Selection on base marker –assisted selection is one of new methods that may improve accuracy and progress of selection in animal breeding. Genetic variants of ovine calpain gene relationship on growth and meat tenderness examined in many researches. This is a candidate gene in meat tenderization. It is located on ovine chromosome 14 and plays important roles in formation of muscles, degradation and meat tenderness after slaughter. It may be beneficial to use calpain genotypes classified in marker assisted selection programs to improve growth traits of lambs and meat tenderness. (2, 1)

Leptin is a 16 Kilo Dalton protein that is synthesised by adipose tissue and it is involved in regulation of feed intake energy balance, fertility and immune function. In cattle, the leptin gene is located on chromosome 4. It consists of 3 exons and 2 introns that only 2 exons translate into protein. Leptin treatment of animals has been shown to cause a decrease in food intake, body weight loss, fat depot weight loss and increase in energy metabolism therefore leptin not only causes reduced food intake but the potential body weight losses are enhanced due to an increased metabolic rate. Leptin may be involved in regulating reproduction in that it may also act as the signal to the reproductive system that sufficient body fat exists to support a successful conception and pregnancy (Fruhbeck et al., 1998). Lagonigro et al. (2003) reported association of five SNP bovine leptin genes with feed intake and fat–related traits. Liefers et al. (2002) reported that heifers with the AB genotype produced 1.32 kg/d more milk and consume 0.73 kg which is 2 times more food compared with the AA genotype. They suggested that B allele could yield a higher milk production without negatively affecting energy balance and fertility. The aim of this study was to estimate the frequency of the leptin gene and its relationship between its polymorphisms with variations in growth and age at successful insemination in an Iranian native cattle, Sistani.

Milk production in dairy cattle controls by various linear and non-linear factors, and dairy production is influenced by interaction between genetic and environmental agents (Kominakis et al., 2002). Many current models in prediction dairy production assume a linear relationship between dependent and independent data. Artificial Neural Network (ANN) can be used to implement a linear or non-linear relationship for prediction. ANN is made up of set of neurons, to consider the process input data and the corresponding output; to elicit non-linear relationship between input and output data. The parallel processing in ANN is specifying close acquaintance for this system (Lacroix et al., 1995). The objective of this study was prediction of second parity milk yield (MY) based on first parity records by ANN, and comparing with current linear model like multiple linear regression (MLR).

In last decade molecular marker information has been directly used in animal breeding programmes. It is expected that molecular markers could speed up the rate of genetic improvement by up to 30% (Kashi et al. 1990). Genetic markers which are related to genes and traits of interest could be used as a marker for selection. It is obvious that milk and reproduction traits are controlled by many genes. However, finding a candidate gene as a genetic marker which may have good influence for increase milk yield is quite important in dairy breeding industry. Some of genetic polymorphism in candidate genes which have significant effects on production traits is widely used. In this study Pit-1 transcription factor gene was used as a candidate gene. Transcription factor Pit-1 gene positively regulates the expression of growth hormone, prolactin and thyrotrophin-beta subunit genes (Zhao et al. 2004). It also plays a role in pituitary cell differentiation and proliferation. The aims of this study were to find the role of Pit-1 polymorphism on milk yield, fat and protein percentage and to study the usage of Pit-1 gene as a candidate gene for milk production traits in dairy cattle.

Estimation of variance components is an important step in the development of animal breeding programs. The genetic and phenotype components of weight traits have been reported for different breeds. The heritability of birth weight in Targhee sheep is 0.22 (Bromley et al., 2000) and heritability of weaning weight in Suffolk sheep is 0.19 (Notter et al., 1998). Research shows that the additive genetic effect in earlylife is low (Nasholm et al., 1996). The objective of this study was to predict additive genetic effect, maternal genetic effect and heritability of lamb body weight in Karakul sheep.

Breeding programmes for the Holstein-Friesian have historically focused on improved milk production with little emphasis on functional traits such as fertility or disease resistance (Yan et al., 2006). Recently, a major breeding programme has been adopted in Northern Ireland using the cross-breeding technique (Holstein cows x Jersey sires) with the aim of improving fertility and disease resistance of dairy cows whilst maintaining milk production capacity. The objectives of the present study were to evaluate possible breed differences in the efficiency of energy utilisation between Holstein and Jersey-Holstein dairy cows offered mixed diets of grass silage with a low or high level of concentrates.

In a previous study at Harper Adams University College (Marsh et al., 2007) the progeny from Limousin bulls with either a Top 1% Beef Value (LM44) or Top 10% Beef Value (LM30) were reared through to slaughter on a cereal beef system. The calves sired by the Top 1% Beef Value bull recorded significantly higher daily liveweight gains, daily carcase gain, slaughter weights, carcase weights, improved conformation scores and carcase values. The objective of this trial was to evaluate the performance of Limousin cross Holstein-Friesian bull and heifer calves sired by bulls with either a Top 1% or Bottom 1% Beef Value.

In Belgium, sport horse breeding is organized by the Belgian Warmblood Horse (BWP) studbook and the Belgian Sport Horse (sBs) studbook. Genetic links between both populations have been suspected because BWP and sBs studbooks had concomitant development after the Second World War, because they are geographically close, and because they have the same selection objectives (model, jumping and dressage ability). The conservation of genetic variability between breeds is important, even in selected populations, in order to allow a long term management of the entire genetic resources available for future improvements. The purpose of this study was to evaluate the genetic links between BWP and sBs populations by the study of their comparative genetic variability. Some studies already dealt with a similar problem (Moureaux et al., 1996; Valera et al., 2005).

The main objective of silkworm breeding programs is collecting the appropriate genes in the populations to improve productive performance lines (Jayaswal et al., 2000). The general aim of selection in animal breeding is to obtain new generation of animals, which under future economic conditions of production system are more efficient than the present generation. In selection index programmes, top animals are selected based on their multiple-trait genetic-economic value named genetic merit. In this method, genetic trend of important traits is directly based on their weights in economic efficiency of production system to acquire maximum improvement in economic merit (Shadparvar et al., 2005). The objective of this study was to study changes in the genetic merit of 6 silkworm lines over 8 generations.

Leptin is a 16-kDa polypeptide hormone synthesized and secreted predominantly by adipose tissue. It functions to regulate body weight, food intake, energy expenditure, reproductive and immune functions. Leptin treatment of animals has been shown to cause a decrease in food intake, body weight loss, fat deposit weight loss and increase in energy metabolism. Therefore leptin not only causes reduced food intake, but the potential body weight losses are enhanced due to an increased metabolic rate (Houseknecht et al. 1998). The gene encoding Leptin was mapped to Bovine chromosome 4 and it consists of 3 exons and 2 introns of which only two exons are translated into protein. The coding region of the leptin gene (501 nucleotides in length) is contained in exon 2 and 3, which are separated by intron of approximately 2 kb. Leptin is considered as a candidate gene for milk performance related traits in cattle. Several polymorphism in this gene have been found (Liefers et al. 2002). In exon three, A59V polymorphism, causes as amino acid change from Alanine to valine. These amino acids both belong to the group of aliphatic amino acids, but Valine is more hydrophobic. The aim of this study was to analyse the frequency of the A59V Polymorphism in exon 3 of Leptin Gene in Iranian Holstein cattle.

Molecular biology techniques are of help in genetic improvement since they permit the identification, mapping and analysis of polymorphisms of genes encoding proteins that act on metabolic pathways involved in economically interesting traits. The somatotrophic axis, which essentially consists of growth hormone releasing hormone (GHRH), growth hormone (GH), insulin like growth factors I and II (IGF-I and IGF-II), and their associated binding proteins and receptors (GHRHR, GHR, IGF-IR and IGF-IIR), plays a key role in the metabolism and physiology of mammalian growth (Curi et al.,2005). Polymorphic sites in genes involved in the mediation of growth factors are logical candidates to study for possible associations with livestock production traits. The objective of this study was to estimate the allele and genotype frequencies of the IGF-I/SnaBI gene polymorphism in Iranian Holstein cows and their relations with performance traits.

Selection in dairy breeding is basically aimed at milk production and composition of milk (Kovacs et al., 2006). Bovine growth hormone gene is an excellent candidate for linkage relationships with quantitative trait loci (QTL). A polymorphic region in exon V of the bovine GH gene results in a nucleotide change related to the occurrence of variants with leucine (Leu) or valine (Val) at amino acid position 127 of the protein. This polymorphism was found to be associated with milk production traits (Lucy et al., 1993). The aim of the present study was to explore the frequency of GH/AluI alleles in Iranian Holstein cows and look for relationships between the bGH gene and milk production traits.

Grain sources and processing have been discussed for many years. Most feedlots select their grain source based on cost of the grain plus its processing. A variety of processing methods have been devised that vary in cost and effectiveness. The primary goal of processing is to increase energy (starch) availability. In addition, processing may destroy mycotoxins and improve mixing characteristics to improve bunk management and thereby enhance animal performance (Owens et al, 1997). Mechanical and chemical alterations during processing increase surface area exposure and improve ruminal, intestinal and total tract starch digestibility of seed grains (Huntington, 1997; Owens et al., 1997). Unprocessed corn can be effectively fed to ruminants because the pericarp of the kernel is extensively damaged by chewing (Beauchemin et al, 1993). So the objective of this study was to investigate effects of processing method and size of corn ground particles on ruminal degradation parameters.

Increasing population and lack of water resources brings the attention of investigators to types of halophytes growing in salty soil and water areas in order to guarantee forage for animals. Kochia Scoparia is a potentially valuable forage plant on arid and semiarid lands, because it yields DE and protein comparable to alfalfa with about half the water requirement (Finley and Sherrod, 1971). However, its value is decreased by poor utilisation of nutrients (Cohen et al., 1989). It has been reported that adding kochia scoparia forage to sheep ration does not affect the nutrient digestibility, but increasing different levels of kochia in cattle and sheep rations cause decreased retention of nitrogen in the body of these animals (Sherrod, 1973). This study is focused on introducing Kochia scoparia as a native forage in Iran and investigates the characteristics of it when ensiled.

The primary goal of making silage is to maximize preservation of original nutrients in the forage crop for feeding at a later date. Unfortunately, fermentation in the silo is an uncontrolled process that usually leads to less nutrient preservation. In order to assist in the fermentation process, various silage additives have been used to improve the nutrient and energy recovery in silage, often with subsequent improvements in animal performance. One method which has been successfully used is inoculating silage with a specially selected lactic acid bacterium (LAB) which is known to process good silage making qualities. This study is focused on some practical aspects of the fermentation process and the uses of silage additives containing lactic acid bacteria (ECOSYL AND BIOTAL).

In ruminant feeding, the prediction of metabolizable protein requires accurate estimates of feed protein degradation in the rumen. Some common feed protein sources have a high concentration of neutral detergent insoluble nitrogen (N-NDF) whose degradation may be dependent on neutral detergent fibre (NDF) degradation and, consequently, on rumen cellulolytic activity. This may lead to an underestimation of the undegraded protein that reaches the small intestine, particularly when animals are fed high starch diets. The objective of this study was to verify if there is a relationship between the ruminal degradability of the NDF and N-NDF of eight feed supplements currently used in ruminant feeding with the in sacco technique.

Barley is a dominant feed grain in Iran, western North America, and Europe. Barley processing is imperative to maximize its utilisation by feedlot and dairy cattle (Yang et al, 2000). Whole grain with an intact pericarp is largely or entirely resistant to digestion by ruminants because whole kernels are resistant to bacterial attachment (Beauchemin et al, 1994) in the rumen. In addition to pericarp, barley grain is surrounded by a fibrous hull, which is of low digestibility. barley kernels are not severely damaged by chewing. Consequently, considerable whole barley kernels are excreted in feces if whole barley kernels are fed. So the objective of this study was to investigate effects of processing on ruminal degradability of barley and trend of ruminal digestion of ground barley in different sizes.

Production of field peas has been promoted in most areas of the world due to their high level of protein content as a substitute for soybean meal. The majority of the field peas are grown under contract for human consumption. Field peas must meet strict quality guidelines to enter the human market. The peas that are not eligible for human consumption are then available for livestock feed. This feed cannot be used judiciously in feeding ruminants because of their high degradability in the rumen. In highly productive ruminants, peas may not provide adequate amounts of escape protein which will necessitate supplementation of the diet with high escape protein sources. Gamma irradiation of soybean meal resulted in denaturation of proteins, increasing hydrophobicity of the protein surface and decreasing degradation of crude protein (CP) in the rumen (Shawrang et al., 2007). The objective of this study was to evaluate the effects of γirradiation on crude protein degradation parameters and, on the fate of true proteins of pea in the rumen.

Safflower seed (Corthamus tinctorius) was recognized to contain the highest concentration of linoleic acid among all oilseeds (Dubois et al., 2007), but research in this field is a few and almost non for Iranian safflower seed. The use of in vitro gas method based on syringes appears to be most convenient in developing countries where resources may be limited in recent years (Makkar, 2004). The Objective of this study was to compare nutritive value of two varieties of safflower seed (IL-111(I) and Native (N)) cultivated in Isfahan, Iran to each other and to the other oilseeds.

Fibrolytic enzymes are typically cellulases that degrade cellulose or xylanases that act on hemicellulose (Beauchemin et al., 1995). Enzymes applied to forages immediately before incubation enhance the digestion of dry matter (DM) and neutral detergent fiber (NDF) suggesting that fibrolytic enzymes applied at feeding can improve digestion in ruminants. The objective of this study was to determine the effect of fibrolytic enzyme on the nutritive value of lucerne hay using in vitro gas production (GP) and in situ techniques.