Mechanical properties of the hoof horn such as hardness, elastic modulus, bending stiffness and fracture toughness were influenced by the moisture content of the hoof horn (Collins et al., 1998; Baillie et al.; 2000). The moisture content of the hoof horn has been found to be affected by the micro-architecture and biochemical composition of the horn and by external factors such as humidity, chemicals and microbiological factors (Budras and Mulling, 1998). The aim of the experiment was to determine the influence of the moisture content and of storage methods, such as refrigerating in plastic bags and freezing, over the punch resistance and elastic modulus of the bovine hoof horn. Storage methods were studied for the determination of an experimental protocol in further research.

Selenium is an essential nutrient for dairy cattle, being a key component of the anti-oxidative protection mechanism. With over 20 seleno-proteins being identified in the body as important nutrients or co-factors for the physiological processes involving production, health and fertility, the need for ensuring a selenium supply which is both efficacious and safe has increased dramatically. Key roles of selenium include supporting the immune function and fertility. In terms of reproduction its main action is to protect the developing embryo from oxidative damage. Concern over the sufficiency of selenium supply has increased in recent years and it is well recognised that the British Isles is deficient in selenium as measured in soils and crops. As a consequence, the animal is totally dependent for its selenium supply on concentrated feedstuffs and mineral supplements. There is a cautious approach to dietary supplementation of selenium because of its toxicity even though a legal limit of 0.50 mg/kg in dairy complete feeds applies. It is also recognised that traditional sources of selenium (sodium selenite) have limited availability and utilisation within the animal. Considerable research effort has been directed at evaluating the key selenium metabolite “L-Selenomethionine” as a potential dietary selenium source. Much of the naturally supplied selenium from feedingstuffs is in this form. Supplying a significant proportion of selenium in the organic methionine form has been found to both reduce potential toxicity problems and boost absorption. The aim of this trial was to compare two selenium supplements, selenium selenite (inorganic) and selenium metalosate (organic) in the dairy cows diet and investigate effects on milk yield, milk composition and hygiene, and fertility.

A high plane of nutrition during early gestation has a detrimental effect on the establishment of pregnancy in adolescent but not mature ewes. Elevated insulin levels in well-fed adolescent ewes have been implicated in maintaining the anabolic drive to maternal growth at the expense of foetal tissue synthesis (Wallace et al., 1997). The adipocyte hormone, leptin has effects on food intake, body weight stasis and the gonadotrophic axis and therefore may also, like insulin, be implicated in the establishment and success of pregnancy. The objectives of the current experiment were to investigate the effects of plane of nutrition in mature and adolescent ewes during the first month of pregnancy on changes in maternal concentrations of insulin, leptin and blood metabolites.

The functional ovary of the mature goose generally contains numerous small white and yellowish follicles, five to nine yellow preovulatory follicles arranged in a follicular hierarchy and several postovulatory follicles. Unlike the mammals, in the birds no corpus luteum is formed following ovulation, but the postovulatory follicles (POF) (Johnson, 1990), which is followed by regressions and resorption via apoptosis. It has been reported that POF are physiologically active during several days and have steroidogenic capacity. Earlier studies in hen showed that 3β-HSD activity was present in the granulosa layer of the postovulatory follicles (Nitta et al., 1993).

Despite strong interest in bird reproductive system there is only little information on the goose ovarian system. Relatively few data are on the steroid concentration in the theca and granulosa layer of the postovulatory follicles in the hen (Dick et al., 1978) but in the goose have not jet been determined. Therefore the aim of the study was to determine concentration of progesterone, estradiol and androgens in different sizes of the postovulatory follicles.

The follicular wall of the ovarian follicles play very important roles for the development of oocyte and ovulation. The major function of this tissue is the biosynthesis of steroids. One of the key enzyme of the steroidogenesis is 3β-hydroksysteroid dehydrogenase (3β-HSD) which converting dehydroepiandrosterone to androstenedione in the ∆5-3β-hydroksysteroid pathway and pregnenolone to progesterone in the ∆4-3-ketosteroid pathway. Lee and Bahr (1994) suggested that both ∆5 and ∆4 pathway are functional in ovarian follicles. Recently Lee et all (1998) reported that theca layer preferentially metabolises steroids via the ∆5 pathways regardless of the maturational stage of the follicles, while the granulosa layer of preovulatory follicles metabolises steroids via the ∆4 pathways. In white follicles the granulosa layer is steroidogenically inactive (Tilly et al., 1991). The changes of 3β-HSD activity in the follicles of the chiken ovary during follicular development are well known (Tilly et al., 1991). However the activity of 3β-HSD in granulosa layer of the yellow preovulatory ovarian follicles of the goose has not yet been determined. Therefore the aim of this study was to determine two steroidogenic pathways present in the isolated granulosa layer of the preovulatory follicles of the goose, by examined enzymatic activity of 3β-HSD using P5 and DEHA as a substrate.

Rate of testis growth was found to be more rapid in ram lambs of a breed with high prolificacy such as the Finnish Landrace than in a non- prolific breed such as the Scottish Blackface (Land and Carr, 1975). Also, Louda et al. (1981), after observing testis growth, and small but consistent differences in the development of sexual activity and of sperm production, suggested that young rams of prolific breeds (Romanov and Finnish Landrace) may differ in their potential reproductive performance, though slightly. Crossbreeding, primarily a breeding system for commercial production is to take advantage, as far as possible, of good qualities of two or more breeds of distinctly different types (Rice et al.1957). Thus, the present study was conducted to evaluate breeds and reciprocal crossbreeding effects on development of two testicular parameters and body growth in growing Awassi, Redkaraman purebred and their reciprocal crossbred ram lambs.

Glycerol is the most commonly used protective substance in diluents for freezing ram semen (Salamon and Maxwell, 2000). Colas (1975) examined two concentrations of 2 and 4% glycerol for freezing ram semen and recommended an optimal level of 4% glycerol, although it may be slightly toxic to spermatozoa. The optimum concentration of glycerol for freezing ram semen is also influenced by type of diluent (Salamon and Maxwell, 2000). The objective of this study was to investigate the effect of three levels of glycerol 3, 4 and 5% and two types of diluents on motility and live rates of Baluchi ram spermatozoa.

Currently in Northern Ireland 47% of prime beef production is sourced from the dairy herd, and this proportion is likely to increase post implementation of the Mid Term Review of the Common Agricultural Policy. Whilst Holstein Friesian cows form the main blood line within the dairy herd there is currently major interest in the use of alternative dairy breeds and cross breeding as a way of improving herd fertility and longevity. The present study was undertaken to investigate the effects of two pure dairy breeds and their reciprocal crosses on the performance of finishing beef cattle.

Feed accounts for a large proportion of the costs of finishing beef cattle. Concentrate supplements are fed either as coarse or pelleted rations. Method of ration preparation may affect feed intake and animal performance. Currently in Northern Ireland 55% of beef farmers are part time and consequently feeding concentrates in one feed per day is a practical option on many units to reduce labour requirement. The effects of method of processing concentrate supplement and number of feeds per day on forage intake and animal performance were also evaluated in this study.

Many factors, including plane of nutrition and gender affect the lifetime growth rate of beef cattle, during both the growth and finishing phases. Previous studies have clearly illustrated that a restriction in growth during one period of life results in compensatory growth later in life provided a high plane of nutrition is available during realimentation. It is essential that producers increase final carcass value by achieving cost effective performance at different stages during the life cycle. The aim of the present study was to evaluate the effects of plane of nutrition during the first winter growth and final winter finishing phases on the performance of finishing steers and heifers. Furthermore the effects of ad libitum concentrate systems during the finishing phase were also evaluated.

Previous work (Hyslop et al, 2003) has shown that when finished intensively, 3/4 beef-bred weaned suckled bulls from the UK suckler herd can produce high quality carcasses efficiently with rapid growth rates. Attempting to finish heifers rapidly has traditionally proved difficult since heifers are prone to high carcass fat levels at unacceptable low carcass weights. The objectives of this study were to examine intake, growth and slaughter parameters of weaned suckled heifers from contrasting suckler cow types which had been sired by either a traditional UK beef breed or a continental beef breed and subsequently finished rapidly to slaughter at 14-15 months of age.

Since feed accounts for 65-85% of the variable costs of beef production, the use of alternative feeds and high-energy forages that have a lower cost per unit of energy are worthy of investigation. The objective of the experiment was to determine the effect of feeding either fermented whole crop (FWC), Head-cut or Low-cut processed urea treated whole crop wheat (Alkalage) in comparison to ad libitum cereals/protein on the performance of intensively finished continental cross beef cattle.

Artificial rearing is a common practice for rearing calves from the dairy herd destined for beef production. Calves fed increased amounts of milk replacer in early life have higher live weight gains than those on lower levels of milk and are subsequently heavier at weaning. After a period of nutritional restriction beef animals can exhibit compensatory growth. However it has been suggested that growth restriction in early life can result in reduced levels of compensation (Ryan, 1990). The objective of this study was to determine the effect of increasing the daily allowance of milk replacer offered on a restricted basis to Continental x Holstein beef calves during the first 6 weeks on compensatory growth from weaning to 11 weeks.

Recent efforts to enhance the productive performance of ruminants through improved synchronisation of energy and N supplies in the rumen did not result in detectable benefits for the animals (Richardson et al., 2003). As suggested by Lapierre and Lobley (2001), the movements of N across the gut play a major role in regulating the amount of ruminally available N and provide an overall plasticity to allow rapid response to any changes in metabolic status. The objective of the present study was to examine the effects of various levels of imbalance between energy and N release in the rumen on the double-muscled Belgian Blue (dm-BB) digestion and N metabolism.

The number of Holstein bulls finished on high concentrate diets in Northern Ireland has increased in recent years. This has reflected the ready availability at low cost of calves from the dairy herd and the availability of bull beef premiums, as well as the reduction in cereal prices realised over the last few years. The addition of yeast cultures to ruminant rations may have beneficial effects on feed efficiency and growth rate and are therefore of considerable interest in view of the current low profitability in the beef industry. The objective of the present study was to evaluate the potential of a yeast culture-based feed additive to improve the performance of Holstein-Friesian bulls when finished on a high-concentrate diet.

Skatole is formed as a result of bacterial degradation of tryptophan in the rumen of cattle and sheep, and the hindgut of pigs. It accumulates in fat where it is an important component of boar taint in pigs (Claus et al, 1994), and with branched chain fatty acids, has been implicated as a contributor to the strong flavour characteristic of sheepmeat (Young et al, 1997). This study examines the role of breed, diet and age on skatole deposition in the fat and perception of beef flavour.

Grazing cattle often require supplemental nutrients, especially at times when forages are dormant. To meet this requirement, producers have several options. They may supplement proteins or non-protein N (such as urea) or a combination. Urea is rapidly hydrolyzed to ammonia; consumption of high levels of urea could lead to ruminal ammonia accumulation, inefficient use of N by the animal and animal ammonia toxicity. Moreover, environment pollution is another problem when inefficient use of N occurs. Natural Zeolite is an Aluminosilicate with Cation Exchange and adsorption properties (Tomlinson, 1998). We hypothesized that Natural Zeolite can adsorb ammonia when its concentration in the rumen is high, and return it when ammonia concentration is low. Therefore, this effect can reduce ammonia toxicity and enhance calves performance and carcass traits. This study was conducted to determine the effect of natural zeolite on ammonia toxicity, carcass traits, performance and nutrient digestibility in finishing Holstein calves.

Parasitic intestinal infections can affect the health of calves inducing symptoms like loss of appetite, diarrhoea, nutritional deficiency, loss of protein, and reduced weight gain. Cooperia punctata is the most prevalent parasitic intestinal nematode in Brazil (Lima, 1998) and its site of fixation is the upper part of the small intestine, i.e., duodenum and jejunum (Bailey, 1949) that are also the sites of greatest dietary phosphorus absorption (Schröder et al., 1995). Thus, the damage caused by the parasite when it penetrates the intestinal epithelium can interfere with phosphorus metabolism. The objective of this experiment was to evaluate the true phosphorus absorption by calves submitted to an acute infection with C. punctata using the 32P isotopic dilution technique.

Selenium (Se) is a trace element of large importance owing to its implications in many metabolisms both in animals and in humans. Se participates in the antioxidant protection of cells and shows profound effects on health as e.g. cancer protection, antiviral effect, cardiomyopathy prevention,… in men (see review by Lyon et al 2003) and as prevention of metritis, mastitis or myopathies in cattle (Jukola et al, 1996). There are areas -Belgium e.g.- in which the Se content of feedstuff for cattle is rather low. Se is available for plants from the soil. The aim of the present work was to increase the Se content in grass silage and winter barley using Se enriched fertilizers for young growing bulls.

Selenium (Se) intake in human is rather low in many countries (Combs 2001). Different strategies to increase human selenium intake were summarized recently by Lyons et al (2003). Selenium fertilization of crops and grass based on the Finnish experiment of the early 80 trebled Se intakes and nearly doubled plasma Se concentration within 3 years of programme’s initiation. Meat from Se supplemented animals contains Se at a high level so that such a meat contributes to a large extent of Se supply for man. The aim of the present work was to assess the effect of selenium enriched winter barley in fattening bulls with large muscle development.

The Major Histocompatibility Complex (MHC) class I genes encode polymorphic cell surface glycoproteins that initiate cytotoxic immune responses by presenting processed antigenic peptides to CD8+ T cells. Due to their functional role and polymorphic nature, MHC class I genes have been used in disease association and vaccine development studies in many species. A prerequisite for such studies is the availability of animals of defined MHC haplotypes. However, the ovine MHC (OLA) class I genes have been studied largely by serology and very limited information is available at the DNA level (Dietert R., 1996). In this study, we aimed to identify the number of transcribed OLA class I genes in two Blackface rams and to obtain sequence data for exons 2 and 3. These data will be used to establish an allele specific PCR based typing system to genotype a cohort of progeny for each ram. This will enable allocation of alleles to individual haplotypes and inform a breeding strategy for the generation of MHC defined animals for functional and disease association studies.