC in lambs (logarithm of the odds=2.68 and 2.21 on chromosomes 3 and X, respectively). We believe this is the first study to report a QTL search for parasite resistance in a free-living animal population and therefore may represent a useful reference for similar studies aimed at understanding the genetics of host-parasite co-evolution in the wild.     

Risk factors associated with lambing traits

The objective of this study was to establish the risk factors associated with both lambing difficulty and lamb mortality in the Irish sheep multibreed population. A total of 135 470 lambing events from 42 675 ewes in 839 Irish crossbred and purebred flocks were available. Risk factors associated with producer-scored ewe lambing difficulty score (scale of one (no difficulty) to four (severe difficulty)) were determined using linear mixed models. Risk factors associated with the logit of the probability of lamb mortality at birth (i.e. binary trait) were determined using generalised estimating equations. For each dependent variable, a series of simple regression models were developed as well as a multiple regression model. In the simple regression models, greater lambing difficulty was associated with quadruplet bearing, younger ewes, of terminal breed origin, lambing in February; for example, first parity ewes experienced greater (P<0.001) lambing difficulty (1.56±0.02) than older ewes. The association between lambing difficulty and all factors persisted in the multiple regression model, and the trend in fixed effects level solutions did not differ from the trend observed in the simple regression models. In the simple regression analyses, a greater odds of lamb mortality was associated with male lambs (1.31 times more likely of death than females), lambs of very light (2 to 3 kg) and very heavy (>7.0 kg) birth weights, quadruplet born lambs and lambs that experienced a more difficult lambing (predicted probability of death for lambs that required severe and veterinary assistance of 0.15 and 0.32, respectively); lambs from dual-purpose breeds and born to younger ewes were also at greater risk of mortality. In the multiple regression model, the association between ewe parity, age at first lambing, year of lambing and lamb mortality no longer persisted. The trend in solutions of the levels of each fixed effect that remained associated with lamb mortality in the multiple regression model, did not differ from the trends observed in the simple regression models although the differential in relative risk between the different lambing difficulty scores was greater in the multiple regression model. Results from this study show that many common flock- and animal-level factors are associated with both lambing difficulty and lamb mortality and management of different risk category groups (e.g. scanned litter sizes, ewe age groups) can be used to appropriately manage the flock at lambing to reduce their incidence.     

Using distance sampling and hierarchical models to improve estimates of Dall's sheep abundance

Management of large mammal populations has often been based on aerial minimum count surveys that are uncorrected for incomplete detection and lack estimates of precision. These limitations can be particularly problematic for Dall's sheep (Ovis dalli dalli) due to the high cost of surveys and variation in detection probability across time and space. The limitations of these methods have been recognized for some time, but previously proposed alternatives for sheep surveys proved to be too costly and logistically unfeasible in most circumstances (Udevitz et al. 2006). We assessed the potential for a combination of distance sampling surveys and a hierarchical modeling approach to provide a more efficient means for estimating Dall's sheep abundance by conducting aerial contour transect surveys over all sheep habitat in Gates of the Arctic National Park and Preserve (GAAR), Alaska in 2009 and 2010. We estimated the population of Dall's sheep was 8,412 (95% CI: 6,517–11,090) and 10,072 (95% CI 8,081–12,520) in 2009 and 2010, respectively. Abundance within the Itkillik Preserve area within GAAR was 1,898 (95% CI: 1,421–2,578) and 1,854 (95% CI: 1,342–2,488) in 2009 and 2010, respectively. Estimates of lamb abundance in 2010 were more than double those of 2009 after correcting for detection bias related to group size, suggesting that the apparent estimate of lambs in the population may be biased in some years depending on the degree of aggregation. Overall, the contour transect surveys were feasible logistically, cost 70–80% less than minimum count surveys, and produced precise estimates of abundance, indicating that the application of these methods could be used effectively to increase the statistical rigor and spatial extent of Dall's sheep abundance surveys throughout Alaska. These methods could be used to improve the assessment of long-term trends in populations and productivity and provide valuable information for harvest management at both local and landscape scales at reduced costs in comparison to traditional minimum count surveys. © 2011 The Wildlife Society.     

The effects of selection indices for sustainable hill sheep production on carcass composition and muscularity of lambs, measured using X-ray computed tomography

A multi-trait selection index designed to improve the overall economic performance of hill sheep, including both maternal and lamb traits, has been developed and tested in a selection experiment over 7 years. Two versions of the index were tested, with different economic weights applied to the traits, on two different hill farms: one version including maternal and growth traits; the other version with additional breeding goals of carcass weight, fatness and conformation scores. Responses to selection, using both versions of the index, suggest that improvements are being made in overall index score and lamb growth. This study investigated the indirect effects of these selection indices on lamb carcass composition and muscularity traits, as measured using X-ray computed tomography (CT) scanning. A total of 499 lambs from the two hill farms were CT scanned at weaning (approximately 120 days of age). Approximately half of the lambs from each farm were from the selection line (S, animals with highest index scores selected for breeding), while the other half were from a control line (C, animals with average index scores selected). Composition and muscularity traits were estimated on each lamb from CT data and differences between genetic lines investigated, within farm, using restricted maximum likelihood analyses, adjusting for either live weight or age. Results showed that the selection index without carcass traits produced lambs with carcass composition that was not significantly different to control lambs at a given live weight or age. Including carcass traits in the index resulted in lambs with no compositional differences (except for a slight increase in bone) at a set age compared with controls. At a given live weight however, selection lambs had less fat and lower carcass weights and killing-out percentage. Muscularity (3-D muscle shape) and muscle area shape (2-D) were not improved as a result of selection on either version of the index (including carcass weight and grades in the breeding goals or not) and, at a fixed live weight, muscularity in hind leg and lumbar regions tended to be higher in the C line. To accelerate changes in carcass composition and muscularity within the context of a multi-trait selection index for hill sheep, consideration should therefore be given to including objective CT-derived carcass traits in the index in addition to the Meat and Livestock Commission (MLC) carcass grades or ultrasound measurements.     

Residues of lindane in adipose tissue of lambs and sheep from islands Krk and Cres

Concentrations of lindane from adipose tissue i.e. omentum of sheep from homesteads of island Krk that were treated with lindane, were compared with the concentrations of lindane measured in adipose tissue of non treated sheep from husbandry cooperative on island Cres. Evaluation of food safety for this samples were estimated by comparing obtained results and maximum tolerance concentration (MTC) for lindane (2.0 and 0.2 mg/kg). In treated lambs from Krk measured concentrations of lindane were in range from 0.0038 to 1.8644 mg/kg, and in treated sheep from 0.0094 to 1.646 mg/kg. In control group of lambs and sheep concentration of lindane was < or = 0.0051 mg/kg. Estimation of food safety based on the results from this research are discussable, regarding the fact that MTC prescribed before year 2007 was 2.0 mg/kg. When the new law Regulations of MTC for residues of pesticides in food and animal feed (NN 119/07) came into the force prescribed MTC was 0.02 mg/kg. If food safety of sheep meat from Krk would be estimated based on latter, then 73.4% of samples of lamb meat and 80% of sheep meat could be proclaimed unsafe for human consumption. It is encouraging that after completion of using lindane in year 2005, levels of lindane in adipose tissue of lamb from Krk in year 2006 were under the concentration set by new legislate (< 0.02 mg/kg).     

Relationships between lamb carcass quality traits measured by X-ray computed tomography and current UK hill sheep breeding goals

Genetic parameters were estimated between current UK hill sheep breeding goals and lamb carcass composition and muscularity traits derived using X-ray computed tomography (CT). To produce these estimates, a total of 648 lambs from two hill farms were CT scanned at weaning (ca 120 days of age), over 3 years, and total weights of carcass muscle (MUSC), fat (CFAT) and bone (BONE) and internal fat (IFAT) were predicted. Previously derived muscularity indices were also calculated for the hind leg (HLMI) and lumbar (LRMI) regions, to assess muscle shape. Data for current breeding goals (lamb performance and maternal traits) were also included from a total of 10 297 lamb records and 12 704 ewe records. Heritabilities were estimated for each trait and genetic and phenotypic correlations were calculated between each CT trait and other lamb or ewe traits. Moderate to high positive genetic correlations were found between CT-predicted tissue weights and breeding goals, which were also weights (lamb weaning weight, carcass weight, mature ewe weight, average weight of lambs reared by the ewe). CFAT was positively genetically correlated with ultrasound backfat depth at weaning (UFD) and subjective fatness grade at slaughter (MLCF), suggesting that carcass fat could be decreased using selection on any of these predictors. Ultrasound muscle depth at weaning (UMD) and subjective conformation score at slaughter (MLCC) had high genetic correlations with the muscularity indices (HLMI and LRMI), but correlations with MUSC were not significantly different from zero. This implies that selection to improve MLCC is likely to be increasing the 'roundness' of muscle shape in the high-priced carcass region, but having little impact on total lean meat yield. Correlations of CT traits with the other ewe traits (number of lambs weaned, number of lambs lost, longevity, fleece weight) were generally small or not significantly different from zero. The genetic parameters generated in this study can now be used in selection index calculations to assess the benefits of including lamb CT traits in future selection programmes for hill sheep.     

Evaluation of some etiological factors predisposing to diarrhoea in lambs in “La Serena” (Southwest Spain)

This study compares some etiological factors involved in the naturally occurrence of lamb scours in 18 Merino sheep farms randomly selected in the area of “La Serena” (Southwest Spain).

A lack of influence of some variables (flock size, type of facilities, type of breeding, lambing percentage, isolation of Campylobacter jejuni, Rotavirus spp., Coronavirus spp. and Salmonella spp.) on lamb mortality rate was detected. The opposite was true for cleaning of the lambing areas, organization of lambing periods, accumulation of lambs in the pens, high content of fat, protein and lactose in milk and low serum gamma globulin and total protein in lambs and ewes. Cryptosporidium spp. and Escherichia coli isolation showed a trend to be linked to the presence of diarrhoea. A positive correlation was found between serum total protein in ewes and serum gamma globulin in lambs. Thus, the measure of serum total protein in ewes before lambing would be a valuable indicator of the risk of lamb scouring and it would be useful to establish an adequate programme to prevent this condition in the farms of this geographical area.     

Temperament and its heritability in Corriedale and Merino lambs

Temperament can be defined as the fearfulness and reactivity of an animal in response to humans and strange, novel or threatening environments. The productive performance of an animal is affected by its temperament, and selection of calm animals might improve their adaptation to the farming environment and handling, as well as improve productivity. The temperament was measured in lambs of two breeds of sheep in Uruguay. The effects of dam’s age, type of birth, age of the lamb and contemporary group (CG; lambs belonging to the same year, flock, sex and rearing group) on the temperament of the lambs and the heritability of temperament were estimated with a Bayesian analysis using Gibbs sampling. Overall, 4962 Corriedale lambs and 2952 Merino lambs from 13 farms were tested. Temperament was measured using the isolation box test, isolating a lamb inside the box for 30 s, and recording the vibrations produced by its movements. The average temperament score (±s.e.m.) of the Corriedale lambs was 24.7 (±0.23) and that of the Merino was 36.8 (±0.45). Temperament was not associated with dam’s age, type of birth or lamb’s age. There were no relevant differences in the agitation score between lambs born in 2010 and 2011. The mean of the distribution of possible values of heritability (±s.d.) was 0.18 (±0.05) for the Corriedale and 0.31 (±0.06) for the Merino. The likelihood of heritability values to be greater than 0.15 exceeded 70% in the Corriedale and 90% in the Merino. The temperament of Merino and Corriedale sheep in Uruguay is moderately heritable. It is not related to dam’s age, type of birth or age of the lambs; however, it is affected by some aspect of the CG.     

Pinealectomy delays puberty in ewe lambs

Fifteen pinealectomized and 15 unoperated ewes were exposed to constant light for 3 weeks before and 10 weeks after lambing. Fourteen pinealectomized and 15 unoperated ewes were allowed to lamb outdoors. Five ewe lambs born in constant light to the 2 groups of dams were pinealectomized at 10 weeks of age. Ewes and lambs were then returned to the field. Puberty (determined by weekly progesterone analysis) was significantly delayed (P less than 0.05) in the pinealectomized ewe lambs. Median pubertal age in pineal-intact ewe lambs was 37 weeks compared to 49 weeks in pinealectomized lambs. Constant light during the first 10 weeks of life had no effect upon puberty onset nor did the pineal status of the dam. Control lambs entered seasonal anoestrus at the time pinealectomized ewe lambs were entering puberty. Pinealectomized lambs entered anoestrus at the same time as control lambs were beginning their second breeding season. These results confirm a key role of pineal-mediated hormonal signals in the control of puberty in the sheep.     

Nematode parasitism in sheep in North-East England: The epidemiology of Ostertagia species

This investigation was undertaken to determine the epidemiology of a single parasite genus, Ostertagia, in natural parasite populations in sheep raised under intensive conditions in North-East England.Over the 2 years of study, striking differences were found in the overall level of parasitism which were related to different climatic conditions, specifically rainfall. Despite the low source of infection derived from the ewes grazing on clean pasture in 1973 the overall level of parasitism in the lamb crop was high, this was attributed to the ideal climatic conditions for parasite translation during Spring and Summer. Ostertagia spp. was found to survive well over Winter and to initiate early infections in the young lambs in the following year. Despite the two sources of egg contamination, from the ewes and lambs, unusually dry conditions were experienced from March to June which resulted in much lower levels of infection in the second year of investigation.Regulation of the parasite population within the lambs was clearly demonstrated. Inhibition of Ostertagia was recorded somewhat earlier in the season than had been hitherto reported and was considered to be induced by a multiplicity of factors.     

Predator-Mediated Indirect Effects of Snowshoe Hares on Dall's Sheep in Alaska

ABSTRACT Indirect interactions among species can strongly influence population dynamics and community structure but are often overlooked in management of large mammals. We estimated survival of Dall's sheep (Ovis dalli) in the central Alaska Range, USA, during years of differing snowshoe hare (Lepus americanus) abundance to test whether indirect interactions with a cyclic hare population affect Dall's sheep either negatively, by subsidizing predators (apparent competition), or positively, by diverting predation (apparent commensalism). Annual survival of adult female sheep was consistently high (0.85 for all yr and age classes combined). In contrast, annual estimates of lamb survival ranged from 0.15 to 0.63. The main predators of lambs were coyotes (Canis latrans) and golden eagles (Aquila chrysaetos), which rely on hares as their primary food and prey on lambs secondarily. Coyotes and eagles killed 78% of 65 radiocollared lambs for which cause of death was known. Lamb survival was negatively related to hare abundance during the previous year, and lamb survival rates more than doubled when hare abundance declined, supporting the hypothesis of predator-mediated apparent competition between hares and sheep. However, stage-specific predation and delays in predator responses to changes in hare numbers led to a positive relationship between abundance of adult Dall's sheep and hares. Lacking reliable estimates of survival, a manager might erroneously conclude that hares benefit sheep. Thus, support for different indirect effects can be obtained from different types of data, which demonstrates the need to determine the mechanisms that create indirect interactions. Long-term survey data suggest that predation by coyotes is limiting this sheep population below levels typical when coyotes were rare or absent. Understanding the nature of indirect interactions is necessary to effectively manage complex predator–prey communities.     

Mortality and lamb body mass growth in free‐ranging domestic sheep – environmental impacts including lethal and non‐lethal impacts of predators

The management and recovery of large predator populations in areas where human persecution has driven them to ecological extinction requires a solid understanding of the effects of both predation and food limitation on prey populations. We used 11 yr of data on reported losses among 17.3 million free‐ranging sheep Ovis aries in the Norwegian farming industry to elucidate the relative roles of climate, vegetation characteristics, sheep densities, lamb body mass and densities of predators and alternative prey on the number of lambs and ewes lost on summer pastures. We first examined whether predator densities predicted autumn lamb body mass through possible impacts of predators on body growth (non‐lethal effects) but found no evidence for such effects in our study system. This might be due to weak anti‐predator behavioral responses in domesticated sheep. However, autumn lamb body mass was predicted by both sheep density and winter and spring weather conditions, probably through food availability. Losses of both lambs and ewes were positively and strongly related to the density of Eurasian lynx Lynx lynx, wolverine Gulo gulo and brown bear Ursus arctos. In addition, food availability and spring weather conditions were associated to losses of lambs, while precipitation in May predicted losses of ewes. There was little evidence for interaction effects of predator species on losses, suggesting that most of the effects of the predators were additive to each other. Given the strong effect of predator densities on sheep losses, we conclude that changing livestock husbandry practices towards a system that actively protects sheep and/or active management of predator densities may be necessary to reduce sheep losses where predators are recolonizing.     

The seasonal pattern of sheep blowfly strike in England and Wales

Abstract. Information on 4049 cases of sheep blowfly strike on 495 farms in England and Wales was gathered in a longitudinal survey conducted in 1991. The breech was the most commonly infested area, accounting for 70.9% of all strikes recorded. Body strikes accounted for 19.7% and foot strikes 11.4% of all strikes. Early in the season the incidences of both breech and body strikes were higher in ewes than in lambs, but from June to October lamb strikes predominated. The incidence of foot strike was greater in ewes than lambs throughout the year, with a peak incidence in September. Regional differences in strike incidence were evident; the highest overall incidences were recorded in the southern regions of England where peak incidence occurred earlier in the year. The highest monthly incidence risk was recorded in August in the south-east of England where there were 14.2 strikes per 1000 lambs and 4.0 strikes per 1000 ewes at risk. The importance of faecal soiling and ambient temperature are discussed.     

Behavioral patterns of domestic sheep and their relationship to coyote predation

Activity patterns between individuals in a large herd of domestic sheep (Ovis aries) were examined to determine whether or not behavioral characteristics predisposed certain individuals to coyote (Canis latrans) predation. Coyotes killed 73 of 958 lambs and 6 of 624 ewes between 24 April and 15 August 1975. Twenty ewes and 19 lambs died from non-predatory causes. Coyote-kills accounted for 79.3% of the lamb losses. The amount of time ewes spent at various activities differed significantly by age or genotype, but the behavior of ewes whose lambs were killed was remarkably similar to that of other ewes. Single lambs were more active and were killed proportionately more often than twins. Within litters in which one of the lambs was killed, the killed sibling tended to be more active. Coyotes killed proportionately more disabled lambs and lambs from disabled ewes than healthy lambs or lambs from healthy ewes. Reduced mobility of either a lamb or a ewe increased the probability of a lamb's being on the periphery of the bed-ground and, hence, the probability that it would be noticed and attacked by a coyote. Coyote predation on domestic sheep was related more to the chance of an animal's being on the periphery of the bed-ground than to the animal's behavioral characteristics.