Muscle fibre type can influence meat quality (Maltin et al 1997). Muscle fibre formation occurs during gestation and in the sheep the total number of fibres in a muscle is essentially fixed at birth. (Ashmere et al 1972). Postnatal growth of muscle is entirely due to elongation and widening of the existing muscle fibres. Therefore the gestational period is important in the long-term growth potential of the animal. By investigating changes in muscle fibre type, the aim of this study was to test the general hypothesis that the poor carcass quality sometimes seen in ruminant animals may be due to poor nutrition at strategic time points during the animal’s development. As agricultural practices continue to become more extensive, variation in the nutrient supply to the animal is becoming more common. Therefore it is important to understand the effect of any changes in nutrient supply to the mother, during gestation on the subsequent muscle development of the fetus and ultimately the effects on meat quality.

It is reported that supplementing pregnant ewes with supra-optimal levels of vitamin E improves neonatal lamb vigour and growth rate (Merrell, 1998). The biochemical mechanism behind these observations has yet to be elucidated as several studies report negligible placental vitamin E transfer in ruminants (Van Saun et al., 1989); consequently, lambs may be clinically deficient in this nutrient at birth and achieve a satisfactory vitamin E status via colostrum ingestion. Lamb vitamin E status may be further diminished by the addition of polyunsaturated fatty acids (PUFAs) to the maternal diet. However, PUFA supplementation demonstrably enhances foetal and neonatal development in human studies (Morley, 1998) although these effects have not been investigated in ruminants to any depth. The objective of this experiment was to investigate the effects of dietary vitamin E in combination with long-chain PUFA supplementation of ewes on ewe and lamb performance.

Vitamin E protects the animal from oxidative stress in vivo and when it is administered at supranutritional levels it enhances the oxidative stability of meat. Studies have shown that poor absorption of vitamin E often occurs when concentrates are fed to lambs. Distribution of vitamin E in plasma, skeletal muscle, liver (short-term and fast release depot) and adipose tissue (long-term and slow release depot) provides useful information about the overall vitamin E status of the animals. This work studied the distribution of vitamin E in the tissues after supplementation in relation to diet and to the dietary level.

Lower cost systems of sheep production, with reduced labour inputs, require examination for the future viability of the sheep industry. Carson and Dawson (2002) demonstrated that ewes lambing under grass-based systems had similar lamb outputs and survival rates to ewes lambing under labour intensive, indoor lambing systems. Although there is a significant amount of information is available on the effect of conserved forage on ewe performance in late pregnancy, there is a scarcity of information on the effect of grazed grass and concentrate supplementation at grass in late pregnancy on subsequent ewe performance. The aims of this study were to investigate the effects of herbage allowance and concentrate feed level during late pregnancy on ewe live weight and body condition change and lamb growth and development.

Much of the phosphorus in feed ingredients is unavailable to the pig because it is locked up in phytic acid and phytates, which the pig cannot digest. Raw ingredients that have not been heat-treated contain endogenous phytases which can be activated by steeping in water prior to inclusion in liquid feed for pigs. This results in an increase in soluble phosphorus due to the hydrolysis of phytic acid and phytates, and hence an increase in the phosphorus available to the pig. However, with heat-treated ingredients such as soyabean meal (SBM) endogenous enzymes are destroyed during processing. In liquid feed systems steeping combinations of raw materials may have an advantageous affect on the availability of phosphorus as the endogenous phytases of the cereal component of the diet may hyrolyse phytates present in SBM. In wheat the phytate phosphorus and phytase is concentrated in the aleurone layer of the grain (Eeckhout and De Paepe 1994). Therefore, the addition of wheatfeed to liquid feed may increase the amount of endogenous wheat phytase present and hence the amount of soluble P released during steeping. The amount of phosphorus that is available to the pig from these raw ingredients is 30%, 42% and 66% of the total phosphorus for SBM, wheat and wheatfeed respectively (Ewing 1997). The objective of this study was to determine the effect of steeping SBM with wheat, wheatfeed or a combination of the two on the release of soluble phosphorus.

Exogenous enzymes have been used in pig feed to reduce the antinutritional factors in the cereal components of the diets and, as a consequence, improve energy and protein digestibility. The predominant fibre components in barley are soluble β-glucans and insoluble arabinoxylans, both of which are known to have anti-nutritional effects in the pig but through different mechanisms. In wheat both soluble and insoluble arabinoxylans are relevant, for the same reasons (Partridge, 2001). Consequently a product with a combination of β-glucanase and xylanase may be necessary to elicit a performance improvement in pigs fed diets containing both barley and wheat. Furthermore, much work in grower/finisher pigs has been undertaken at single inclusion levels of enzyme product. The object of the current study was to compare the response of growing and finishing pigs fed diets containing barley and wheat supplemented with a β-glucanase and xylanase product included at different levels in the diet.

Phosphorus (P) is an essential mineral for pigs and deficiency can cause rickets, osteomalacia or osteoporosis and has been associated with poor fertility and production performance. Traditionally P has been supplied in the inorganic form as the organic form found in cereal grain (phytic acid) is unavailable to pigs as they lack endogenous phytase. Dietary phytases have been shown to play a major role in pig diets, releasing P from phytic acid thus decreasing the need for supplementary P and reducing P excretion (Harper et al 1997). Phytase supplementation has also been reported to improve digestibility of nitrogen, calcium, magnesium, zinc and copper (Jongbloed et al 1993). Some researchers (e.g. Jongbloed and Kemme 1990) suggest that diet processing may reduce enzyme activity and therefore liquid enzyme products have been developed which can be applied after processing. The aims of this study were to examine the effectiveness of several phytase products (including dry vs. liquid) in improving overall digestibility and reducing excretion of P and other nutrients.

Feeding and management during gestation focuses on preparing the sow for parturition and lactation. Despite improvements in husbandry in recent years, mortality remains around 10% and may be increasing (Herpin et al., (1993). Cole, (1990) found that foetal growth rate in the last trimester of pregnancy increases dramatically compared with early and mid-gestation and Cromwell et al., (1989) reported that a 75% increase in feed intake during the last 23 days of gestation increased reproductive performance and also increased birth weight of piglets (1.48 vs. 1.44, P < 0.003). Results from previous studies have also shown that an increase in feed intake from 2.3 kg to 3.9 kg per day can reduce sow backfat loss during the reproductive cycle and increases reproductive life (Miller et al., 2000). The study reported here investigated the influence of three different diet forms fed to gestating gilts for 14 days pre-farrowing, on litter characteristics at birth.

Gastrointestinal infections associated with E. coli represent a serious problem for neonatal pigs. These bacteria are present in the sow’s intestine in large numbers but increase dramatically just prior to farrowing due to stress occasioned by movement and parturition (Maclean and Thomas, 1974). Consequently, just 24 hours after farrowing, E.coli are found in high numbers (over 108/g) in the faeces of piglets. However, at this stage of its life the piglet is not equipped to deal with such a large microbial load and unless immunological assistance is provided, they have very little chance of survival. In pigs, all immunological assistance at birth is concentrated in the mother’s colostrum. Thus elimination, or at least minimizing, all the factors which negatively affect the sow’s ability to produce sufficient amount of milk becomes essential challenge of each efficient swine production. The main aim of this study was to investigate the potential of fermented liquid feed (FLF) to control the pathogen load within the piglet’s environment by reducing the rapid E. coli multiplication in sows associated with farrowing. The possible laxative effect of FLF, in order to prevent constipation and the problems it causes during farrowing, was also examined.

Achieving adequate feed intakes by sows, and particularly gilts, in lactation can often be a problem under intensive farrowing-house conditions. It has been shown that sow feed intake during lactation can significantly affect subsequent reproductive efficiency such as remating interval, pregnancy rate and embryo survival (Einarsson and Rojkittikhun, 1993). There are many nutritional, environmental and physiological factors that influence the sow’s appetite during lactation. The physical form of the diet (wet or dry) has also been shown to affect feed intake as sows ate 12 % more feed given as a wet mash compare with dry form (O’Grady and Lynch, 1978; Genest and Dallaire 1995). The growth of the piglets during the first 2 weeks of lactation depends entirely on the milk supply of the mother. As this has been shown to be influenced by the level of feed intake (Koketsu et al., 1996), factors controlling feed intake during lactation should determine the rate and efficiency of piglet growth. The aim of this study was to investigate the effect of three different forms of diet on lactation feed intake of gilts and growth performance of their piglets.

Salt (NaCl) is an essential mineral and its rate of inclusion in diets has been implicated in the development and expression of biting behaviour. Falkowski et al., (1998) found that withholding salt from diets reduced the feed intake and feed conversion ratio of weaned pigs and significantly decreased growth rate. Studies reported by Fraser (1987), suggested that heightened appetite for salt could make pigs particularly attracted to pen mates with injured tails. More recently Tsourgiannis, et al., (2002) reported that 1.5% salt inclusion levels can significantly reduce the incidence of tail-biting, providing that there is unrestricted access to fresh water. This study investigated the effect on growth performance of pigs fed liquid diets containing high and low dietary salt levels for growing/finishing pigs.

Simulation models allow the effects of a range of environmental and other variables on animal performance to be considered simultaneously in a way that cannot be done by direct experimentation. Consequently, limiting factors within a system can be identified, the effects of genetic selection predicted and areas needing further research highlighted. The aim here is to develop, test and evaluate a deterministic dynamic model that predicts over time the effect of genotype, the nutritional and thermal environments, including any interactions, on the voluntary feed intake (VFI), growth and body composition of pigs.

The association among feeding, body fat reserves, plasma leptin concentration and intake has been indicated in many reports, however the characteristics of these associations in late pregnant ruminants is not yet completely clear. As part of a larger experiment concerned with nutrition during the dry period (DP), a study was undertaken to identify the relationship between precalving fat and protein supplementation with plasma leptin concentration and the association of leptin with fat reserves and dry matter intake (DMI) during the periparturient period. Further results associated with this experiment were reported elsewhere (Jaurena et al., 2001a.,b; Jaurena et al., 2003).

Nutritional regime during the dry period (DP) has been shown to affect lactational performance in dairy cows. These responses could be mediated by a variety of mechanisms (e.g. increased labile body proteins, function of the mammary gland or the liver, or modifying endocrine status), which are likely to exert an overlapping function.This study analysed the effect of protein (P) and/or fat (F) supplementation in the DP on plasma metabolite and hormone concentrations, as a complement to studies on body composition (Jaurena et al. 2001b.) and subsequent milk production (Jaurena et al., 2001a.) performance. Other results also associated with this work are presented in Jaurena et al. (2003).

In bovine conceptuses, the trophoblast elongates rapidly from the 13th to the 19th day of pregnancy, while the embryonic disc differentiates to set up the primary germ layers and the axis of the fetus. Observations on pregnancies of cloned fetuses underline placental abnormalities which could originate from earlier gene deregulations occurring during this long pre-implantation period. To allow screenings with individual trophoblasts we used amplification protocols involving either PCR or in vitro transcription steps. For that purpose we used a bovine-specific macro-array starting from a cDNA library generated on early in vivo elongating conceptuses. RNAs from adult somatic tissues were used to compare hybridisation patterns generated with amplified and unamplified polyA+ probes.

The deficiency of some blood elements and metabolites such as phosphorus, calcium, haematocrit, hemoglobin, glucose and protein, and also increased the urea and total protein in blood appears to have an important role to control reproductive failures in dairy cows. Recent studies showed that some metabolites and nutritional factors are responsible for dairy cows infertility (Mc Clure, 1994, Ramakrishna, 1996). The energy shortage in postpartum period led to decrease in luteinizing hormone secretion frequency and dynamic follicle diameter, however it increases interval calving time (Almeida, 1995). The objective of this study was to investigate the relation between blood metabolites and elements on reproductive failures in dairy cows.

High genetic merit dairy cows were managed on four contrasting grassland based systems of milk production over a three-year period (Ferris et al., 2000). Each of the four systems were designed to incorporate a range of different approaches to increasing nutrient intakes. Key performance data from this study are presented in Table 1. The aim of this paper is to examine the effects of the four milk production systems on dairy cow fertility.

Bull calves have an increase in Gonadotrophin Releasing Hormone (GnRH) pulse frequency early in life that is responsible for a short-lived rise in circulating levels of LH. It has been shown that bulls with a higher early rise in LH attain puberty at younger ages and have comparatively enhanced semen quality once they mature (Evans et al., 1995). Furthermore testicular growth has been enhanced in calves by artificially inducing a premature increase in LH through administering GnRH i.v. every 2 hours between 4 and 6 weeks of age (Chandolia et al., 1997).

Introduction of a ram to anoestrous ewes induces an almost instantaneous rise in LH pulse frequency. This is commonly sufficient to overcome the seasonal suppression of the hypothalamic-pituitary axis and induce a synchronous first ovulation. This study investigates the application of repeated fence-line ram exposure during the beginning of the breeding season to synchronize oestrus and subsequent lambing in ewes.

Ovulation rate (OR) is depended to energy intake level (EIL) and body condition score (BCS) in ewe (Gordon, 1997). There is a high correlation between BCS and plasma leptin concentration (PLC) in sheep (Blache et al, 2000). Corresponding to leptin is a metabolic stimulant for reproduction (Barb et al, 1999), it is possible that leptin is involved in the ovulation rate in ewe. Therefore, first experiment was conducted to study the effect of EIL on body weight (BW), BCS, OR and PLC in a long period, and second experiment was designed to investigate the effect of EIL and leptin administration on OR in a short period in fat-tailed Shal ewes.