RESUMEN
Rumen bacterial species belonging to the genus Butyrivibrio are important degraders of plant polysaccharides, particularly hemicelluloses (arabinoxylans) and pectin. Currently, four species are recognized; they have very similar substrate utilization profiles, but little is known about how these microorganisms are able to coexist in the rumen. To investigate this question, Butyrivibrio hungatei MB2003 and Butyrivibrio proteoclasticus B316T were grown alone or in coculture on xylan or pectin, and their growth, release of sugars, fermentation end products, and transcriptomes were examined. In monocultures, B316T was able to grow well on xylan and pectin, while MB2003 was unable to utilize either of these insoluble substrates to support significant growth. Cocultures of B316T grown with MB2003 revealed that MB2003 showed growth almost equivalent to that of B316T when either xylan or pectin was supplied as the substrate. The effect of coculture on the transcriptomes of B316T and MB2003 was assessed; B316T transcription was largely unaffected by the presence of MB2003, but MB2003 expressed a wide range of genes encoding proteins for carbohydrate degradation, central metabolism, oligosaccharide transport, and substrate assimilation, in order to compete with B316T for the released sugars. These results suggest that B316T has a role as an initiator of primary solubilization of xylan and pectin, while MB2003 competes effectively for the released soluble sugars to enable its growth and maintenance in the rumen.IMPORTANCE Feeding a future global population of 9 billion people and climate change are the primary challenges facing agriculture today. Ruminant livestock are important food-producing animals, and maximizing their productivity requires an understanding of their digestive systems and the roles played by rumen microbes in plant polysaccharide degradation. Butyrivibrio species are a phylogenetically diverse group of bacteria and are commonly found in the rumen, where they are a substantial source of polysaccharide-degrading enzymes for the depolymerization of lignocellulosic material. Our findings suggest that closely related species of Butyrivibrio have developed unique strategies for the degradation of plant fiber and the subsequent assimilation of carbohydrates in order to coexist in the competitive rumen environment. The identification of genes expressed during these competitive interactions gives further insight into the enzymatic machinery used by these bacteria as they degrade the xylan and pectin components of plant fiber.
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Butyrivibrio/crecimiento & desarrollo , Butyrivibrio/metabolismo , Pectinas/metabolismo , Xilanos/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Butyrivibrio/genética , Medios de Cultivo/química , Medios de Cultivo/metabolismo , Filogenia , Azúcares/metabolismoRESUMEN
KEY MESSAGE: Genomic prediction models for multi-year dry matter yield, via genotyping-by-sequencing in a composite training set, demonstrate potential for genetic gain improvement through within-half sibling family selection. Perennial ryegrass (Lolium perenne L.) is a key source of nutrition for ruminant livestock in temperate environments worldwide. Higher seasonal and annual yield of herbage dry matter (DMY) is a principal breeding objective but the historical realised rate of genetic gain for DMY is modest. Genomic selection was investigated as a tool to enhance the rate of genetic gain. Genotyping-by-sequencing (GBS) was undertaken in a multi-population (MP) training set of five populations, phenotyped as half-sibling (HS) families in five environments over 2 years for mean herbage accumulation (HA), a measure of DMY potential. GBS using the ApeKI enzyme yielded 1.02 million single-nucleotide polymorphism (SNP) markers from a training set of n = 517. MP-based genomic prediction models for HA were effective in all five populations, cross-validation-predictive ability (PA) ranging from 0.07 to 0.43, by trait and target population, and 0.40-0.52 for days-to-heading. Best linear unbiased predictor (BLUP)-based prediction methods, including GBLUP with either a standard or a recently developed (KGD) relatedness estimation, were marginally superior or equal to ridge regression and random forest computational approaches. PA was principally an outcome of SNP modelling genetic relationships between training and validation sets, which may limit application for long-term genomic selection, due to PA decay. However, simulation using data from the training experiment indicated a twofold increase in genetic gain for HA, when applying a prediction model with moderate PA in a single selection cycle, by combining among-HS family selection, based on phenotype, with within-HS family selection using genomic prediction.
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Técnicas de Genotipaje , Lolium/genética , Genómica , Desequilibrio de Ligamiento , Modelos Genéticos , Fenotipo , Fitomejoramiento , Polimorfismo de Nucleótido SimpleRESUMEN
Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne's disease in ruminants, which is characterized by chronic progressive granulomatous enteritis. The infection leads to wasting and weight loss in the animals and eventually death, causing considerable production losses to the agricultural industry worldwide. Currently available ELISA- and PCR-based diagnostic tests have limited sensitivity and specificity during early MAP infection in cattle, suggesting that there is an urgent demand for alternative diagnostic tests. Circulating microRNA (miRNA) have recently gained attention as potential biomarkers for several diseases in humans. However, knowledge and use of miRNA as biomarkers in diseases of ruminants, including Johne's disease, are very limited. Here we used NanoString nCounter technology (NanoString, Seattle, WA), a digital platform for amplification-free and hybridization-based quantitative measurement of miRNA in the sera of noninfected and naturally MAP-infected cattle with different severity of infection. Using probes developed against human miRNA, 26 miRNA were detected in cattle serum; 13 of these miRNA were previously uncharacterized for cattle. Canonical discrimination analysis using 20 miRNA grouped animals into 4 distinct clusters based on their disease status, suggesting that the levels of these miRNA can reflect disease severity. A model was developed using a combination of 4 miRNA (miR-1976, miR-873-3p, miR-520f-3p, and miR-126-3p), which distinguished moderate and severely infected animals from noninfected animals. Our study demonstrated the ability of the NanoString nCounter technology to detect differential expression of circulating miRNA in cattle and contributes to widely growing evidence that miRNA can be used as biomarkers in infectious diseases in cattle.
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Enfermedades de los Bovinos/diagnóstico , Perfilación de la Expresión Génica/veterinaria , MicroARNs/sangre , Mycobacterium avium subsp. paratuberculosis/aislamiento & purificación , Paratuberculosis/diagnóstico , Animales , Biomarcadores/análisis , Bovinos , Enfermedades de los Bovinos/microbiología , Femenino , Perfilación de la Expresión Génica/instrumentación , Perfilación de la Expresión Génica/métodos , Humanos , Mycobacterium avium subsp. paratuberculosis/genética , Paratuberculosis/microbiología , Sensibilidad y EspecificidadRESUMEN
Dietary protein is considered more satiating than carbohydrate, and whey protein is more satiating than other protein sources. The purported satiating effect of whey protein may be due to direct effects of the unique mixture of proteins in whey, due to the effects of peptides released upon digestion and/or its amino acid composition. The objective of the present study was to compare the satiating effects of intact whey protein isolate (WPI) or a free amino acid mixture (AAM) simulating the amino acid composition of the WPI. A single-blind completely randomised block design included twenty, healthy, adult women (age 24·2 (sem 0·8) years) of normal weight (BMI 22·7 (sem 0·4) kg/m2). Following consumption of isoenergetic (approximately 1800 kJ) preload meals enriched (52 g amino acid equivalent) with WPI or AAM, consumption of an ad libitum test meal 120 min later and subjective feelings of appetite using visual analogue scales (VAS) were determined. There were no significant differences (P=0·24) in the ad libitum test meal intakes between the WPI (268·5 (sem 27·3) g) and the AAM (238·4 (sem 22·7) g) preload meals. Subjective VAS ratings of appetite did not differ significantly between the WPI and the AAM preload meals (P>0·05). Intact whey protein and a free AAM simulating the whey protein showed similar effects on satiety. This suggests that the satiating effect of whey protein may be related to its specific amino acid composition.
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Aminoácidos/administración & dosificación , Depresores del Apetito/administración & dosificación , Desayuno , Condimentos , Alimentos Especializados , Respuesta de Saciedad , Proteína de Suero de Leche/administración & dosificación , Adulto , Aminoácidos/efectos adversos , Animales , Depresores del Apetito/efectos adversos , Condimentos/efectos adversos , Ingestión de Energía , Femenino , Preferencias Alimentarias , Alimentos Formulados/efectos adversos , Alimentos Especializados/efectos adversos , Humanos , Almuerzo , Nueva Zelanda , Periodo Posprandial , Autoinforme , Método Simple Ciego , Proteína de Suero de Leche/efectos adversos , Adulto JovenRESUMEN
Protein is the most satiating macronutrient and dairy whey protein is thought to be more satiating than other protein sources. The purported satiating effect of whey protein may be attributable to the presence of glycomacropeptide (GMP). The objective of this study was to investigate the role of GMP in the satiating effect of whey protein. Isoenergetic (~1600 kJ) preload drinks contained GMP isolate (86% GMP, "GMP"), whey protein isolate (WPI) with 21% naturally occurring GMP, WPI with 2% naturally present GMP, or maltodextrin carbohydrate ("carbohydrate"). Satiety was assessed in 22 normal-weight adult women by determining the consumption of a test meal provided ad libitum 120 min following ingestion of a preload drink, and also by using visual analogue scales (VAS) for rating feelings of hunger, desire to eat, prospective consumption and fullness (appetite). The ad libitum test meal intake was significantly different between the preload drinks (p = 0.0003), with food intake following ingestion of both WPI preload drinks (regardless of the amount of GMP) being ~18% lower compared with the beverages enriched with carbohydrate or GMP alone. There were no significant differences (p > 0.05) in the VAS-rated feelings of appetite among the four preload drinks. GMP alone did not reduce subsequent food intake compared with a drink enriched with carbohydrate, but whey protein had a greater satiating effect than carbohydrate. The presence of GMP in whey does not appear to be the cause of the observed effect of whey protein on satiety.
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Apetito/efectos de los fármacos , Caseínas/farmacología , Proteínas en la Dieta/farmacología , Ingestión de Energía/efectos de los fármacos , Proteínas de la Leche/farmacología , Fragmentos de Péptidos/farmacología , Saciedad/efectos de los fármacos , Adolescente , Adulto , Peso Corporal , Dieta , Ingestión de Alimentos/efectos de los fármacos , Femenino , Humanos , Estudios Prospectivos , Valores de Referencia , Método Simple Ciego , Proteína de Suero de Leche , Adulto JovenRESUMEN
AIM: To examine the psychometric properties of the 'Jefferson Scale of Empathy'. DESIGN: A methodological study was conducted. METHODS: A sample of 230 nursing students was used to analyse the psychometric properties of the 'Jefferson Scale of Empathy'. Exploratory and confirmatory factor analysis was used to test construct validity. Cronbach's alpha and item-total correlations were carried out to test internal consistency reliability. RESULTS: The mean score of the empathy SUM was 112.0 (SD: 12.6). A three-factor model was explored. This factor structure does not replicate the original 'Jefferson Scale of Empathy' when it was validated with medical students, but it is in line with later research with nursing students. The Cronbach's alpha coefficient was 0.80 for the SUM and 0.80-0.84 for individual items. Item-total correlation coefficients were 0.01-0.63. NO PATIENT OR PUBLIC CONTRIBUTION: Because this study focused on nursing students. No patients or the public were involved.
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Empatía , Estudiantes de Enfermería , Humanos , Psicometría , Reproducibilidad de los Resultados , Reino UnidoRESUMEN
Although bone fracture has become a serious global health issue, current clinical assessments of fracture risk based on bone mineral density are unable to accurately predict whether an individual is likely to suffer a fracture. There is increasing recognition that the chemical structure and composition, or microstructure, of mineralized tissues has an important role to play in determining the fracture resistance of bone. The objective of this preliminary study was to evaluate the use of specular reflectance Fourier transform infrared (SR FT-IR) microspectroscopy in conjunction with discriminant analysis as an innovative technique for providing future insights into the origins of orthopedic abnormalities. The impetus for this approach was that SR FT-IR microspectroscopy would offer several advantages over conventional transmission methods. Bone samples were obtained from young racehorses at known fracture predilection sites and spectra were successfully obtained from calcified cartilage and subchondral bone for the first time. By applying discriminant analysis to the spectral data set in biologically relevant regions, microstructural differences between groups of individuals were found to be related to features associated with both the mineral and organic components of the bone. The preliminary findings also suggest that differences in bone microstructure may exist between healthy individuals of the same age, raising important questions around the normal limits of individual variation and whether individuals may be predisposed to later fracture as a result of detrimental microstructural changes during early growth and development.
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Calcinosis/patología , Microtecnología/métodos , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Animales , Análisis Discriminante , Caballos , Microscopía Electrónica , Reproducibilidad de los ResultadosRESUMEN
Differences in the time interval between preload and test meal may account for the variation in the satiating effects of whey protein found in previous preload studies. The objective was to compare the satiating effects (ad libitum meal intake at a set time after ingestion of preload) of whey protein (including glycomacropeptide) and maltodextrin carbohydrate and to determine whether such effects were influenced by the timing of preloads. On nine separate days, 19 healthy normal weight women consumed mixed composition preloads containing either water, or maltodextrin, or whey protein, 30, 60 or 120 min before an ad libitum test meal. Whey protein reduced food intake (p < 0.05) at the test meal more than maltodextrin and water (respective food energy intakes were 2343, 2584 and 3135 kJ). The time interval between preload and test meal did not affect the food intake response. Total energy intake (preload+test meal) differed, with intake for the maltodextrin-enriched preload being greater than that for the whey protein-enriched preload, which was greater than for the water control. Total respective energy intakes were 3955, 3676 and 3135 kJ. Subjective ratings of appetite did not support a greater satiating effect of whey protein versus maltodextrin on food intake but there was evidence for a satiating effect of maltodextrin and whey protein versus the water control.
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Ingestión de Alimentos/fisiología , Ingestión de Energía/fisiología , Adolescente , Adulto , Apetito/efectos de los fármacos , Apetito/fisiología , Índice de Masa Corporal , Caseínas/administración & dosificación , Carbohidratos de la Dieta/administración & dosificación , Femenino , Humanos , Comidas , Proteínas de la Leche/administración & dosificación , Fragmentos de Péptidos/administración & dosificación , Polisacáridos/administración & dosificación , Saciedad/efectos de los fármacos , Saciedad/fisiología , Método Simple Ciego , Factores de Tiempo , Proteína de Suero de Leche , Adulto JovenRESUMEN
AIM: To evaluate the effects of a novel, immersive digital story intervention on empathy. DESIGN: A randomized trial with three phases. RESULTS: A total of 238 2nd year nursing students were recruited between May 2018 and December 2019. At baseline, no significant differences in empathy between the groups were found (p = .760). However, at post-test, empathy was significantly higher in the intervention group (M: 118.76, SD: 10.65) than it was in the control group (M: 114.60, SD: 15.40) (p = .012). At follow-up, there were no significant differences in empathy between the groups (p = .364). CONCLUSION: The intervention resulted in an immediate increase in empathy in nursing students. However, further development of effective intervention delivery modes and fundamental redesign of the intervention itself would be needed to sustain this improvement over the long term.
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Bachillerato en Enfermería , Estudiantes de Enfermería , Pruebas Diagnósticas de Rutina , Empatía , HumanosRESUMEN
The objective of this study was to determine whether divergent feeding regimes during the first 41 weeks of the life of a calf are associated with long-term changes in the rumen microbiota and the associated fermentation end-products. Twenty-four calves (9 ± 5 days of age) were arranged in a 2 × 2 factorial design with two divergent treatments across three dietary phases. In phase 1 (P01), calves were offered a low-milk volume/concentrate starter diet with early weaning (CO) or high-milk volume/pasture diet and late weaning (FO). In phase 2 (P02), calves from both groups were randomly allocated to either high-quality (HQ) or low-quality (LQ) pasture grazing groups. In phase 3 (P03), calves were randomly allocated to one of two grazing groups and offered the same pasture-only diet. During each dietary phase, methane (CH4) and hydrogen (H2) emissions and dry matter intake (DMI) were measured in respiration chambers, and rumen samples for the evaluation of microbiota and short-chain fatty acid (SCFA) characterizations were collected. In P01, CO calves had a higher solid feed intake but a lower CH4 yield (yCH4) and acetate:propionate ratio (A:P) compared with FO calves. The ruminal bacterial community had lower proportions of cellulolytic bacteria in CO than FO calves. The archaeal community was dominated by Methanobrevibacter boviskoreani in CO calves and by Mbb. gottschalkii in FO calves. These differences, however, did not persist into P02. Calves offered HQ pastures had greater DMI and lower A:P ratio than calves offered LQ pastures, but yCH4 was similar between groups. The cellulolytic bacteria had lower proportions in HQ than LQ calves. In all groups, the archaeal community was dominated by Mbb. gottschalkii. No treatment interactions were observed in P02. In P03, all calves had similar DMI, CH4 and H2 emissions, SCFA proportions, and microbial compositions, and no interactions with previous treatments were observed. These results indicate that the rumen microbiota and associated fermentation end-products are driven by the diet consumed at the time of sampling and that previous dietary interventions do not lead to a detectable long-term microbial imprint or changes in rumen function.
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The present study aimed to determine whether dietary supplementation with methanogen inhibitors during early life may lead to an imprint on the rumen microbial community and change the rumen function and performance of calves to 49-weeks of rearing. Twenty-four 4-day-old Friesian x Jersey cross calves were randomly assigned into a control and a treatment group. Treated calves were fed a combination of chloroform (CF) and 9,10-anthraquinone (AQ) in the solid diets during the first 12 weeks of rearing. Afterward, calves were grouped by treatments until week 14, and then managed as a single group on pasture. Solid diets and water were offered ad libitum. Methane measurements, and sample collections for rumen metabolite and microbial community composition were carried out at the end of weeks 2, 4, 6, 8, 10, 14, 24 and 49. Animal growth and dry matter intake (DMI) were regularly monitored over the duration of the experiment. Methane emissions decreased up to 90% whilst hydrogen emissions increased in treated compared to control calves, but only for up to 2 weeks after treatment cessation. The near complete methane inhibition did not affect calves' DMI and growth. The acetate:propionate ratio decreased in treated compared to control calves during the first 14 weeks but was similar at weeks 24 and 49. The proportions of Methanobrevibacter and Methanosphaera decreased in treated compared to control calves during the first 14 weeks; however, at week 24 and 49 the archaea community was similar between groups. Bacterial proportions at the phylum level and the abundant bacterial genera were similar between treatment groups. In summary, methane inhibition increased hydrogen emissions, altered the methanogen community and changed the rumen metabolite profile without major effects on the bacterial community composition. This indicated that the main response of the bacterial community was not a change in composition but rather a change in metabolic pathways. Furthermore, once methane inhibition ceased the methanogen community, rumen metabolites and hydrogen emissions became similar between treatment groups, indicating that perhaps using the treatments tested in this study, it is not possible to imprint a low methane microbiota into the rumen in the solid feed of pre-weaned calves.
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OBJECTIVES: This study aimed to evaluate the trauma and injury severity score (TRISS), IMPACT (international mission for prognosis and analysis of clinical trials), and CRASH (corticosteroid randomization after significant head injury) prognostic models for prediction of outcome after moderate-to-severe traumatic brain injury (TBI) in the elderly following road traffic accident. DESIGN: This was a prospective observational study. MATERIALS AND METHODS: This was a prospective observational study on 104 elderly trauma patients who were admitted to tertiary care hospital, over a consecutive period of 18 months from December 2016 to May 2018. On the day of admission, data were collected from each patient to compute the TRISS, IMPACT, and CRASH and outcome evaluation was prospectively done at discharge, 14th day, and 6-month follow-up. RESULTS: This study included 104 TBI patients with a mean age of 66.75 years and with a mortality rate of 32% and 45%, respectively, at discharge and at the end of 6 months. The predictive accuracies of the TRISS, CRASH (computed tomography), and IMPACT (core, extended, laboratory) were calculated using receiver operator characteristic (ROC) curves for the prediction of mortality. Best cutoff point for predicting mortality in elderly TBI patients using TRISS system was a score of ≤88 (sensitivity 94%, specificity of 80%, and area under ROC curve 0.95), similarly cutoff point under the CRASH at 14 days was score of >35 (100%, 80%, 0.958); for CRASH at 6 months, best cutoff point was at >84 (88%, 88%, 0.959); for IMPACT (core), it was >38 (88%, 93%, 0.976); for IMPACT (extended), it was >27 (91%, 89%, 0.968); and for IMPACT (lab), it was >41 (82%, 100%, 0.954). There were statistical differences among TRISS, CRASH (at 14 days and 6 months), and IMPACT (core, extended, lab) in terms of area under the ROC curve (P < 0.0001). CONCLUSION: IMPACT (core, extended) models were the strongest predictors of mortality in moderate-to-severe TBI when compared with the TRISS, CRASH, and IMPACT (lab) models.
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Malignant melanoma in the head and neck area is rare. The incidence of oral malignant melanomas of the head and neck is approximately four per 10 million populations per year. They are derived from epidermal melanocytes and are most frequently seen on the palate and maxillary gingiva. They are asymptomatic initially but become painful with progress and enlargement. Later, they are associated with ulceration, bleeding, mobility of tooth, paresthesia and ill-fitting prosthesis. The diagnosis is often delayed due to silent growth and development of the lesion. Oral malignant melanomas are associated with poor prognosis due to their invasive and metastasizing tendencies. This case report is presented to emphasize the role of a dentist in identifying the pigmented lesions of the oral cavity.
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Modified, agricultural landscapes are susceptible to damage by insect pests. Biological control of pests is typically successful once a control agent has established, but this depends on the agent's capacity to co-evolve with the host. Theoretical studies have shown that different levels of genetic variation between the host and the control agent will lead to rapid evolution of resistance in the host. Although this has been reported in one instance, the underlying genetics have not been studied. To address this, we measured the genetic variation in New Zealand populations of the pasture pest, Argentine stem weevil (Listronotus bonariensis), which is controlled with declining effectiveness by a parasitoid wasp, Microctonus hyperodae. We constructed a draft reference genome of the weevil, collected samples from a geographical survey of 10 sites around New Zealand, and genotyped them using a modified genotyping-by-sequencing approach. New Zealand populations of Argentine stem weevil have high levels of heterozygosity and low population structure, consistent with a large effective population size and frequent gene flow. This implies that Argentine stem weevils were able to evolve more rapidly than their biocontrol agent, which reproduces asexually. These findings show that monitoring genetic diversity in biocontrol agents and their targets is critical for long-term success of biological control.
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During the peripartum period, dairy cows often have signs of inflammation. Various stresses, including infectious and metabolic diseases, have been discussed as causative for this inflammation. In this study, expression profiles for 17 immune markers were measured in whole blood preparations from 78 dairy cows over a time frame starting 1 wk before calving to 4 wk after calving. Additionally, the effects of far-off and close-up feeding on immune function of dairy cows during the peripartum period were investigated. Cows were assigned to 1 of 2 feeding levels in late lactation to achieve a low and high BCS at the time of dry-off (approximately 4.25 and 5.0 on a 10-point scale). Following dry-off, both herds were managed to achieve a BCS of 5.0 one month before calving; this involved controlled feeding (i.e., maintenance) and over-feeding of ME during the far-off dry period. Within each far-off feeding-level treatment, cows were offered 65, 90, or 120% of their precalving ME requirements for 3 wk precalving in a 2 × 3 factorial arrangement. Analysis of gene expression profiles from blood cells revealed effects of time indicating that the transition cow's immune system counteracts the peripartum inflammation, whereas later postcalving it becomes activated to provide protection against postpartum infections. Far-off feeding affected (P < 0.05) the expression of 2 of the investigated genes at calving. Interleukin-6 (IL-6) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression in unstimulated, peripheral leukocytes were lower (P < 0.05) in animals from the Far-Off_Over-fed group compared with the Far-Off_Control-fed group. Close-up feeding had several effects on gene expression, indicating that immune function in Feed120 animals was distinct from the Feed90 and Feed65. In conclusion, feeding management precalving becomes an important intervention to ensure immunocompetence at and after calving.
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Bovinos/fisiología , Ingestión de Alimentos , Ingestión de Energía , Inflamación/veterinaria , Transcriptoma , Animales , Bovinos/genética , Bovinos/inmunología , Femenino , Gliceraldehído-3-Fosfato Deshidrogenasas/genética , Inmunocompetencia , Interleucina-6/genética , Lactancia , Periodo Periparto , Periodo PospartoRESUMEN
The establishment rate of Cooperia oncophora related to host age and previous infection was investigated in young calves. Calves of similar age were kept on a feed pad and allocated into multiple groups, based on their age and weight. Two groups (each n = 16) received trickle infections with an ivermectin-susceptible C. oncophora isolate of 2000 or 10,000 infective stage larvae per week while another group (n = 16) was kept as an uninfected control. At intervals over a period of 11 months, two animals from each group were challenged with 15,000 infective stage larvae of an ivermectin-resistant isolate, 25 days later orally treated with ivermectin and 5 days after that slaughtered for worm counts. On three occasions additional calves (n = 2), subjected to the high trickle infection rate, received an ivermectin treatment to remove the existing worm burden, prior to challenge as above. Further calves (n = 4) of similar age were introduced at the beginning and the end of the experiment to determine the effect of larval age on establishment rate. The establishment in the two trickle infection groups declined to <10% within the first three months, which was significantly different from the control group. In the animals receiving the high trickle infection, but an anthelmintic treatment before challenge the establishment rate was not significantly different from the controls. Over the duration of the experiment establishment in the control group declined from 53% to <20%, which was similar to the decrease recorded at the beginning and the end of the experiment in the animals to determine the effect of larval age. The findings indicate that an existing C. oncophora burden had a strong effect on the establishment of incoming larvae in the trickle infected groups, but this was not observed if the existing burden was removed before the final challenge. The decline in establishment rate in the control group was attributed to the age of the larvae and not the age of the calves per se.
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Enfermedades de los Bovinos/parasitología , Tricostrongiloidiasis/inmunología , Tricostrongiloidiasis/parasitología , Animales , Bovinos , Enfermedades de los Bovinos/tratamiento farmacológico , Susceptibilidad a Enfermedades/inmunología , Susceptibilidad a Enfermedades/parasitología , Ivermectina/uso terapéutico , Recuento de Huevos de Parásitos , Trichostrongyloidea/inmunología , Tricostrongiloidiasis/tratamiento farmacológicoRESUMEN
A replicated field trial was conducted to measure the effect on liveweight gain of failing to adequately control anthelmintic resistant populations of Cooperia oncophora and to determine whether populations, and hence production losses, increased with time. Eight mobs of 10 Friesian-Hereford calves were run on independent farmlets from January to December, over each of two years. All mobs were routinely treated with a pour-on formulation of eprinomectin every six weeks, which controlled parasites other than Cooperia. Four mobs also received six weekly treatments with an oral levamisole plus albendazole combination anthelmintic to control Cooperia. Liveweights, condition scores, faecal egg counts and larval numbers on pasture were measured throughout. In the first year animals treated with eprinomectin alone were 12.9â¯kg lighter in November than those treated with eprinomectin plus albendazole and levamisole, however, in the second year there was no difference between the treatment groups. The data, therefore, support the view that while C. oncophora is less pathogenic than other cattle parasite species it can still cause production losses when present in sufficient numbers. In the first year of the study, parasite load, as measured by faecal nematode egg count and larval numbers on herbage, tended to be higher and calf growth rates lower than in the second year. In both years, counts of infective larvae on herbage declined over winter-spring to be at low levels before mid-summer. This suggests that the carry-over of infection from one crop of calves to the next was relatively small and hence that the level of challenge to the young calves at the start of each year was largely due to the effectiveness of the quarantine treatments administered when the animals arrived on the trial site. Low survival of larvae on pasture between grazing seasons, resulting in small larval populations on pasture when drenching programmes start each summer, might help to explain the widespread development of anthelmintic resistance in this parasite under New Zealand grazing systems.
Asunto(s)
Antihelmínticos/administración & dosificación , Bovinos/parasitología , Trichostrongyloidea/efectos de los fármacos , Tricostrongiloidiasis/veterinaria , Aumento de Peso/efectos de los fármacos , Albendazol/administración & dosificación , Albendazol/uso terapéutico , Animales , Antihelmínticos/uso terapéutico , Enfermedades de los Bovinos/tratamiento farmacológico , Enfermedades de los Bovinos/epidemiología , Enfermedades de los Bovinos/parasitología , Ivermectina/administración & dosificación , Ivermectina/análogos & derivados , Larva/efectos de los fármacos , Levamisol/administración & dosificación , Levamisol/uso terapéutico , Nueva Zelanda/epidemiología , Recuento de Huevos de Parásitos , Carga de Parásitos , Tricostrongiloidiasis/tratamiento farmacológico , Tricostrongiloidiasis/epidemiologíaRESUMEN
Twenty male Saanen goats were randomly assigned to four levels of lovastatin supplementation and used to determine the optimal dosage and sustainability of naturally produced lovastatin from fermentation of palm kernel cake (PKC) with Aspergillus terreus on enteric methane (CH4) mitigation. The effects on ruminal microbiota, rumen fermentation, feed digestibility and health of animal were determined over three measuring periods (4-, 8- and 12-weeks) and the accumulation of lovastatin in tissues was determined at the end of the experiment. The diets contained 50% rice straw, 22.8% concentrates and 27.2% of various proportions of untreated or treated PKC to achieve the target daily intake level of 0 (Control), 2, 4 or 6 mg lovastatin/kg body weight (BW). Enteric CH4 emissions per dry matter intake (DMI), decreased significantly (P<0.05) and equivalent to 11% and 20.4%, respectively, for the 2 and 4 mg/kg BW groups as compared to the Control. No further decrease in CH4 emission thereafter with higher lovastatin supplementation. Lovastatin had no effect on feed digestibility and minor effect on rumen microbiota, and specifically did not reduce the populations of total methanogens and Methanobacteriales (responsible for CH4 production). Similarly, lovastatin had little effect on rumen fermentation characteristics except that the proportion of propionate increased, which led to a decreasing trend (P<0.08) in acetic: propionate ratio with increasing dosage of lovastatin. This suggests a shift in rumen fermentation pathway to favor propionate production which serves as H+ sink, partly explaining the observed CH4 reduction. No adverse physiological effects were noted in the animals except that treated PKC (containing lovastatin) was less palatable at the highest inclusion level. Lovastatin residues were detected in tissues of goats fed 6 mg lovastatin/kg BW at between 0.01 to 0.03 µg/g, which are very low.
Asunto(s)
Alimentación Animal/análisis , Dieta/veterinaria , Digestión , Fermentación , Lovastatina/farmacología , Metano/análisis , Microbiota , Rumen/fisiología , Animales , Productos Biológicos/farmacología , Suplementos Dietéticos , Cabras , Masculino , Rumen/efectos de los fármacosRESUMEN
Vertical transmission of symbiotic Epichloë endophytes from host grasses into progeny seed is the primary mechanism by which the next generation of plants is colonized. This process is often imperfect, resulting in endophyte-free seedlings which may have poor ecological fitness if the endophyte confers protective benefits to its host. In this study, we investigated the influence of host genetics and environment on the vertical transmission of Epichloë festucae var. lolii strain AR37 in the temperate forage grass Lolium perenne. The efficiency of AR37 transmission into the seed of over 500 plant genotypes from five genetically diverse breeding populations was determined. In Populations I-III, which had undergone previous selection for high seed infection by AR37, mean transmission was 88, 93, and 92%, respectively. However, in Populations IV and V, which had not undergone previous selection, mean transmission was 69 and 70%, respectively. The transmission values, together with single-nucleotide polymorphism data obtained using genotyping-by-sequencing for each host, was used to develop a genomic prediction model for AR37 seed transmission. The predictive ability of the model was estimated at r = 0.54. While host genotype contributed greatly to differences in AR37 seed transmission, undefined environmental variables also contributed significantly to seed transmission across different years and geographic locations. There was evidence for a small host genotype-by-environment effect; however this was less pronounced than genotype or environment alone. Analysis of endophyte infection levels in parent plants within Populations I and IV revealed a loss of endophyte infection over time in Population IV only. This population also had lower average tiller infection frequencies than Population I, suggesting that AR37 failed to colonize all the daughter tillers and therefore seeds. However, we also observed that infection of seed by AR37 may fail during or after initiation of floral development from plants where all tillers remained endophyte-infected over time. While the effects of environment and host genotype on fungal endophyte transmission have been evaluated previously, this is the first study that quantifies the relative impacts of host genetics and environment on endophyte vertical transmission.