In order to assess the impact of methane (CH4) production from ruminants on the environment, and to measure the effects of various mitigation strategies for methanogenesis, it is necessary to accurately measure CH4 output under different scenarios. Techniques which enable measurement of CH4 output from individual animals can facilitate a meaningful investigation of factors affecting methanogenesis. Indirect open-circuit respiration calorimetry chambers are an efficient way to measure CH4 production from individual animals. However, chamber measurements cannot be used to measure CH4 output from grazing animals. To overcome this, the sulphur hexafluoride (SF6) tracer technique was developed by Johnson et al. (1994), and is widely used to measure CH4 emissions from individual grazing ruminants. Although the SF6 technique has been used quite extensively, relatively few studies have been carried out to validate its accuracy compared to respiration calorimetry studies. Additional validation studies are required to clarify the situation, especially for dairy cows which are major producers of CH4. Consequently, the objective of this experiment was to use indirect open-circuit respiration calorimetry chambers to validate the SF6 technique for measuring CH4 emissions from dairy cows, and to develop a prediction model for actual CH4 production of dairy cows from SF6 estimates.

Lactic acid bacteria (LAB) are often used as an inoculant to control the ensiling fermentation by rapid production of lactic acid and the consequent decrease in pH and improved silage preservation with minimal fermentation losses and fermentation of grass and legume silages. Microbial inoculation appears to have minimal effects on the fermentation of corn silage (Bolsen et al, 1992). However, changes in silage fermentation have not always been related to improved animal performance. However, Wohlt (1989) reported that inoculated silages appeared to be more stable upon exposure to air and, when fed to cows, increased FCM by 0.7 kg/d. The objective of this study was to determine the effect of microbial inoculation on the fermentation of corn silage treated with bacterial inoculants and the subsequent effect on nutritive value and performance by lactating dairy cattle.

Feeding high starch, low fibre diets to ruminants has been shown to decrease milk fat content (Choi et al. 2005). This effect may be due to the production of trans-10, cis-12 CLA in the rumen, which is a known inhibitor of milk fat synthesis in ruminants. Forage particle length may also have an influence on milk fat synthesis by altering ruminal pH (Beauchemin et al., 2003) and subsequently the production of trans-10, cis-12 CLA. The objectives of the current study were to evaluate the effects of starch content and forage particle length on the performance and production of trans-10, cis-12 CLA in dairy ewes.

Trans-10, cis-12 conjugated linoleic acid (CLA), a biohydrogenation intermediary produced in the rumen, has been shown to be a potent inhibitor of milk fat synthesis in dairy cows. Lock et al. (2006) demonstrated that milk fat synthesis in sheep was reduced to a similar extent as in dairy cows when a supplement containing CLA was fed at an equivalent level (metabolic body weight basis), although only one level of CLA inclusion was investigated. The objectives of this study were to examine the effects of level of inclusion of a ruminally protected source of trans-10, cis-12 CLA on milk fat synthesis and performance of dairy ewes.

Ewes are normally shorn once yearly, usually in early summer, to maintain sheep welfare and to minimize fly strike. Winter conditions in Ireland are characterized as relatively mild. Consequently ewes which are housed unshorn may have difficulty dissipating body heat due to the unique insulating properties of the fleece, leading to ineffective heat regulation. Results from previous studies at Athenry (Keady et al 2007, Keady and Hanrahan 2007) showed that shearing at housing increased lamb birth and weaning weights by up to 0.63 and 2.5 kg respectively. Shearing at housing may require a greater management input as ewes are normally housed in smaller groups and need to be dry prior to shearing. However, shearing in the autumn prior to mating enables the total flock to be assembled under more favourable conditions. The number of lambs weaned per ewe mated is the major factor influencing efficiency of prime lamb production (Keady and Hanrahan 2006). It is unknown if shearing prior to mating, in a temperate climate, impacts on subsequent ewe fertility and litter size whilst at the same time producing heavier lambs relative to shearing at the conventional time in early summer. The aim of this study was to evaluate the effect of the season of shearing on ewe fertility of March lambing ewes and subsequent lamb birth and weaning weights.

Ewes housed during the winter feeding period are predominantly offered grass silage as the sole forage. Approximately 55% of grass silage is ensiled in big bales on Irish sheep farms. Maize silage can be produced at a similar cost to grazed grass and approximately 20% cheaper than grass silage (Keady et al. 2002a). Recent studies have shown that maize silage inclusion in the diet increases the performance of dairy (Keady et al. 2002b, 2003) and beef (Keady and Gordon 2006, Keady et al. 2007) cattle. The objective of the present study was to evaluate the effects of grass silage harvest system, maturity of maize at harvest and protein supplementation of maize silage diets on the performance of ewes in mid and late pregnancy and subsequent lamb performance. The potential concentrate sparing effect of maize silage was also determined.

Dry matter intake (DMI) regulation is important in ruminants as DMI is a major determinant of milk and meat production. It is known that the gut peptides glucagon-like peptide-17, 36 amide (GLP-1) and cholecystokinin-8 (CCK) can reduce DMI in nonruminants (Walsh, 1994). In ruminants, there is little information on the function or effects of diet on plasma concentrations of these peptides. Previous studies have shown that supplemental dietary fat (Relling and Reynolds, 2007b) increases plasma concentrations of GLP-1 and CCK and decreases DMI. In contrast, increased metabolizable energy intake (MEI) in early lactation also increases GLP-1 and CCK concentration in dairy cows (Relling and Reynolds, 2007a). Therefore, our objective was to determine if plasma concentrations of GLP-1 and CCK are affected by supplemental fat, and if the response differs for ad libitum versus restricted DMI.

Whole soybeans (SB) are mostly used in feeding of dairy cows, but protein in raw SB is degraded readily by rumen microbes and cannot meet the high demand of rumen undegradable protein (RUP) in early lactation. Heat treatment of SB, especially roasting, reduces ruminal protein degradation and improves the nutrient balance for cows. However, there have been conflicting results regarding animal response to feeding heat treated SB. In many studies, increase in milk yield may be related to type of forage in the diet, as improved performance is usually achieved by diets with lucerne silage as the forage because of the high solubility of its protein, but mixed lucerne hay-maize silage as the primary forage source of diets that are used widely in tropical areas like Iran, was not tested. So, the main objective of this study was to investigate the performance responses of Iranian Holstein cows in early lactating to the feeding of Iranian roasted SB, raw SB and SBM in combination with lucerne hay-maize silage diets.

Pith bagasse one of industrial agriculture’s by product that is produced by several sugar cane factories in south west of Iran. The low dry matter digestibility of pith bagasse is influence by crud fibre content and is the reason of the poor quality. It is claimed that low dry matter digestibility improve by steam pressure hydrolysis (Medeiros et al. 1993, pessoa et al. 1997). There isn’t adequate information about the effect of hydrolyzed pith bagasse in ruminant nutrition. Therefore the aim of this experiment was to examine the effect of dietary containing different levels of pith bagasse on performance and carcass characteristics of fattening Arabi lambs.

There are numerous calf rearing systems but the last decade has seen increased interest in the use of computerised machine feeders for group reared calves in place of systems based on bucket rearing with individual housing. Automated machines are expensive but are becoming more common due to reductions in labour and advances in technology allowing regulation of milk intakes (Hepola, 2003). The objective of this experiment was to evaluate the effect of rearing dairy-bred bull calves on either a computerised machine or twice a day milk feeding system to weaning at 6 weeks old.

Enzymes are used to improve the nutritive value of feeds for nonruminants. Many experiments showed that enzymes substantially improved feed digestibility and animal performance in sheep and cattle, but results were often inconsistent (yang et al, 1999). Various results from recent studies can be contributed to a number of factors including diet composition, type of enzyme preparation, complement of enzyme activities, amount o enzyme provided, enzyme stability, and method of application (Schingoethe et al, 1999). Some experiments showed that type of forage and grains in rations can be as an important factor for effecting enzyme in diets (Beauchemin et al, 1999). The objectives of this experiment were to determine the effects of type of forage (Corn silage vs. barley silage) in diets with and without mixture enzyme in the diets of dairy cows on food intake, milk production, and milk production.

The effect of increasing energy supply through fat supplementation (Douglas et al., 2004) in transition period on plasma leptin concentrations was not elaborated. The main objective of this study was to determine the effects of supplemental fat in transition cow diets, with differing caloric densities, on plasma leptin, glucose and NEFA concentrations.

Previous investigations have quantified the significant variability in frozen semen quality from sport horse stallions based primarily in the UK (Tucker et al., 2007). Many competition stallions do not produce semen suitable for freezing, which limits the global distribution of their genetics. In this study, the second part of a series of trials, the influence of dietary supplementation with anti-oxidants on semen quality parameters was evaluated.

In recent years, the importance of fibre provision within the horse’s diet has been realised (Ralston 2005). Consideration of the evolutionary design of the animal, combined with a greater understanding of the aetiology of metabolic disorders, has re-iterated the need for horses to be fed diets high in fibre, especially those horses on maintenance rations. It has been acknowledged that although older horses can survive on maintenance rations, they are often at risk of weight loss (Ralston, 2005), a factor that is increased if dentition is poor (Dacre, 2005). Therefore nutritional management is vital to optimise nutrient provision. In dentally compromised animals, diet type and feed availability should be managed to promote ease of consumption, and subsequent factors compromising such consumption should be eliminated. Various methods of enhancing voluntary feed intake (VFI) have been devised (Dacre, 2005). Soaking hay may alleviate some problems associated with the ingestion and mastication of a course forage product, but can lead to consequences with decreased nutrient intake. Provision of softer fibre sources (haylage, silage) could also be considered, but will, conversely, increase nutrient intake. Short chopped fibre may decrease the overall need to chew. Other products, such as fibre pellets, may be fed soaked to horses with the most serious dental problems, thus removing the need for mastication. Currently there exists little information relating to VFI of various forage sources offered to older horses with compromised dentition. The aim of this study was to investigate dry matter intake (DMI), VFI and consumption rates of three fibre sources, hay (H), DM– 915g/kg, short-chop forage (SF), DM -860g/kg and soaked fibre pellets (FP), DM – 900g/kg, in veteran horses with poor dentition. SF and FP were both commercially available preparations consisting of high temperature dried grass and alfalfa (SF) and sugar beet and alfalfa (FP).

Selenium (Se) is a trace element of importance implicated in many processes such as antioxidant mechanisms, immune response, fertility in males and females, protection factor for cardiovascular diseases and some cancer processes (see review by Rayman 2000). There are mainly two modes of action for Se either by a direct implication of metabolites such as the methylselenol or by the specific effects of selenoproteins in which Se is an essential compound in the active site as selenocysteine. Glutathion peroxidase (GPx), thioredoxine reductase, iodothyronine deionidase are some of the selenoproteins. Most feedstuffs produced in Western Europe are low in Se. So, Se has to be supplemented in animal diets. This could be done either on an organic or on an inorganic form. Selenate contained in fertilizers is naturally transformed in organic forms such as selenomethionine by the plants. The aim of the present work was to assess, in exercised horses, the effects on the antioxidant status of feedstuffs produced with Se enriched fertilizers.

Probiotics have been found to stop pathogenic bacteria from colonising and flourishing in the gut and thus could potentially prevent illness and even death (Kyriakis et al., 1999). The organisms contained within probiotics are also suggested to be able to break down food into a higher number of volatile fatty acids, which increases energy production for the horse (Yuyama et al., 2004). Probiotics are however not very heavily researched in horses and the research which is present is either focused on neonates, young foals or older horses (Kumagai et al. 2004). Lactobacillus spp. are some of the most commonly used bacteria in equine probiotic supplements as they have shown good success in human based trials and seem to induce positive effects which would be useful to the horse (Laake et al., 2005). Research is however required in this area to investigate if Lactobacillus spp. can survive the acidic and bile environments of the equine gastrointestinal tract to a sufficient level to induce beneficial effects. The aims of this study were to discover if feeding a mixed culture probiotic supplement would alter the Lactobacillus spp. count in horses and whether this effect is similar in horses of different ages.

Weight estimation in foals is of vital importance for dosing of medication and antihelminthics as well as for assessing nutritional requirements to optimise growth. Calibrated weighbridges are not routinely available and estimates by eye or using weightapes can be inaccurate due to differences between adult and foal body dimensions. This study aimed to assess the applicability to Sport Horse type foals of two body weight estimation equations developed for American Thoroughbred (Staniar et al, 2004) and Warmblood (Hois et al, 2005) foals.

Many domestic horses are kept in an environment very different from that of free-living horses, consuming a varied ad libitum forage based diet for up to 18 hours of the day (Harris, 1999). Encouraging foraging behaviour, defined by Goodwin et al. (2002) to include sniffing, manipulating, biting, chewing or ingesting food, is thought to allow domesticated horses to spend more time eating, approaching the time spent on this activity in free-living horses. The diet of the free-living horse includes a selection of grasses and herbs (Putman et al., 1987) whereas most domestic horses are provided with a single forage diet (Goodwin et al., 2002). In a short term trial Goodwin et al. (2002) found that offering more than one source of forage to stabled horses resulted in them spending significantly more time foraging compared to a horse on a single forage diet. This effect was found to continue for longer periods by Thorne et al. (2005), with four forages being identified as maximising foraging time and minimising standing time (Dumbell and Tackley, 2007). Storing and using four forages may however be impractical for the single horse owner. The present study aimed to determine whether providing two forages or one forage as two different stem lengths increased foraging time when compared to a single forage.

Horses have evolved to naturally eat a mixed forage based diet (Thorne et al., 2005). Domestication has lead to restricted access to pasture and controlled monotonous diets unnatural to the horse, which may lead to Equine Gastric Ulcer Syndrome or Exertional Rhabdomyolysis (Azorturia), as well as behavioural ramifications. The discovery of a highly preferred forage type, more natural to the horse, may enrich the monotonous restricted environment and reduce the high amount of concentrates fed (Goodwin et al., 2007).

The Grassland Development Centre is a dedicated extension team embedded in a Research Institute whose remit spans from the cell to the landscape, from plant breeding to animal metabolomics, and from empirical blue sky science to applied farming systems research. The team seeks to bridge the gap between the researcher and potential end users and to develop research outcomes into commercial land use context with stakeholders.