RESUMEN
Physical inactivity is an important public health problem, which could be addressed by health promotion initiatives in primary care. The interventions most widely available to primary care clinicians are advice/counselling and exercise referral. A review of four systematic reviews found that brief advice from a general practitioner, supported by written materials, has a modest short-term effect on physical activity lasting 6-12 months. Exercise referral schemes have been introduced throughout Wales and the rest of the UK. A systematic review and meta-analysis found that such schemes resulted in a statistically significant increase in the proportion of sedentary people becoming moderately active, but the absolute risk reduction was small, with 17 sedentary people needing to be referred for one to become moderately active. This small effect size could partly be explained by poor rates of uptake and adherence and was not likely to be an efficient use of resources. These findings were in concordance with the guidance from the National Institute for Health and Clinical Excellence, which states that schemes should only be recommended if they are part of a properly designed and controlled research study. Since 2007, a national exercise referral scheme is being rolled out throughout Wales in three phases, and is being evaluated in a pragmatic randomised controlled trial comparing exercise referral with an advice booklet.
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Ejercicio Físico , Conductas Relacionadas con la Salud , Promoción de la Salud/métodos , Consejo , Medicina Familiar y Comunitaria , Humanos , Ensayos Clínicos Controlados Aleatorios como Asunto , Derivación y Consulta , GalesRESUMEN
Understanding how disease affects commercial production is imperative for pig producers to quantify its full impact on pig performance, carcass quality, and net returns. The objective of this experiment was to assess the productivity and economic importance of naturally occurring health challenges (HC) under commercial conditions. Three 1,000 pig grow-finish facilities received 936 pigs each. The experimental period started approximately 34 d post placement at an average start BW of 13.1 ± 0.2 kg. Barns were characterized based on the relative HC, determined by diagnostic assessments as the main characterization tool, along with other health indicators. Barns were characterized as low challenge health (LCh), moderate challenge health (MCh), and high challenge health (HCh). All barns tested positive for porcine reproductive and respiratory syndrome virus infection prior to the start of the experiment. Additionally, the MCh and HCh barns experienced influenza type A virus of swine. Similar to commercial production conditions, the disease challenge was not imposed but rather occurred naturally. Reduced ADG, ADFI, and G:F were observed with an increased HC (P < 0.001). Similarly, mortality was increased when the HC increased (P < 0.001). Decreased ADG increased days to achieve harvest BW, by 10 and 15 d in the MCh and HCh treatments compared with LCh, respectively (P < 0.001). No differences were observed for percent lean, loin depth, or fat depth (P > 0.10). The economic impact of the HC was assessed by applying these growth performance data to two economic models encompassing the two main marketing methods used by U.S. pig producers: fixed-weight and fixed-time. Financial losses attributed to the variation in disease severity that occurred in the present study ranged from $8.49 and $26.10 U.S. dollars (USD)/pig marketed using a fixed-market weight model, or between $11.02 and $29.82 USD/pig using a fixed-time model, depending on feed costs and market hog prices. In conclusion, increasing severity of HC under commercial conditions reduced ADG by 8% and 14% and resulted in mortality as high as 19.9%. Losses of $8.49 to $29.82/pig marketed underscore the potential magnitude of the economic impact of mixed etiology concurrent diseases in pork production.
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The kinetics and mechanism of the reduction of oxidized cytochrome c by ascorbate has been investigated in potassium nitrate, potassium 4-morpholineethanesulfonate (KMes), potassium sulfate and potassium ascorbate media. The results are consistent with simple second order electron transfer from ascorbate dianion to cytochrome c and do not support electron transfer from an ascorbate dianion bound to the protein of the cytochrome as recently proposed by Myer and Kumar. A rate constant of 8 X 10(5) M-1 X s-1 (25 degrees C, ionic strength, 0.1) was found for the electron-transfer step. This rate constant is essentially independent of the specific ions used in controlling ionic strength.
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Ácidos Alcanesulfónicos , Ácido Ascórbico/metabolismo , Grupo Citocromo c/metabolismo , Compuestos de Potasio , Alcanosulfonatos , Animales , Transporte de Electrón , Caballos , Cinética , Morfolinas , Miocardio/enzimología , Nitratos , Oxidación-Reducción , Soluciones , SulfatosRESUMEN
The influence of a low and a high level chronic immune system (IS) activation on growth and dietary nutrient needs of pigs was evaluated. All pigs were of a single genetic strain and geographical site of origin, and the low and high IS pigs were created by physically isolating pigs from or continuously exposing pigs to major vectors of environmental antigen transmission. In each IS group, four littermate barrows in each of six litters were allotted at 25 +/- 2 d of age to one of four dietary amino acid regimens (.60, .90, 1.20, or 1.50% dietary lysine. Dietary lysine concentrations were achieved by altering the ratio of corn to soybean meal resulting in lysine being the first-limiting amino acid in each diet. Pigs were individually penned in facilities maintained at 25.6 +/- 2 degrees C and allowed to freely consume feed from 6.2 to 26.5 kg BW. On the basis of the differences in serological antibody titers, lymphocyte CD4+:CD8+ ratios, and serum alpha-1-acylglycoprotein concentrations, low and high levels of IS activation were established and maintained during the study. Minimizing the degree of chronic IS activation resulted in greater feed intakes (P < .09), body weight and protein gains (P < .01), gain:feed ratios (P < .01), and body leanness (protein:lipid, P < .01). The level of IS activation did not influence the partial efficiency of energy utilization for body protein and lipid accretion. To allow their greater capacity for body growth and protein accretion to be expressed, the low IS pigs required greater dietary lysine concentrations and daily lysine intakes than high IS pigs.
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Peso Corporal/fisiología , Dieta/veterinaria , Ingestión de Alimentos/fisiología , Sistema Inmunológico/fisiología , Lisina/farmacología , Porcinos/crecimiento & desarrollo , Porcinos/inmunología , Animales , Anticuerpos/sangre , Composición Corporal/efectos de los fármacos , Composición Corporal/fisiología , Antígenos CD4/análisis , Antígenos CD8/análisis , Relación Dosis-Respuesta a Droga , Glicoproteínas/sangre , Metabolismo de los Lípidos , Lisina/administración & dosificación , Lisina/análisis , Masculino , Necesidades Nutricionales , Proteínas/metabolismo , Distribución Aleatoria , Glycine max/química , Porcinos/fisiología , Linfocitos T/inmunología , Aumento de Peso/fisiología , Zea mays/químicaRESUMEN
The influence of a low and high level of chronic immune system (IS) activation on body nitrogen retention, partial efficiency of dietary lysine utilization, and lysine needs of pigs at three body weights was determined. All pigs were of a single genetic strain and geographical site of origin, and the low and high IS pigs were created by physically isolating pigs from or continuously exposing pigs to major vectors of antigen transmission. In each IS group, four littermate barrows in each of six litters were allotted at 25 d of age to one of four dietary amino acid regimens (.60, .90, 1.20, or 1.50% dietary lysine). Pigs were individually penned and allowed to freely consume feed from 6.2 to 26.5 kg BW. Nitrogen balance during 4-d periods was determined for each pig at BW of 10, 17.5, and 25 kg. Minimizing the level of chronic IS activation resulted in 4.7 to 7.7 g/d greater body nitrogen retention, 147 to 201 g/d greater BW gain, and 101 to 147 g more gain per kilogram of feed in pigs at the three BW. Dietary lysine intakes needed to maximize each of these criteria at BW of 10, 17.5, and 25 kg were a minimum of 2, 2, and 3 g/d greater in the low vs high IS pigs. However, the partial efficiency of lysine utilization for body nitrogen retention was similar between IS groups. On the basis of these data, the greater dietary lysine needs of the low IS pigs are due to their greater biological capacity for body nitrogen accretion and not to differences in their efficiency of dietary lysine utilization.
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Ingestión de Alimentos/fisiología , Sistema Inmunológico/fisiología , Lisina/metabolismo , Nitrógeno/metabolismo , Porcinos/metabolismo , Animales , Peso Corporal/fisiología , Antígenos CD4/análisis , Antígenos CD8/análisis , Relación Dosis-Respuesta a Droga , Glicoproteínas/sangre , Lisina/farmacología , Masculino , Distribución Aleatoria , Porcinos/genética , Porcinos/fisiología , Linfocitos T/inmunología , Aumento de Peso/fisiologíaRESUMEN
The effect of a low and a high level of chronic immune system (IS) activation on the rate, efficiency, and composition of body growth and dietary lysine needs of pigs fed from 6 to 112 kg body weight was evaluated. All pigs were of a single genetic strain and geographical site of origin, and the low and high IS pigs were created by physically isolating pigs from and continually exposing pigs to major vectors of environmental antigen transmission. In each IS group, five littermate barrows from each of seven litters were individually penned and randomly allotted to one of five dietary amino acid regimens (.6, .9, 1.20, 1.50, and 1.80% lysine from 6 to 27 kg BW and .45, .60, .75, .90, and 1.05% lysine from 27 to 112 kg BW). Dietary lysine concentrations were achieved by altering the ratio of corn to soybean meal in the diets, and diets were formulated such that lysine was the first-limiting amino acid. Low IS pigs possessed lower (P < .01) T lymphocyte CD4+:CD8+ ratios and serum alpha-1-acylglycoprotein concentrations. Low IS pigs also consumed more (P < .01) feed, gained body weight faster (P < .01), required less (P < .01) feed per unit of gain, and at 112 kg BW produced bodies with more (P < .12) muscle and less (P < .10) fatty tissue and offal than high IS pigs. To allow their elevated capacities for proteinaceous tissue to be expressed, low IS pigs required .15 to .30 percentage units greater dietary lysine concentrations and 2 to 5 g higher daily lysine intakes at each 14-kg BW increment from 6 to 112 kg BW.
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Peso Corporal/fisiología , Dieta/veterinaria , Ingestión de Alimentos/fisiología , Sistema Inmunológico/fisiología , Lisina/farmacología , Porcinos/crecimiento & desarrollo , Porcinos/inmunología , Animales , Anticuerpos/sangre , Composición Corporal/fisiología , Antígenos CD4/análisis , Antígenos CD8/análisis , Ensayo de Inmunoadsorción Enzimática/veterinaria , Glicoproteínas/sangre , Lisina/administración & dosificación , Lisina/análisis , Masculino , Carne/normas , Proteínas de la Leche/química , Músculo Esquelético/fisiología , Necesidades Nutricionales , Distribución Aleatoria , Glycine max/química , Porcinos/fisiología , Linfocitos T/inmunología , Aumento de Peso/fisiología , Proteína de Suero de Leche , Zea mays/químicaRESUMEN
An experiment was conducted to determine the effect of ractopamine, energy intake, dietary fat level, and sex on performance and carcass composition in finishing pigs. Three hundred six barrows and gilts were used in a factorial arrangement of treatments replicated over three seasons. Treatments consisted of two ractopamine levels (0 vs 44.7 mg/d), two sexes (barrows and gilts), two levels of fat addition (0 vs 5% added fat), and four energy intake levels (8.3, 8.9, 9.5, and 10.1 Mcal of ME/d for barrows and 7.7, 8.3, 8.9, and 9.5 Mcal of ME/d for gilts). Diets were formulated to maintain an equal lysine (28.5 g/d) intake at each feeding level through cornstarch dilution of the basal (7.7 Mcal of ME/d) diets. Pigs were fed daily based on a standard feed intake curve and prior weekly body weights. At slaughter (104 kg), carcass measurements and TOBEC HA-1 scanner measurements were recorded. Dietary fat addition improved live weight and lean efficiency (grams of carcass lean gain/kilogram of feed, P < .05). Dietary fat addition did not affect growth rate or carcass composition. Increasing energy intake resulted in a linear increase in average daily gain for both barrows and gilts (P < .01). Dietary ractopamine influenced the response of lean tissue accretion, lean tissue accretion efficiency, and fat tissue accretion to energy intake. Pigs with no added ractopamine demonstrated increased lean tissue accretion and improved efficiency and decreased fat tissue accretion with increasing energy intake (up to 9.5 Mcal of ME intake for barrows and 8.9 Mcal of ME intake for gilts). In contrast, pigs with added ractopamine did not respond to increasing energy intake and demonstrated increased fat tissue accretion with increasing energy intake. The response to ractopamine for growth was greatest from d 6 to 22 on test or during the test gain period of 7 to 18 kg. After d 22, the response of ractopamine declined linearly. These results indicate that ractopamine increases growth rapidly at the onset of feeding until a plateau is reached, after which there is a linear decline in growth response.
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Agonistas Adrenérgicos beta/farmacología , Grasas de la Dieta/farmacología , Ingestión de Energía/fisiología , Fenetilaminas/farmacología , Porcinos/crecimiento & desarrollo , Tejido Adiposo/diagnóstico por imagen , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/crecimiento & desarrollo , Animales , Composición Corporal/efectos de los fármacos , Composición Corporal/fisiología , Dieta , Femenino , Sustancias de Crecimiento/farmacología , Masculino , Desarrollo de Músculos , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/crecimiento & desarrollo , Caracteres Sexuales , Factores de Tiempo , Ultrasonografía , Aumento de Peso/efectos de los fármacos , Aumento de Peso/fisiologíaRESUMEN
The effect of dietary amino acid regimen and genetic capacity for lean tissue growth on the lactational performance of sows was determined in primiparous sows with a high (350 to 390 g/d) or low (240 to 280 g/d) genetic capacity for lean tissue growth from 18 to 110 kg of body weight. During lactation, sows were offered daily 6.5 kg of one of four fortified corn-soybean meal diets containing .58, .77, .96, and 1.15% lysine (L). Litters were standardized to 14 pigs within 8 h after birth. On d 2 of lactation, the high lean growth (LG) sows possessed more proteinaceous tissues and protein and less fat tissue and lipid. During lactation (d 2 to 28 postpartum), high LG sows consumed more feed, mobilized more body protein, and lost less body lipid. Milk, milk energy, and milk lysine yields (pooled across dietary regimens) were similar between genotypes. As daily dietary lysine intakes increased from 27 to 62 g and total digestible lysine supplies (from diet and mobilized tissues) increased from 39 to 68 g, daily yields of milk, milk energy, and milk lysine increased, but the magnitude of the response differed (P < .05) between genotypes, evidently because of differences in the ability of the high and low LG sows to mobilize energy from body tissue. Based on these data, the lactational capacities of high and low LG sows nursing 12 to 14 pigs are similar when similar supplies of lysine and energy are available from dietary intake and mobilized body tissue stores. When supplies of ME do not limit milk synthesis, daily digestible lysine intakes of at least 54 g (> or = 66 g from a corn-soy diet) are needed by these sows nursing litters of 12 to 14 pigs to support milk synthesis and minimize maternal protein losses. This is equivalent to a total digestible lysine need of 4.3 to 4.6 g/kg of milk produced. When ME provided by the diet is less than that needed to fuel maximum milk synthesis, however, the dietary amino acid needs of genetically lean sows may be reduced because of their inability to mobilize sufficient body fat stores.
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Composición Corporal/fisiología , Suplementos Dietéticos , Lactancia/fisiología , Lisina/administración & dosificación , Porcinos/fisiología , Análisis de Varianza , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Composición Corporal/genética , Estudios de Cohortes , Femenino , Genotipo , Lactancia/genética , Tamaño de la Camada , Masculino , Paridad , Probabilidad , Porcinos/genética , Porcinos/crecimiento & desarrolloRESUMEN
BACKGROUND: Anxiety is an important consideration in teaching, with implications for classroom success. AIMS: We investigated the nature of anxiety in student teachers. SAMPLES: Approximately 1000 student teachers in Canada were involved in four studies to explore education-related anxieties. METHODS: Incorporating a cross-cultural focus, student teachers were tested on an anxiety measure designed for British student teachers, then examined for (1) the impact of practice teaching, (2) the value of instructional preparation, (3) demographic variables, and (4) models that predict anxiety. RESULTS: Anxiety factors (i.e., evaluation, pedagogical, class management, and staff relations), similar to those for British participants, emerged with evaluation anxiety being highest. A practice teaching experience generated reduced anxiety for both sexes, but more so for females, with the greatest reductions for evaluation and pedagogical anxiety. In one study, participants reported anxieties prior to instruction (PRETEST), following instruction (POST-INSTR) and following practice teaching (POST-TEACH). Females showed higher anxiety ratings than males (PRETEST and POST-INSTR) but were comparable to males after practice teaching. Females in the lower grades division showed higher anxiety scores. Anxiety decreased between PRE-TEST and POST-INSTR for all four scales, and between POST-INSTR and POST-TEACH for evaluation, pedagogy and staff relations; however, class management anxiety did not decrease after practice teaching. Also, anxiety increased as placement grade level decreased. All models (demographic, experiential, and dispositional) were predictive but the best predictor was the psychological disposition to feel overwhelmed. CONCLUSIONS: Student-teacher anxieties are related to demographic variables, experiential variables, and dispositional variables.
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Ansiedad/etiología , Ansiedad/prevención & control , Cuidadores/psicología , Evaluación del Rendimiento de Empleados , Relaciones Interprofesionales , Práctica Psicológica , Enseñanza , Adulto , Análisis de Varianza , Análisis Factorial , Femenino , Humanos , Estudios Longitudinales , Masculino , Modelos Psicológicos , Ontario , Análisis de Regresión , Muestreo , Factores SexualesRESUMEN
Pasteuria penetrans is an endospore-forming bacterial parasite of Meloidogyne spp. This organism is among the most promising agents for the biological control of root-knot nematodes. In order to establish the phylogenetic position of this species relative to other endospore-forming bacteria, the 16S ribosomal genes from two isolates of P. penetrans, P-20, which preferentially infects M. arenaria race 1, and P-100, which preferentially infects M. incognita and M. javanica, were PCR-amplified from a purified endospore extraction. Universal primers for the 16S rRNA gene were used to amplify DNA which was cloned, and a nucleotide sequence was obtained for 92% of the gene (1,390 base pairs) encoding the 16S rDNA from each isolate. Comparison of both isolates showed identical sequences that were compared to 16S rDNA sequences of 30 other endospore-forming bacteria obtained from GenBank. Parsimony analyses indicated that P. penetrans is a species within a clade that includes Alicyclobacillus acidocaldarius, A. cycloheptanicus, Sulfobacillus sp., Bacillus tusciae, B. schlegelii, and P. ramosa. Its closest neighbor is P. ramosa, a parasite of Daphnia spp. (water fleas). This study provided a genomic basis for the relationship of species assigned to the genus Pasteuria, and for comparison of species that are parasites of different phytopathogenic nematodes.
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A midwestern community hospital established an Acute Pain Service to implement epidural analgesia on the general care units. It developed a multidisciplinary quality assurance plan using the Joint Commission on Accreditation of Healthcare Organizations' 10-step monitoring and evaluation process. Quality assurance monitors provided information regarding important aspects of care. Data collected from the monitors enabled nurses and other disciplines to make decisions and changes about the growing epidural analgesia program.
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Analgesia Epidural/normas , Grupo de Atención al Paciente/organización & administración , Garantía de la Calidad de Atención de Salud/organización & administración , Analgesia Epidural/enfermería , Protocolos Clínicos , Humanos , Registros de Enfermería/normas , Enfermería OrtopédicaRESUMEN
Excess nitrogen in soil, aquatic and atmospheric environments is an escalating global problem. Eutrophication is the principal threat to surface water quality in the Republic of Ireland. European Union Water Framework Directive (2000/60/EC) water quality status assessments found that 16% of Irish groundwater bodies were 'at risk' of poor status due to the potential deterioration of associated estuarine and coastal water quality by nitrate from groundwater. This paper presents a methodology for evaluating pressure and pathway parameters affecting the spatial distribution of groundwater nitrate, investigated at a regional scale using existing national spatial datasets. The potential for nitrate transfer to groundwater was rated based on the introduced concepts of Pressure Loading and Pathway Connectivity Rating, each based on a combination of selected pressure and pathway parameters respectively. In the region studied, the South Eastern River Basin District of Ireland, this methodology identified that pathway parameters were more important than pressure parameters in understanding the spatial distribution of groundwater nitrate. Statistical analyses supported these findings and further demonstrated that the proportion of poorly drained soils, arable land, karstic flow regimes, regionally important bedrock aquifers and high vulnerability groundwater within the zones of contribution of the monitoring points are statistically significantly related to groundwater nitrate concentrations. Soil type was found to be the most important parameter. Analysis of variance showed that a number of the pressure and pathway parameters are interrelated. The parameters identified by the presented methodology may provide useful insights into the best way to manage and mitigate the influence of nitrate contamination of groundwater in this region. It is suggested that the identification of critical source areas based on the identified parameters would be an appropriate management tool, enabling planning and enforcement resources to be focussed on areas which will yield most benefit.
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Monitoreo del Ambiente , Agua Subterránea/química , Nitratos/análisis , Contaminantes Químicos del Agua/análisis , Agricultura , Hidrología , Irlanda , Análisis EspacialRESUMEN
The objective of this study was to investigate the relationships among birth weight, birth order, or litter size on growth performance, carcass quality, and eating quality of the ultimate pork product. Data were collected from 98 pig litters and, with the addition of recording birth weight and birth order, farrowing and piglet management were according to normal barn practices. In the nursery and during growout, the pigs received the normal feeding program for the barn and, with the addition of individual tattooing, were marketed as per standard procedure. From 24 litters, selected because they had at least 12 pigs born alive and represented a range of birth weights, 4 piglets were chosen (for a total of 96 piglets) and sent to Agriculture and Agri-Food Canada-Lacombe Research Centre (Lacombe, Alberta, Canada) when they reached 120 kg for extensive meat quality and sensory analysis. Individual BW was measured at birth, on the day of weaning, 5 wk after weaning, at nursery exit, at first pull, and at the time of marketing. Litter sizes were divided into 3 categories: small (3 to 10 piglets), medium (11 to 13 piglets), and large (14 to 19 piglets). There were 4 birth-weight quartiles: 0.80 to 1.20, 1.25 to 1.45, 1.50 to 1.70, and 1.75 to 2.50 kg. Increased litter size resulted in reduced mean birth weight (P < 0.05), but had no effect on within litter variability or carcass quality (P > 0.05) when slaughtered at the same endpoint. Lighter birth-weight pigs had reduced BW at weaning, 5 and 7 wk postweaning, and at first pull and had increased days to market (P < 0.05). Birth weight had limited effects on carcass quality, weight of primal cuts, objective quality, and overall palatability of the meat at the same slaughter weight (P > 0.05). In conclusion, increased litter size resulted in decreased mean birth weight but no change in days to market. Lighter birth-weight pigs took longer to reach market. Despite some differences in histological properties, birth weight had limited effects on carcass composition or final eating quality of the pork when slaughtered at the same BW and large litter size resulted in more pigs weaned and marketed compared with the smaller litters. We concluded that based on the conditions of this study, other than increased days to market, there is no reason based on pig performance or pork quality to slow down the goal of the pork industry to increase sow productivity as a means to increase efficiency.
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Peso al Nacer/fisiología , Tamaño de la Camada/fisiología , Carne/normas , Músculo Esquelético/química , Porcinos/crecimiento & desarrollo , Animales , Femenino , Masculino , Carne/análisis , Porcinos/fisiología , Aumento de Peso/fisiologíaAsunto(s)
Linfocitos/citología , Mitógenos/farmacología , Bazo/citología , Timo/citología , Envejecimiento , Animales , Linfocitos B/inmunología , División Celular , Supervivencia Celular , Células Cultivadas , Concanavalina A/farmacología , Relación Dosis-Respuesta Inmunológica , Lipopolisacáridos/farmacología , Fitohemaglutininas/farmacología , Linfocitos T/inmunología , Timidina/metabolismo , Tuberculina , XenopusRESUMEN
Understanding how energy is utilized by the pig, and how the pig responds to changes in dietary energy concentration, is essential information in determining the optimal concentration of dietary energy under farm conditions, which are often highly diverse. The objective of these experiments was to determine how changes in dietary DE concentration, achieved through graded changes in diet composition, would affect the performance and carcass composition of growing pigs. In Exp. 1, which was conducted in a research facility, 300 pigs (31.1 +/- 2.6 kg) were assigned to diets containing 3.09, 3.24, 3.34, 3.42, or 3.57 Mcal of DE/kg. Experiment 2, which was conducted at a commercial swine farm, involved 720 pigs (36.8 +/- 5.9 kg) assigned to diets containing 3.12, 3.30, or 3.43 Mcal of DE/kg. Increased DE concentration was attained by using more wheat, soybean meal, and fat and less barley; true ileal lysine was adjusted as DE increased, and minimal AA:lysine ratios were maintained. In Exp. 1, ADG improved linearly as the energy content of the diet increased (P = 0.03). Feed intake decreased (P < 0.001) and feed efficiency and daily caloric intake improved (P = 0.005) with increased DE content. Variability in growth was not affected by treatment. Carcass index and LM thickness were not affected by increasing dietary DE content; backfat thickness, however, was increased (P < 0.001). In Exp. 2, overall ADG was unaffected by dietary energy content, although an improvement in growth was observed until the pigs reached approximately 80 kg of BW. Overall feed intake decreased with increasing energy content (P = 0.01), although this was not observed during the initial 6 wk of the experiment. Carcass index, lean yield, and backfat were not affected by increasing dietary energy content, whereas LM thickness tended to increase (P = 0.08). The value per pig was unaffected by increasing dietary energy content in both experiments, and returns above feed costs were reduced. Increasing the energy density of the diet for growing pigs through incremental changes in dietary composition had a variable impact on overall growth performance and carcass quality. Increasing the dietary DE had no effect on variations in BW at the time of marketing.
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Dieta/veterinaria , Digestión/fisiología , Grano Comestible/metabolismo , Porcinos/fisiología , Crianza de Animales Domésticos/economía , Animales , Ingestión de Energía/fisiología , Femenino , Análisis de los Mínimos Cuadrados , Masculino , Distribución Aleatoria , Porcinos/crecimiento & desarrollo , Porcinos/metabolismoRESUMEN
Ten sets of 5 littermate pigs from each of 2 genetic strains were utilized to determine the impact of the dietary concentration of 5 B vitamins (riboflavin, niacin, pantothenic acid, cobalamin, and folacin) on growth from 9 to 28 kg of BW in pigs with high or moderate capacity for lean growth. All pigs (penned individually) were reared via a segregated, early weaning scheme, so that the lean growth potential of each strain could be expressed. The basal diet provided the 5 test vitamins at concentrations of total and estimated bioavailability equivalent to a minimum of 100 and 70%, respectively, of their estimated requirements (NRC, 1998) for 5- to 10-kg pigs. At a BW of 9 +/- 0.9 kg, pigs within each litter were allotted to the basal diet supplemented with sources of the 5 test vitamins equivalent to an additional 0, 100, 200, 300, or 400% (bioavailable) of the NRC requirements. Pigs from the high lean strain consumed less feed (P < 0.05) and gained BW faster (P < 0.02) and more efficiently (P < 0.01) than pigs of the moderate lean strain. In both lean strains, the rate and efficiency of growth were improved (P < 0.01) as dietary B vitamin concentrations were increased. However, the dietary B vitamin concentrations needed to optimize G:F were greater (P < 0.03) in the high (>470% of NRC, 1998) vs. moderate (270%) lean strain. Based on these data, the dietary needs for 1 or more of the 5 B vitamins are greater than current NRC (1998) estimates, particularly in pigs expressing a high rate of lean tissue growth. The greater need for these vitamins is not associated with greater dietary energy intake or body energy accretion rate but is potentially due to shifts in the predominant metabolic pathways.