Peripheral nerve regeneration in rats using nerve graft in a vein conduit pre-filled with platelet-rich fibrin (PRF).

Treatment of peripheral nerve injury is not always satisfactory. To improve results, specific adjuvant methods have been used, such as platelet-rich fibrin (PRF) and vein conduits. The goal of this study was to assess whether use of PRF and vein conduits after nerve suture improves nerve regeneration as measured by a functional score and histomorphometry analysis. Ten isogenic spontaneously hypertensive rats were randomly assigned to 4 experimental procedures: 1) Sham group (n = 10); 2) Nerve graft (NG) group (n = 10); 3) Nerve graft covered with a vein conduit (NGVC) (n = 10); and 4) Nerve graft covered with a vein conduit pre-filled with PRF (NGVCP) (n = 10). Nerve repair results were evaluated on: sciatic functional index (SFI) at 0, 30, 60 and 90 days; morphometric and morphologic analysis of the distal nerve; and histological analysis of Fluoro-Gold® stained motor neurons in the anterior horn of the spinal cord. Compared to the Sham control group, the NGVC and NGVCP groups exhibited lower SFI on all measures. The NGVC group showed improvement in SFI at day 90, which was significant compared to the NG group. Fiber and axon diameters were comparable in the NGVC and NGVCP groups, which were both significantly lower than in the Sham and NG groups. Significant improvement was expected with PRF, but in fact the release of factors from this substance was not as effective as hoped.

The role of seagrass vegetation and local environmental conditions in shaping benthic bacterial and macroinvertebrate communities in a tropical coastal lagoon.

We investigated the influence of seagrass canopies on the benthic biodiversity of bacteria and macroinvertebrates in a Red Sea tropical lagoon. Changes in abundance, number of taxa and assemblage structure were analyzed in response to seagrass densities (low, SLD; high, SHD; seagrasses with algae, SA), and compared with unvegetated sediments. Biological and environmental variables were examined in these four habitats (hereafter called treatments), both in the underlaying sediments and overlaying waters, at three randomly picked locations in March 2017. Differences between treatments were more apparent in the benthic habitat than in the overlaying waters. The presence of vegetation (more than its cover) and changes in sedimentary features (grain size and metals) at local scales influenced the observed biological patterns, particularly for macroinvertebrates. Of note, the highest percentage of exclusive macroinvertebrate taxa (18% of the gamma diversity) was observed in the SHD treatment peaking in the SA for bacteria. Benthic macroinvertebrates and bacteria shared a generally low number of taxa across treatments and locations; approximately, 25% of the gamma diversity was shared among all treatments and locations for macrofauna, dropping to 11% for bacteria. Given the low overlap in the species distribution across the lagoon, sustaining the connectivity among heterogeneous soft sediment habitats appears to be essential for maintaining regional biodiversity. This study addresses a current scientific gap related to the relative contributions of vegetated and unvegetated habitats to biodiversity in tropical regions.

Progressive secondary exo-focal dopaminergic neurodegeneration occurs in not directly connected midbrain nuclei after pure motor-cortical stroke.

Transsynaptic anterograde and retrograde degeneration of neurons and neural fibers are assumed to trigger local excitotoxicity and inflammatory processes. These processes in turn are thought to drive exo-focal neurodegeneration in remote areas connected to the infarcted tissue after ischemic stroke. In the case of middle cerebral artery occlusion (MCAO), in which striato-nigral connections are affected, the hypothesis of inflammation-induced remote neurodegeneration is based on the temporal dynamics of an early appearance of inflammatory markers in midbrain followed by dopaminergic neuronal loss. To test the hypothesis of a direct transsynaptic mediation of secondary exo-focal post-ischemic neurodegeneration, we used a photochemical induction of a stroke (PTS) in Sprague-Dawley rats restricted to motor cortex (MC), thereby sparing the striatal connections to dopaminergic midbrain nuclei. To dissect the temporal dynamics of post-ischemic neurodegeneration, we analyzed brain sections harvested at day 7 and 14 post stroke. Here, an unexpectedly pronounced and widespread loss of dopaminergic neurons occurred 14 days after stroke also affecting dopaminergic nuclei that are not directly coupled to MC. Since the pattern of neurodegeneration in case of a pure motor stroke is similar to a major stroke including the striatum, it is unlikely that direct synaptic coupling is a prerequisite for delayed secondary exo-focal post ischemic neurodegeneration. Furthermore, dopaminergic neurodegeneration was already detected by Fluoro-Jade C staining at day 7, coinciding with a solely slight inflammatory response. Thus, inflammation cannot be assumed to be the primary driver of exo-focal post-ischemic cell death. Moreover, nigral substance P (SP) expression indicated intact striato-nigral innervation after PTS, whereas opposing effects on SP expression after striatal infarcts argue against a critical role of SP in neurodegenerative or inflammatory processes during exo-focal neurodegeneration.

Transverse resonance island buckets for synchrotron-radiation based electron time-of-flight spectroscopy.

At the Metrology Light Source (MLS), the compact electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB) with a circumference of 48 m, a specific operation mode with two stable closed orbits for stored electrons was realized by transverse resonance island buckets. One of these orbits is closing only after three turns. In combination with single-bunch operation, the new mode was applied for electron time-of-flight spectroscopy with an interval of the synchrotron radiation pulses which is three times the revolution period at the MLS of 160 ns. The achievement is of significant importance for PTB's future programs of angular-resolved electron spectroscopy with synchrotron radiation and similar projects at other compact electron storage rings. The scheme applied here for selecting the photons originating from a particular orbit by optical imaging has been used before in fs slicing applications and may be relevant for the BESSY VSR project of the Helmholtz-Zentrum Berlin.

Coral reef degradation affects the potential for reef recovery after disturbance.

The loss of coral cover is often accompanied by an increase of benthic algae, a decline in biodiversity and habitat complexity. However, it remains unclear how surrounding communities influence the trajectories of re-colonization between pulse disturbance events. Over a 12-month field experiment in the central Red Sea, we examined how healthy (hard-coral dominated) and degraded (algae-dominated) reef areas influence recruitment and succession patterns of benthic reef foundation communities on bare substrates. Crustose coralline algae and other calcifiers were important colonizers in the healthy reef area, promoting the accumulation of inorganic carbon. Contrary, substrates in the degraded area were predominantly colonized by turf algae, lowering the accumulation of inorganic carbon by 178%. While coral larvae settlement similarly occurred in both habitats, degraded areas showed 50% fewer recruits. Our findings suggest that in degraded reefs the replenishment of adult coral populations is reduced due to recruitment inhibition through limited habitat complexity and grazing pressure, thereby restraining reef recovery.

DALYs, dollars and dogs: how best to analyse the economics of controlling zoonoses.

Decision-makers increasingly require comprehensive economic metrics summarising and comparing the benefits and costs of controlling zoonotic diseases. The impact of disease in people is conventionally quantified in non-monetary terms, usually a disability-adjusted life year (DALY), whereas the losses due to disease in animals, particularly livestock, are quantified in monetary terms. The potential for the development of a non-monetary metric for ill health in animals, based on life years lost and disability, is discussed and rejected. Within and across animal species and livestock production systems, maximising life spans is not a consistent goal and morbidity/disabilities have very different weights and often lead to culling. By relating livestock losses to a measure of national income forgone, the recently developed alternative of converting monetary losses due to livestock illness into an animal loss equivalent (ALE) provides a viable solution. Based on this, the literature on the economics of controlling zoonoses is revisited and four options for quantifying and comparing benefits and costs are examined and illustrated using numerical examples. These are i) the simplistic grouping of all monetary elements and their comparison to DALYs averted (described as the aggregate net cost method), ii) the separable costs method, iii) the use of ALEs to convert all benefits to a non-monetary equivalent, termed the zoonotic DALY (zDALY), or iv) the use of a full monetary cost-benefit analysis, based on converting DALYs to a monetary equivalent. The strengths and weaknesses of each are discussed. For effective prioritisation and decision-making, it is vital that an analytical approach is widely adopted which yields consistent results and which supports the control of zoonoses.

Les décideurs politiques sont de plus en plus dépendants de méthodes exhaustives de mesure économique permettant de synthétiser et de comparer les avantages et les coûts de la lutte contre les zoonoses. Par convention, l'impact des maladies humaines est quantifié en des termes non monétaires, à savoir, le plus souvent, en « années de vie corrigées de l'incapacité ¼ (DALY), tandis que les pertes dues aux maladies animales, en particulier celles affectant les animaux d'élevage, sont quantifiées en termes monétaires. Dans cet article, les auteurs envisagent (et réfutent) la possibilité de mettre en oeuvre un système de mesure non monétaire des problèmes sanitaires chez les animaux qui soit basé sur les années de vie perdues ou d'incapacité. La longévité n'est pas un objectif uniformément recherché dans tous les systèmes de production, ni pour toutes les espèces animales, voire pour tous les individus au sein d'une même espèce, et la morbidité et l'incapacité représentent des fardeaux très variables, conduisant souvent à l'abattage. Parce qu'elle relie les pertes animales à une mesure de la réduction du revenu intérieur entraînée, la récente proposition de convertir les pertes monétaires dues aux maladies du bétail en un « équivalent pertes animales ¼ (indicateur ALE : animal loss equivalent) constitue une solution viable. À partir de ces considérations, les auteurs examinent la littérature dédiée aux aspects économiques de la lutte contre les zoonoses en détaillant quatre méthodes possibles pour en quantifier et comparer les avantages et les coûts, avec des exemples chiffrés. Ces possibilités sont : i) le simple regroupement de tous les éléments monétaires et leur comparaison en termes de DALY évitées (méthode dite de la présentation agrégée des coûts nets) ; ii) la méthode des coûts séparables ; iii) l'utilisation d'un indicateur ALE pour convertir l'ensemble des bénéfices en leur équivalent non monétaire, désigné sous le terme de DALY zoonotique (zDALY) ; iv) le recours à une analyse monétaire coûts-avantages exhaustive, après avoir converti les DALY en leur équivalent monétaire. Les auteurs font ressortir les atouts et les faiblesses de chacune de ces méthodes. La priorisation et la prise de décisions gagneront en efficacité si les décideurs adoptent et appliquent largement une approche analytique permettant d'obtenir des résultats cohérents et de renforcer la lutte contre les zoonoses.

Cada vez más, las instancias decisorias necesitan parámetros econométricos integrales, que sirvan para sintetizar y comparar los costos y beneficios de la lucha contra enfermedades zoonóticas. Convencionalmente, los efectos de una enfermedad en las personas se cuantifican en términos no monetarios, por lo general en forma de «años de vida ajustados en función de la discapacidad¼ (AVAD), mientras que las pérdidas inducidas por las enfermedades en animales, en particular el ganado, se cuantifican en valores monetarios. Los autores examinan y descartan la posible definición de parámetros no monetarios, basados en los años de vida perdidos y en la discapacidad, para cuantificar problemas zoosanitarios. Con independencia de la especie animal o el sistema de producción ganadera de que se trate, el de lograr una longevidad máxima no es un objetivo habitual, y los niveles de morbilidad o discapacidad, que suelen desembocar en el sacrificio sanitario, tienen un peso muy variable. En fechas recientes ha aparecido una alternativa que, al establecer una relación entre las pérdidas de ganado y una medida de la renta nacional prevista, ofrece una solución viable: se trata de convertir las pérdidas monetarias causadas por enfermedades del ganado en un «equivalente a las pérdidas animales¼ (animal loss equivalent: ALE). Partiendo de esta idea, los autores repasan la bibliografía sobre la economía de la lucha contra las zoonosis y examinan cuatro opciones para cuantificar y comparar beneficios y costos, ilustrándolas con ejemplos numéricos. Se trata de las siguientes: i) el simplificador procedimiento de agrupar todos los elementos monetarios y compararlos con los AVAD evitados (método que describen como del «costo agregado neto¼); ii) el método de los costos específicos; iii) el uso de «equivalentes a las pérdidas animales¼ para convertir todos los beneficios en un equivalente no monetario que denominan AVAD por zoonosis; y iv) el uso de un análisis monetario completo de la relación entre beneficios y costos, basado en la conversión de los AVAD en un equivalente monetario. A continuación examinan los puntos fuertes y débiles de cada uno de esos métodos, y concluyen que para fijar prioridades y adoptar decisiones con eficacia es vital aplicar de forma generalizada un mismo planteamiento analítico, que arroje resultados coherentes y ayude así a combatir las zoonosis.

Impacts of a high-discharge submarine sewage outfall on water quality in the coastal zone of Salvador (Bahia, Brazil).

Carbon and nitrogen stable isotopic signatures of suspended particulate organic matter and seawater biological oxygen demand (BOD) were measured along a coastal transect during summer 2015 to investigate pollution impacts of a high-discharge submarine sewage outfall close to Salvador, Brazil. Impacts of untreated sewage discharge were evident at the outfall site by depleted δ(13)Corg and δ(15)N signatures and 4-fold increased BOD rates. Pollution effects of a sewage plume were detectable for more than 6km downstream from the outfall site, as seasonal wind- and tide-driven shelf hydrodynamics facilitated its advective transport into near-shore waters. There, sewage pollution was detectable at recreational beaches by depleted stable isotope signatures and elevated BOD rates at high tides, suggesting high bacterial activity and increased infection risk by human pathogens. These findings indicate the urgent necessity for appropriate wastewater treatment in Salvador to achieve acceptable standards for released effluents and coastal zone water quality.

High-energy anomaly in the angle-resolved photoemission spectra of Nd(2-x)Ce(x)CuO4: evidence for a matrix element effect.

We use polarization-dependent angle-resolved photoemission spectroscopy (ARPES) to study the high-energy anomaly (HEA) in the dispersion of Nd(2-x)Ce(x)CuO4, x=0.123. We find that at particular photon energies the anomalous, waterfall-like dispersion gives way to a broad, continuous band. This suggests that the HEA is a matrix element effect: it arises due to a suppression of the intensity of the broadened quasiparticle band in a narrow momentum range. We confirm this interpretation experimentally, by showing that the HEA appears when the matrix element is suppressed deliberately by changing the light polarization. Calculations of the matrix element using atomic wave functions and simulation of the ARPES intensity with one-step model calculations provide further evidence for this scenario. The possibility to detect the full quasiparticle dispersion further allows us to extract the high-energy self-energy function near the center and at the edge of the Brillouin zone.

X-ray photoemission study of CeTIn(5) (T = Co, Rh, Ir).

We investigated CeTIn5 (T = Co, Rh, Ir) using temperature- and angle-dependent x-ray photoemission spectroscopy. The Ce 3d core level has a very similar shape for all three materials and is indicative of weak f-hybridization. The spectra were analyzed using a simplified version of the Anderson impurity model, which yields a Ce 4f occupancy that is larger than 0.9. The temperature dependence shows a continuous, irreversible and exclusive broadening of the Ce 3d peaks, due to oxidation of Ce at the surface.

Persistence of brucellosis in pastoral systems.

Regarded as a highly contagious, zoonotic disease with worldwide distribution, brucellosis is endemic in many countries and settings and is responsible for a considerable economic and health-related burden. Limited information is available on the persistence and prevalence of brucellosis in pastoral communities, due to the difficulty in gathering information and to their mobility. However, since these communities are economically and culturally dependent on livestock, it is important to further determine the cause of persistent disease and develop possible methods for its management. The two main objectives of this paper are to review the literature, identifying various epidemiological and social factors that affect the persistence of brucellosis in pastoral ecosystems, and determine prevalence estimates within these communities. The general trend of the summarised studies indicates low-level, relatively stable transmission of brucellosis in pastoral areas, when compared to transmission in intensive and semi-intensive peri-urban production systems. A formal mathematical analysis can be undertaken using matrix models or coupled differential equations. This allows an examination of the various conditions under which the number of diseased, infected or exposed animals remains stable. The authors examined an existing mathematical differential equation model for brucellosis in Mongolia for its equilibrium conditions and found it reasonably robust, though clearly more data are needed to estimate threshold densities for brucellosis transmission in other regions of the world. However, the results indicate the importance of livestock demographic determinants for brucellosis persistence. The paper concludes that brucellosis remains largely persistent in pastoral areas of the world, despite (varying) control efforts. Plans to control brucellosis in pastoral settings should include ecological considerations, such as sustaining ecosystem services in pastoral areas. This approach would include placing limitations on livestock stocking density, land reform, improved governance and integrated social and economic development.

Probing the complex ion structure in liquid carbon at 100 GPa.

We present the first direct experimental test of the complex ion structure in liquid carbon at pressures around 100 GPa, using spectrally resolved x-ray scattering from shock-compressed graphite samples. Our results confirm the structure predicted by ab initio quantum simulations and demonstrate the importance of chemical bonds at extreme conditions similar to those found in the interiors of giant planets. The evidence presented here thus provides a firmer ground for modeling the evolution and current structure of carbon-bearing icy giants like Neptune, Uranus, and a number of extrasolar planets.

Electronic states and the influence of oxygen addition on the optical absorption behaviour of manganese phthalocyanine.

The effects of electronic states and air exposure on the spectroscopic properties of manganese phthalocyanine (MnPc) have been examined. The observed features of the Q-band in the absorption spectra can be explained by intrinsic electronic properties of MnPc, i.e., the formation of singly charged molecules by charge transfer excitations. However, the reaction of MnPc with atmospheric molecular oxygen leads to deviations in peak intensities but does not change the fundamental characteristics of the spectra. Nevertheless, the reaction with oxygen changes the spin state from S = 3/2 to S = 1/2. X-ray diffraction measurements also indicate a slow diffusion process of the oxygen into the MnPc crystal. We discuss both influences to explain the behaviour of MnPc in various spectroscopic methods (EELS, ellipsometry, PES). Furthermore, we support the experimental investigations by detailed ab-initio calculations of spectroscopic properties using methods of the density functional theory framework.

[Fetoscopic laser coagulation in 100 consecutive monochorionic pregnancies with severe twin-to-twin transfusion syndrome]. / Coagulation laser en fœtoscopie des anastomoses vasculaires placentaires: étude observationnelle de 100 grossesses gémellaires monochoriales consécutives compliquées de syndrome transfuseur-transfusé sévère.

OBJECTIVES: To report pre- and post-surgical datas of large series of severe twin-to-twin transfusion syndrome (TTTS) managed with laser ablation surgery in our centre, to evaluate the incidence of complications, perinatal outcome and to compare with other cohorts. PATIENTS AND METHODS: Observational study of 100 cases of TTTS consecutively treated with fetoscopic laser coagulation between January 2004 and April 2010 in CMCO-SIHCUS of Schiltigheim. RESULTS: There are nine stage I, 49 stage II, 38 stage III and four stage 4. Median gestation at time of laser is 20.6 weeks (14-29) whereas median gestation at delivery is 32.6 weeks (16.3-39). Overall perinatal survival rate is 68.5% (137 children over 200). Eighty-five percent have one or more surviving twins. The survival rate is the same for donors and for recipients. Preterm premature rupture of the membranes are observed in 17% of cases and the median gestational age for this complication is 30 weeks (20-34). Cerebral abnormalities are present in 7% of newborns. CONCLUSION: Our results for the management of severe TTTS are comparable to the other reported series. There are still many questions remaining concerning the optimal management of TTTS.

[Transmission dynamics and cost-effectiveness of rabies control in dogs and humans in an African city]. / Dynamique de transmission et coût de la lutte contre la rage chez les chiens et les hommes dans une ville Africaine.

Control of human rabies in developing countries depends on prevention in dogs. The purpose of this study was to evaluate the cost-saving potential for the public health sector of intervention to control rabies in animal-host reservoirs. An existing deterministic model was adapted to allow study of dog-to-human rabies transmission. Model parameters were fitted to data from routine weekly reports on the number of rabid dogs and human rabies exposures in N'Djamena, Chad. At the onset of study, the estimated effective reproductive ratio (Re) was 1.01 indicating stable low-level endemic rabies transmission. Simulations were performed to determine what effects mass vaccination and culling of dogs would have on the incidence of human rabies. Findings showed that a mass campaign allowing single parenteral vaccination of at least 70% of the canine population would be sufficient to interrupt transmission of rabies to humans for at least 6 years. The cost-effectiveness of mass dog vaccination was compared to that of "postexposure prophylaxis" (PEP) which would not reduce future human exposure. Results showed that a sustained 5-year PEP program together with a dog-vaccination campaign would be as cost-effective as PEP alone. Beyond a time-frame of 7 years, combining parenteral dog vaccination campaigns with human PEP appeared to be more cost-effective than human PEP alone.

High convergence of olfactory and vomeronasal influence in the telencephalon of the terrestrial salamander Plethodon shermani.

Previous work suggested that the telencephalic pathways of the main olfactory and vomeronasal systems of vertebrates are mostly isolated from each other, with the possible exception of convergence of the two systems into a small part of the olfactory amygdala. We tested the hypothesis of convergence between the main olfactory and vomeronasal systems by investigating the physiology of telencephalic olfactory responses in an in vitro brain preparation of the salamander Plethodon shermani. This animal was chosen because its olfactory and vomeronasal nerves can be separated and stimulated independently. The nerves were stimulated by short current pulses delivered through suction electrodes. Evoked field potentials and intracellular responses were systematically recorded in the telencephalon. The results showed an abundant overlap of olfactory and vomeronasal nerve-evoked field potentials in the ipsilateral lateral telencephalon and the amygdala. Single neurons receiving bimodal main olfactory and vomeronasal input were found in the dorsolateral telencephalon and amygdala. A classification of response latencies suggested that a subset of these neurons received direct input from both the main and accessory olfactory bulbs. Unimodal excitatory main olfactory responses were mostly found in neurons of the caudal telencephalic pole, but were also present in the striato-pallial transition area/lateral pallium region and striatum. Unimodal excitatory vomeronasal responses were found in neurons of the striato-pallial transition area, vomeronasal amygdala, and caudal amygdala. We conclude that the main olfactory and vomeronasal systems are extensively integrated within the salamander telencephalon and probably act in concert to modulate behavior.

[A furoncular ankle cellulitis in a teenager with a difference: Dermatobia hominis]. / Un passager clandestin à ne pas méconnaître: Dermatobia hominis, à propos d'un cas.

We report a case of botfly myiasis presenting as an ankle cellulitis in a teenager returning from Guyana. Main clinical features and therapeutic approaches are described.

Transmission dynamics and economics of rabies control in dogs and humans in an African city.

Human rabies in developing countries can be prevented through interventions directed at dogs. Potential cost-savings for the public health sector of interventions aimed at animal-host reservoirs should be assessed. Available deterministic models of rabies transmission between dogs were extended to include dog-to-human rabies transmission. Model parameters were fitted to routine weekly rabid-dog and exposed-human cases reported in N'Djaména, the capital of Chad. The estimated transmission rates between dogs (beta(d)) were 0.0807 km2/(dogs x week) and between dogs and humans (beta(dh)) 0.0002 km2/(dogs x week). The effective reproductive ratio (R(e)) at the onset of our observations was estimated at 1.01, indicating low-level endemic stability of rabies transmission. Human rabies incidence depended critically on dog-related transmission parameters. We simulated the effects of mass dog vaccination and the culling of a percentage of the dog population on human rabies incidence. A single parenteral dog rabies-mass vaccination campaign achieving a coverage of least 70% appears to be sufficient to interrupt transmission of rabies to humans for at least 6 years. The cost-effectiveness of mass dog vaccination was compared to postexposure prophylaxis (PEP), which is the current practice in Chad. PEP does not reduce future human exposure. Its cost-effectiveness is estimated at US $46 per disability adjusted life-years averted. Cost-effectiveness for PEP, together with a dog-vaccination campaign, breaks even with cost-effectiveness of PEP alone after almost 5 years. Beyond a time-frame of 7 years, it appears to be more cost-effective to combine parenteral dog-vaccination campaigns with human PEP compared to human PEP alone.

Electronic properties of potassium doped FePc from electron energy-loss spectroscopy.

We have studied the electronic structure of potassium doped iron phthalocyanine (FePc) phases using electron energy-loss spectroscopy. The electronic excitation spectrum of FePc is rather complex and comprises both pi-pi( *) transitions of the phthalocyanine ligand and transitions that involve the Fe 3d orbitals. This allows deeper insight into the orbital occupation in FePc. Potassium doping, i.e., the addition of electrons to the FePc molecules causes significant changes in the electronic excitations, which signal filling of pi( *) as well as Fe 3d orbitals.

Estimates of the optimum dietary ratio of standardized ileal digestible valine to lysine for eight to twenty-five kilograms of body weight pigs.

Valine is among the limiting AA in low protein diets for pigs, but data are currently lacking for empirical requirement studies. Therefore, 2 growth assays and 1 N-balance trial were conducted to determine the Val requirement of weaned pigs (8 to 25 kg of BW) expressed as the ratio of standardized ileal digestible (SID) Val to Lys. In Exp. 1, 48 pigs (individual housing; equal proportion of castrates and females; initial BW = 8.0 kg) were randomly subdivided into groups receiving 6 dietary treatments. Dietary SID Val:Lys ratio was increased by adding L-Val from 0.56 to 0.84% (planned increments of 0.06%) at an average SID Lys level of 0.99%. Other crystalline AA were supplied to meet optimum SID AA:Lys ratios based on the concept of an ideal protein. All diets were isocaloric (13.6 MJ of ME/kg) and isonitrogenous (17.8% CP). For the 35-d period, ADG and ADFI increased linearly (P < 0.01) and quadratically (P < 0.01) with increasing SID Val:Lys. However, the data were not suitable for estimation of Val requirement. Therefore, in Exp. 2 the dietary basal level of Val was reduced to 0.49% SID Val and 4 increments of 0.04% and 1 increment of 0.08% L-Val were used to give 6 dietary treatments (48 pigs; individual housing; equal proportion of castrates and females; initial BW = 7.9 kg). The SID Lys level averaged 0.99%, and SID Val:Lys ratios ranged from 0.49 to 74%. Other crystalline AA were supplied to meet optimum SID AA:Lys ratios. All diets were isocaloric (13.7 MJ of ME/kg) and isonitrogenous (17.7% CP). For the 34-d period, ADG, ADFI, and G:F increased linearly (P < 0.01), and ADG and G:F quadratically (P < 0.01) as the SID Val:Lys ratio increased. Estimates of optimum SID Val:Lys were 66, 67, and 61% for ADG, ADFI, and G:F, respectively. These estimates were confirmed by minimized concentrations of plasma urea and Lys and by markedly increased concentrations of plasma Val. To verify the estimates of the growth trials, a total of 24 N balances were conducted with 12 pigs using the dietary treatments of Exp. 2 (Exp. 3; equal proportion of males and females; average BW = 14.1 kg; 2 balances per pig). Pigs were restrictively fed 3 times daily. Precollection and collection periods lasted 7 d each and were repeated after rearranging the animals to treatments. Increasing the dietary SID Val:Lys ratio linearly increased N retention (P < 0.04) and quadratically decreased plasma concentrations of urea (P < 0.01). Optimal SID Val:Lys ratios of 65 and 62% were estimated for N retention and N utilization, respectively. We conclude that an optimum SID Val:Lys ratio of 65 to 67% is needed for optimal performance in 8- to 25-kg pigs.

Estimation of the optimum ratio of standardized ileal digestible isoleucine to lysine for eight- to twenty-five-kilogram pigs in diets containing spray-dried blood cells or corn gluten feed as a protein source.

Two growth assays and 1 N balance trial were conducted to determine the standardized ileal digestible (SID) Ile:Lys ratio in 8- to 25-kg pigs using spray-dried blood cells or corn gluten feed as a protein source. In Exp. 1, 48 individually penned pigs (initial BW = 7.7 kg) were used in a 6-point SID Ile titration study (analyzed SID Ile of 0.36, 0.43, 0.50, 0.57, 0.64, and 0.72%) by addition of graded levels of L-Ile. The basal diet contained 1.00% SID Lys, 18.4% CP, and 13.6 MJ of ME/kg. Diets were based on wheat, barley, corn, and 7.5% spray-dried blood cells as a protein source. Dietary SID Leu and Val levels were 1.61 and 1.02%, respectively. For the 35-d period, ADG, ADFI, and G:F increased linearly (P < 0.01) and quadratically (P < 0.04) with increasing SID Ile:Lys. Estimates of optimal SID Ile:Lys ratios were 59% for ADG and ADFI. In Exp. 2, 24 N balances were conducted using the Exp. 1 diets (12 pigs; individually penned; average BW = 11.5 kg). Pigs were fed 3 times daily with an amount equal to 1.0 MJ of ME/kg of BW(0.75). Preparation and collection periods (7 d each) were repeated after rearranging the animals to treatments. Increasing the dietary SID Ile:Lys ratio increased N retention linearly (P < 0.01), and N utilization linearly (P < 0.01) and quadratically (P < 0.01). An optimal SID Ile:Lys ratio of 54% was estimated for N retention. In Exp. 3, 48 individually penned pigs (initial BW = 8.0 kg) were fed grain-based diets in a 6-point SID Ile titration (analyzed SID Ile of 0.35, 0.41, 0.49, 0.56, 0.62, and 0.69%). Dietary SID Ile was increased by graded addition of L-Ile. The basal diet contained 0.97% SID Lys, 16.8% CP, and 13.6 MJ of ME/kg. In contrast to Exp. 1 and 2, spray-dried blood cells were excluded and corn gluten feed was used as a protein source. Dietary SID Leu and Val were set to 1.05 and 0.66%. For the 42-d period, ADG, ADFI, and G:F increased linearly (P < 0.01) and quadratically (P < 0.01) with increasing SID Ile:Lys. Estimated optimal SID Ile:Lys ratios were 54, 54, and 49 for ADG, ADFI, and G:F, respectively. These experiments suggest that the optimal SID Ile:Lys ratio depends on diet composition. In Exp. 1, AA imbalances because of increased Leu contents may have led to increased Ile nutritional needs. For ADG and ADFI, an optimum SID Ile:Lys ratio of 54% was estimated for 8- to 25-kg pigs in diets without Leu excess.