In order to evaluating genetic improvement in a selected population, variation resulted from environment and genetic should be dissociated. Because of positive genetic correlation between milk production and fat and protein yield, selection for milk production often resulted in an increase in fat and protein yields however response for fat percentage is negative. However positive genetic trends between 26 to 173 Kg in a year for milk production in Holstein Cattle are reported in some studies that milk yield had less importance in selection index, also negative values are reported. Based on previous researches, genetic improvement of milk yield up to 1 percent due to selection is possible and from theoretical view, an improvement about 2 percent is reported. With attention to performed selection in the herd and using progeny tested sperms from foreign countries that have suitable genetic potential, this study was accomplished in order to estimating genetic parameters of milk production trait and investigating genetic and environment trends during 1990 until 2001.

Blood is a good source of DNA, although other tissues such as skin biopsies or hair follicles can be used (Heal et al, 2002). Milk, which is widely available and obtained non-invasively, would be the source of choice in lactating animals. However, it is difficult to extract DNA from small samples of milk in quantities sufficient for simultaneous genotyping at multiple loci. The objective of this study was to determine whether genomic DNA isolated from small amounts of milk could be amplified to provide sufficient material for running multiple genotyping reactions.

Nicobari fowl is an endangered breed of chicken with an estimated population of 7524 (Chatterjee and Yadav, 2003). This breed is endemic to Andaman and Nicobar Islands and are distributed in a scattered form. Andaman and Nicobar group of Islands are located in the Bay of Bengal (Latitude 6°′/ N and 13°41′ N, longitude 92°12′ E and 93°57′E) and have a typical maritime climate. The bird is brownish matty in colour, medium in size, short-legged and hardy with compact body conformity. The bird has short and thick neck, black plumage tipped with brown shade, breast bulging in front, medium sized tail and long saddle feathers (Chatterjee et al., 2003). The present study was an effort to characterize the growth, production and reproductive performance of the breed under backyard system in Middle Andaman, India.

Antimicrobial peptides represent an abundant of innate immunity with over 300 different protein sequences described in species ranging from insects to mammals (Boman, 1995). One group of such peptides, due to its antibiotic and cytotoxic activity against bacteria, viruses and fungi was called defensins. Expressions of ß-defensin genes were shown in the cow’s mammary gland and in famale urogenital tract (Ryniewicz etal. 2002). Cattle defensin genes have been localized on chromosome 27. Because defensin peptides protect animals against bacterial, viral and fungal infections, the genes encoding these peptides seem to be potential markers in studies on the genetically determined resistance (or susceptibility) of the mammary gland and also on the reproductive rate. This experiment was conducted to study the presence and comparing the frequencies of various alleles of defensin genes in cows differing in udder health statuses and in some reproductive traits.

The kappa-casein gene has been extensively studied in cattle for its stabilizing role of the casein micelles and, therefore, its influence on the manufacturing properties of milk. In Holstein dairy cattle the B variant of kappa-casein (CSN3) is associated with a higher protein content, better quality of crud and increased yield of cheese. It has been suggested that identification of CSN3 genotypes could be an economically important selection criterion for dairy herds designated for industrial milk production (Pederson, J. 1991). Genotyping of milk proteins, such as CSN3, can be performed by electrophoresis, directly from milk samples, as the expression of the caseins occurs only during the lactation phase in mammary gland cells. Therefore, the use of electrophoresis for genotyping of milk proteins is strongly limited because it can only be used in cows in the lactation stage. With newly developed techniques based on DNA analysis, which include polymerase chain reaction and restriction fragment length polymorphisms (PCR-RFLP) methods, it is now possible to determine the CSN3 genotype of all individuals in a given population under selection, regardless of sex, age or physiological stage (Lara, M.A.C. et al. 2002). The Kappa-casein genotypes has not been detected so far in Sistani cows.

Since UK slaughter generation lambs are produced from many different breeds in a wide range of environments, the possibility of interactions between genotype and feed treatment is of both practical and theoretical interest. Such an interaction exists for growth rate in different selection lines of Suffolk sheep on different levels of concentrate feeding (Lewis et al., 2002). Whether interactions exist between breed and feed treatment for lamb growth and carcass composition was investigated using two diverse breeds in several different nutritional environments.

There is considerable interest in the eradication of all transmissible spongiform encephalopathies (TSE’s) in food producing animals, to minimise any possible risk to human health. Scrapie, a TSE and a notifiable disease, is a fatal neuro-degenerative disease of sheep and goats. Susceptibility is strongly linked to the prion protein (PrP) genotype on three codons 136, 154 and 171. The ARR alleles confer the greatest resistance to disease; ARQ and ARH are intermediates, whereas VRQ confers greatest susceptibility. UK and EU eradication policies are presently selecting for resistance to scrapie and farmers are taking advantage of genotyping schemes to position themselves better in the market place should scrapie resistance become a major market requirement. The objectives of the study were to find out PrP genotypic frequencies and thus PrP gene-associated susceptibility to scrapie in a flock of Welsh mountain sheep and to predict changes in scrapie genotypes as a result to selection.

The effect of a DNA polymorphism in the MC4R gene on fatness, growth and feed intake traits of pigs was first reported by Kim et al in 2000 (1). That study of 1720 animals showed significant effects in several selected breeding populations for days to 110kgs (p<.001), 10th rib backfat (p<.001), test daily gain (p<.001) and feed intake (p<.01). However, in the same paper the effect within a small sample (124) from a Meishan synthetic line was not significant and the (small) effect of backfat was in the opposite direction to that reported for other lines. Subsequently, Andersson and colleagues (2) reported a failure to detect an effect in a small QTL population derived from crossing Large White pigs with wild boar. Several explanations have been proposed (1,2) including an epistatic effect. Here we report the results of an experiment to test whether the results from the Meishan population was due to sampling. The results indicated an effect of MC4R within the Meishan line for fatness, growth and feed intake traits in the same direction as previously reported for other lines.

The accurate estimation of starch degradation is important for the efficient feed utilisation. The current in vivo and in sacco methodologies contain a number of drawbacks, including animal welfare issues and high experimental costs including those associated with maintaining surgically modified animal. In addition for many feedstuffs excessive particle loss from in sacco bags renders this technique inapplicable. There is, therefore, an opportunity to identify a simple in vitro technique to provide the desired data. In pursuit of this goal actual starch degradation was estimated from an analysis of fermentation residues obtained from the in vitro degradation of wheat and maize grain. The results were supported with data regarding volatile fatty acid production and fermentation gas release kinetics.

In spite of the importance of starch-based feeds for all sectors of the livestock industry, it is difficult to obtain reliable starch estimates. Much of the variation in the accuracy relates to differences in the procedures used. Most starch analyses are enzymatic, relying on the specificity of the enzymes to distinguish the glucose in starch from that in other carbohydrates following gelatinisation. The aims of this study were to compare the accuracy of five different techniques with the aim of selecting the most optimum for future in vitro and in vivo degradation studies.

Cereal grains provide the major source of energy for ruminants in intensive production systems. Starch digestion in the rumen appears to be determined by the rate at which both the endosperm cell walls and, more importantly, the protein matrix surrounding the granule can be disrupted by enzymes than the properties of the starch itself. The presence of phenolic compounds influence seed coat digestibility and could interact with the protein matrix to affect starch digestibility. While processing and mastication are sufficient to disrupt these barriers, the rapid fermentation of starch in the rumen is not considered desirable as it can adversely affect animal health (e.g. acidosis) or via a lowered rumen pH inhibit fibre digestion. Processing methods are also criticised in terms of cost relative to inexpensive grain, and environmental issues e.g. alkali loss. A largely unexplored strategy to improve grain digestibility is pre-feeding treatment with exogenous enzymes. In this respect the potential of enzyme preparations, that cleave side-chain linked phenolics, to improve grain digestibility was examined in this study.

Many reports indicate that mixed microbial populations preferentially incorporate peptides or NH4+ rather than free amino acids [e.g. Pittman and Bryant, 1964]. As part of a study to evaluate a novel encapsulation process, an in vitro technique to examine amino acid degradation was developed using a compliment test based on the Reading Pressure Technique [Mauricio et al., 1999]. In this methodology, the ability of rumen microorganisms to ferment a pure carbohydrate substrate in a nitrogen-deficient medium was significantly correlated to the level of available nitrogen. It therefore followed that fermentation gas release could be used as a simple technique to examine and quantify nitrogen availability. The study described compared three nitrogen sources offered either alone or in combination.

The buffered incubation medium used in many in vitro ruminant feedstuff degradation assays is essentially that described by Goering and Van Soest [1970]. Hungate [1966] suggested that the actual composition of the inorganic salts in the medium was not vital as long as it provided sufficient buffering capacity and was of a similar osmotic potential to rumen fluid, while Tilley and Terry [1963] argued that sufficient trace elements and “growth stimulants” would be provided by the rumen fluid inoculum or substrate and that fermentation gas would maintain anaerobic conditions. The divergent composition of these media reflects that the microbiologists were attempting to create a “habitat-simulating” media [Hungate, 1966] while nutritionists were using a slightly modified rumen environment in vitro to permit microbial degradation of feedstuffs. The objectives of this study were to identify whether reduction of media is necessary prior to use, and to develop a nitrogen free media which could be used for determining the effects of nitrogen supplementation on the fermentation of feedstuffs.

High producing or rapidly growing ruminants require more high quality protein than is provided by rumen microorganisms. This protein can be supplied by increasing the amount of dietary protein escaping degradation in the rumen. Solvent-extracted soya bean meal (SBM), which is a commonly used protein supplement to high producing dairy cows, is palatable with a well-balanced amino acid composition. However, SBM proteins are extensively degraded in the rumen. Attempts to decrease the rate and extent of ruminal degradation of soya bean meal proteins involved treatment with physical and chemical agents. Recently Tuncer and Sacakli (2003) reported that xylose reduce soya bean meal crude protein (CP) degradation in the rumen. To our knowledge, little information is available concerning the type of proteins of un- and xylose treated soya bean meal that leaves the rumen undegraded. The main objectives of our research were to evaluate the degradation of un- and xylose treated soya bean meal proteins by using SDS-PAGE and determine Effective Rumen Degradation (ERD) and intestinal digestibility of un- and xylose treated soya bean meal CP.

It is widely accepted that diets containing large amounts of forage affect animal performance due to low digestibility of structural carbohydrates. This limitation is mainly attributed to lignification and to covalently bound hydroxycinnamic acids. Most of the work related to the effect of hydroxycinnamic acids on cell wall digestibility has been conducted towards specific plant species and distinct plant parts. However, the results regarding the influence of hydroxycinnamic acids on the digestibility of roughages such as hays and straws are rather scarce. The objective of the present study was to investigate several methodologies in order to evaluate the influence of phenolic compounds on the digestibility of northern Portugal meadow hays.

Maize silage (MS) is a major diet component in Iranian dairy farms. Forage produced from tropical maize hybrids is noted for its high lignin and low water soluble sugar concentrations. This is possibly related to the lower grain and higher non-grain portion of tropical hybrid plants compared to the other hybrids varieties. In addition as tropical maize silage has low nitrogen concentration, it has been suggested to treat the silage by non-protein nitrogen (NPN) in order to alleviate nutritional deficiency in the rumen and enhance roughage utilization. This study was conducted to evaluate the chemical composition and in situ protein degradability of maize silage treated with urea (U) and sulphuric acid (SA).

The development of mankind has reached the point that a variety of new resources need to be tapped in order to fill our basic needs for food, feed and freshwater. Halophytes such as Kochia scoparia, Atriplex dimorphostegia, Suaeda arcuata and Gamanthus gamocarpus are widely grown in salty lands of central Iran. Halophyte is a plant that naturally grows where it is affected by salinity in the root area or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs, and seashores. These plants are grazed by sheep, goats and camels, specially during the prolonged seasons of drought. The dynamic interactions within the rumen are difficult to simulate. In situ techniques allow us to study digestion within the rumen itself and reduce the need for ruminal simulation. Such techniques have been used extensively during the last two decades (Vanzant et al, 1998). The aim of this study was to determine the in situ dry matter and crude protein degradability of some halophytes located of central Iran.

Modern protein evaluation systems for ruminants describe the supply and requirement of true protein that can be absorbed from the small intestine. Amino acids that are available for absorption from the small intestine is primarily the sum of those of microbial protein that is synthesized in the rumen by microorganism and dietary by-pass protein ( Harstad and prestlØkken, 2001). The objective of this experiment was to determine the DM, CP and AA disappearance from barley grain (BG) and corn grain (CG) in the rumen, small intestine and total tract of steer.

The undegraded intake protein content of feeds is regarded as a major limiting factor for high performance lactating cows (NRC, 2001). The rate and extent of ruminal protein degradation determine the availability of nitrogen to the microorganisms, and of nitrogenous products in the small intestine. The ruminal and post-ruminal disappearance rates of dry matter (DM) and protein (CP) of protein feeds were shown to be higher than those of energy and forage feeds (Danesh Mesgaran, 2003). On the other hand, the nutritive value of crops is affected by the climatic conditions, and its determination is essential for optimum feeding. The objective of the present study was to determine the in situ DM and protein degradability of some Iranian feedstuffs.

Lucerne hay or silage is major forage fed to dairy cows in Iran. During fermentation, a large proportion of the CP in lucerne (L) is broken down to NPN; typically, 50 to 60 % to more than 80 %. Therefore, broken down of true protein in lucerne silage (LS) to NPN substantially reduce efficiency of CP utilization in lactating cows (Broderick et al., 1995). The objective of the present experiment was to compare the nutrient content, and in situ DM and protein degradability of LS treated with urea and HCl.