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Objective of this paper was to review relevant work and to present a general account of the bluetongue outbreak, which occurred in Greece in 2014. In total, 2895 outbreaks of the disease have been reported by the veterinary authorities of Greece; sheep, goats and cattle were affected with officially reported morbidity rates of 11.0%, 2.0% and 3.5%, respectively. No vaccinations were allowed and conservative measures were implemented to attempt to limit the disease, which at the end had expanded throughout the country. In field investigations, a significantly higher bluetongue morbidity rate (27.5%) in sheep has been reported. During that work, clinical anaemia was encountered, which was characterised as macrocytic, hypochromic, regenerative and non-haemolytic. Other investigations, which are reviewed in this paper, have described an outbreak of Citrobacter freundii -associated enteritis in newborn kids, offspring of goats subclinically infected with Bluetongue virus , increased rate of early embryonic deaths, reduced conception rates, increased incidence risk of mastitis and reduced milk yield in herds of subclinically-infected cattle and detection of the virus from hunter-harvested tissue samples of roe-deer. In 2015, vaccines against the disease have been licenced; vaccinations started in May 2015. Then, in 2015, only one outbreak of the disease was confirmed, which could have been the result of a combination of reasons acting concurrently to prevent further cases. [ABSTRACT FROM AUTHOR]

The physical quality of Merino wool affects the processing route and efficiencies, the quality and uses of end products and thus the commercial price of both raw wool and wool textiles. The paper is the first of two and is organised into four disciplines relevant to the on-farm sector, being: nutrition, health, reproduction and management. A fifth discipline, breeding and genetics, will be covered in a second paper. Better integration is required of wool quality as part of integrated enterprise management and genetics strategies. There is an essential need to integrate wool quality metrics into pasture improvement activities, particularly on-farm extension activities and enterprise budgeting and modelling. A number of basic areas of wool harvesting and sheep management have been overlooked for decades and need clarification in the face of improved practices in other aspects of wool quality, such as longer staple length as a consequence of improved genetics and/or nutrition requiring increased shearing frequency. The review identifies practices which should be incorporated into all wool production and quality experiments as a consequence of advances in understanding of fibre growth, reduced costs of fibre testing and statistical analyses. The review identifies tools available to aid farmer’s adoption of new approaches but there is still a need to develop improved tools to assist wool producers gain the maximum benefits from the current state of knowledge regarding the best management of Merino sheep for wool quality. [ABSTRACT FROM AUTHOR]

• Mammary involution is the regression of mammary tissue to non-secreting state. • Mammary involution is influenced by hormonal and local mechanims. • The mammary gland is particularly susceptible to infections after cessation of lactation. • Udder health management at the end of a lactation period aims to cure intramammary infections and prevent new ones. • Culling ewes contributes to decreasing mastitis incidence. • Culling should be complemented with intramammary antibiotic administration at the end of a lactation period. Objective of the paper is to describe mechanisms leading to mammary involution in ewes and changes taking place in the mammary gland during that period. Mammary involution is the regression of mammary tissue to non-secreting state and takes place as initiated, gradual or senile. In mutton-type production systems cessation of lactation is abrupt, whilst in dairy-type production systems it is progressive or abrupt. The period from cessation of milk removal until the beginning of subsequent lactation period is termed 'dry-period' and is distinguished into stage of active involution, stage of the 'steady-state' involution and stage of redevelopment and lactogenesis. The 'dry-period' is important in health management of sheep for optimum milk production during the subsequent lactation period, as it is necessary for renewal of mammary epithelial cells. Mammary involution is influenced by decreased activity of galactopoietic hormones and local mechanisms in response to milk accumulation in the gland. Milk accumulation plays a major role in triggering apoptosis of epithelial cells. There are two pathways leading to apoptosis, an intrinsic and an extrinsic. During involution, significant histological changes take place in the mammary gland, mainly reduction (up to 3.6% up to the 4th day) of the epithelial area of the gland and increase of its stromal part. The mammary gland is particularly susceptible to infections after cessation of lactation; progressively, that changes; a keratin plug is formed at the teat orifice, leucocytes accumulate in the gland and concentrations of immunoglobulins and lactoferrin increase. Udder health management at the end of a lactation period aims to cure infections that have occurred during the previous lactation period and prevent new intramammary infections during the 'dry-period'. Culling ewes with at least one mammary gland permanently damaged or ones chronically affected or others with incidents of relapsing mastitis or not fully respondent to mastitis treatment during the preceding lactation period contributes to decrease of veterinary expenses for mastitis control in the flock, elimination of sources of potential infection for other animals in the flock and decrease of flock bulk somatic cell counts in the subsequent lactation period. Culling should be complemented with intramammary antibiotic administration at the end of a lactation period. In many clinical studies from around the world, administration of antimicrobial agents at the end of a lactation period has been found beneficial. Antibiotic administration at drying-off may be performed to all animals in a flock ('complete') or only to those considered to be infected ('selective'). In all cases, maintenance of the prescribed withdrawal periods is essential to safeguard public health. The procedure should always be applied as part of a strategic udder health management plan in a flock; implementation improves the welfare of animals and affords significant financial benefits to the farmer. Correct udder health management in ewes at the end of a lactation period will contribute to improved mammary health for the forthcoming lactation period. [ABSTRACT FROM AUTHOR]

Highlights • Mortality of ewes to 600+ days is significantly influenced by sire, location, year of birth and weaning weight. • Assessing the risk factors affecting mortality can provide valuable welfare data. • Risk factors affecting mortality include both genetic and environmental influences. Abstract In on-farm animal welfare assessment schemes mortality is a commonly used measure to assess welfare states, as well as to ascertain the effectiveness of different management strategies. While decreases in welfare and mortality are linked it is likely that monitoring and measuring the factors that influence mortality will be key in using this relationship to improve animal welfare. Therefore, this paper aimed to identify various factors that influence mortality in adult ewes. Once identified these factors may then be suitable for inclusion in an on-farm welfare assessment, or for a broader framework designed to manage risks to mortality. The data used in this analysis was collected on an Australian sheep flock from 2007 to 2010, and focused on identifying variables that increase the risk of mortality of ewes from weaning to a mature age (∼ 660 days). Given that neither mortality, nor the factors affecting it, were routinely recorded in this data set an individual ewe was considered dead when she was identified as missing at consecutive regular husbandry events. Analysis of the data indicated that sire (P < 0.005), location of birth (P < 0.001), year of birth (P < 0.005) and weaning weight (P < 0.001) are all factors that had an impact on mortality to 660 days. Additionally, mortality was increased by 1.8% in the 7 days following a fly strike event while light ewes (<40 kg) or ewes with poor body condition score (< 2) were also at an increased risk of mortality in the 90 days following measurement. Given these results, risk factors for mortality that may be valuable for inclusion in an on-farm welfare assessment include weaning weight, body condition score and liveweight change over time and incidence of fly strike. Factors that have been identified as useful for a risk management framework include genetic and environmentally-influenced factors, such as individual sire and year of birth, respectively. [ABSTRACT FROM AUTHOR]

Characterising copy number variants (CNV) of genes has gained popularity in human and animal studies since 2006. Several studies have revealed CNV play an important role in phenotypic diversity. However, only five papers have been published about CNV in sheep. This study detected CNV in 385 sheep belonging to different genetic groups, genotyped using Illumina OvineSNP50 BeadChips and analysed using SVS, PennCNV, and cnvPartition algorithms. In total, SVS detected 29,935 and 33,880 CNV segments by univariate and multivariate methods, respectively, that merged into 749 CNV regions (CNVR) (size range: 15.3–6,600.0 kb). PennCNV and cnvPartition algorithms found 4758 and 6676 CNV segments, that merged into 464 (size range: 16.4–2,108.8 kb) and 104 (size range: 87–12,093.7 kb) CNVR, respectively. Most of the detected CNVR were losses and only 69 CNVR were detected by all three algorithms. A total of 4635 Ensembl genes were identified in CNVR. In addition, the study revealed huge differences in CNV segments as well as CNVR among five breeds that were compared. [ABSTRACT FROM AUTHOR]

Sheep liveweight and liveweight change are important data both for research and commercial farm management worldwide. However, they can contain errors when procedures in collection are not standardised, including when weighing occurs around other husbandry tasks resulting in varying time delays between removal from grazing and weighing. This research had three stages with different objectives: 1) a liveweight loss study, to quantify liveweight and liveweight change over three and six hours of delay prior to weighing within a handling facility, and to develop a correction equation for delayed liveweights; 2) a validating process, to examine the correction ability of the equation by using it on a different set of delayed liveweights collected under a range of situations; and 3) a management simulation, to explore what impact delayed and corrected delayed liveweights could have when liveweight change was used to assign ewes to feeding levels. Results from each stage showed that: 1) ewes lost a significant amount of liveweight after three (1.8 ± 0.5 kg or 3.5 ± 0.8% liveweight) and six (2.9 ± 0.6 kg or 5.6 ± 1.0% liveweight) hours delay during a practical handling operation ( p < 0.001). The following equation was developed to correct delayed liveweights: y = 100 ( x/ (100 + (-0.9301 t + 0.07106))) where y , x and t are corrected liveweight (kg), delayed liveweight (kg) and time delayed in decimal hours, respectively; 2) the correction equation provided a more accurate and precise estimate of liveweight than a delayed liveweight alone; and 3) use of delayed liveweights, to determine liveweight change over a two month period, resulted in significantly more animals being assigned wrongly to higher feeding levels ( p < 0.001), than if the delayed liveweights had been corrected by time elapsed since gathering from grazing fields. To conclude, a short-term delay prior to weighing associated with a practical handling operation significantly reduces the numerical liveweight recorded for each sheep. Using variably delayed liveweights in research and on commercial farms will have significant consequences for research results and management practices globally. Therefore collection of liveweights should occur without delay. However, when this is not feasible delayed liveweights should be corrected and in the absence of locally formulated correction equation, the one presented in this paper could be used. [ABSTRACT FROM AUTHOR]

Objectives of the present paper were to review ultrasonographic foetometry in sheep and to present detailed data regarding sheep embryo development by using real-time B-mode ultrasonographic examination. Publications pertaining to use of ultrasonography in embryological studies in sheep are reviewed. Further, work including ultrasonographic observations and measurements regarding sequential events of embryonic or foetal development throughout gestation are presented. It is concluded that, in general, ultrasonographic evaluation of sheep embryos/foetuses can be used (among others) for estimation of their intrauterine age, for prediction of bodyweight at forthcoming birth and for diagnosis of foetal growth retardation. The findings of the present work provide reference values for various parametres through the intrauterine period of ovine conceptuses, which may be employed in research or clinical studies. [ABSTRACT FROM AUTHOR]

Objective of the paper is to review work relevant to ultrasonographic examination of the udder of ewes. Udder structures that can be readily imaged ultrasonographically (B-mode or Doppler examination) are mammary parenchyma, the gland cistern, the lactiferous ducts, the mammary vessels, the teat and the supramammary lymph nodes. Conventional diagnostic approaches for mastitis (i.e., combination of clinical, bacteriological and cytological examinations) provide a good means for diagnosis of mastitis; hence, in diagnosis of mastitis, use of ultrasonographic examination has, in general, an ancillary role, for example during investigation of cases, in which clinical diagnosis alone can prove of little help, e.g., in animals with small-sized, deep mammary nodules. The technique can be used at the end of a lactation period as part of routine udder examination performed at that point, which would provide additional useful information, e.g., regarding presence of abcesses or of increased quantity of fibrous tissue. Further, estimation of the dimensions of gland cistern of ewes in a flock would support decisions regarding milking frequency to be applied. Finally, examination of the teat can provide indications regarding optimising use of the milking machine by applying the appropriate settings. [ABSTRACT FROM AUTHOR]

Accurate ultrasonographic determination of foetal number between 45 to 90 days of gestation has revolutionised reproductive management in sheep over 30 years ago and is now established as an essential component of flock health planning and productivity. Ultrasonographic measurements of fat and muscle depths over ribs 12 and 13 in growing lambs can accurately reflect carcass composition and have been incorporated in breeding programmes in sheep meat breeds. These ultrasound services may often be delivered by para-professionals, who individually scan tens of thousands of sheep annually. Currently, ultrasonographic examination in small ruminant practice is largely confined to the investigation of individual valuable pedigree animals referred to veterinary schools or other centres of expertise, despite publication of clinical papers illustrating its application in a wide range of common diseases, including respiratory diseases, urolithiasis, liver and kidney pathologies. Typically, ultrasonographic examination of any organ system should take no more than 1–2 min with the results available immediately, affording a much more informed diagnosis and prognosis. Presently, examination of all adult sheep in the flock for ovine pulmonary adenocarcinoma is being researched in an attempt to eliminate this disease, which has no commercially available diagnostic test or obvious flock control measure. Ultrasonographic investigation is much cheaper than common clinical biochemistry tests, e.g., haematological examination or protein measurements (albumin and globulin, acute phase proteins, fibrinogen and haptoglobin). The ability to record ultrasonographic findings as images or video files directly to mobile telephones, tablets and laptops allows clinicians to transmit such data to a specialist should a second opinion prove necessary. Tele-medicine is well established in several veterinary disciplines and will become increasingly common for diagnostic imaging in small ruminant practice during the next decade. Comparison of images collected over a period of time allows a disease process to be accurately monitored. Re-evaluation of ultrasonographic recordings is an invaluable learning exercise should necropsy results become available. [ABSTRACT FROM AUTHOR]

Objective of the present paper is to review applications of Doppler ultrasonography in sheep. Principles of Doppler ultrasonography and their physiological background are initially presented, as well as haemodynamic parametres that can be used for evaluation of the findings. In sheep, Doppler ultrasonography has been used in clinical work primarily for examination of the reproductive system and of foetuses. It has also been used in studies, where sheep had served as model for studying various conditions in human physiology or medicine, e.g., examination of the heart, which can be performed by conventional Doppler echocardiography or tissue Doppler imaging. Main uses of the modality include evaluation of changes in follicular blood flow in measuring uterine and ovarian blood flow and for determining changes in blood perfusion during various reproductive stages; blood flows in the umbilical artery have also been measured, which can have a clinical application in identifying pregnancies at risk, as well as a model for human medicine. As technology advances, use of Doppler ultrasonography will increase. With more frequent use, new diagnostic and therapeutic approaches will arise, which would be based on estimating functional status (as evidenced by blood perfusion) of the organs examined. [ABSTRACT FROM AUTHOR]

Recent renewed drives to maintain farming activities on extensive areas have been encouraged at the EU level, which previously had witnessed a phenomenon of partial abandonment and reduction in flock sizes. Successful restocking with naïve animals from outwith the farm is a challenge, as these animals are not familiar with the landscape and may lack the social interactions and ‘hefting’ qualities their homebred counterparts develop. This paper presents results from an experiment where young ewes from different origins (homebred and bought-in) were reintroduced onto a mountain range grazing area. Focal animals of both types were monitored using GPS tracking collars over a one year period whilst performance was recorded for the whole flock over a two year period, to gauge whether or not their origin had an influence on ranging behaviour and performance. Although initially the bought-in animals developed their own home range and interacted little with the main flock, after one summer grazing period they appeared to learn from and socially interact with their homebred counterparts, developing a knowledge of the grazing landscape. Despite initial weight change differences, later performance results of the animals were not affected by their origin. Provided that animals are encouraged and given opportunity to socially interact with the main homebred flock, this study indicates that it is feasible to restock extensive farms with animals from different origins. [ABSTRACT FROM AUTHOR]

Sheep flocks are sensitive to the top soil intake, via their grazing activity and the ingestion of soil particles incorporated into the hay especially during harvesting operations. Such intake is estimated between 2 and 20% of the dry matter from grass and hay and may vary accounting for seasonal and geographical differences in the quality of pastures. The persistent organic pollutants accumulated in soil such as polychlorodibenzo- p -dioxins and -furans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (DL-PCBs), may transfer through the food chain. In this paper, the authors consider the quality of soils and the toxicokinetic factors that allow the transfer of the contamination to milk and the edible tissues in sheep. The wide range of PCDD/F concentration reported in milk (0.05–30 pg WHO 1998 -TEQ/g fat), meat (0.18–4.9 pg WHO 1998 -TEQ/g fat) and liver (4.8–161 pg WHO 1998 -TEQ/g fat) from extensively reared flocks in areas of European countries under different industrial and urban pressures, indicate the opportunity to adopt risk management options based on environmental quality standards and good agriculture practices, able to support the access to a safe and nutritious food. With respect to the PCDD/F and DL-PCB intake, liver represents the most contaminated food item, for its ability to bind such lipophilic contaminants irrespective of its lipid content. Case-studies from the Mediterranean area are illustrated, to support the environment and health approach also in terms of sustainability of family farms production. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA), an important widespread cause of severe infection in both humans and animals, is a pathogen of significant public health concern. In this paper the prevalence of MRSA in sheep and goat bulk tank milk from southern Italy was assessed and nasal swabs from people working on the positive farms were collected. MRSA isolates from milk and nasal swabs were characterized by spa typing, MLST and SCC mec typing and tested for antimicrobial resistance. MRSA was detected in 2 of the 162 (1.23%) bulk tank samples analysed: the first from a sheep farm (Farm 1) and the second from a goat farm (Farm 2). As for farm personnel, no MRSA was detected in the unique nasal swab from Farm 1; while MRSA was detected in all the 3 nasal swabs from Farm 2. The MRSA isolate from Farm 1 was spa type t127, ST1, SCC mec IVa. The MRSA isolates from bulk tank milk and humans in Farm 2 showed an identical genetic profile: spa type t1255, ST398, SCC mec V. In Farm 2 all the isolates had the characteristics of general multidrug resistance and the milk and human MRSA had the same antimicrobial resistance pattern. Although the results showed low prevalence of MRSA in sheep and goat milk from southern Italy, the detection of recognized zoonotic genotypes in milk of both farms and the isolation in people working in one of the positive farm of MRSA strains with a genetic profile identical to that of MRSA from milk, emphasize the public health concern and highlight the need for additional surveillance including the detection of MRSA. [ABSTRACT FROM AUTHOR]

The paper discusses assessment of animal welfare in small ruminant production systems and reports on developments regarding various monitoring schemes, which are used to assess small ruminant welfare at farm level. Further, welfare assessment protocols are presented; these have been derived as results in the Animal Welfare Indicators (‘AWIN’) project, which had been funded within the European Commission’s 7th Framework Program. The role of the European Food Safety Authority (EFSA) in providing a scientific basis for future legislation on animal welfare is described. Finally, emergency medicine to reduce small ruminant suffering and support appropriate decisions to promote welfare of individual animals or populations of animals is also discussed. [ABSTRACT FROM AUTHOR]

Despite its importance little is known about the attitudes of different stakeholder categories towards issues that impact the welfare of sheep. This study determined the relevance attributed by various stakeholders to different sheep welfare indicators and assessed which demographic characteristics can influence their scores. Data were collected through a questionnaire presented on paper face-to-face to 15 sheep farmers in Italy during farm visits in June and July 2020 and the same questionnaire was transferred online to a Google Form and an announcement was sent by email and on social platforms to consumers, with a total of 311 respondents completed the questionnaire. The survey was composed of two parts. In the first part respondents were asked to declare their demographic characteristics. In the second part they rated the relevance attributed to eleven indicators of sheep welfare (eight animal-based: leanness, fleece condition, fleece cleanliness, skin lesions, tail docking, lameness, hoof overgrowth, occurrence of mastitis; and three resource-based: insufficient clean drinking water availability, thermal discomfort, access to pasture) using a ten-point Likert scale. An ordinal logistic regression descending function with stepwise selection was used to analyze the effects within demographic data and the distribution of the Likert scale for each indicator. The number of respondents (n = 311) was quite small, nevertheless, the differences that are reported give some guidance on the relative importance accorded to each of these groups of stakeholders to each of the welfare indicators. Female respondents gave higher relevance to most of the indicators compared with male respondents (P < 0.05), whereas respondents with a lower education level gave more relevance to four out of the eleven welfare indicators compared with stakeholders with a higher education level (P < 0.05). As for respondent categories, non-farmer experts attributed more relevance to lameness, whereas farmers gave a lower relevance to tail docking, while expressing a higher level of concern for leanness compared with the other categories (P < 0.05). Finally, more frequent consumers of sheep products considered leanness to be most important (P < 0.05). No significant difference was found based on the nationality or the work declared. This study provides information about how different stakeholder categories perceive different aspects of sheep welfare and whether this perception is affected by demographic characteristics, thus promoting informed dialogue between society and the scientific community about the relevance to be attributed to different sheep welfare indicators. • Attitudes of different stakeholder categories (suppliers; owners; investors; etc.) towards issues that impact the welfare of sheep identified. • Women gave more importance to most sheep welfare indicators than men. • Farmers gave least importance to tail docking. • Animal scientists (investigating problems associated with livestock production and management), attributed most importance to lameness. • Lower education level respondents gave higher importance to most of the sheep welfare indicators. [ABSTRACT FROM AUTHOR]

This paper reports four cases of nasal polyps in adult sheep from Piedmont and Sicily farms. The clinical course and post-mortem findings are described. Macroscopically numerous nasal polyps obstructing the nasal cavities, with the erosion of nasal concha, were observed. Histologically the neoformations, consisting of a different number of fusiform fibrocytic cells arranged in a variable amount of amorphous mesenchymal matrix, were located in the submucosa and covered by a simple disorganized columnar epithelium. Non-suppurative infiltration was also observed. Microbiological investigations revealed positivity for Pseudomonas aeruginosa only in one case; no bacteria were isolated in polyps collected from the other three sheep. Chronic and massive infestation by Oestrus ovis was present in three cases. The etiology and pathogenesis of these proliferations remain to be clarified, even if the authors postulate that one biological agent (bacterium or parasite) may have been responsible for the reaction of the nasal mesenchyma. [ABSTRACT FROM AUTHOR]

Dicrocoelium dendriticum is the most common liver fluke in domestic ruminants in Italy, reaching prevalence values of 67% on ovine farms in the southern regions. It causes economic losses and clinical problems. The present paper reviews the results of a controlled field trial conducted in southern Italy to evaluate the efficacy of a single or double administration of albendazole micronised against D. dendriticum in pastured sheep naturally infected by the small liver fluke. The trial was conducted in a sheep farm located in the Campania region, southern Italy. Sixty female crossbreed sheep were selected on the basis of the D. dendriticum positive faecal egg counts (FEC). Ewes were divided into 3 groups, of 20 sheep each, based on D. dendriticum FEC. One group (A-group) was treated once and the other group (B-group) treated twice at an interval of one week, whereas the control group (C-group) was untreated. The efficacy of treatment was evaluated by FEC and necropsy examination for D. dendriticum . Following the WAAVP guidelines for evaluating the efficacy of anthelmintics in ruminants, the double administration of albendazole micronized, showed a high efficacy (up to 99% based on FEC reduction), whereas the single treatment was less effective (up to 96% based on FEC reduction) against D. dendriticum . This difference was significant ( P < 0–0.05). The results were also confirmed by necropsy examinations. At day 14 the mean D. dendriticum burdens of the slaughtered sheep of the A-group, B-group and C-group were 87, 70 and 1274 adults ( P < 0.001), respectively following necroscopic examinations. [ABSTRACT FROM AUTHOR]

Production diseases are established when there is an intense imbalance between what is offered to the animal (as food) and what is required (in the form of milk/meat/offspring). In such situations, the solution involves not only the assessment of animal ration or the health program, but also, their health status. This information can only be accessed by performing blood tests, measuring a series of specific metabolites and enzymatic activities, and interpreting them in the scenario in which the animals are, which is known as clinical biochemistry. The aim of this paper is to address the information we get through the measurement of the different profiles, with special emphasis on the metabolic ones; when to do it, and when not to, what precautions should be taken so that blood collected by venipuncture can be reliable for further analysis and interpretation. [ABSTRACT FROM AUTHOR]

• Estimation of genetic parameters for growth traits of indigenous sheep in pastoral production system within a crossbreeding program is feasible. • The direct heritability estimates were of moderate value for all the growth traits • Genetic and phenotypic correlations were high and positive among all growth traits with weaning weight a preferred key trait for selection purposes. • Remarkable good genetic gain was achieved by the Red Maasai sheep compared to other breed groups • Effects of various environmental factors were considerably smaller in pure Red Maasai sheep relative to other breed groups. The Red Maasai are indigenous sheep breeds known for their adaptability in arid and semi-arid environments while the Dorper is known for its good mutton production. A field experiment cross breeding program for the two breeds was set up in 2003 to exploit these traits. In this paper, we present the genetic parameters for birth weight (BWT), weaning weight (WWT) and weight at nine months (MWT) for pure Red Maasai (RRRR), pure Dorper (DDDD), 75% Dorper (DDDR) and 50% Dorper (DDRR) breeds. The genetic parameters were estimated by fitting four different multivariate animal models while ignoring or including maternal effects. The model with the lowest Akaike's Information Criterion (AIC) was chosen as the best model for the estimation of genetic parameters. The average annual genetic gain of the studied traits for each breed group was estimated by regressing the estimated breeding values on year of birth. Records from 5442 lambs recorded over a period of 17 years (2003-2019) were used in this analysis. The breed group, sex, type of birth, season of birth and age of the dam significantly (P < 0.001) affected the weights of the animals. The direct heritability estimates for BWT, WWT and MWT were highest in the RRRR (0.40 ± 0.08, 0.39 ± 0.08, 0.45 ± 0.08 respectively). Direct heritability was lowest for BWT in the DDDR (0.18 ± 0.06), and for WWT and MWT in the DDDD (0.10 ± 0.07, 0.08 ± 0.06 respectively). The maternal heritability estimates were highest in BWT for DDRR (0.12 ± 0.05) and at WWT for DDDD (0.05 ± 0.03), and lowest in BWT for DDDR (0.03 ± 0.03) and at WWT for DDRR (0.00 ± 0.01). The maternal heritability for MWT for all the breed groups was close to zero. Genetic and phenotypic correlations between the traits were all high and positive across all breed groups. The phenotypic correlations ranged from 0.41 to 0.73 while the genetic correlations ranged from 0.40 to 0.99. The pure Red Maasai had an average annual genetic gain of 0.012 ± 0.005 kg, 0.144 ± 0.037 kg and 0.170 ± 0.047 kg for BWT, WWT and MWT respectively while the pure Dorper had an average annual genetic gain of 0.006 ± 0.006 for BWT, 0.047 ± 0.033 for WWT and 0.069 ± 0.044 for MWT. Between the crosses, the 50% Dorper had higher annual genetic gains for all the traits. The observed genetic gains demonstrate that selective breeding based on estimated breeding values can lead to significant genetic improvement in the Red Maasai sheep and its crosses. [ABSTRACT FROM AUTHOR]

• The udder characteristics are essential for the ovine milk production. • There are various methods for monitoring the udder traits. • There is a close relation between udder characteristics and milkability. • The mammary gland morphology is a key factor in animal selection. In current dairy sheep management, there is a widespread trend to improve the morphology of the udder for machine- and hand-milking ability. The purpose of this review is to present the literature regarding udder morphological traits related to milk production of sheep. The ovine udder consists of two mammary glands. Various techniques have been employed to appraise the mammary morphology and anatomy. Articles referring to all these methods are referred to. The typology and the linear scoring of udders and their measurable variables are described. Non-invasive methods, e.g., ultrasonography or digital image analysis, are assessed. Relationships between morphological and production traits are analyzed. Comparative results of quantitative trait loci detection for udder morphology traits in dairy sheep are included. Papers related to milkability are evaluated within the udder and teat morphological context. Use of mammary morphological traits is recommended in order to improve the morphology of the udder and, accordingly, the milkability of the sheep. Thus, their inclusion in programs of genetic improvement could increase the productivity of the animals. [ABSTRACT FROM AUTHOR]