Recent studies at this centre (Flanagan 2003, Keady et al. 2006) have shown that grazing swards in the winter (extended grazing), either in mid, late or throughout pregnancy, provides a low-cost system for wintering ewes. With decoupling of subsidy from production post Mid Term Review of the Common Agricultural Policy it is essential to improve efficiency and reduce costs of production. One of the major costs in sheep production is the cost of rearing replacements. The aim of the present study was to evaluate the effect of herbage allowance and concentrate supplementation on animal performance during extended grazing and on compensatory growth during the subsequent grazing season. Furthermore the potential herbage allowance sparing effect of concentrate supplementation was also determined.

In sheep production the ability of the animal to retain and mobilize body fat reserves is of considerable importance in determining the sheep productivity or even its survival. The most common way to predict body fat reserves is the body condition score. On the other hand, it is accepted that breeds have a different fat distribution within the body (Taylor et al., 1989). In general, ewes breed for milk production tend to deposit more fat in internal depots and those breed for meat production deposit more fat in the carcass depot (Frutos et al., 1997). This kind of fat distribution can explain the use of an objective and more precise way to predict the internal fat in ewes of the Churra breed, in which the internal fat depots plays an important role. Thus, it is reasonable hypothesize that the internal fat depots are related with muscle and subcutaneous fat measurements. As a result, the study herein reported was undertaken to achieve the relationship between real time ultrasound measurements obtain over thoracic, lumbar and sternum regions to predict the internal fat depots of Churra da Terra Quente (CTQ) milk breed.

In the UK lamb mortality is a major factor limiting profitability of sheep operations ranging from 15-22% from birth to weaning with the majority occurring in the first 24h of life (Teagasc 1991). Lamb survival to some extent is affected by micronutrient status of the ewe pre-lambing, which can be manipulated by dietary supplementation with subsequent effects on vitality and resistance to infections in the lamb (Rook et al. 2004) inadequate dietary supply of micronutrients to the lamb at later growth stages, will affect resistance to nematode and bacterial infections (Suttle and Jones 1989) and hence efficiency of growth to slaughter weight – the second major factor for profitability. The practicalities of management, labour time and concerns of cost-effectiveness, often result in no micronutrient supplementation of the sheep or the use of a drench at critical times in the sheep production cycle as a quick-fix to potential micronutrient deficiencies in sheep. This study was carried out to evaluate a micronutrient drench supplementation programme as a means of improving productivity and profitability of lamb production under commercial conditions.

DNA-based molecular methods have made possible genotyping of animals of any age and sex for milk and meat genes, thus providing a potentially more efficient and flexible selection tool. Among specific genes that may affect economically important traits in sheep, the Beta-lactoglobulin (BLG) locus has been extensively studied [Barillet et al., 2005]. The genotype BB of BLG seems to be associated with higher milk yield; on the other hand genotypes AA and AB seem to be superior in protein and casein content and crude yield [Garzon et al., 1992]. Another genes intensively investigated in farm animal are that of calpastatin (CAST) and calpain (CAPN). Calpastatin and calpain (CAPN) deserves special attention because of their major role in meat production. The calpain-calpastatin system (CCS) comprises a family of calcium dependent neutral proteases. The CAPNs have been shown to play the major role in post mortem tenderization in beef, lamb, and pork by degrading specific muscle structural proteins. The aim of the present study was to identify genotypes of BLG, CAST and CAPN genes in Kurdi sheep breed by PCR.

Sugarcane bagasse and pith, by-product which the residue after rind removal, are highly lignified by products of the sugar and paper industries, are the most abundant by-product in Iran. The use of by-product in animal nutrition is necessity since it may increase the availability of feed for animal and avoid accumulation that contributes to environmental problems. The main nutritional constraints for these crop residues as animal feeds are their slow rate of digestion and low nitrogen content (Liu et al., 2000). Steam-pressure treatment cleavage the bounds between lignin and the other component of the cell wall, in order to improve it’s degradability by enzymes of the rumen microbial ecosystem. The aim of this study were to evaluate the effect of increasing dietary steam treated pith content on feed intake, milk yield and composition of lactating dairy saanen goats.

Major changes have been occurring over the last 20 years in the UK dairy industry, with improvements in cow genetics and nutritional management resulting in a doubling of average milk yields to 6,750 litres/cow/year by 2004 (DEFRA, 2005). The same period has resulted in a decline of dairy cow fertility parameters with recent studies having identified a 1% fall in conception rates per annum (Royal et al., 2000). The role of organic forms of trace minerals has been examined in ruminant diets with particular regard to their role in immune function (Spears, 2000). The aim of the study was to examine the effect of feeding an organic source of zinc (Bioplex Zinc™, Alltech Inc. USA) and selenium yeast (Sel-Plex™, Alltech Inc. USA) to high yielding Holstein dairy cows on production and reproductive performance.

Type traits have been used as indirect measures of selection for herd life in last few decades, because type traits can be measured earlier in first lactation, they have relative higher heritability than longevity traits and are correlated moderately with herd life. Increased herd life leads to lower replacement costs, longer use of high performance animals in their herds and also obtaining more progenies from high yielding animals.

An undisturbed re-organisation of the cervix postpartum is a basic pre-condition for an undisturbed puerperium (Wehrend et al., 2003). This aspect of the puerperal involution has been insufficiently considered in the literature. It was shown that some cows developed a disorder of the cervical involution (Wehrend and Bostedt, 2003). LeBlank et al. (2002) concluded that the size of cervix in cows with clinical endometritis were associated with a decrease in pregnancy rate. With the use of the ultrasonic technique instead of using fingers of the human hand, more exact data on cervix regression can be delivered. Meanwhile, little is known about the effect of diet on cervix regression after parturition. The objective of this study was to evaluate the effect of palm oil fatty acids on cervix regression during the first 40 days postpartum in Iranian Holstein dairy cows using ultrasonic technique.

Reproduction and milk production are the principal factors that are influencing dairy farm profitability. The dairy industry in Iran has changed dramatically in the last decade. The shift toward more productive cows and larger herds in Iran is associated with a decrease reproductive efficiency (Heravi Moussavi et al., 2004). Increased knowledge about the principal causes of reduced fertility is essential. The root cause of the declining fertility is probably a combination of a variety of physiological and management factors that have an additive effect on reproductive efficiency. Dairy cattle are inseminated and pregnancy is established while dairy cows are lactating. Based on the analyses of large datasets, there is clearly an antagonistic relationship between milk production and reproduction in dairy cattle (Lucy, 2001). It was shown that the hazard ratio for cumulative first 60-day milk yield and conception in high producer cows was 8 percent less than the others and also high milk yield was a risk factor for several reproductive disorders (Grohn and Rajala-Schultz, 2000). The objective of this study was to evaluate the effect of first 60-day cumulative milk yield on days open in Iranian Holstein dairy cows.

Variation in milk production is depended on different factors including: temperature, humidity and day length, which are changing at different months of year (Saremi et al., 2003, Naerian et al., 2003). Dairy industry sustain loss or make profit according to amount of milk production or ingredients during year (Barbano et al., 1991). Traditional Bazaar and dairy industry are influenced by milk processing technology so that increased shelf time of products and whole milk and its products having the opportunity to distribute more effective (Erba et al., 1996). Seasonal changes in milk production leads to more processing of milk and changes in total solids of milk, which can influence price of milk (Stephenson et al., 1989). This study designed to investigate seasonal changes in milk production and its fat content in addition to investigating these changes between years (1988-2003).

Cow longevity is highly related to dairy farm profit. Cows are culled for a variety of reasons. The predominant reasons for culling are reproduction (i.e., failure to conceive), health, and low production (Bascom and Young, 1998). Half of the herd removals occur involuntarily and prematurely because of health disorders (Beaudeau et al., 2000). The decision to cull is a complex one. Farmers may consider many individual (such as age, stage of lactation, milk production, health status, and reproductive performance) and economic (such as milk price, the price of culled cows, and the price and availability of replacement heifers) factors when deciding to cull a cow. On the other hand, the risk of culling is not consistent across all stages of lactation. Cows experience the highest risk shortly after calving (Fetrow et al., 2006). Survival analysis allows for a more appropriate management of censored data and time-dependent covariates. Analyses of the reason and timing of culling is needed to predict herd performance. The objective of this study was to study the reasons and timing of cows leaving herd in two large Holstein dairy farms in Iran.

Previous studies have shown that including fish oil (FO) in the diet of beef cattle resulted in increased long chain C20n-3 PUFA (C20:5n-3 and C22:6n-3) in muscle resulting in a lower n-6:n-3 ratio (Scollan et al., 2005). Fish oil is considered to be a good inhibitor of biohydrogenation in the rumen, resulting in increased production of C18:1 trans-11 (Vaccenic acid), the precursor for conjugated linoleic acid (CLA cis-9, trans-11) in muscle. This study investigated the effects of incremental levels of FO in the diet on fatty acid metabolism in the rumen.

In a previous study at Harper Adams University College (Marsh & Pullar 2002) the progeny from bulls with either a high (Top 10% Beef Value [LM29]) or below average Beef Value (Bottom 25% Beef Value [LM7]) were reared through to slaughter on a silage beef system. The calves sired by the Top 10% Beef Value bull recorded significantly higher carcass weights. The objective of this trial was to evaluate the performance of Limousin cross Holstein Friesian calves sired by bulls with either a Top 1% Beef Value or Top 10% Beef Value.

Now a days, scientists like to find about association of major genes and quantitative traits. In the first step, breeding value of quantitative trait should be predicted and genotype of animals for special major gene locus should be detected. Then, GLM analyses are used to compare all levels of genotypes and study about their association with quantitative traits. The accuracy of prediction of breeding value may influence the result of analyses. Different models with different accuracy of prediction may be utilized to predict breeding value. In this article, different models, with and without using the Genotypic Data of Major Genes Loci were used in order to identify the better model for genetic evaluation in this situation.

In dairy farm animals, production of milk and its components varies in a curvilinear pattern over the course of the lactation. Knowledge of the lactation curve may provide a worthwhile information source about the pattern of milk production which in turn could be used for herd management decisions. Moreover, inter-relationships among lactation curve parameters could be utilised in applied animal breeding programmes to change more effectively the shape of the lactation. Many studies have been undertaken to apply different mathematical models to obtain more accurate prediction of the shape of the lactation curve among which the incomplete gamma function first proposed by Wood (1967) has been broadly used by previous research workers (Rekaya et al., 2000; Tekerli et al., 2000). The main objective of the present research was to apply Wood’s function for estimating phenotypic correlations among lactation curve parameters in Iranian first lactation buffaloes.

Candidate gene approaches facilitate discovering and localizing causative genes for quantitative traits and polymorphisms within selected candidate genes can be tested for association with variationin the quantitative trait (Campbell et al., 2003). Leptin is a 16-kDa protein that is synthesized and secreted predominantly by white adipocytes tissue and its expression is regulated by body fatness and energy balance. Leptin gene expressed in a variety of tissues including adipose tissue, placenta, mammary glands, skeletal muscles, gastric mucosa, brain and pituitary glands. In cattle, the leptin gene is located on chromosome 4 and consists of three exons. Several studies shown the association between polymorphism at the leptin gene and feed intake, energy balance, fertility and immune functions. It has been shown that leptin gene influences milk performance in cattle and reproduction in beef cattle(Liefers et al., 2002). Buchanan et al. (2002) described a cytosine (C) to thymine (T) substitution in exon 2 of the leptin gene of the B. taurus breeds, suggesting the existence CC, TT and CT genotypes. The aim of this study was to identify the single nucleotide polymorphism of exon 2 in Iranian Taleshi cattle.

Prolactin plays an important regulatory function in mammary gland development, milk secretion, and expression of milk protein genes. Hence the PRL gene is a potential genetic marker of production traits in dairy cattle. The gene was mapped on chromosome 23 by Hallerman et al. (1988). It consists of 5 exons and four introns (Camper et al. 1984) encoding the 199-amino-acid mature protein (Wallis 1974). On the basis of sequence analysis of four different cDNA clones, seven possible nucleotide substitutions were described by Sasavage et al. (1982). One of them, recognized by RsaI endonuclease, has become a popular genetic marker used for genetic characterization of cattle populations by means of PCR-RFLP (Mitra et al., 1995). Two allelic variants (B and b) have been distinguished at the DNA level, based on RsaI polymorphism in the third exon of the coding region. It has been suggested that prolactin alleles correlate with milk yield (Lewin et al., 1992).

Buffaloes have important role in Khuzestan agricultural economy in Iran. They are adapted to harsh environmental conditions in the area. They are well resistant against ticks and disease and used to eat low quality feeds. In order to establish a breeding plan, estimation of genetic parameters is necessary. The objective of this study was to explore production and genetic capacity of Khuzestan’ buffalos.

In order to evaluate genetic improvement in a selected population, variation resulted from environment and genetics should be dissociated. Because of the positive genetic correlation between milk fat yield and milk and protein yield, selection for milk production has often resulted in an increase in fat and protein yields however response for fat percentage is negative. However positive genetic trends between 0.73 to 0.95 kg per annum for milk fat yield in Holstein cattle have been reported in some studies that milk fat yield had less importance in selection index, also negative values are reported. Based on previous research, genetic improvement of milk fat yield up to 1 percent due to selection is possible and from a theoretical view, an improvement of about 2 percent is reported. With attention to selection in the herd and using progeny tested semen from foreign countries that have suitable genetic potential, this study was accomplished in order to estimate genetic parameters for milk fat and investigate genetic and environmental trends during 1990 to 2001.

Protein degradation in the rumen often proceeds at a rate which exceeds the ability of the microbial population to utilize the resulting breakdown products. Bacteria are the most active proteolytic organisms in the rumen, and many species of rumen bacteria are known to be proteolytic (Wallace et al., 1985). The commonly isolated proteolytic bacteria are also able to break down peptides and amino acids, and it was assumed that they were responsible for the ruminal degradation of intact protein through to ammonia. However, studies comparing the specific activities of ammonia production between mixed ruminal bacteria and the well-known proteolytic bacteria noted that no individual bacterium had an activity which could explain the activity of the mixed ruminal culture (Russell et al., 1988). Subsequently, three gram-positive, monensin-sensitive, ammonia hyper producing (HAP) bacteria were isolated from the rumen. The present study reports the sequence of 16sr RNA for ruminal ammoniabacters of Iranian Holstein cows.