The Northern Ireland beef herd currently incorporates a very diverse range of genotypes which produces a very varied product in terms of carcass weight, fatness and conformation (Kirkland et al., 2004). However, factors other than genotype may also influence the expression of maternal traits and progeny carcass characteristics. The objective of the present study was to evaluate the influence of dam conformation, irrespective of genotype, on dystocia and progeny carcass traits.

In contrast to the Holstein-Friesian (HF) breed, Norwegian dairy cattle (NC) have been selected with emphasis on disease resistance and beef characteristics as well as milk production, and hence may be more suited to beef production than high genetic merit Holstein animals. The objective of this study was to evaluate the beef production potential of NC bulls, and to compare their performance with that of HF bulls.

Recent CAP reforms for the sheep sector are likely to partially shift the emphasis from intensive to lower input, ‘easy care’ husbandry systems. The ability of sheep to lamb unaided would be crucial to the success of these systems. Dystocia is the most common cause of parturient lamb mortality, and pelvic dimensions are important factors in causing dystocia in ewes (Quinlivan, 1971). This study uses pelvimetry, based on both external and in vivo measures obtained by computed tomography (CT), to undertake preliminary studies on the associations among the incidence of dystocia, and other factors including maternal behaviour score (MBS) (Lambe et al., 2001).

Good bone quality in breeding ewes is important for the mineralisation of foetal skeletons and to sustain maternal dentition, as tooth loss is the main reason for culling sheep in the UK. Among other functions, bone is a storage depot for calcium and other key minerals that are mobilised to meet major demands such as during lactation. As other studies in humans and poultry have shown, there is substantial genetic variation (h2 between 0.5 and 0.8) for bone properties, suggesting a similar situation in ewes. These properties, e.g. bone density, are key to successful production and nurturing of healthy lambs, which can be used in selective breeding strategies to extend breeding ewes’ productive lives. CT has been shown to be a useful method of assessing bone properties in sheep (Rubin et al., 2001). This study quantifies the main bone types in Scottish Blackface ewes and investigates environmental factors affecting bone quality.

Scrapie is a transmissible spongiform encephalopathy (TSE) and belongs to a category of incurable diseases that include BSE in cattle. An association exists between the Prion-Protein (PrP) genotype of an animal and the risk of developing disease after exposure (Tongue et al., 2004). This PrP genetic information is the basis of the National Scrapie Plan (NSP) which aims, through genotyping, to eradicate those individuals which have the susceptible alleles. Studies into scrapie risk (Jeffrey et al., 2002) have highlighted several alleles which confer scrapie susceptibility. The NSP have used these alleles to categorise individuals according to risk with group one being most scrapie resistant to group five being least resistant. VRQ alleles are synonymous with infection however the ARQ affords susceptibility but not the disease itself. Genotype may however not be the sole indicator of scrapie risk. There is an inference of a relationship between phenotypic characteristics (hornedness, coat colour) and scrapie risk. These alternative indicators of scrapie risk may affect the final choice of susceptible individuals. Scrapie risk studies carried out on the Shetland Isles (Jeffrey et al., 2002) investigated the alleles concerned with scrapie infection. Results confirmed that VRQ alleles are synonymous with scrapie infection however the ARQ alleles, even though they afford susceptibility, do not necessarily confer disease, the animal still has to be exposed to the scrapie agent. Using survey-type questionnaires, the study investigated any potential relationship between the PrP gene, coat colour and hornedness.

Dystocia is defined as a prolonged, or difficult, parturition and is one of the most economically significant secondary traits. Any attempt for decreasing dystocia rate will result in decreasing farming cost and improving animal welfare. The disproportion between calf size (birth weight) and pelvic opening of the dam is the major cause of calving difficulty. Heifers have smaller pelvic area and experience more incidence of dystocia. Calving difficulty in heifers is considered as a different trait from those of later parities (Weller et. al. 1988). Calf birth weight is the most important factor influencing dystocia. Calving difficulty and calf birth weight are characters influenced by maternal effects, so considering maternal effect in data analysis will increase model accuracy. The objective of this study was to estimate genetic parameters of calving difficulty and birth weight.

Improvement of longevity by direct selection of sires based on theirs daughters’ longevity measures is impractical because of a low heritability and generation intervals prolonged by waiting until all cows complete their productive life. As an alternative to direct evaluation of sires for longevity is indirect prediction from genetically correlated production traits measures in the first lactation. The objectives this study were 1) to estimate genetic parameters of longevity and production traits 2) to examine relationships between longevity and first lactation milk production traits and 3) to determine selection index for sires’ longevity based on production traits.

The main aim of animal breeding programmes is to increase productivity and profitability of farm livestock through genetically improving the economic merit of farm livestock (Smith, 1998). This can be achieved by increasing the mean value of a population for one or several economically important traits by the genetic improvement of the animals in this population. In dairy cow husbandry, many traits of economic importance such as lactation milk yield and reproductive traits have long been of interests for breeders to increase profitability of dairy farms. Age at first calving is economically important because it determines when an animal begins its productive life and therefore could influence the lifetime productivity of an animal. Also, age at first calving can be considered as a measure of heifer fertility performance associated with reproductive efficiency. The main objective of the present research is to analyse genetic aspects of lactation milk yield and age at first calving for Holstein heifers in Khorasan province of Iran.

Biodiversity among domesticated animals in developing countries is enormous. However, due to introduction of superior animal breeds with excellent performance, the native animal resources with good adaptability but lower productivity are in great danger. The list of extinct local breeds and deteriorated remaining ones are becoming longer every year. Erosion of genetic diversity in a breed may cause increase in the rate of inbreeding and genetic abnormalities thereby decrease in animal performance, particularly for reproductive traits. These will virtually reduce the global gene pool for future development and can be considered as a serious threat for universal food security. Therefore the urgency and need to conservation of genetic resources in animal biodiversity is clear particularly for those in the developing countries (Hall, et al. 1995). Buffalo play an important role in animal production in some province of Iran. Present study follow to evaluate the genetic diversity and existing relationship among three Iranian native buffalo populations by using microsatellite markers.

Breeding schemes with multiple ovulation and embryo transfer opens up a possibility to enhance genetic improvement through intense female selection and short generation intervals. The potential improvement in genetic response may increase when elite cows produce a number of embryos, instead of one calf per year. Also different ratio of proven bull and young bull semen may be used to inseminate cows in the herd. The objective of this project has been to investigate genetic response and coefficient of inbreeding, when elite cows produce number of embryos during a year, instead of reproducing one calf per year. Also genetic response and inbreeding coefficient were estimated when different ratio of proven bull and young bull semen were used to inseminate cows in the herd.

The goal of a breeding programme is to select animals that will be more profitable or efficient than their parents. Two main methods have been developed to allow selection on the breeding objective. The first method is use of selection index that combines individual trait breeding values with economic weights to provide a single measure on which to select animals. The second method measures the breeding objective (e.g. net profit or lifetime profit) directly and provides genetic evaluations for this measure (Visscher and Goddard, 1995). The profitability of a dairy cow is dependent on both outputs (incomes of milk, fat, protein, calving, etc.) and inputs (costs of feed, labour, facilities, etc). Outputs have received considerable attention in breeding objectives for dairy cattle, whilst there has been less consideration of inputs. Feed is a major cost input for dairy producers. Hence, breeding for increasing main gross incomes (milk, fat and protein) and reducing main variable cost (feed) potentially can be of considerable importance. This study was conducted to estimation of genetic variation in income over feed cost (IOFC), as a single trait, and its association with some of other traits in Holstein dairy cows.

Improvement of herd life increases profitability due to lower replacement costs of heifers, higher proportion of mature cows that produce at their maximum potential and increased opportunity for voluntary culling. Functional productive life (PL) after adjustment for production is the ability of a cow to remain healthy and delay involuntary culling (Ducrocq et al 1988). Survival or failure time analysis has replaced linear model approaches for routine genetic evaluation of dairy cattle in several countries (Sewalem et. al. 2003). It allows proper treatment of censored data, inclusion of time-dependent covariates and skewed or non normal distribution of data. Approximate estimates of the heritability of longevity traits typically range from 0.05 to 0.10 and 0.15 to 0.20 using linear models and survival analysis, respectively (Vollema et al. 2000 and Caraviello et. al. 2004). The objective of this study was to apply survival analysis methodology for assessing the most important factor influencing PL, estimation of genetic parameters of productive life and genetic evaluation in Iranian Holstein dairy cattle.

The method for establishing a selection criterion for a given selection objective is referred to as selection index methodology. Usually in the flock sheep, The first selection for lambs that substitution ewes and rams, is at three month of age. Genetic and phenotypic correlations for weight traits at different ages are high and range of those were from 0.42 to 0.94 and from 0.06 to 0.56 respectively. Thus, the aim of this study was to predict the coefficient of selection index.

Meat production is the most important goal of sheep breeders in Iran. Crossbreeding between rams from relatively heavier breeds with ewes from light breeds (terminal crossing) is common method for increasing meat production in many countries (Bunch et al., 2004; Guney, 1990; Macit et al., 2001). The objective of this study was to compare the growth and feed-lot performance of crossbred lambs, resulted from Shall, Moghani and Afshari (three heavy breeds) rams and Kordi (a light breed) ewes. The performance of pure Kordi lambs was also adopted as a comparison benchmark.

In spite of the fact that there are many sheep breeds in Iran, few studies have been established with respect to their economical traits. Moghani sheep is one of the best Iranian meat type breeds with a 5.5 million population. Some specifications of this breed include Resistance to weather conditions, big body size and ability to producing heavy lambs. The aim of this research was to survey the environmental effects and estimates of genetic parameters for birth weight (BW), average daily gain from birth to three mounts of age (ADG1), three months age weight (TRW), average daily gain from three to six months age (ADG2), six months age weight (SIW), nine months age weight (NIW), yearly weight (twelve months age weight or TWW), lamb fleece weight (LFW) and yearly greasy fleece weight in mature sheep (YFW). The effect of birth year, ewe’s gestation period (or age for yearling greasy fleece weight), birth type and sex as fixed effect and sires (nested in years) as random effect on aforesaid traits were studied.

Animal breeding generally aims to obtain a new generation of animals that will produce desired products more efficiently under future farm economic and social circumstances than the present generation of animals (Groen, 2000). Definition of the breeding objective is generally regarded as the primary step in the development of structured breeding programmes (Ponzoni, 1988). Clearly defined breeding objectives are vital for effective genetic improvement of all livestock species. So, they stipulate the animal characteristics to be improved and the desired direction for genetic change. The breeding objective involves calculation of economic values for all biological traits that have an impact upon profitability. This study focuses on the derivation of a breeding objective based on a profit function for three commercial silkworm lines in Iran and effect of limitation in production system size on economic values.

Silkworms are well-known industrial insects, which produce natural fiber silk. Because of economic importance for silk yarn, an effort to breed new silkworm variety has been made for thousand years. High cocoon yielding due to high resistance, high silk reeling ability and productivity, better silk quality in neatness and lousiness is essential for new silkworm variety to increase silk productivity. Today, several hundred varieties have been bred accordingly various interests and purposes (Kang et al., 2001, 2002). Pupation rate, single cocoon weight, cocoon shell weight and cocoon shell percentage are the main factors affecting the high yielding of cocoon (Kang et al., 2001, 2002). Native silkworm varieties have the low performance and could not be commercially employed. Indigenous strains are valuable genetic resources. They have been affected by natural selection in the successive generations and adapted to indigenous diseases and environmental conditions. Genetic and phenotypic characterization of locally available native silkworm populations provides essential information to make rational decisions for the improvement and development of effective breeding programmes. Hence, the present study was undertaken to identify genetic potential of indigenous silkworm for designing suitable breeding programmes.

Straw constitutes a vast, valuable, and under utilised agricultural by-product, which has a great potential for utilisation as an animal feedstuff. However, due to the way in which it is constructed, the digestible sugars, cellulose and hemicelluloses, are tightly chemically bound by heavily lignified cell walls which provide the wheat plant stem with its strength and structure, but in doing so greatly inhibit the digestibility and nutritive value of the material to ruminant animals. Therefore, the utilisation of this resource as an animal feed can only be realised effectively, if the nutritional and digestibility values of the material can be improved by the innovation and successful application of an effective treatment method, be that physical, chemical or biological. Previously devised methods of upgrading the digestibility and nutritive value of forages, with the possible exception of urea treatment, have proven either insufficient, environmentally unsound, or economically infeasible to those concerned, particularly those in developing world. Therefore, there is a distinct need to develop techniques which can avoid these pitfalls and still yield the desired results in the context of animal nutrition. Previous research has indicated that members of the genus Pleurotus white rot fungi, have great potential for application in the biological upgrading of wheat straw. Therefore, the objective of this work was to investigate biological techniques, using 3 strains of Pleurotus fungi which may have the potential to be utilised in the biological upgrading of wheat straw.

The phenolic compounds are substances which reduce feed intake, protein digestibility and reduce ruminal activity in sheep and goats. To reduce the effects of tannins a lot of synthetic materials, for example PEG (polyethylene glycol) is tested as tannin-binding agent, and let protein free for the digestibility. The aim of this work was to test the effect of tannins in the rumen microbial growth using the in vitro 32P incorporation technique.

Clinical and sub clinical parasite infection depresses live-weight gain, feed intake, milk and wool production and can impair soft tissue deposition and skeletal growth. To date these infections have been controlled using anthelmintics, however the increasing prevalence of multiple anthelmintic resistance points towards the urgent need for alternative methods to reduce our reliance upon chemoprophylaxis. In addition, the worldwide growth of organic agriculture, in which the use of synthetic products is strongly restricted, needs alternatives for helminthes control. The aim of this experiment was to evaluate the effect of dietary condensed tannins (CT) on Haemonchus contortus infection in sheep.