A large quantity of whey is produced in Iran and mostly is discharged into streams and seasonal rivers, which cause environmental pollution. Whey as a nutritious dairy by-product can effectively be fed to ruminants (Bayat et al. 2002). This experiment was conducted to study the effects of concentrate substitution by liquid whey on performance, rumen and blood parameters of the Holstein steers.

In vitro supplementation of 0.05% [on a substrate basis (wt/wt)] - but not of 0.01% - of 9,10-Anthraquinone (AQ) inhibited rumen methanogenesis, reduced total volatile fatty acid (VFA) concentrations and molar proportions of acetate (Acet), increased proportions of propionate (Prop) and butyrate (But) and resulted sometimes in H2 accumulation (Garcia-Lopez et al., 1996). In vivo administration of high amounts of AQ [5% on a substrate basis (wt/wt)] to lambs depressed CH4 and increased H2 concentrations in ruminal gases during the complete 19 days of administration, whereas original concentrations were re-installed within 6 days after the removal of AQ from the diet (Kung et al., 1996). In this experiment we aimed to study the dose effect of AQ on in vitro rumen fermentation and modifications to rumen fermentation when administering 0.05% of AQ in vivo.

Balancing the supply of nitrogen and energy-yielding substrates to rumen micro-organisms was proposed as a mechanism to maximise the capture of rumen degradable nitrogen (RDN) and to optimise microbial growth rate and efficiency. The objective of this study was to examine the effect of various time periods of imbalance between nitrogen and energy supplies for the rumen micro-organisms on the microbial protein synthesis (SPM) in growing double-muscled Belgian Blue bulls. This was realised by giving the same feedstuffs according to different meal patterns, which is one of the most robust test of the ‘synchrony’ hypothesis (Dewhurst et al., 2000).

Farmed red deer (Cervus elaphus) are highly seasonal animals and thus the majority of venison is available during the autumn and winter months. To compete with other red meats, alternative marketing systems for venison need to be developed. Previous ADAS trials have shown that red deer can be finished intensively at 10-12 months of age by extending day length (Davies et al, 1995) but it incurs increased feed costs. An alternative strategy to lower production costs is to reduce growth rates and finish deer at 24-26 months of age. Preliminary trials have shown (Davies and Deakin 1998) that silage only diets, during the second winter, are not sufficient to maintain body weight and a small supplement is required. However the type of supplement needs further investigation. The objective of this study was to examine the effect of feeding high energy and protein diets to yearling deer during their second winter, on winter growth and subsequent performance at grass.

High levels of dietary concentrates are often used to support milk production and it is important to investigate ways to feed them efficiently. Fats have the greatest energy density of any feed ingredient and the inclusion of protected fats in the dairy cow ration enables a high energy but balanced ration to be fed. The aim of this trial was to investigate the effect of feeding different levels of Megalac (Volac International Ltd, Herts) to dairy cows and to compare milk yield, milk composition, fertility and body condition score (BCS).

Recent developments in maize breeding and in agronomic practices, particularly the development of degradable full cover plastic mulch, have resulted in the possibility of consistently producing high yields of high starch maize silage in Northern Ireland. However, there is considerable variability in the quality of maize and grass silages produced. In a recent study Keady et al. (2002) concluded that the highest yield of fat and protein from dairy cows was obtained from maize silage ensiled at approximately 30% dry matter (DM) when offered as 40% of the forage component of the diets consisting of either medium or high feed value grass silages supplemented with concentrates. Also Keady et al. (2002) concluded that replacing 40% of the grass silage component of the diet with maize silage had a concentrate sparing effect, as determined for milk yield, of up to 1.9 kg/cow/d. The objective of the current study was to examine further the effect of maturity of maize silage at harvest on the performance of dairy cattle offered grass silages differing in feed value. The potential concentrate sparing effect of contrasting maize silages was also examined.

While the milk yield response of spring calving dairy cows to concentrate supplementation during the main summer grazing period has been examined in a number of studies, there is little information available concerning the milk yield response to supplementation in late summer/early autumn. With milk yield at this stage of the lactation having declined considerably, supplementation might appear unnecessary. However, herbage quality and availability are also lower in late season, and as such, responses to concentrate supplementation might be expected. This study was conducted to examine the milk yield response to concentrate supplementation of dairy cows grazing late summer/autumn grass.

Dairy cows are increasingly being fed high levels of starch to increase energy intake and promote milk protein content. However, too high levels of degradable starch can cause rumen acidotic effects leading to poor rumen health, laminitis and ultimately reduced efficiency of milk production. Fibrous feeds have known benefits on rumen health by helping to buffer rumen pH, but little is known of the effects of replacing starch with fibre in high maize silage based rations for dairy cows. The objective of this trial was to determine the effects of incremental replacement of cereal grain with sugar beet feed in a total mixed ration on dry matter intake, milk yield, milk composition and yield of milk constituents of lactating dairy cows receiving a high starch diet based on maize silage.

During the recent years, the use of yeast products as feed additives has been increased in animal nutrition (Newbold et al 1996). Results from various experiments indicate that these microorganisms are able to alter ruminal fermentation patterns and have positive effects on the performance of ruminants (Wolht, et al. 1998). Therefore, the aim of this experiment was to investigate the effects of Biosaf, a live yeast strain of saccharomyces cerevisiae (Sc 47), on feed intake, milk yield and composition in lactating Holstein cows.

The variation in milk production is a regular phenomenon in all milking animals, broadly the factors which are responsible for such variations can be divided into 1) Physiological, which will be governed by the genetically make up and 2) Environmental, such as age, number of previous lactations, pregnancy, season of calving, calving interval and nutrition status. The season of calving has got a marked effect on the total production. The objective of this study was to investigate the effect of season of calving and parity of Iranian Holstein dairy cows on the milk production.

The use of body tissue by dairy cows to support lactation is increasing, since selection has led to cows that can eat only around half of their incremental feed requirements per unit increase in genetic merit for milk production (Veerkamp et al., 1995). Continuing with this selection policy is likely to result in increasing use of body tissue to fuel milk production and to lead to thinner cows with associated health and fertility problems. This has created increasing interest in body condition scoring (CS) in dairy cows as both an important management tool and also for use in selection indices. The ability to automatically record CS would increase the use of this measure in farm management and enable large volumes of data to be collected for use in national evaluations.

The alcohol test is used as the initial classification of milk in dairy farms. It’s used as a measure of the natural pH of milk, which is a critical factor for stabilizing casein micelles in milk serum phase during heating (Barros et al., 2000). In practical conditions the test could be also positive immediately after milking, and this type of milk is rejected by dairy processing industry. An experiment was conducted to evaluate the effects of negative energy balance and low level of blood glucose on incidence of alcohol-positive milk in Holstein high milking cows (Sobhani et al., 2002).

Mountain pastures utilisation in the Basque Country by means of a free-range mixed-grazing system has suffered substantial changes during the last decades. Beef cattle production has increased partially favoured by CAP (Common Agricultural Policy) measures, mainly milk-quotas and the extensification premium. The use of mountain areas is constrained by both biotic and abiotic factors in cattle (Senft et al, 1985; Bailey, 1995) which are necessary to be identified in order to improve habitat management of these mountain zones, usually declared as protected areas. The objective of the current work was to study the influence of physical factors on the behaviour of beef-cattle herds managed in a transhumant free-range system.

Agriculture in general, and dairy production in particular, has been identified as one of the major sources of greenhouse gas emissions and other environmental pollutants such as nitrogen (N) (as ammonia, N and Nitrous oxides, and N leaching). Availability of cheap sources of protein has led to increased consumption of protein supplements. However, the protein is often utilised inefficiently and excess nitrogen is excreted particularly in urine, which has much more potential to pollute the environment. One of the obvious ways of reducing pollution is by evaluating the pollution potential of diets and formulating more balanced rations. A few technical mathematical models have been published but rarely do they consider more than one pollutant at a time. The objective of the present study was to develop a decision support system (DSS) by first integrating mechanistic models of N (Kebreab et al., 2002) and methane (Mills et al., 2001) with a rumen model (Dijkstra, 1994) and then develop a graphical user interface (GUI) for ease of use and analysis of outputs.

Previous attempts to apply statistical models, which correlate nutrient intake with methane production, have been of limited value where predictions are obtained for nutrient intakes and diet types outside those used in model construction. Dynamic mechanistic models have proved more suitable for extrapolation, but they remain computationally expensive and are not applied easily in practical situations. The first objective of this research focussed on employing conventional techniques to generate statistical models of methane production appropriate to UK dairy systems. The second objective was to evaluate these models and a model published previously using both UK and North American datasets. Thirdly, non-linear models were considered as alternatives to the conventional linear regressions. The UK calorimetry data used to construct the linear models were also used to develop the three non-linear alternatives that were all of modified Mitscherlich (monomolecular) form.

The primary emphasis in dairy cattle selection is for yield traits because highest producing cows usually are more profitable. Selection on yield traits alone could decrease merit for other traits. Selection on type traits associated with increased herd life may be benefical to decrease involuntry culling and increase profitability. One of the primary reasons for collecting and utilizing information on type is to aid breeders in selecting profitable, functional cows. So that early culling for causes unrelated to yield (involuntry culling) can be avoided [Misztal et al, 1992]. The objectives of the present study were to evaluate the effects of some environmental factors on and to estimate genetic parameters of some type traits.

The Iranian Animal Breeding Center (IABC) is currently milk recording and sampling three time per test-day(8 hours interval) approximately once every month. Milk samples are analyzed for fat and protein contents. There are some difficulties for having precise milk samples in some farms especially for three times sampling per day, and the costs of three times recording and sampling is also a problem. Estimation of lactation yield for milk, fat and protein yield is done based on test-day records and samples and the accuracy of there estimates depend on the precision of test day records especially milk sampling. The results of milk content are not satisfactory for farmer and specialist in the current milk recording system. Some researches have been done to reduce milk recording and sampling per test day (1, 2). In addition potential benefits of reducing milk recording and sampling are that more herds can be supervised and recorded per month. The objective of this research was to consider the possibility of reducing milk recording and sampling in herds with three times milking per test-day in industrial Holstein farms.

Recent research suggests that the genetic makeup of a pig may contribute to the expression of tail biting (Breuer et al., 2002). To date there has been little investigation into the genetics of tail biting. A significant population of tail biters was found at a commercial pig breeding farm at which an experiment on the genetic basis of the expression of harmful social behaviour was being performed. As pedigree data for each pig on the farm were available, the opportunity was taken to investigate the heritability of tail biting by recording the perpetrators of clinical tail biting.

In practical dairy cattle breeding programmes, usually a small number of animals (selected from a large population) have a major influence on the genetic gain of the concerned population over a period of time (Hofer, 1998). Candidate animals are usually selected based on their breeding values that are predicted by using animal models. In order to predict breeding values, genetic parameters (calculated from variance and covariance components) of the traits under consideration should be estimated to be used in genetic evaluation systems either based on lactation or test day models. The use of test day models has increasingly become of interest in genetic evaluation of dairy cattle due to the fact that they can take more accurate account of the effects of environmental factors influencing test day milk yield over the course of lactation. The main objective of this study was to use a repeatability test day animal model to estimate genetic parameters of monthly test day milk production traits in first parity Iranian Holsteins.

In Iran, sheep is a main domestic animal with population about 60 millions. So, evaluation of genetic variation in Iranian sheep is a critical necessity. This study is the first research on genetic variation within and between a small part of Iranian sheep using microsatellite markers.