Iranian Sheep Research Articles

Estimates of covariance functions for growth of Kordi sheep in Iran using random regression models

In the current paper, restricted maximum likelihood estimates of covariance functions for growth records from birth to 360 days of age in Kordi sheep population were estimated using random regression models (RRM). Kordi sheep is an important breed known for adaptability and resistance to unfavorable climatic conditions and suitable feed efficiency in mountainous regions of Iran. Data included 23,720 body weight records of 6730 Kordi lambs collected from 1989 to 2012 at Hossein Abad Kordi sheep Breeding Station in Shirvan city, North Khorasan province, Iran. Fixed effects in the model were lamb sex, birth type, and birth year as well as dam age. Legendre polynomials (LP) of order 3 was used for age to illustrate the average growth curve. In the random part, the functions with different orders were included to model variances associated to direct and maternal effects. Results showed that a model with LP of order 4,3,4,3 for direct additive genetic effects, animal permanent environmental effects, maternal additive genetic and maternal permanent environmental effects was sufficient to model changes in (co)variances with age, according to Akaike’s Information Criterion (AIC) and Bayesian information criterion (BIC). Direct additive genetic and animal permanent environment variances increased with age. Direct heritability (h2a) increased with age from 0.133 ± 0.021 at birth to 0.391 ± 0.034 at 360 days of age. The ratio of animal permanent environmental variances to phenotypic variance (pe2) was 0.047 ± 0.083 at birth, increased with age and reached 0.537 ± 0.034 at the end of the growth trajectory. Maternal heritability (h2m) was 0.152 ± 0.025 at birth decreased to 0.067 ± 0.016 until weaning and then fluctuated between 0.06 and 0.10. The ratio of maternal permanent environmental variances to phenotypic variance (mpe2) was 0.082 ± 0.02 at birth; however, it gradually decreased until the end of trajectory. The first eigenvalues of the coefficient matrices explained 69% and 91% of the total direct additive variance and maternal genetic variance, respectively. Direct genetic correlations ranged from low and negative to positively high, and generally decreased as the distance between tests increased. Current study has demonstrated that RRM have potential for modeling growth of Kordi sheep and a greater response to selection would be expected, if selection focuses on body weights from 30 days of age to 120 days of age.

A survey of biochemical and acute phase proteins changes in sheep experimentally infected with Anaplasma ovis

Objective: To determine the biochemical and acute phase proteins changes in sheep experimentally infected with Anaplasma ovis (A. ovis). Methods: One Iranian sheep naturally infected with A. ovis (parasitemia 0.02%) but with no other blood parasites based on blood smear and polymerase chain reaction methods was selected as donor, and it was splenectomized to induce high level of parasitemia. Then, three weeks after splenectomy when parasitemia was 6%, donor’s blood was intravenously administered to each recipient animal. Five 5-6 months old Iranian male sheep without any blood parasites were selected as recipient animals. The percent of parasites, packed cell volume, serum biochemical parameters (urea, creatinine, bilirubin, aspartate aminotransferase activity, cholesterol, total protein, albumin, globulin, Fe), acute phase proteins (haptoglobin, total iron binding capacity, fibrinogen), were evaluated in sheep before and after being experimentally infected with A. ovis (until day 38). In addition, body weights of sheep were measured on days 0, 20 and 38. Results: In recipient sheep, microscopic examination of erythrocytes revealed a significant rise of parasitemia on days 12 and 15. The lowest level of packed cell volume in sheep was seen on day 15 post infection. A significant rise existed in mean urea and bilirubin (total, direct and indirect) on days 15 and 20. The increase of indirect bilirubin level was higher than direct bilirubin. Furthermore, serum Fe significantly increased on days 20 and 23. The mean total protein concentration significantly increased on day 38. A significant increase was found in the serum globulin concentration from days 20 and 27 to 38. Maximum values of haptoglobin were observed on days 27 and 30. Moreover, aspartate aminotransferase activity (from days 20-30) and cholesterol concentration (on day 20) significantly decreased. However, no significant changes were found in other parameters. Conclusions: Experimental ovine anaplasmosis caused by A. ovis could be associated with some changes in measured parameters, which presumably could be helpful for evaluation on staging of disease.

A survey of management practices and flock performance and their association with flock size and ewe breed type on Irish sheep farms

SUMMARYA detailed survey was undertaken to assess the rate of production and current management practices on Irish sheep farms and quantify their associations with flock size and ewe breed type. A total of 39 questions relating to the farm production system and farm management practices were devised, including: producer age, location, farm size, livestock numbers and type, in addition to flock management data such as flock breeding policy, lamb finishing strategy, flock health, lambing date, winter housing and feeding practices. A total of 717 sheep producers were surveyed across 45 different discussion groups. The surveyed respondents were sub-divided into four groups depending on flock size (very small, small, medium and large) and into three groups depending on ewe breed type (maternal, terminal and hill). The average survey respondent was 48 years old, with a flock size of 150 breeding ewes on a farm size of 58 ha. The average stocking rates were 6·55 and 3·14 ewes/ha and weaning rates were 1·44 and 1·02 lambs per ewe joined to the ram for the lowland and hill flocks, respectively. Relative to very small flocks (<62 ewes), larger flocks (>190 ewes) had higher stocking rates (6·98v.5·66 ewes/ha) and ewe to ram ratios (40v.30), and tended to lamb later in the year. The rate of technology adoption such as faecal egg sampling and pregnancy scanning was greater on larger flocks compared with smaller flocks. Flocks with maternal ewe breeds had higher scanning and weaning rates, and drafted a greater proportion of lambs off grass compared with flocks with terminal and hill ewe breeds. Flocks with maternal and terminal ewe breed types were more likely to winter house ewes, lamb indoors, test silage quality and have a handling unit compared with flocks with hill-type ewe breeds. Results from the present study provide a bank of knowledge on current Irish sheep industry performance and show that flock size and ewe breed type have a significant impact on key flock performance variables.

Variant <i>GDF9</i> mRNA is likely not the main cause of larger litter size in Iranian Lori-Bakhtyari, Shal, Ghezel, and Afshari sheep breeds

Abstract. This study was carried out to screen the GDF9 gene and evaluate the polymorphism effect on litter size of four Iranian sheep breeds using the PCR-RFLP and PCR-SSCP methods. First, sequencing of the GDF9 gene in 16 twin-birth, 4 triplet-birth, and 2 infertile ewes showed that, in addition to G2, G3, G4, G5, and G6 mutations that have been previously reported in other breeds, a new G0 mutation, called C25T, exists in the GDF9 sequence of 1 out of 22 ewes and causes L9F substitution in the signal peptide region. None of the triplet-birth or infertile ewes carried G1, G4, G7, FecGE, G8, or FecGT mutations. In the second experiment, a large dataset was used: 605 individuals including 496 ewes (145 Afshari, 54 Shal, 126 Ghezel, and 171 Lori-Bakhtyari sheep), and 109 rams (26 Afshari, 23 Shal, 10 Ghezel, and 50 Lori-Bakhtyari sheep. There were no sheep carrying the G7, G8, or Thoka mutations. Among all 109 rams that were used in this study, none of them were homozygous for the G1 mutation. Moreover, abundance of heterozygote rams (G1/G+) varied from 0.0 (Afshari) to 28.6 % (Lori-Bakhtyari and Ghezel). The highest and the lowest frequencies of the G4 mutation were 30.6 and 3.0 % in Shal and Afshari breeds, respectively. Moreover, G4 abundance varied from 0.0 to 42.3 %, from 3.0 to 26.9, and from 3.0 to 30.6 % in rams, ewes, and overall, respectively. There was a significant difference in the abundance of G1 and G4 mutations between breeds. However, neither the G1 nor the G4 mutation was associated with litter size in Afshari, Ghezel, Lori-Bakhtyari, or Shal sheep breeds. In conclusion, the results of this study showed that GDF9 G1 and G4 mutations are not the reason for higher litter size in Iranian sheep. Moreover, the GDF9 G0 and G6 mutations do not cause triplet births or infertility in Iranian ewes. Therefore, it is unlikely that variant GDF9 mRNA induces larger litter size or infertility in Iranian ewes.

A nationwide survey of anthelmintic treatment failure on sheep farms in Ireland

BackgroundBetween 2013 and 2015 the Department of Agriculture, Food and the Marine (DAFM) administered a sheep technology adoption programme (STAP), with the aim of increasing profitability on Irish sheep farms by encouraging the adoption of best management practices. One of the options available to STAP participants was to test the efficacy of the anthelmintic treatment (benzimadazole, levamisole or macrocyclic lactone) used in their flocks by means of a drench test, which is a modification of the faecal egg count reduction test; individual faecal samples were collected from the same group of lambs before and after anthelmintic treatment, the number of eggs present pre and post treatment was subsequently determined from a pooled sample.ResultsIn total, 4211 drench tests were undertaken by farmers during the 3 years of the programme. Information on the anthelmintic product used was available for 3771 of these tests; anthelmintics from the classes benzimidazole (BZ), levamisole (LV) and macrocyclic lactone (ML) (avermectins (AVM) plus moxidectin (MOX)) were used in 42.0%, 23.4% and 32.5% of tests, respectively. The remaining 2.1% of tests involved an inappropriate product. The efficacy of treatment against ‘other trichostrongyles’ (excluding Nematodirus spp and Strongyloides papillosus.) could be established for 1446 tests, and 51% of these tests were considered effective (i.e. a reduction of faecal egg count (FEC) ≥ 95%). There was a significant difference among the drug groups in efficacy; 31.5%, 51.9%, 62.5% and 84% of treatments were considered effective for BZ, LV, AVM, MOX, respectively. The efficacy of treatment against Nematodirus spp. could be established for 338 tests and the overall efficacy was 96%.ConclusionsDue to the significant difference among the anthelmintic classes for efficacy against ‘other trichostrongyles’ along with the high level of efficacy against Nematodirus spp., a genus for which anthelmintic resistance is rarely reported, it is concluded that anthelmintic resistance was responsible for the majority of the anthelmintic treatment failures observed.

Molecular analysis of CIB4 gene and protein in Kermani sheep.

The human calcium- and integrin-binding protein (CIB) family is composed of CIB1, CIB2, CIB3, and CIB4 proteins and the CIB4 gene affects fertility. Kermani sheep is one of the most important breeds of Iranian sheep breeds. The aim of this study was to analyze for the first time molecular characteristics of the CIB4 gene and protein in Kermani sheep. Different tissues were collected from the Kermani sheep and real time PCR was performed. The PCR products were sequenced, comparative analyses of the nucleotide sequences were performed, a phylogenetic tree was constructed, and different characteristics of CIB4 proteins were predicted. Real time PCR results showed that the CIB4 gene is expressed only in testis of Kermani sheep. The cDNA nucleotide sequence was identical with small tail Han sheep, cattle, goat, camel, horse, dog, mouse and human, respectively 100, 99, 99, 98, 98, 96, 96, and 96%. Hence, it can be suggested that the CIB4 gene plays a role in male fertility. Based on the phylogenetic analysis, sheep CIB4 gene has a close relationship with goat and cattle first, and then with camel and whale. Although we demonstrated that CIB4 is a testis-specific gene, expressed only in the testis and it interacts with other proteins, the mechanisms by which CIB4 expression is regulated need to be elucidated.

Genetic parameters for lameness, mastitis and dagginess in a multi-breed sheep population

The objective of the present study was to quantify the extent of genetic variation in three health-related traits namely dagginess, lameness and mastitis, in an Irish sheep population. Each of the health traits investigated pose substantial welfare implications as well as considerable economic costs to producers. Data were also available on four body-related traits, namely body condition score (BCS), live weight, muscle depth and fat depth. Animals were categorised as lambs (<365 days old) or ewes (⩾365 days old) and were analysed both separately and combined. After edits, 39 315 records from 264 flocks between the years 2009 and 2015 inclusive were analysed. Variance components were estimated using animal linear mixed models. Fixed effects included contemporary group, represented as a three-way interaction between flock, date of inspection and animal type (i.e. lamb, yearling ewe (i.e. females ⩾365 days but <730 days old that have not yet had a recorded lambing) or ewe), animal breed proportion, coefficients of heterosis and recombination, animal gender (lambs only), animal parity (ewes only; lambs were assigned a separate ‘parity’) and the difference in age of the animal from the median of the respective parity/age group. An additive genetic effect and residual effect were both fitted as random terms with maternal genetic and non-genetic components also considered for traits of the lambs. The direct heritability of dagginess was similar across age groups (0.14 to 0.15), whereas the direct heritability of lameness ranged from 0.06 (ewes) to 0.12 (lambs). The direct heritability of mastitis was 0.04. For dagginess, 13% of the phenotypic variation was explained by dam litter, whereas the maternal heritability of dagginess was 0.05. The genetic correlation between ewe and lamb dagginess was 0.38; the correlation between ewe and lamb lameness was close to zero but was associated with a large standard error. Direct genetic correlations were evident between dagginess and BCS in ewes and between lameness and BCS in lambs. The present study has demonstrated that ample genetic variation exists for all three health traits investigated indicating that genetic improvement is indeed possible.

Association of the calpastatin genotypes, haplotypes, and SNPs with meat quality and fatty acid composition in two Iranian fat- and thin-tailed sheep breeds

This study was conducted to investigate the relationship between variation within Calpastatin (CAST) gene and meat quality and fatty acid profiles in fat-tailed (Chall) and thin-tailed (Zel) Iranian sheep breeds using PCR–SSCP, DNA sequence, and genotype, haplotype, and SNP effect analyses. Six previously identified SNPs including C24T, G62A, G65T, and T69- located in intron 5 and c.197A>T and c.282G>T localized in exon 6 were observed. These SNPs constituted six haplotypes of CAST-1, CAST-2, CAST-6, CAST-8, CAST-10, and CAST-11, corresponding to six genotypes of “B”, “C”, “D”, “F”, “I”, and “J”. Animals inheriting genotype “I” had lower value of shear force (P<0.03), concentration of palmitic acid (P<0.05), cholesterol (P<0.05), and n−6:n−3 ratio (P<0.02), and higher content of palmitoleic acid (P<0.04) compared to those inheriting the other genotypes. Also, animals containing one copy of CAST-10 haplotype showed lower value of shear force (P<0.005), lower n−6:n−3 ratio (P<0.02), higher concentration of palmitoleic acid (P<0.04) and total mono-unsaturated fatty acid (P<0.02) than those containing the other haplotypes. SNP effect analyses showed that three SNPs including G62A, G65T, and c.197A>T had significant effects on the content of some fatty acids and their selected ratios (P<0.05 to P<0.001), shear force (P=0.006 and P<0.001), and the cholesterol content of longissimus dorsi muscle (P<0.05). Overall, it seems that genotype “I”, haplotype CAST-10, the “AA” genotype of SNP G62A, and the “GT” genotype of G65T SNP were the most desirable genotypes and haplotype when selecting lambs in terms of both tenderness and fatty acid composition of meat, because selecting these genotypes and this haplotype would increase tenderness and proportion of healthy fatty acids, and also decrease proportion of harmful fatty acids of meat.

The first genetic identification of Theileria ovis subtype KP019206 in sheep in Iran

Ticks and tick-borne diseases, including theileriosis, constitute a major constraint to livestock production. Two species, known as Theileria lestoquardi and Theileria ovis, are suspected to contribute to ovine theileriosis in Iran. However, the epidemiological aspects of ovine theileriosis are poorly understood in this country. In a survey, designed to identify Theileria species in sheep, 52 (47.27%) out of 110 blood samples were positive, based on polymerase chain reaction (PCR) results. Among 52 positive samples, 100% (52/52) were positive for T. ovis, while T. lestoquardi was not detected in any of the samples. The 18S rRNA gene sequence of T. ovis isolated from Kurdistan, Iran has been submitted to the GenBank and can be retrieved by the accession number, KP019206. The current study presents the first report of T. ovis in Iran, using molecular identification techniques. Moreover, this study evaluated the present status of Theileria infection in the west of Iran.

P5050 A genome-wide scan for signature of positive selection in some Iranian sheep breeds

P5050 A genome-wide scan for signature of positive selection in some Iranian sheep breeds

P5050 A genome-wide scan for signature of positive selection in some Iranian sheep breeds

The sheep is the earliest grazing animals to be domesticated that produces a great scale of animal-based protein for human consumption and plays an essential role in the modern agricultural economy. Iran is one of the important centers for sheep genetic resources and breeding in the world. The aim of the present study was to investigate the selective sweeps between three Iranian sheep breeds, namely Baluchi, Lori-Bakhtiari and Zel using the Illumina ovine SNP50k BeadChip. The Weir and Cockerham’s FST (Theta) method was applied to detect the selection sweeps across the genome. In total, thirty eight genomic regions were identified on 1, 2, 3, 4, 5, 7, 8, 10, 11, 12, 13, 15, 16, 18 and X chromosomes with high population differentiation between different Iranian sheep breed comparisons. Study of the genes has already been reported in these regions and revealed that almost all of these loci are associated with the genes involved in reproduction traits, cytology cells and nervous system, immune system, muscular system, sugar and energy metabolism. Our results reported genomic scans for selective sweeps in Iranian sheep breeds and could help detect functional candidate genes under positive selection and also better understand the relationship between genomic composition and phenotypic diversity for further genetic and breeding research in Iranian sheep breeds.

Rumen fluke in Irish sheep: prevalence, risk factors and molecular identification of two paramphistome species.

BackgroundRumen flukes are trematode parasites found globally; in tropical and sub-tropical climates, infection can result in paramphistomosis, which can have a deleterious impact on livestock. In Europe, rumen fluke is not regarded as a clinically significant parasite, recently however, the prevalence of rumen fluke has sharply increased and several outbreaks of clinical paramphistomosis have been reported. Gaining a better understanding of rumen fluke transmission and identification of risk factors is crucial to improve the control of this parasitic disease. In this regard, a national prevalence study of rumen fluke infection and an investigation of associated risk factors were conducted in Irish sheep flocks between November 2014 and January 2015. In addition, a molecular identification of the rumen fluke species present in Ireland was carried out using an isolation method of individual eggs from faecal material coupled with a PCR. After the DNA extraction of 54 individual eggs, the nuclear fragment ITS-2 was amplified and sequenced using the same primers.ResultsAn apparent herd prevalence of 77.3 % was determined. Several risk factors were identified including type of pasture grazed, regional variation, and sharing of the paddocks with other livestock species. A novel relationship between the Suffolk breed and higher FEC was reported for the first time. The predominant rumen fluke species found was C. daubneyi. Nevertheless, P. leydeni was unexpectedly identified infecting sheep in Ireland for the first time.ConclusionsAn exceptionally high prevalence of rumen fluke among Irish sheep flocks has been highlighted in this study and a more thorough investigation is necessary to analyse its economic impact. The isolation of individual eggs coupled with the PCR technique used here has proven a reliable tool for discrimination of Paramphistomum spp. This technique may facilitate forthcoming studies of the effects of paramphistomosis on livestock production. The most noteworthy finding was the identification of P. leydeni affecting sheep in Ireland, however further studies are required to clarify its implications. Also, a significant relationship between Suffolk breed and a heavier infection was found, which can be used as a starting point for future research on control strategies of rumen fluke infection.

Polymorphism in the SCD gene is associated with meat quality and fatty acid composition in Iranian fat- and thin-tailed sheep breeds

The enzyme stearoyl-coenzyme A-desaturase (SCD) has been proposed as a key regulator for fat content and fatty acid composition of meat. In this study, a DNA sequence and single-strand confirmation polymorphism analysis were performed in an attempt to investigate the relationship between variation within the SCD gene and fatty acid profiles, physicochemical composition, and the quality characteristics of longissimus dorsi (LD) muscle in two traditional fat- (Chall) and thin- (Zel) tailed Iranian sheep breeds. Only one previously reported SNP (g.379A>T) located in the 5′ untranslated region of the SCD gene was observed. Two previously reported allelic variants, SCD-1 and SCD-2, constituted two previously reported genotypes, “A” and “B”. Based on t-test, no allelic and genotypic frequency differences were observed between Chall and Zel breeds. Lambs with genotype “B” significantly had lower total saturated fatty acid (SFA) level (p<0.05) and more linoleic (p<0.02), arachidonic (p<0.002), and eicosapentaenoic (EPA) (p<0.001) acids and total poly-unsaturated fatty acid (PUFA) (p=0.002) contents and PUFA: SFA ratio (p<0.004) than those with genotype “A”. Meat color of the genotype “B” lambs was lower for a* (p<0.05) and higher for L* (p<0.08) compared to the genotype “A” ones. There were some interactions between breed and SCD gene in terms of palmitic acid (p<0.04), cooking loss (p<0.05), and protein content (p<0.03) of LD muscle. SCD locus explained 17.3%, 15.3%, 13%, and 12% of the phenotypic variation in terms of EPA and arachidonic acid, and PUFA contents and PUFA: SFA ratio, respectively. Interestingly, the results of the correlation analyses showed the significant negative correlations between healthy fatty acid indices (PUFA and PUFA: SFA) and meat color measures of a* and b* (r=−0.26 to r=−0.40, p<0.05) and the significant positive correlations between n–6: n–3 PUFA, one of the main harmful fatty acid indices, and a* (r=0.41, p<0.01) and b* (r=0.27, p<0.05) values which are coordinated with the effect of SCD genotypes on fatty acid composition and color of meat. So, both fatty acid composition and meat color traits should be considered in marker-assisted selection based on SCD gene. Overall, it seems that the genotype “B” of SCD gene is a more desirable genotype when selecting lambs in terms of both fatty acid composition and color of meat, because selecting this genotype would result in higher proportion of healthy fatty acids, lower proportion of harmful fatty acids, and better meat color.

Identification of latent neosporosis in sheep in Tehran, Iran by polymerase chain reaction using primers specific for the Nc-5 gene.

Little is known about latent infection and molecular characterisation of Neospora caninum in sheep (Ovis aries). In this study, 330 sheep samples (180 hearts and 150 brains) were analysed for N. caninum DNA by nested polymerase chain reaction (PCR) targeting the Nc-5 gene. Neospora caninum DNA was detected in 3.9% (13/330) of sheep samples. The parasite’s DNA was detected in 6.7% of heart samples (12/180) and 0.7% (1/150) of brain samples. No clinical signs were recorded from infected or uninfected animals. Sequencing of the genomic DNA revealed 96% – 99% similarity with each other and 95.15% – 100% similarity with N. caninum sequences deposited in GenBank. To our knowledge, this is the first report on the use of PCR to identify latent neosporosis in sheep in Iran. The results of this study have the potential to contribute to our understanding of the role of N. caninum-infected sheep in the epidemiology of neosporosis.

Multilocus genotypic data reveal high genetic diversity and low population genetic structure of Iranian indigenous sheep.

Iranian livestock diversity is still largely unexplored, in spite of the interest in the populations historically reared in this country located near the Fertile Crescent, a major livestock domestication centre. In this investigation, the genetic diversity and differentiation of 10 Iranian indigenous fat-tailed sheep breeds were investigated using 18 microsatellite markers. Iranian breeds were found to host a high level of diversity. This conclusion is substantiated by the large number of alleles observed across loci (average 13.83, range 7-22) and by the high within-breed expected heterozygosity (average 0.75, range 0.72-0.76). Iranian sheep have a low level of genetic differentiation, as indicated by the analysis of molecular variance, which allocated a very small proportion (1.67%) of total variation to the between-population component, and by the small fixation index (FST =0.02). Both Bayesian clustering and principal coordinates analysis revealed the absence of a detectable genetic structure. Also, no isolation by distance was observed through comparison of genetic and geographical distances. In spite of high within-breed variation, signatures of inbreeding were detected by the FIS indices, which were positive in all and statistically significant in three breeds. Possible factors explaining the patterns observed, such as considerable gene flow and inbreeding probably due to anthropogenic activities in the light of population management and conservation programmes, are discussed.

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.

Occurrence and antimicrobial resistance of emergent Arcobacter spp. isolated from cattle and sheep in Iran.

This study is conducted to determine the occurrence and antimicrobial resistance of Arcobacter spp. isolated from clinically healthy food animals. A total of 308 samples from cattle (200) and sheep (108) were collected from Shiraz slaughterhouse, southern Iran to investigate the presence of the important Arcobacter spp. using cultivation and Polymerase Chain Reaction (PCR) methods. Antimicrobial susceptibility of Arcobacter isolates was determined for 18 antibiotics using disk diffusion method. Among 308 samples, 27 (8.7%) and 44 (14.28%) were positive for the presence of Arcobacter species with cultivation and PCR procedures, respectively. The predominant species was A. butzleri in both cattle (58.33%) and sheep (55%). In addition, concurrent incidence of the species was observed in 25% of the positive samples. All Arcobacter isolates were resistant to rifampicin, vancomycin, ceftriaxone, trimethoprim and cephalothin. The isolates showed high susceptibility to tetracycline, oxytetracycline, erythromycin, ciprofloxacin, kanamycin, amikacin, gentamicin and enrofloxacin. No significant difference among cattle and sheep isolates in resistance pattern was observed. The results indicate that cattle and sheep are significant intestinal carriers for Arcobacter spp. Moreover, tetracycline and aminoglycosides showed great effects on Arcobacter species in antibiogram test and can be used for treatment of human Arcobacter infections.

Characterisation of ivermectin and multi-drug resistance in two field isolates of Teladorsagia circumcincta from Irish sheep flocks

Ivermectin resistant Teladorsagia circumcincta were isolated from two Irish sheep farms. Parasite naïve lambs were artificially challenged with the isolates in order to test their sensitivity to benzimidazole (BZ), levamisole (LEV) and ivermectin (IVM) by means of a faecal egg count reduction test (FECRT). Both isolates were found to be resistant to all three anthelmintics with reductions of 47% (C.I. 10–68), 92% (C.I. 74–97) and 50% (C.I. 24–68) for the Farm A isolate and of 85% (C.I. 59–94), 89% (C.I. 69–96) and 73% (C.I. 49–86) for the Farm B isolate for BZ, LEV and IVM, respectively. A controlled efficacy test (CET) was undertaken to confirm resistance to IVM and to determine the efficacy of moxidectin (MOX). In agreement with the FECRT, IVM resistance was confirmed for both isolates, with reductions in worm burden of 78% (C.I. 67–85) and 80% (C.I. 45–93) for the Farm A and B isolates respectively. Both isolates were found to be MOX susceptible, with reductions in worm burden of 97% (C.I. 91–99) and 100% for the Farm A and B isolates respectively. Additionally, in vitro tests confirmed the results of the FECRT; results from the larval development assay (LDA) confirmed that both isolates were resistant to BZ and LEV with development observed at the discriminating dose for each drug, while the larval migration inhibition assay (LMIA) confirmed IVM resistance and indicated MOX susceptibility in both isolates. These results represent the first confirmed cases of IVM resistance on Irish sheep farms as well as the first report of multiple anthelmintic resistant gastrointestinal nematodes in Ireland.

The impact of infection with Schmallenberg virus on weaning rate in Irish sheep flocks

Schmallenberg virus (SBV) disease emerged in Europe in 2011, with the virus initially identified in Germany, and the first confirmed case of SBV infection in Ireland diagnosed in a dairy calf in October 2012. SBV was subsequently confirmed by RT-PCR in 49 cattle herds and 39 sheep flocks. While these studies provide a good representation of the spatial distribution of SBV in Ireland, they do not quantify the impact of SBV on productivity. The objectives of this study were to assess the impact of SBV on weaning rate in Irish sheep flocks, based on data reported by Irish sheep farmers, and to evaluate weaning rate in sheep flocks as an indicator to be used in emerging disease surveillance systems. A questionnaire on productivity and management practices in sheep flocks was developed to gather data from sheep farmers. Valid responses from 267 sheep farmers were received. Negative binomial regression indicated that flocks with a confirmed SBV diagnosis had a weaning rate 0.9 times that of flocks free of SBV. The 10% reduction in weaning rates as a result of SBV is a justifiable concern for farmers and should be considered in formulating flock breeding policy. This study shows the value of a production database as an indicator of an emerging disease and the economic impact of that disease in Irish sheep flocks.

Exposure to Schmallenberg virus in Irish sheep in 2013

MALFORMED fetuses attributable to Schmallenberg virus (SBV) were found in 49 cattle herds and 30 sheep flocks exclusively in the southern and eastern parts of Ireland (Barrett, D., More, S....