METHANOGENESIS IN RABBIT CAECUM AS AFFECTED BY THE FERMENTATION PATTERN: IN VITRO AND IN VIVO MEASUREMENTS

[EN] Methane formation and caecal fermentation patterns were studied in vivo and in vitro in 16 white New Zealand rabbits (70-80 d and 2.27 ± 0.064 kg) allocated to four diets formulated to have a similar neutral detergent fibre (33.8±0.53%) and protein (17.7±0.33%) content, with two different fibre sources (alfalfa hay, AH or sugar beet pulp, SP) and starch (wheat or maize). Animals received the diet for 16 to 20 days before methane production was measured in vivo in a respiratory chamber. Animals were subsequently slaughtered at approximately 9:00 and caecal contents were sampled and used as inoculum for in vitro incubations to determine gas and methane production. Volatile fatty acid (VFA) and purine base (PB) concentrations were determined from both caecal content and incubation medium after 6 h. Total VFA concentration in caecal content decreased (P<0.05) in rabbits fed AH-maize diet compared with rabbits fed AH-wheat and SP-maize diets (37.7 vs. 59.6 mM), with those fed SP-wheat showing an intermediate value (53.0 mM). Fermentation pattern was affected when maize was the source of starch compared to wheat, with lower acetate (0.72 vs. 0.79; P<0.01) and higher butyrate (0.19 vs. 0.14; P<0.001) molar proportions. Fermentation in vivo vs. in vitro showed some differences (molar proportions of acetate, 0.76 vs. 0.73, P<0.001, and propionate, 0.069 vs. 0.091, P<0.001, in vivo and in vitro, respectively), probably due to differences in pH (6.0 vs. 6.7 in vivo and in vitro; P<0.001). Only 2 out of 16 rabbits produced a substantial volume of methane in vivo (on average, 12.6 ml/BW0.75/d or 0.56 mmol/BW0.75/d), showing a high inter-individual variability that hindered comparison of treatment differences. In contrast, methane was detected in vitro in all cases and volumes were more homogenous, a higher formation (P<0.05) being observed with maize compared to wheat. A similar effect was shown in total gas production. The low methane production and H2 recovery suggest the importance of H2 disposal mechanisms other than methanogenesis, such as reductive acetogenesis. PB concentration in caecal content and the incubation medium, as an index of microbial concentration, was highest when SP was added with maize (P<0.05).For the realisation of this work, A. Belenguer and L. Abecia received grants from the Spanish Ministry of Education and Science and the Basque Government, respectively. This work was financed by the Diputación General de Aragón through project DGA PM095/2006.Belenguer, A.; Fondevila, M.; Balcells, J.; Abecia, L.; Lachica, M.; Carro, M. (2011). METHANOGENESIS IN RABBIT CAECUM AS AFFECTED BY THE FERMENTATION PATTERN: IN VITRO AND IN VIVO MEASUREMENTS. World Rabbit Science. 19(2):75-83. doi:10.4995/wrs.2011.826SWORD758319

Estudio comparativo entre el cultivo convencional y ecológico de trigo para alimentación animal

El objetivo de este estudio fue investigar las diferencias en el rendimiento productivo y el valor nutritivo entre el cultivo ecológico y convencional de trigo invernal para su utilización en alimentación animal. La producción de forraje fue determinada en el mes de mayo de tres años consecutivos y la producción de paja y grano se determinó en el mes de julio de los dos primeros años. Las muestras fueron secadas para determinar su composición química y su digestibilidad in vitro. Adicionalmente, 500 mg de cada muestra fueron incubados con 50 mL de líquido ruminal tamponado a 39°C. En estas incubaciones se midió la producción de gas a diferentes tiempos para estimar la cinética de fermentación y se analizaron los parámetros de fermentación tras 24 horas de incubación. La producción de forraje, grano y paja fue mayor en las parcelas convencionales que en las ecológicas. El contenido en proteína bruta fue más bajo en el cultivo ecológico que en el convencional, tanto para el forraje como para el grano. La digestibilidad in vitro fue similar para los dos tipos de cultivo y no existieron diferencias en la cinética de degradación ni en la producción de ácidos grasos volátiles. Los resultados indican que el cultivo ecológico provocó una disminución de la producción y en el contenido de proteína en el forraje y en los granos de trigo, pero no se observaron efectos en la degradación ruminal. Estos resultados indican que el sistema de cultivo del trigo afecta a su composición química y por ello debe realizarse una valoración previa del mismo cuando se utilice para alimentación animal.The objective of this study was to assess the differences in yield and nutritive value of organically and conventionally grown wheat crops as animal feeds. Forage yield was determined in May in three consecutive years and straw and grain yield was determined in July in the two first years. Samples were dried to determine their chemical composition and in vitro digestibility. Additionally, 500 mg of each sample were incubated with 50 mL of buffered rumen fluid at 39°C to estimate rumen fermentation kinetics and fermentation parameters after 24 hours. Forage, grain and straw yield was greater in conventionally grown crops than in organic ones. Crude protein content was lower in organically grown wheat, both for the forage or the grain. In vitro digestibility was similar in both types of cultures and there were no differences in degradation kinetics parameters or volatile fatty acids production. Results indicate that organic cultivation lead to a decrease in yield and crude protein content in forage and wheat grain, but there were no differences in their ruminal degradation. These results indicate that cultivation system affects chemical composition of wheat and, therefore, it is necessary to assess the nutritive value of organically grown cereals intended for animal feeding

In vitro caecal fermentation of carbohydrate-rich feedstuffs in rabbits as affected by substrate pre-digestion and donors' diet

[EN] The influence of substrate pre-digestion and donors’ diet on in vitro caecal fermentation of different substrates in rabbits was investigated. Eight crossbreed rabbits were fed 2 experimental diets containing either low (LSF; 84.0 g/kg dry matter [DM]) or high soluble fibre (HSF; 130 g/kg DM) levels. In vitro incubations were conducted using batch cultures with soft faeces as inoculum and four fibrous or fibre-derived, low-starch and low-protein substrates: D-cellobiose (CEL), sugar beet pectin (PEC), sugar beet pulp (SBP) and wheat straw (WS). Substrates in half of the cultures were subjected to a 2-step pepsin/pancreatin in vitro digestion without filtration, and the whole residue (soluble, insoluble and added enzymes) was incubated at 39°C. Gas production was measured until 144 h, and volatile fatty acid (VFA) production at 24 h incubation was determined. Cultures without substrate (blanks) were included to correct gas production values for gas released from endogenous substrates and added enzymes. Pre-digestion had no influence on in vitro gas production kinetic of WS, and only reduced the time before gas production begins (lag time; by 31%; P=0.042) for SBP, but for both substrates the pre-digestion decreased the molar proportion of acetate (by 9%; P≤0.003) and increased those of propionate and butyrate (P≤0.014). For CEL, the pre-digestion increased the gas and total VFA production (by 30 and 114%), shortened the lag time (by 32%), and only when it was combined with LSF inoculum 38 percentage units of acetate were replaced by butyrate (P≤0.039). Treatments had a minor influence on in vitro fermentation traits of SBP pectin. The results showed that the pre-digestion process influenced the in vitro caecal fermentation in rabbits, but the effects were influenced by donors’ diet and the incubated substrate. Pre-digestion of substrate is recommended before conducting in vitro caecal fermentations. The level of soluble fibre in the donors’ diet also influenced the in vitro caecal fermentation, but its effect depended on the type of substrate.Funding from the Spanish Ministry of Economy and Competitiveness (Projects AGL2011-23885 and AGL2011-22628) and the Comunidad Autónoma de Madrid (CAM; Project MEDGAN ABI-2913) is gratefully acknowledged.Ocasio-Vega, C.; Abad-Guamán, R.; Delgado, R.; Carabaño, R.; Carro, M.; García, J. (2018). In vitro caecal fermentation of carbohydrate-rich feedstuffs in rabbits as affected by substrate pre-digestion and donors' diet. World Rabbit Science. 26(1):15-25. https://doi.org/10.4995/wrs.2018.7854SWORD152526

Influence of maturity stage on nutritive value of typha for ruminants

The study evaluated the influence of maturity on the nutritive value and fermentation parameters of Typha. Typha samples were collected at two different stages of growth, as indicated by the height of the plants: either 0.5 m (Low Typha; LT, age 3-6months) or 1.5 m (High Typha; HT, age 9-12 months). Samples were analyzed for chemical composition, and incubated in vitro with ruminal fluid from sheep to determine the main fermentation parameters. As maturity advanced, the dry matter, fiber and lignin content (25.30%, 70.40%, 47.30% and 10.58%) in the Typha increased, whereas the content of ashes and protein (12.18% and 12.24%) decreases. The changes in chemical composition caused a significant reduction in both the in vitro ruminal degradability after 96 h of incubation (38.6 and 22.9% for LT and HT, respectively) and the production of volatile fatty acids after 24 h of incubation (6.08 and 5.87 mmol/g dry matter incubated), indicating that the nutritive value of the Typha declines with advancing maturity. The results indicate that Typha plants for ruminant feeding should be preferably harvested at early growth stages

RICORS2040 : The need for collaborative research in chronic kidney disease

Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is 'solved' by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020-2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true

Acute kidney injury in patients treated with immune checkpoint inhibitors

BACKGROUND: Immune checkpoint inhibitor-associated acute kidney injury (ICPi-AKI) has emerged as an important toxicity among patients with cancer. METHODS: We collected data on 429 patients with ICPi-AKI and 429 control patients who received ICPis contemporaneously but who did not develop ICPi-AKI from 30 sites in 10 countries. Multivariable logistic regression was used to identify predictors of ICPi-AKI and its recovery. A multivariable Cox model was used to estimate the effect of ICPi rechallenge versus no rechallenge on survival following ICPi-AKI. RESULTS: ICPi-AKI occurred at a median of 16 weeks (IQR 8-32) following ICPi initiation. Lower baseline estimated glomerular filtration rate, proton pump inhibitor (PPI) use, and extrarenal immune-related adverse events (irAEs) were each associated with a higher risk of ICPi-AKI. Acute tubulointerstitial nephritis was the most common lesion on kidney biopsy (125/151 biopsied patients [82.7%]). Renal recovery occurred in 276 patients (64.3%) at a median of 7 weeks (IQR 3-10) following ICPi-AKI. Treatment with corticosteroids within 14 days following ICPi-AKI diagnosis was associated with higher odds of renal recovery (adjusted OR 2.64; 95% CI 1.58 to 4.41). Among patients treated with corticosteroids, early initiation of corticosteroids (within 3 days of ICPi-AKI) was associated with a higher odds of renal recovery compared with later initiation (more than 3 days following ICPi-AKI) (adjusted OR 2.09; 95% CI 1.16 to 3.79). Of 121 patients rechallenged, 20 (16.5%) developed recurrent ICPi-AKI. There was no difference in survival among patients rechallenged versus those not rechallenged following ICPi-AKI. CONCLUSIONS: Patients who developed ICPi-AKI were more likely to have impaired renal function at baseline, use a PPI, and have extrarenal irAEs. Two-thirds of patients had renal recovery following ICPi-AKI. Treatment with corticosteroids was associated with improved renal recovery