the use of a random regression model on the estimation of genetic parameters for weight at performance test in appenninica sheep breed

The Appenninica breed is an Italian meat sheep; the rams are approved according to a phenotypic index that is based on an average daily gain at performance test. The 8546 live weights of 1930 Appenninica male lambs tested in the performance station of the ASSONAPA (National Sheep Breeders Association, Italy) from 1986 to 2010 showed a great variability in age at weighing and in number of records by year. The goal of the study is to verify the feasibility of the estimation of a genetic index for weight in the Appenninica sheep by a mixed model, and to explore the use of random regression to avoid the corrections for weighing at different ages. The heritability and repeatability (mean±SE) of the average live weight were 0.27±0.04 and 0.54±0.08 respectively; the heritabilities of weights recorded at different weighing days ranged from 0.27 to 0.58, while the heritabilities of weights at different ages showed a narrower variability (0.29÷0.41). The estimates of live weight heritability by random regressions ranged between 0.34 at 123 d of age and 0.52 at 411 d. The results proved that the random regression model is the most adequate to analyse the data of Appenninica breed

The role of mitochondrial DNA to determine the origin of domestic chicken

Mitochondrial DNA (mtDNA) is has recently lost relevance especially when utilised to study species that are characterised with a history of several migrations. Nonetheless, mtDNA can still represents a useful additional tool in the study of molecular genetic diversity. The reason for the adoption of mtDNA is that it is easy to amplify because it appears in multiple copies in the cells and the mitochondrial gene content is strongly conserved across generations. Thousands of published studies have reached conclusions about population history, patterns of gene flow, genetic structure, and species limits, on the basis of mtDNA sequence variation. MtDNA has been used to study phylo-geographic structure of avian species, and to identify the number of maternal lineages and their geographic origins. Most studies of chicken mtDNA rely on sequences of partial control region but recent researches used the complete mtDNA genome to reconstruct the history of animal domestication. The first genetic study on mtDNA suggests that the Indochinese Red Junglefowl subspecies Gallus gallus gallus is the primary ancestor of the domestic chicken (Gallus gallus domesticus). Other studies showed that at least three subspecies of Gallus gallus were enrolled in the origin of domestic chicken breeds, and that there may be at least two domestication centres: one in Southeast Asia and one in the Indian subcontinent. The authors suggested nine highly divergent clades (named clade A-I) related to geographical distribution in a wide range of domestic chickens and Red Junglefowls across Eurasian regions. Understanding when chickens were transported out of domestication centres and the directions in which they were moved provides information about prehistoric human migration, trade routes and cultural diffusion. MtDNA has been used to infer regions of domestication and to identify the number of maternal lineages and their geographic origins in macroevolution studies.peer-reviewe

Wool quality in Gentile di Puglia sheep breed as measure of genetic integrity

The Gentile di Pugliais a breed created in the 15th century by crossing Merino Spanish rams and "gentile" ewes reared in some areas of Southern Italy, mainly Apulia and Basilicata. The crisis of the wool industry, the poor quantity of milk, the inadequacy of Gentile di Pugliato be milked by machine and the passage from transhumant to permanent rearing caused a dramatic reduction of this population, which was largely crossed with other breeds and declined from about one million heads in the sixties to 5,000 at the present time. In order to save the ancient typical Gentile di Pugliabreed, the aim of this work was to estimate the "genetic integrity" of the remaining Gentile di Pugliapopulation by means of an analysis of wool quality measured through the diameter of the fibre and the homogeneity of the fleece. Our hypothesis was that the animals originated from outcrosses to other Merino derived breeds specialised for meat would show larger diameters of the fibres and a reduced homogeneity of the fleece. The research was carried out using Herd Book registered animals from 9 farms: 1 from Isernia, 2 from Campobasso and 6 from Foggia province. The statistical analysis on the diameter of the fibre was carried out on a dataset of 38,200 observations (200 records x 191 animals) divided in four classes (ultrafine, fine, croisè, ordinary). The high frequencies of ultrafine and fine fibre classes show that the quality of the wool is still good in the population. This consideration can be extended to all the farms involved in the study that could therefore be suitable in the conservation programs for this breed. The homogeneity of the fleece was also good in provid- ing further evidence of the genetic integrity of the population. Other analysis carried out on the quality of the wool in relation to the body size confirmed that the observed Gentile di Pugliais well representative of the ancient breed

Genetic characterization of Appenninica sheep breed by microsatellites

The conservation of genetic variability is one of the main objectives in the field of genetics applied to domestic livestock. A strong input in that direction was made by molecular biology techniques. Among molecular markers nowadays available, microsatellites are particularly appreciated and widely utilized for the study of animal genome. In this study, a genetic characterization of Appenninica sheep breed was carried out with thirty microsatellite markers; the genetic relationships between Appenninica and three Italian merinos-derived breeds were also investigated. The results show a good genetic variability of Appenninica and all the other studied breeds. At the same time, the genetic identity of each breed is confirmed. These molecular data can be utilized to improve the present selection schemes and the plans to preserve the genetic diversit

morphological and genetic characterisation of pagliarola breed and its genetic relationships with other three indigenous italian sheep breeds

Sheep are an important livestock species in the socio-economic contest around the world. In the past, exotic sheep breeds were utilised in crosses with local breeds in order to improve their production traits. The Pagliarola is an ancient sheep population spread over many areas of the central Italy, mainly in Abruzzo region. The aim of this paper was to identify this breed from other sheep breeds living in the same area trough morphological and genetic characterisation. Fifty-three Pagliarola sheep animals (two flocks) were sampled together with 30 sheep of Appenninica, Gentile di Puglia and Merinizzata Italiana. Biometrical measures and 25 microsatellite markers were studied for the characterisation. In the morphological analysis, the Pagliarola was observed to be well separated from the other breeds and the genomic results confirmed the morphological study. In the molecular approach, a total of 330 alleles were detected. In the neighbour-Net tree, each breed clustered independently and no clear cluster was observed. The expected heterozygosity was the highest in Appenninica (0.78), while Pagliarola had the lowest (0.70). Results of STRUCTURE analyses at K=5 showed Pagliarola breed splitted in two sub-clusters. Both biometric and molecular results allow to consider the residual Pagliarola as an original genotype. Moreover, the variability still remaining in this population can be useful to plan suitable conservation programs

Origin and complete breed standard of Maltese black breed

This review is a first attempt to give a comprehensive historical account on the evolution of the Maltese Black chicken breed. The initiative consolidates available information to propose hypothesis on the origins of the breed, and to develop a comprehensive breed standard in conformity with the format of the American Breed Standard. The Maltese Black was established in 1950 as a rustic, dual purpose breed capable of producing adequate egg and chicken for consumption. In the 1960's, it was replaced with commercially available stock, marginalising the breed and restricting its existence to small dispersed populations. An initial attempt to have an in-situ conservation of the Maltese Black started in 1998 with a small flock of about 400 chickens that were later relocated to the Agricultural Research and Development Centre in Malta with the intention of maintaining a nucleus flock as a measure for a long term ex-situ conservation strategy. A recent survey highlights that the present population has drifted significantly away from standards first published in 1950. In efforts to consolidate the breed standard definition of the Maltese Black, the breed standards of related Mediterranean breeds, as confirmed by molecular markers, were consulted to translate and address the missing gaps in the previous breed standards. The updated breed standard presented will act as the bench mark against which all future breeding and selection programs are compared.peer-reviewe

Investigating the influence of extracellular matrix and glycolytic metabolism on muscle stem cell migration on their native fibre environment

The composition of the extracellular matrix (ECM) of skeletal muscle fibres is a unique environment that supports the regenerative capacity of satellite cells; the resident stem cell population. The impact of environment has great bearing on key properties permitting satellite cells to carry out tissue repair. In this study, we have investigated the influence of the ECM and glycolytic metabolism on satellite cell emergence and migration- two early processes required for muscle repair. Our results show that both influence the rate at which satellite cells emerge from the sub-basal lamina position and their rate of migration. These studies highlight the necessity of performing analysis of satellite behaviour on their native substrate and will inform on the production of artificial scaffolds intended for medical uses

Suitability of linear scoring in meat sheep: the practical case of Merinizzata Italiana breed

Linear scoring is widely applied in domestic animal species, mainly in cattle and horses. There are only few cases of linear scoring in sheep, probably because the small body size and the narrow range of the classes make difficult to correctly evaluate the measures. In this paper the results of a linear scoring test carried out on Merinizzata Italiana sheep breed in order to verify the feasibility of this method in sheep, are reported. Twenty untrained people, with three different levels of scoring experience in meat sheep morphology, evaluated 52 pluriparous ewes for body length, chest circumference, chest width, rump height, rump width, and withers height; to check for misclassification, their scores were compared with a reference score, previously obtained measuring the same animals by the suitable tools (measuring tape and a Lydtin stick). The percentage of correct scoring ranged from 44.4% for body length to 61.8% for withers height, and was not affected by the experience of the judge. In all characters, the distance of the class from the trait mean had a significant effect in increasing the intensity of misclassifications; the judge's experience showed a positive effect in reducing the intensity of the misclassification for body length, that was the hardest trait to score. These results encourage to further verifying in practice the linear scoring in the Merinizzata Italiana sheep and in other meat breeds

Lamb meat traceability: The case of Sambucana sheep

Genetic traceability has a key role in the product certification, but it is rarely implemented in sheep so far, especially in the fresh meat sector. In this study, the case of the Sambucana sheep is analysed with the aim of developing a genetic system able to certify the origin of its traditional product, the Sambucano lamb, protected by a registered trademark. A set of 14 microsatellite markers was identified as an efficient tool to genetically discriminate the Sambucana sheep from other breeds potentially involved in mislabelling and to allow for an effective allocation test of meat cuts labelled as ‘Guaranteed sambucano lamb’. The paternity test proved to be an additional means to improve the reliability of the control. The traceability system here described is easy to implement in local minor sheep breeds and is recommended in the framework of meat certification

Genetic diversity in four populations of Nguni (Zulu) sheep assessed by microsatellite analysis

Zulu sheep are found mainly in the rural KwaZulu-Natal province and the numbers are declining due to indiscriminate inbreeding. There is thus a need for phenotypic and genetic characterisation as a first phase for planning conservation strategies. Zulu sheep populations sampled were from Makhathini research station (MS) (n=33), University of Zululand (UZ) (n=21), a community at KwaMthethwa (KM) (n=32) and from Msinga (EM) (n=33). One European breed Appen - ninica (AP) was used as out group. Microsatellite analysis using 29 microsatellite loci was used in this study. Among the Zulu sheep, the mean number of alleles per locus was the lowest (3.86) in UZ and the highest (6.24) was realised in EM. The mean values of observed and expected heterozygosity were 0.57 and 0.61, respectively. Neighbour-joining tree showed two main Zulu sheep clusters: the UZ, KM and MS sheep populations clustered together and the second cluster included only representatives from the EM population. The STRUCTURE analysis showed that KM, AP and EM were founded in separate clusters, whereas UZ and MS clustered together. The study demonstrated that there was a common origin of the population from the research stations (MS and UZ populations). It also demonstrated that the EM had a different history for the other three populations. This work suggests that exchange of rams could be useful in reducing inbreeding when considering conservation breeding programmes