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An experiment was carried out to examine the effects of offering beef cattle five silage diets. These were perennial ryegrass silage (PRGS) as the sole forage, tall fescue/perennial ryegrass silage (FGS) as the sole forage, PRGS in a 50:50 ratio on a dry matter (DM) basis with lupin/triticale silage (LTS), lupin/wheat silage (LWS) and pea/oat silage (POS). Each of the five silage diets was supplemented with 4 and 7 kg of concentrates/head/day in a five silages × two concentrate intakes factorial design. A total of 90 cattle were used in the 121-day experiment. The grass silages were of medium digestibility and were well preserved. The legume/cereal silages had high ammonia N, high acetic acid, low lactic acid, low butyric acid and low digestible organic matter concentrations (542, 562 and 502 g/kg DM for LTS, LWS and POS, respectively). Silage treatment did not significantly affect liveweight gain, carcass gain, carcass characteristics, the instrumental assessment of meat quality or fatty acid composition of the M. longissimus dorsi muscle. In view of the low yields of the legume/cereal crops, it is concluded that the inclusion of spring-sown legume/cereal silages in the diets of beef cattle is unlikely to be advantageous.
An experiment was carried out to examine the effects of offering beef steers grass silage (GS) as the sole forage, lupins/triticale silage (LTS) as the sole forage, a mixture of LTS and GS at a ratio of 70:30 on a dry matter (DM) basis, vetch/barley silage (VBS) as the sole forage, a mixture of VBS and GS at a ratio of 70:30 on a DM basis, giving a total of five silage diets. Each of the five silage diets was supplemented with 2 and 5 kg of concentrates/head/day in a 5 × 2 factorial design to evaluate the five silages at two levels of concentrate intake and to examine possible interactions between silage type and concentrate intake. A total of 80 beef steers were used in the 122-day experiment. The GS was well preserved while the whole crop cereal/legume silages had high ammonia-nitrogen (N) concentrations, low lactic acid concentrations and low butyric acid concentrations For GS, LTS, LTS/GS, VBS and VBS/GS, respectively, silage DM intakes were 6.5, 7.0, 7.2, 6.1 and 6.6 (s.e.d. 0.55) kg/day and live weight gains were 0.94, 0.72, 0.63, 0.65 and 0.73 (s.e.d. 0.076) kg/day. Silage type did not affect carcass fatness, the colour or tenderness of meat or the fatty acid composition of the intramuscular fat in the longissimus dorsi muscle.
Lamb mortality represents a major loss to the sheep industry with up to 10% of lambs born dead and a further 12% dying from birth to weaning (Dawson and Carson, 2002). Supplementing ewes in late pregnancy with fish oil has been demonstrated to improve lamb vigour at birth (Capper et al., 2002). However, Annett et al. (2004) observed that fish oil supplementation severely reduced colostrum yield and lamb output at weaning. The aim of the current study was to evaluate the effect of level and source of fish oil on ewe and lamb performance in order to minimise the negative effects on colostrum production and performance up to weaning.
Adipose tissue becomes more saturated and less unsaturated with age (Kemp et al., 1981). Desaturation of stearic acid to the oleic acid is catalysed by stearoyl-CoA desaturase (SCD) and increasing the degree of desaturation of lamb is likely to be beneficial in terms of human nutrition. By altering the levels of ovine SCD mRNA, the supply of oleic acid to the tissue could be manipulated, resulting in a practical method of changing the fatty acid profile of the animals meat. Previous work in our laboratory has shown variability between adipose tissue depots in their expression of SCD and that this variability is associated with changes in oleic acid content (Daniel et al, 2004). Such differences in SCD expression between depots implies that there may be even larger variation in SCD expression between breeds. A sheep breed with particularly high level of SCD mRNA could then be exploited through breeding programmes to produce animals with increased desaturase activity and therefore increased oleic acid content. Three sheep breeds, Texel, Beulah and Soay, were therefore used to study the influence of breed and age on SCD expression.
Data from the US (Van Amburgh et al., (2001)) suggests that the current UK recommendations for feeding the neonatal calf (˜500g milk replacer/d, at ˜230 g crude protein per kg fresh milk powder) are inadequate to sustain high growth rates in early life. It has been suggested that increasing nutrition during the first 6-8 weeks of the calf’s life will improve lifetime production, health and fertility. An experiment was therefore initiated to investigate the influence of level of milk replacer feeding and the crude protein content of the milk replacer on calf performance during the first 8 weeks of life, under UK conditions.
Relative to purebreeding, crossbreeding in the hill flock has been shown to increase lamb growth rates from birth to weaning by up to 12% and weight of lamb weaned by up to 24%, depending on ewe and ram breeds concerned (Carson et al 2001). Traditionally crossbred females produced in the hill are sold to the lowland as replacement females, so that potential hybrid vigour effects associated with crossbreeds are not fully exploited in the hill environment. A research programme has been established in Northern Ireland to investigate the potential for retaining crossbred females in the hill environment, as replacement breeding females, to improve the genetic potential of the hill flock. This paper presents the results from the first phase of the study which involved the production of the crossbred lambs from Scottish Blackface ewes (over 3-years) and the first year of the second phase, an evaluation of the performance of crossbred ewes as breeding females in the hill sector.
Results of a recent study (Wicks et al. 2005) indicate that increasing the protein content of the milk replacer fed to autumn-born Holstein-Friesian calves reduced growth rates in the first 8 weeks of life. Van Amburgh et al., (2001) previously suggested that increasing both milk replacer intake and protein content maximised the growth of calves during this early phase of life. An experiment was undertaken to investigate the influence of level of milk replacer and crude protein content on calf performance during the first 8 weeks of life of spring-born calves.
Lowland sheep farmers in Northern Ireland depend heavily on the hill sector for replacement breeding ewes. Thus changes in the genetics of the ewes and rams used in the hills are likely to have major implications on the performance of lowland breeding ewes. Crossbred females were produced in the study by Carson et al. (2000) as a result of crossing Scottish Blackface and Wicklow Cheviot ewes with a range of sire breeds. The objective of this study was to provide information on the productivity of these crossbred females for lowland producers.
Wilting of grass prior to ensiling generally produces positive responses in dry matter (DM) intake of cattle, but the responses in animal performance are often small, or even negative. The primary objective of the present study was to compare energy utilization from heavily wilted and unwilted silages by growing cattle when given at equal metabolisable energy (ME) intakes. A secondary objective was to evaluate effects of silage additive type (inoculant v. formic acid) on energy utilization.
Four silages were produced from unwilted and wilted grasses (DM 193 and 450 g/kg) obtained from a perennial ryegrass sward. The wilted grass was dried in the field for 26 hours using rapid wilting techniques involving crop conditioning and spreading. At ensiling both the unwilted and wilted grasses were each treated with two additives, a bacterial inoculant (Ecosyl, Zeneca Bioproducts Limited) and a formic acid additive (ADD-F, BP Chemicals Ltd.).
The intensity ratios of HCO+/HCN and HNC/HCN (1-0) reveal the relative influence of star formation and active galactic nuclei (AGN) or black holes on the circum-nuclear gas of a galaxy, allowing the identification of X-ray dominated regions (XDRs) and Photon-dominated regions (PDRs). It is not always clear in the literature how this intensity ratio calculation has been, or should be performed. This paper discusses ratio calculation methods for interferometric data.
A survey of the Milky Way disk and the Magellanic System at the wavelengths of the 21-cm atomic hydrogen (H i) line and three 18-cm lines of the OH molecule will be carried out with the Australian Square Kilometre Array Pathfinder telescope. The survey will study the distribution of H i emission and absorption with unprecedented angular and velocity resolution, as well as molecular line thermal emission, absorption, and maser lines. The area to be covered includes the Galactic plane (|b| < 10°) at all declinations south of δ = +40°, spanning longitudes 167° through 360°to 79° at b = 0°, plus the entire area of the Magellanic Stream and Clouds, a total of 13 020 deg2. The brightness temperature sensitivity will be very good, typically σT≃ 1 K at resolution 30 arcsec and 1 km s−1. The survey has a wide spectrum of scientific goals, from studies of galaxy evolution to star formation, with particular contributions to understanding stellar wind kinematics, the thermal phases of the interstellar medium, the interaction between gas in the disk and halo, and the dynamical and thermal states of gas at various positions along the Magellanic Stream.
The purpose of this study was to examine global epidemiological trends in human norovirus (NoV) outbreaks by transmission route and setting, and describe relationships between these characteristics, viral attack rates, and the occurrence of genogroup I (GI) or genogroup II (GII) strains in outbreaks. We analysed data from 902 reverse transcriptase–polymerase chain reaction-confirmed, human NoV outbreaks abstracted from a systematic review of articles published from 1993 to 2011 and indexed under the terms ‘norovirus’ and ‘outbreak’. Multivariate regression analyses demonstrated that foodservice and winter outbreaks were significantly associated with higher attack rates. Foodborne and waterborne outbreaks were associated with multiple strains (GI+GII). Waterborne outbreaks were significantly associated with GI strains, while healthcare-related and winter outbreaks were associated with GII strains. These results identify important trends for epidemic NoV detection, prevention, and control.
InxGa1-xN-based LED structures were grown on digital AlxGa1-xN/GaN DBR substrate to enhance emission extraction. Same LED structure was grown on sapphire substrate as a comparison. LEDs grown on DBR substrate exhibited similar IV characteristics to that grown on sapphire substrate but emission-angle-dependent EL spectra were observed. Also, the resonant vertical cavity modes were observed in EL spectra of LEDs with DBR structure and compared to simulated results. Image processing analysis results show that light extraction of LEDs is enhanced with use of DBR substrate.
The dry period is required to facilitate cell turnover in the bovine mammary gland in order to optimize milk yield in the next lactation. Traditionally, an 8-week dry period has been a standard management practice for dairy cows based on retrospective analyses of milk yields following various dry period lengths. However, as milk production per cow has increased, transitioning cows from the nonlactating state to peak milk yield has grown more problematic. This has prompted new studies on dry period requirements for dairy cows. These studies indicate a clear parity effect on dry period requirement. First parity animals require a 60-day dry period, whereas lactations following later parities demonstrate no negative impact with 30-day dry period or even eliminating the dry period when somatotropin (ST) is also used to maintain milk yields. Shortened dry periods in first parity animals were associated with reduced mammary cell turnover during the dry period and early lactation and increased numbers of senescent cells and reduced functionality of lactating alveolar mammary cells postpartum. Use of ST and increased milking frequency postpartum reduced the impact of shortened dry periods. The majority of new intramammary infections occur during the dry period and persist into the following lactation. There is therefore the possibility of altering mastitis incidence by modifying or eliminating the dry period in older parity animals. As the composition of mammary secretions including immunoglobulins may be reduced when the dry period is reduced or eliminated, there is the possibility that the immune status of cows during the peripartum period is influenced by the length of the dry period.
Government policies relating to red meat production take account of the carbon footprint, environmental impact, and contributions to human health and nutrition, biodiversity and food security. This paper reviews the impact of grazing on these parameters and their interactions, identifying those practices that best meet governments’ strategic goals. The recent focus of research on livestock grazing and biodiversity has been on reducing grazing intensity on hill and upland areas. Although this produces rapid increases in sward height and herbage mass, changes in structural diversity and plant species are slower, with no appreciable short-term increases in biodiversity so that environmental policies that simply involve reductions in numbers of livestock may not result in increased biodiversity. Furthermore, upland areas rely heavily on nutrient inputs to pastures so that withdrawal of these inputs can threaten food security. Differences in grazing patterns among breeds increase our ability to manage biodiversity if they are matched appropriately to different conservation grazing goals. Lowland grassland systems differ from upland pastures in that additional nutrients in the form of organic and inorganic fertilisers are more frequently applied to lowland pastures. Appropriate management of these nutrient applications is required, to reduce the associated environmental impact. New slurry-spreading techniques and technologies (e.g. the trailing shoe) help reduce nutrient losses but high nitrogen losses from urine deposition remain a key issue for lowland grassland systems. Nitrification inhibitors have the greatest potential to successfully tackle this problem. Greenhouse gas (GHG) emissions are lower from indoor-based systems that use concentrates to shorten finishing periods. The challenge is to achieve the same level of performance from grass-based systems. Research has shown potential solutions through the use of forages containing condensed tannins or establishing swards with a high proportion of clover and high-sugar grasses. Relative to feeding conserved forage or concentrates, grazing fresh grass not only reduces GHG emissions but also enhances the fatty acid composition of meat in terms of consumer health. It is possible to influence biodiversity, nutrient utilisation, GHG emissions and the nutritional quality of meat in grass-based systems, but each of these parameters is intrinsically linked and should not be considered in isolation. Interactions between these parameters must be considered carefully when policies are being developed, in order to ensure that strategies designed to achieve positive gains in one category do not lead to a negative impact in another. Some win–win outcomes are identified.
Magneto—optic studies on InGaAs/GaAs and GaAs/GaPAs strained—layer superlattices are used to determine the in—plane light—hole valence—band effective masses. Also, hydrostatic pressure—dependent magneto—optic studies have been performed on these samples for magnetic fields up to 65 kG andpressures to 4 kbar in the temperature range of 1.6 - 4 K. The experimental pressure coefficients of the band—gap energy and the effective mass in the InGaAs/GaAsSLS structures were determined.
Epitaxical growth rates depend strongly on the crystalline orientations of substrate surfaces. Multilayer growth on pre-patterned substrates with various crystal facets exposed results in a large variation of layer thicknesses in the lateral direction. This lateral definition can be used in device applications. Alternating layers of GaAs and AIGaAs were grown by molecular beam epitaxy on (100) GaAs substrates patterned with grooves and ridges along the [01T] and  directions by chemical etching. The results were analyzed with transmission electron microscopy using vertical cross-section techniques. Examples of using this method to fabricate ridges with tips of atomic sharpness and quantum-well lasers are presented.
We have examined the optical and transport properties of In.2Ga.8As/GaAs straled-kayer superlZotices (SLS's), which have been implanted either with 5 × 1015/cm2, 250keV Zn+ or with 5 × 1014/cm2, 70keV Be+ and annealed under an arsenic overpressure at 600 °C. For both cases, electrical activation in the implantation-doped regions equalled that of similar implants and anneals in bulk GaAs, even though the Be implant retained the SLS structure, while the Zn implant intermixed the SLS layers to produce an alloy semiconductor of the average SLS composition. Photoluminescence intensities in the annealed implanted regions were significantly reduced from that of virgin material, apparently due to residual implant damage. Diodes formed from both the Be- and the Zn-implanted SLS's produced electroluminescence intensity comparable to that of grown-junction SLS diodes in the same chemical system, despite the implantation processing and the potential for vertical lattice mismatch in the Zn-disordered SLS device. These results indicate that Zn-disordering can be as useful in strained-layer superlattices as in lattice-matched systems.
Heteroepitaxial ZnSe grown by molecular beam epitaxy (MBE) has been characterized using low temperature photoluminescence (PL) and reflectance. Excitonic PL linewidths of thick (relaxed) ZnSe layers are>1.4 meV, and depend little on the type of substrate or buffer layer used (e.g. GaAs or AlAs). In contrast, thin (pseudomorphic) ZnSe layers on AlAs buffer layers of moderate thickness are found to exhibit by far the sharpest (FWHM=0.22-0.37 meV) excitonic features ever observed for heteroepitaxial ZnSe grown by any technique. A tentative explanation for this result is that step-grading the lattice constant (by the AlAs buffer layer) has eliminated the crystal defects which produce localized strain fields that inhomogeneously broaden the peaks in ZnSe/GaAs. Acceptor-related PL peaks are discussed, and the first discrete donor-acceptor pair line spectrum in heteroepitaxial ZnSe is reported.
We have grown ZnSe epitaxial layers on bulk GaAs substrates and on GaAs epitaxial layers, with both As-rich and Ga-rich surface terminations. We have also grown ZnSe on AlAs epitaxial surfaces with different As to Al ratios. In all cases, abrupt, layer-by-layer growth is observed on the As-rich surfaces, while 3-dimensional nucleation is observed on the group III-rich surfaces. GaAs was also grown on ZnSe layers. In this case, microtwins form at the interface whose density diminishes as the layer is made thicker. A growth model is proposed consistent with these results which requires over-all electronic balance at the interface.