To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Giardia duodenalis and Cryptosporidium spp. are common intestinal protozoa that can cause diarrhoeal disease. Although cases of infection with Giardia and Cryptosporidium have been reported in Alaska, the seroprevalence and correlates of exposure to these parasites have not been characterised. We conducted a seroprevalence survey among 887 residents of Alaska, including sport hunters, wildlife biologists, subsistence bird hunters and their families and non-exposed persons. We tested serum using a multiplex bead assay to evaluate antibodies to the Giardia duodenalis variant-specific surface protein conserved structural regions and to the Cryptosporidium parvum 17- and 27-kDa antigens. Approximately one third of participants in each group had evidence of exposure to Cryptosporidium. Prevalence of Giardia antibody was highest among subsistence hunters and their families (30%), among whom positivity was associated with lack of community access to in-home running water (adjusted prevalence ratio [aPR] 1.15, 95% confidence interval (CI) 1.02–1.28) or collecting rain, ice, or snow to use as drinking water (aPR 1.09, 95% CI 1.01–1.18). Improving in-home water access for entire communities could decrease the risk of exposure to Giardia.
A 4-year (2010–2013) plot study was undertaken to evaluate the effect of nitrogen (N) fertilizer rate (0, 60, 120, 196 and 240 kg N/ha/year) on seasonal responses and species persistency in frequently and tightly grazed (⩽4 cm) grass-only (GO) and grass white clover swards (GWc). Increasing N application rate increased herbage removed and pre-grazing sward height. Cows frequently grazed the GWc tighter than the GO. Increasing N rate reduced clover content, especially during the warmest months of the year, but less so up to 120 kg N/ha/year. The GWc had greater amounts of herbage removed than GO in the May–September period but the effect was less as N rate increased. Cumulative herbage removed from GWc was greater than GO swards receiving the same N rate and herbage quality was better in GWc than GO. Such effects were reduced as swards aged and with increasing N rate. It was concluded that under frequent and tight grazing management: (1) clover inclusion increased annual herbage removed; (2) herbage removed from GWc swards receiving no N was the same as the GO sward receiving 240 kg N/ha, and greater for the 240 GWc swards than the 240 GO swards; (3) clover inclusion benefits were mainly from summer onwards; (4) the management strategy applied in the current experiment may be capable of alleviating the detrimental effect of N fertilizer on clover, to a point between 60 and 120 kg N/ha.
Sustainable ruminant production systems depend on the ability of livestock to utilize increased quantities of grazed herbage. The current study aimed to compare the effect of white clover (WC) inclusion and perennial ryegrass (PRG) ploidy on herbage dry matter (DM) production, plant morphology, nutritive value and biological nitrogen (N) fixation (BNF) under high N fertilizer use (250 kg N/ha) and high stocking rates (2.75 livestock units/ha). Four sward treatments (diploid-only, tetraploid-only, diploid-WC, tetraploid-WC) were evaluated over a full grazing season at a farmlet scale. White clover inclusion had a significant effect on herbage DM production, herbage growth rate, tiller density, organic matter digestibility, crude protein and BNF. Tetraploid swards had a lower tiller density, lower sward WC content and post-grazing sward height and increased organic matter digestibility and crude protein than diploid swards. White clover inclusion improved herbage DM production and nutritive value across a full grazing season, with tetraploid and diploid swards producing similar herbage DM yields across the year. Perennial ryegrass ploidy had an effect on WC morphology as plants in diploid-WC swards had narrower, longer stolons, fewer branches and more petioles than tetraploid-WC swards. The current study highlights the benefit of including WC in grass-based systems under a high N fertilizer regime and high stocking rate.
The Irish Sport Horse has commanded huge respect amongst horse owners and competitors of other nations, winning international, championship and Olympic medals for Great Britain (Shear L’eau, Supreme Rock), USA (Custom Made and Brazil (Special Envoy). The Irish Studbook continues to top the World Breeders Federation of Sport Horse (WBFSH) rankings for event horses based on competition results. The production of young horses through competition (training, novice and intermediate levels) has been an acknowledged format for identifying horses with the potential to excel at the highest levels of competition. However increasing production costs may be affecting the profitability of sport horse production. Reduced profit margins or possible negative returns may reduce the number of producers and this combined with the scientific improvements within other studbooks may threaten to reduce the potential for the Irish Sport Horse to retain its WBFSH event horse ranking. Furthermore, prize money offered in novice and intermediate competition appear to represent only nominal returns and fail to meet the costs of training and production.
The current experiment was undertaken to investigate the effect of including white clover (Trifolium repens L.; WC) into perennial ryegrass (Lolium perenne L.; PRG) swards (PRG/WC) receiving 250 kg nitrogen (N) per hectare (ha) per year compared with PRG only swards receiving 250 kg N/ha/year, in an intensive grass-based spring calving dairy production scenario. Forty spring-calving cows were allocated to graze either a PRG/WC or PRG sward (n = 20) from 6 February to 31 October 2012. Fresh herbage was offered daily (17 kg dry matter (DM)/cow) supplemented with concentrate in times of herbage deficit (total supplementation 507 kg/cow). Pre-grazing herbage mass (HM), sward WC content and milk production were measured for the duration of the experiment. Herbage DM intake was estimated in May, July and September. Pre-grazing HM (±s.e.) was similar (1467 ± 173·1 kg DM/ha) for both treatments, as was cumulative herbage production (14 158 ± 769 kg DM/ha). Average WC content of the PRG/WC swards was 236 ± 30 g/kg DM. The PRG/WC cows had greater average daily milk yield and milk solids yield from June onwards. Cumulative milk yield and milk solids yield were greater for the PRG/WC cows compared with the PRG cows (5048 and 4789 ± 34·3 kg milk yield/cow, and 400 and 388 ± 1·87 kg milk solids/cow, respectively). Cows had similar DM intake in all measurements periods (15·1 ± 0·42 kg DM/cow/day). In conclusion, including WC in N-fertilized PRG swards increased milk production from cows grazing the PRG/WC swards compared with PRG, particularly in the second half of the lactation.
In agricultural production systems, nitrogen (N) losses to the environment can occur through nitrous oxide (N2O) emissions and nitrate (NO3−) leaching. The objectives of the present study were to evaluate: (1) if urine excreted by non-lactating dairy cows pulse-dosed with dicyandiamide (DCD) and applied to lysimeters reduced N2O-N emissions and NO3−-N leaching on two soil types; and (2) if urine + DCD would increase herbage production over winter. Lysimeters were used to measure N2O emissions and NO3-N leaching. The soils used were a free-draining acid brown earth of sandy loam to loam texture (termed free-draining) and a poorly drained silt loam gley (termed poorly drained). Grass plots were established on the free-draining soil to measure herbage production. The N loading rate of the urine + DCD was 508 kg N/ha and the urine without DCD (urine only) was 451 kg N/ha. Total NO3−-N leaching losses from the free-draining and poorly draining soils were reduced from 100 and 81 kg NO3−-N/ha on the urine-only treatment, respectively, to 9 and 11·6 kg NO3−-N/ha on the urine + DCD treatment, respectively. Total N2O-N emissions from the free-draining and poorly drained soils were reduced significantly from 13·6 and 12·1 kg N2O-N/ha on the urine-only treatment, respectively, to 2·23 and 5·24 kg N2O-N/ha on the urine + DCD treatment, respectively. Applying urine with DCD to pastures inhibited the nitrification process for up to 56 days after treatment application. In the current experiment, there was no significant effect on spring herbage production when urine + DCD was applied to grass plots. Therefore, feeding DCD to dairy cows to apply DCD directly in urine patches was shown to be an effective mitigation strategy to reduce NO3−-N leaching and N2O-N emissions but did not appear to increase spring herbage production.
Historically, American Indian/Alaska Native (AI/AN) populations have suffered excess morbidity and mortality from influenza. We investigated the risk factors for death from 2009 pandemic influenza A(H1N1) in persons residing in five states with substantial AI/AN populations. We conducted a case-control investigation using pandemic influenza fatalities from 2009 in Alaska, Arizona, New Mexico, Oklahoma and Wyoming. Controls were outpatients with influenza. We reviewed medical records and interviewed case proxies and controls. We used multiple imputation to predict missing data and multivariable conditional logistic regression to determine risk factors. We included 145 fatal cases and 236 controls; 22% of cases were AI/AN. Risk factors (P < 0·05) included: older age [adjusted matched odds ratio (mOR) 3·2, for >45 years vs. <18 years], pre-existing medical conditions (mOR 7·1), smoking (mOR 3·0), delayed receipt of antivirals (mOR 6·5), and barriers to healthcare access (mOR 5·3). AI/AN race was not significantly associated with death. The increased influenza mortality in AI/AN individuals was due to factors other than racial status. Prevention of influenza deaths should focus on modifiable factors (smoking, early antiviral use, access to care) and identifying high-risk persons for immunization and prompt medical attention.
We performed a study to determine rates of reinfection in three groups followed for 2 years after successful treatment: American Indian/Alaska Native (AI/AN) persons living in urban (group 1) and rural (group 2) communities, and urban Alaska non-Native persons (group 3). We enrolled adults diagnosed with H. pylori infection based on a positive urea breath test (13C-UBT). After successful treatment was documented at 2 months, we tested each patient by 13C-UBT at 4, 6, 12 and 24 months. At each visit, participants were asked about medication use, illnesses and risk factors for reinfection. We followed 229 persons for 2 years or until they became reinfected. H. pylori reinfection occurred in 36 persons; cumulative reinfection rates were 14·5%, 22·1%, and 12·0% for groups 1, 2, and 3, respectively. Study participants who became reinfected were more likely to have peptic ulcer disease (P = 0·02), low education level (P = 0·04), or have a higher proportion of household members infected with H. pylori compared to participants who did not become reinfected (P = 0·03). Among all three groups, reinfection occurred at rates higher than those reported for other US populations (<5% at 2 years); rural AI/AN individuals appear to be at highest risk for reinfection.
The current paper aims to determine regional impacts of climate change on Irish farms examining the variation in farm responses. A set of crop growth models were used to determine crop and grass yields under a baseline scenario and a future climate scenario. These crop and grass yields were used along with farm-level data taken from the Irish National Farm Survey in an optimizing farm-level (farm-level linear programming) model, which maximizes farm profits under limiting resources. A change in farm net margins under the climate change scenario compared to the baseline scenario was taken as a measure to determine the effect of climate change on farms. The growth models suggested a decrease in cereal crop yields (up to 9%) but substantial increase in yields of forage maize (up to 97%) and grass (up to 56%) in all regions. Farms in the border, midlands and south-east regions suffered, whereas farms in all other regions generally fared better under the climate change scenario used in the current study. The results suggest that there is a regional variability between farms in their responses to the climate change scenario. Although substituting concentrate feed with grass feeds is the main adaptation on all livestock farms, the extent of such substitution differs between farms in different regions. For example, large dairy farms in the south-east region adopted total substitution of concentrate feed while similar dairy farms in the south-west region opted to replace only 0·30 of concentrate feed. Farms in most of the regions benefitted from increasing stocking rate, except for sheep farms in the border and dairy farms in the south-east regions. The tillage farms in the mid-east region responded to the climate change scenario by shifting arable production to beef production on farms.
In most countries, male pigs are physically castrated soon after birth to reduce the risk of boar taint and to avoid behaviours such as fighting and mounting. However, entire male pigs are more feed efficient and deposit less fat than barrows. In addition, many animal welfare organizations are lobbying for a cessation of castration, with a likelihood that this could lead to inferior pork unless an alternative method is used to control boar taint. An alternative to physical castration is immunization against gonadotrophin releasing factor (GnRF) which allows producers to capitalize on the superior feed efficiency and carcass characteristics of boars without the risk of boar taint. From a physiological perspective, immunized pigs are entire males until shortly after the second dose, typically given 4 to 6 weeks before slaughter. Following full immunization, there is a temporary suppression of testicular function and a hormonal status that resembles that of a barrow. Nutrient requirements will be different in these two phases, before and after full immunization. Given that there have been few published studies comparing the lysine requirements of entire males and barrows in contemporary genotypes, it is useful to use gilt requirements as a benchmark. A series of meta-analyses comparing anti-GnRF immunized boars and physical castrates and use of nutritional models suggest that the lysine requirement of entire males before the second immunization is 5% higher than for gilts, from 25 to 50 kg BW, and by 8% from 50 to 95 kg. Given that the penalty in growth performance for having inadequate dietary lysine is greater in males than in gilts or barrows, it is important to ensure that lysine requirements are met to obtain the maximum benefits of entire male production during this phase. After the second immunization, the lysine requirement of immunized males decreases and may become more like that of barrows. In addition, a consistent effect of full immunization is a marked increase in voluntary feed intake from about 10 days after the second dose. Putting these together, the estimated lysine requirement, expressed in terms of diet composition, falls to 94% of the gilt level. Although general principles can be described now, further research is needed to fully define the lysine requirements of immunized boars. It is important that the temporal pattern of tissue deposition rates and feed intake be explored to be incorporated into models to predict nutrient requirements over the period of rapidly changing metabolism.
Grass growth in temperate regions is highly seasonal and difficult to predict. A model that can predict grass growth from week to week would offer a valuable management and budgeting tool for grassland farmers. Many grass growth models have been developed, varying from simple empirical to complex mechanistic models. Three published grass growth models developed for perennial ryegrass swards in temperate climates were selected for evaluation: Johnson & Thornley (1983) (J&T model), Jouven et al. (2006) (J model) and Brereton et al. (1996) (B model). The models were evaluated using meteorological data and grass growth data from Teagasc Moorepark as a framework for further refinement for Irish conditions. The accuracy of prediction by the models was assessed using root mean square error (RMSE) and mean square prediction error (MSPE). The J&T model over-predicted grass growth in all 5 years examined and predicted a high primary grass growth peak, while the J and B models predicted grass growth closer to that measured. Overall, the J model had the smallest RMSE in 3 of the 5 years and the B model in 2 of the 5 years. In spring (February–April), the B model had the lowest RMSE and MSPE. In mid-season (April–August), the B model had the closest prediction to measured data (lowest RMSE), while in autumn (August–October) the J model had the closest prediction. The models with the greatest potential for grass growth prediction in Ireland, albeit with some modifications, are the J model and the B model.
There is a continual requirement for grass-based production systems to optimize economic and environmental sustainability through increased efficiency in the use of all inputs, especially nitrogen (N). An N balance model was used to assess N use efficiency and N surplus, and to predict N losses from grass-based dairy production systems differing in the length of the grazing season (GS). Data from a 3-year grazing study with a 3×3 factorial design, with three turnout dates (1 February, 21 February and 15 March) and three housing dates (25 October, 10 November and 25 November) were used to generate estimates of N use efficiency and N losses. As the length of the GS increased by a mean of 30 days, milk production, milk solids production and milk N output increased by 3, 6 and 6%, respectively. The increase in milk production as the length of the GS increased resulted in a 2% decline in N surplus and a 5% increase in N use efficiency. Increasing GS length increased the proportion of grazed grass in the diet, which increased N cycling within the system, resulting in an 8% increase in milk solids/ha produced/kg of surplus N. The increased cycling of N reduced the quantity of N partitioned for loss to the environment by 8%. Reducing fertilizer N input by 20% increased N use efficiency by 22% and reduced total N losses by 16%. The environmental and production consequences of increased length of the GS and reduced N loss are favourable as the costs associated with N inputs increase.
The orientation distribution of crystalline grains in calcium phosphate coatings produced by pulsed laser deposition was investigated using an X-ray pole-figure diffractometer. Increased laser energy density of a KrF excimer laser in the 4–7 J/cm2 range leads to the formation of hydroxyapatite grains with the c-axis preferentially aligned perpendicularly to the substrates. This preferred orientation is most pronounced when the plume direction of incidence is normal to the substrate. This crystallographic texture of hydroxyapatite grains in the coatings is associated with the highly directional and energetic nature of the ablation plume. Anisotropic stresses, transport of hydroxyl groups, and dehydroxylation effects during deposition all seem to play important roles in texture development. Studies of cell adsorption using human Mesenchymal stem cells reveal that hydroxyapatite coatings with strong texture and random orientation show different cell adsorption behavior, which is consistent with the notion that protein attach differently on different faces of hydroxyapatite crystals. Cells seeded on textured coatings exhibit better spreading and adhesion compared to those placed on randomly oriented coatings.
We have investigated the design parameters for high-Q photonic-crystal (PC) bandgap modes in the emission wavelengths of InGaN/GaN multiple quantum wells. We demonstrate experimental schemes to realize 2D triangular-lattice PC membrane structures, which is essential to obtain photonic bandgap (PBG) modes, and the optical properties of L7 membrane nanocavities that consist of seven missing holes in the Γ-K direction. L7 cavities show pronounced resonances with Q factors of 300 to 800 in the PBG as well as the enhancement of light extraction of the broad InGaN/GaN multiple-quantum-well emission by the 2D PBG.