Retrospective and projected warming-equivalent emissions from global livestock and cattle calculated with an alternative climate metric denoted GWP.

Limiting warming by the end of the century to 1.5°C compared to pre-Industrial times requires reaching and sustaining net zero global carbon dioxide (CO2) emissions and declining radiative forcing from non-CO2 greenhouse gas (GHG) sources such as methane (CH4). This implies eliminating CO2 emissions or balancing them with removals while mitigating CH4 emissions to reduce their radiative forcing over time. The global cattle sector (including Buffalo) mainly emits CH4 and N2O and will benefit from understanding the extent and speed of CH4 reductions necessary to align its mitigation ambitions with global temperature goals. This study explores the utility of an alternative usage of global warming potentials (GWP*) in combination with the Transient Climate Response to cumulative carbon Emissions (TCRE) to compare retrospective and projected climate impacts of global livestock emission pathways with other sectors (e.g. fossil fuel and land use change). To illustrate this, we estimated the amount and fraction of total warming attributable to direct CH4 livestock emissions from 1750 to 2019 using existing emissions datasets and projected their contributions to future warming under three historical and three future emission scenarios. These historical and projected estimates were transformed into cumulative CO2 equivalent (GWP100) and warming equivalent (GWP*) emissions that were multiplied by a TCRE coefficient to express induced warming as globally averaged surface temperature change. In general, temperature change estimates from this study are comparable to those obtained from other climate models. Sustained annual reductions in CH4 emissions of 0.32% by the global cattle sector would stabilize their future effect on global temperature while greater reductions would reverse historical past contributions to global warming by the sector in a similar fashion to increasing C sinks. The extent and speed with which CH4 mitigation interventions are introduced by the sector will determine the peak temperature achieved in the path to net-zero GHG.

A global dataset of enteric methane mitigation experiments with lactating and non-lactating dairy cows conducted from 1963 to 2022.

A dataset of descriptive information was compiled from 213 peer-reviewed scientific publications that focused on dairy cow experiments and measured enteric methane emissions. This dataset was primarily based on the bibliography used by Arndt et al. (2022), with the addition of studies conducted from 2019 to 2022. The articles were identified for inclusion in the dataset using the "Web of Science Core Collection" database, using various combinations of search terms related to methane, dairy, cattle, rumen, ruminant, energy balance, energy metabolism, energy partitioning, and enteric emissions. For inclusion in the dataset, studies had to be written in English and provide information on enteric methane emission, as well as report feed dry matter intake along with measures of variance. Both continuous and crossover design studies were included, resulting in a comprehensive dataset with 797 records (rows) and 162 variables (columns). The variables cover various aspects such as publication information, experimental design, animal description, methane measurement method, and diet nutrient composition. Additionally, when available, the dataset includes treatment means and measures of variance for feed dry matter intake, rumen fermentation parameters, nutrient digestibility, nitrogen excretion, milk yield, milk components, as well as enteric methane, carbon dioxide, and hydrogen emissions. Researchers can use this dataset to assess the effectiveness of different enteric methane mitigation strategies and their impact on milk yield and other essential dairy cow nutrition and performance variables. Furthermore, it offers the opportunity to explore potential interactions between nutrients and feed additives.

Invited review: Current enteric methane mitigation options.

Ruminant livestock are an important source of anthropogenic methane (CH4). Decreasing the emissions of enteric CH4 from ruminant production is strategic to limit the global temperature increase to 1.5°C by 2050. Research in the area of enteric CH4 mitigation has grown exponentially in the last 2 decades, with various strategies for enteric CH4 abatement being investigated: production intensification, dietary manipulation (including supplementation and processing of concentrates and lipids, and management of forage and pastures), rumen manipulation (supplementation of ionophores, 3-nitrooxypropanol, macroalgae, alternative electron acceptors, and phytochemicals), and selection of low-CH4-producing animals. Other enteric CH4 mitigation strategies are at earlier stages of research but rapidly developing. Herein, we discuss and analyze the current status of available enteric CH4 mitigation strategies with an emphasis on opportunities and barriers to their implementation in confined and partial grazing production systems, and in extensive and fully grazing production systems. For each enteric CH4 mitigation strategy, we discuss its effectiveness to decrease total CH4 emissions and emissions on a per animal product basis, safety issues, impacts on the emissions of other greenhouse gases, as well as other economic, regulatory, and societal aspects that are key to implementation. Most research has been conducted with confined animals, and considerably more research is needed to develop, adapt, and evaluate antimethanogenic strategies for grazing systems. In general, few options are currently available for extensive production systems without feed supplementation. Continuous research and development are needed to develop enteric CH4 mitigation strategies that are locally applicable. Information is needed to calculate carbon footprints of interventions on a regional basis to evaluate the impact of mitigation strategies on net greenhouse gas emissions. Economically affordable enteric CH4 mitigation solutions are urgently needed. Successful implementation of safe and effective antimethanogenic strategies will also require delivery mechanisms and adequate technical support for producers, as well as consumer involvement and acceptance. The most appropriate metrics should be used in quantifying the overall climate outcomes associated with mitigation of enteric CH4 emissions. A holistic approach is required, and buy-in is needed at all levels of the supply chain.

Manure management strategies are interconnected with complexity across U.S. dairy farms.

Among one of the key challenges in dairy production is the management of manure in a way that is beneficial for agricultural production, with minimal environmental and public health impacts. Manure management systems (MMS)-the entire system of handling, storage, and application of manure-are diverse in countries with developed dairy industries such as the United States, enabled by a number of different technologies. The ways in which dairy farmers manage manure is driven by varying tradeoffs, including economic, social, and environmental; however, existing research has not examined the relationships between components of MMS. Here we use data from the National Animal Health Monitoring System's Dairy 2014 study to explore the ways in which manure handling, storage, and application are related, using a series of logistic regression models and network associations. We found significant associations between how manure is handled, stored, and applied, especially driven by the consistency of manure. For solid manure, we found highly heterogeneous systems, where farmers may have a suite of alternative manure management strategies available to them, and substitution is viable. Conversely, farms using liquid manure systems have very few substitutes in their MMS, suggesting greater investment in certain infrastructures, which are not easily changed. Such findings have important implications for shifting farmers towards management practices with minimal environmental and public health impacts, demonstrating that not all farm systems are easily changed. We highlight these results in light of current policies, which may not fully capture the relationships across the MMS, and suggest that greater financing may be necessary to shift MMS on some farms. Furthermore, we suggest that different MMS have varying tradeoffs across environmental, social, and economic aspects, which demonstrates that MMS are highly individualized to a given farm's goals and priorities.

Enteric methane mitigation interventions.

Mitigation of enteric methane (CH4) presents a feasible approach to curbing agriculture's contribution to climate change. One intervention for reduction is dietary reformulation, which manipulates the composition of feedstuffs in ruminant diets to redirect fermentation processes toward low CH4 emissions. Examples include reducing the relative proportion of forages to concentrates, determining the rate of digestibility and passage rate from the rumen, and dietary lipid inclusion. Feed additives present another intervention for CH4 abatement and are classified based on their mode of action. Through inhibition of key enzymes, 3-nitrooxypropanol (3-NOP) and halogenated compounds directly target the methanogenesis pathway. Rumen environment modifiers, including nitrates, essential oils, and tannins, act on the conditions that affect methanogens and remove the accessibility of fermentation products needed for CH4 formation. Low CH4-emitting animals can also be directly or indirectly selected through breeding interventions, and genome-wide association studies are expected to provide efficient selection decisions. Overall, dietary reformulation and feed additive inclusion provide immediate and reversible effects, while selective breeding produces lasting, cumulative CH4 emission reductions.

A dataset of human-inedible byproduct feeds consumed by dairy cows in the United States.

Dairy cows convert human-indigestible forages and byproducts nutrients into edible food for humans [1]. Because of microbiota located in their rumen, dairy cows can digest fibrous forages and feeds which are not exploited by humans and monogastric animals like pigs. Dairy cows in the U.S. have been fed byproduct feeds as part of their diet for decades [2], [3]. Dairy nutritionists use complex nutrition models to develop economical and nutritious diets composed of grains, byproduct feeds, and forages. Accurate, complete, up-to-date information on byproduct feed consumption by dairy cows would be useful for both public and private researchers seeking to understand the type and extent of byproduct usage on US dairies. In collaboration with the American Feed Industry Association (AFIA), a survey was sent to US feed company representatives inquiring about the types and amounts of byproducts sold as dairy cow feed during the last year, the number of lactating cows serviced, the amount of milk produced by these lactating cows, and the states where these cows were located. A similar survey was sent to practicing US dairy nutritionists inquiring about their typical daily feeding rates of byproduct feeds by type, the number of cows consuming these byproducts, the amount of milk produced by the lactating cows, and the states where these cows were located. Survey data are representative of 33.5% of US lactating cows and 35.7% of US milk production in 2019 [4]. Amounts of each type of byproduct feed consumed per US milking cow (including replacement heifers and dry cows) and per kg of milk produced were calculated for the US and its four regions [5]. Total 2019 regional and US byproduct consumption by type was calculated. Nutrient compositions of each byproduct feed were reported.

The Ruminant Farm Systems Animal Module: A Biophysical Description of Animal Management.

Dairy production is an important source of nutrients in the global food supply, but environmental impacts are increasingly a concern of consumers, scientists, and policy-makers. Many decisions must be integrated to support sustainable production-which can be achieved using a simulation model. We provide an example of the Ruminant Farm Systems (RuFaS) model to assess changes in the dairy system related to altered animal feed efficiency. RuFaS is a whole-system farm simulation model that simulates the individual animal life cycle, production, and environmental impacts. We added a stochastic animal-level parameter to represent individual animal feed efficiency as a result of reduced residual feed intake and compared High (intake = 94% of expected) and Very High (intake = 88% of expected) efficiency levels with a Baseline scenario (intake = 100% of expected). As expected, the simulated total feed intake was reduced by 6 and 12% for the High and Very High efficiency scenarios, and the expected impact of these improved efficiencies on the greenhouse gas emissions from enteric methane and manure storage was a decrease of 4.6 and 9.3%, respectively.

Cirugía robótica colorectal, en un hospital de comunidad cerrada: experiencia inicial leído en sesión SACP, 11 de octubre de 2019 / Colorectal robotic surgery in a closed community hospital: initial experience read in SACP session, october 11, 2019

Introducción: La introducción del sistema Da Vinci, ha revolucionado el campo de la cirugía mínima invasiva en el cual el cirujano tiene control de la cámara 3D y los instrumentos son de gran destreza y confort ergonómico, acortando la curva de aprendizaje quirúrgica. Objetivo: Describir nuestra experiencia inicial de cirugía robótica colorectal en un hospital de comunidad cerrada de la Ciudad Autónoma de Buenos Aires. Materiales y Método: Estudio retrospectivo descriptivo sobre una base prospectiva de cirugías colorectales robóticas realizadas por el mismo equipo quirúrgico desde mayo de 2016 a abril de 2019. Resultados: Se operaron 41 pacientes. Trece de ellos fueron colectomías derechas, 17 colectomías izquierdas y 11 cirugías de recto. El tiempo quirúrgico promedio fue de 170 minutos (90-330), la estadía hospitalaria de 4 días (3-30), la tasa de conversión de 7,31% (3/41 pacientes) y la tasa de dehiscencia anastomótica del 9,75% (4/41 pacientes). Morbilidad global del 19.5% (8/41 pacientes). Conclusión: Hemos repasado los resultados iniciales de nuestra experiencia en cirugía robótica colorectal en un número reducido de casos, pero suficiente para evaluar la seguridad y reproducibilidad del método al comienzo de una curva de aprendizaje.

Introduction: The introduction of the Da Vinci System, has revolved the field of invasive minimal surgery in which the surgeon has control of the 3d camera and the instruments are of great strength and ergonomic comfort by cutting the surgical learning curve. Objective: Of this preliminary presentation is to describe our initial experience of colorectal robotic surgery in a closed community hospital of the Autonomous City of Buenos Aires. Materials and Method: Retrospective descriptive study on a prospective basis of robotic colorectal surgeries performed by the same surgical team from May 2016 to April 2019.Results: 41 patients were operated. 13 of them were right colectomies, 17 left colectomies and 11 rectum surgeries. The average surgical time was 170 minutes (90-330), the average hospital stay of 4 days (3-30), the conversion rate of 7.31% (3/41 patients) and the anastomotic dehiscence rate of 9 , 75% (4/41 patients). Overall morbidity of 19.5% (8/41 patients).Conclusion: We have reviewed the initial results of our experience in colorectal robotic surgery in a reduced number of cases but sufficient to evaluate the security and reproducibility of the methodic learning of a learning curve.

Key Considerations for the Use of Seaweed to Reduce Enteric Methane Emissions From Cattle.

Enteric methane emissions are the single largest source of direct greenhouse gas emissions (GHG) in beef and dairy value chains and a substantial contributor to anthropogenic methane emissions globally. In late 2019, the World Wildlife Fund (WWF), the Advanced Research Projects Agency-Energy (ARPA-E) and the Foundation for Food and Agriculture Research (FFAR) convened approximately 50 stakeholders representing research and production of seaweeds, animal feeds, dairy cattle, and beef and dairy foods to discuss challenges and opportunities associated with the use of seaweed-based ingredients to reduce enteric methane emissions. This Perspective article describes the considerations identified by the workshop participants and suggests next steps for the further development and evaluation of seaweed-based feed ingredients as enteric methane mitigants. Although numerous compounds derived from sources other than seaweed have been identified as having enteric methane mitigation potential, these mitigants are outside the scope of this article.

Laparotomía abreviada y terapia de presión negativa para el cierre temporal del abdomen como tratamiento de la peritonitis diverticular Hinchey III/IV / Abbreviated laparotomy and negative pressure therapy for temporary closure of the abdomen as treatment of diverticular peritonitis Hinchey III/IV

Introducción: Los pacientes que se presentan con cuadros de peritonitis de origen diverticular (estadios Hinchey III o IV) en un contexto de sepsis severa con inestabilidad hemodinámica (shock séptico) la realización de anastomosis primaria presenta una alta tasa de dehiscencia anastomótica y mortalidad operatoria, aconsejándose la realización de una resección y abocamiento a la manera de Hartmann. Sin embargo, la alta tasa de complicaciones relacionadas a la confección del ostoma, la complejidad de la cirugía de restauración del tránsito intestinal, asociado a que entre el 40 % y el 60 % de los Hartmann no se reconstruyen, ha estimulado a que se intenten otras variables de resolución para esta compleja y grave patología. Diversas publicaciones en los últimos años han propuesto la táctica de "cirugía del control del daño" con el objeto de disminuir la morbimortalidad de estos gravísimos cuadros sépticos y a su vez reducir la tasa de ostomías. El objetivo de este trabajo es presentar nuestra experiencia inicial con esta modalidad de manejo de la peritonitis diverticular Hinchey III/IV sepsis severa e inestabilidad hemodinámica (shock séptico) y realizar una revisión bibliográfica del tema. Material y método: Estudio observacional, descriptivo, de series de casos. Entre noviembre de 2015 y diciembre de 2016. Servicio de coloproctología del complejo médico hospitalario Churruca-Visca de la ciudad de Buenos Aires y práctica privada de los autores. Se utilizó la técnica de laparotomía abreviada y cierre temporal del abdomen mediante un sistema de presión negativa. Resultados: En el periodo descripto se operaron 17 pacientes con peritonitis generalizada purulenta o fecal de origen diverticular. Catorce casos fueron Hinchey III (82,36%) y 3 casos Hinchey IV (17,64%). En 3 casos se observó inestabilidad hemodinámica en el preoperatorio o intraoperatorio. Todos ellos correspondientes al estadio IV de Hinchey. Se describen los 3 casos tratados mediante esta táctica quirúrgica. Discusión: La alta tasa de morbimortalidad de este subgrupo de pacientes incentivó a diversos grupos quirúrgicos a implementar la técnica de control del daño, permitiendo de esta manera estabilizar a los pacientes hemodinámicamente y en un segundo tiempo evaluar la reconstrucción del tránsito intestinal. En concordancia con estas publicaciones, dos de nuestros pacientes operados con esta estrategia, pudieron ser anastomosados luego del segundo lavado abdominal. Conclusión: En pacientes con peritonitis diverticular severa asociado a shock séptico el concepto de laparotomía abreviada con control inicial del foco séptico, cierre temporal del abdomen con sistema de presión negativa y posterior evaluación de la reconstrucción del tránsito intestinal, es muy alentador. Permitiendo una disminución de la morbimortalidad como así también del número de ostomías. (AU)

Introduction: Patients presenting with diverticular peritonitis (Hinchey III or IV stages) in a context of severe sepsis with hemodynamic instability (septic shock), performing primary anastomosis has a high rate of dehiscence anastomotic and operative mortality, advising the realization of a resection and ostoma in the manner of Hartmann. However, the high rate of complications related to performing of ostoma, the complexity of intestinal transit restoration surgery, associated with the 40% to 60% of Hartmann reversal not performed, has encouraged other variables to be attempted resolution for this complex and serious pathology. Several publications in recent years have proposed the tactic of "damage control surgery" in order to reduce the morbidity of these serious septic charts while reducing the rate of ostomies. The objective of this study is to present our initial experience with this modality of management of the diverticular peritonitis Hinchey III/IV severe sepsis and hemodynamic instability (septic shock) and to carry out a bibliographic review of the subject. Material and method: Observational, descriptive study of case series. Between November 2015 and December 2016. Coloproctology service of the Churruca-Visca hospital medical complex in the city of Buenos Aires and private practice of the authors. The technique of abbreviated laparotomy and temporary closure of the abdomen was used by a negative pressure system. Results: In the period described, 17 patients with generalized purulent or fecal peritonitis of diverticular origin were operated. Fourteen cases were Hinchey III (82.36%) and 3 cases Hinchey IV (17.64%).In 3 cases, hemodynamic instability was observed in the preoperative or intraoperative period. all of them corresponding to Hinchey's Stage IV. The 3 cases treated using this surgical tactic are described. Discussion: The high morbidity rate of this subgroup of patients encouraged various surgical groups to implement the damage control technique, thus allowing patients to stabilize hemodynamically and in a second time evaluate reconstruction intestinal transit. In line with these publications, two of our patients operated on with this strategy could be anastomosated after the second abdominal wash. Conclusion: In patients with severe diverticular peritonitis associated with septic shock, the concept of abbreviated laparotomy with initial control of the septic focus, temporary closure of the abdomen with negative pressure system and subsequent evaluation of transit reconstruction intestinal, it's encouraging. Allowing a decrease in morbidity as well as the number of ostomies. (AU)

Respuesta al tratamiento neoadyuvante con capecitabine y radioterapia en el cáncer de recto inferior localmente avanzado / Response to neoadjuvant treatment with capecitabine and radiotherapy in locally advanced lower rectal cancer

Introducción: La importancia del tratamiento neoadyuvante con quimio y radioterapia en el manejo de los tumores de recto extraperitoneal localmente avanzado ha quedado claramente demostrada. La droga que ha sido históricamente más utilizada para este fin fue el 5-Fluorouracilo (5-FU). Una nueva molécula de administración por vía oral, la prodroga capecitabine, ha reemplazado al 5-FU en el tratamiento neoadyuvante en los últimos tiempos, con mejores resultados y mayor comodidad. Objetivo: Valorar la eficacia, toxicidad y complicaciones del tratamiento neoadyuvante con capecitabine más radioterapia en el tratamiento del cáncer de recto extraperitoneal localmente avanzado. Diseño: Estudio observacional, descriptivo, retrospectivo. Población y Métodos: Se incluyeron 33 pacientes (66% de sexo masculino) con tumores de recto extraperitoneal localmente avanzado (cT3/cT4 o cN+) con indicación de neoadyuvancia. La dosis de radioterapia fue de 45 Gy más un boost de 5,04 Gy administradas en 25 sesiones durante un período de 5 semanas. La dosis de capecitabine fue de 850 mg/m2, dos veces al día durante los días en que se administraba la radioterapia. Se reevaluó a los pacientes entre la 8º y 10º semana. Aquellos pacientes con respuesta clínica completa (RCC) se les ofreció ingresar al protocolo de Watch & Wait, mientras que aquellos pacientes con respuesta clínica incompleta o nula se les indicó la resección quirúrgica entre las 10-12 semanas posttratamiento neoadyuvante. Resultados: 10 pacientes (30,3%) tuvieron respuesta clínica completa (RCC). De estos, 7 entraron a protocolo Watch & Wait. Se operaron 26 pacientes, luego de un promedio de 11,71 semanas posteriores a la neoadyuvancia, siguiendo en todos los casos la técnica de excisión total del mesorrecto. Se observó un 19,3% de RPC y un downstaging del 57,69%. A dieciséis pacientes (61,53%) se les efectuó una resección anterior ultrabaja con ostomía de protección. Nueve pacientes fueron sometidos a una amputación abdominoperineal (34,61%) y una paciente recibió una operación de Hartmann (3,84%). El principal efecto adverso fue la diarrea grado I en el 36% de los casos, seguida por la dermatitis grado I en el 33%. Tuvimos dos dehiscencias anastomóticas que se resolvieron sin reintervención. Conclusiones: El tratamiento neoadyuvante con capecitabine es una opción segura, con alta tasa de respuesta clínica y patológica completa, con escasa toxicidad y complicaciones, y el beneficio de la comodidad de su administración por vía oral. (AU)

Background: The importance of neoadjuvant chemotherapy and radiation therapy in the management of extraperitoneal rectal tumors locally advanced has been clearly demonstrated. The drug has been historically used for this purpose was 5-fluorouracil (5-FU). A new molecule oral administration, the prodrug capecitabine, has replaced the 5-FU in the neoadjuvant treatment in recent times, with better results and greater comfort. Objective: To evaluate the efficacy, toxicity and complications of neoadjuvant capecitabine plus radiation therapy in the treatment of locally advanced rectal cancer extraperitoneal. Design: Observational, descriptive, retrospective study. Population and Methods: 33 patients (66% male) with extraperitoneal rectal tumors locally advanced (cT3 / cT4 or cN +) with indication of neoadjuvant were included. Radiation dose was 45 Gy plus a boost of 5.04 Gy administered in 25 sessions over a period of 5 weeks. Capecitabine dose was 850 mg / m2 twice daily on days that radiotherapy was administered. It was reevaluated patients between the 8th and 10th week. Patients with clinical complete response (CCR) were offered to enter the protocol Watch & Wait, while patients with incomplete or no clinical response were instructed surgical resection neoadjuvant between 10-12 weeks post-treatment. Results: 10 patients (30.3%) had clinical complete response (CCR). Of these, seven entered Watch & Wait protocol. 26 patients were operated after a mean time of 11,71 weeks (range 10-15), in all cases following the total mesorectal excision technique. 19.3% of RPC and downstaging of 57.69% was observed. Sixteen patients (61.53%) were made ultra-low anterior resection with protective stoma. Nine patients underwent an AP amputation (34.61%) and one patient received a Hartmann operation(3.84%). The main side effect was diarrhea grade I in 36% of cases, followed by the degree I dermatitis in 33%. We had two anastomotic dehiscences which resolved without reoperation. Conclusions: Neoadjuvant capecitabine therapy is a safe choice, with high rate of complete clinical and pathological response with low toxicity and complications, and the benefit from the comfort of oral administration. (AU)

The effects of crude protein concentration and slow release urea on nitrogen metabolism in Holstein steers.

This experiment was conducted to determine the effects of slow release urea (SRU) and its interaction with crude protein (CP) level in the diet on N metabolism in Holstein steers. Eight rumen-cannulated Holstein steers (body weight 265 ± 18 kg) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial treatment structure. Treatment factors were the CP level in the diet, 10.9% versus 12.1% CP, and the non-protein nitrogen source used, urea versus SRU. Total collection of urine and faeces for 7 days allowed the estimation of N retention and diet digestibility. In addition, blood and rumen sampling allowed estimation of rumen fermentation and blood N profiles. Decreasing CP intake from 12.1% to 10.9% reduced urinary N output, but also reduced diet digestibility and N retention. When compared to urea, SRU did not alter N retention, but reduced ruminal ammonia and plasma urea concentrations. Although SRU did not improve N retention at either CP level, rumen ammonia and plasma urea concentrations were reduced, which may indicate that SRU may carry a lower risk for toxicity when compared to urea when fed at higher dietary concentrations.

Fermentation of wheat: effects of backslopping different proportions of pre-fermented wheat on the microbial and chemical composition.

The objective of the study was to examine effect of backslop on the chemical and microbiological characteristics of fermented wheat (FW). Coarsely ground wheat was mixed with water (1:3 wt/wt) and inoculated with 6 log cfu ml(-1) each of an overnight culture of Lactobacillus plantarum and Pediococcus pentosaceus. Four fermentation treatments were conducted in 45 1, closed, PVC containers over 48 hours. Three treatments investigated the benefits of the addition of previously fermented wheat (backslopping, BSL) at different proportions (0.20, 0.33 or 0.42 kg) to freshly prepared wheat. The control treatment contained no addition of BSL. Elimination of coliforms from the FW within 48 h was only achieved through backslopping; where coliform bacteria counts decreased from approximately 6.5 log10 cfu ml(-1) to less than 3 log10 cfu ml(-1). There was no apparent advantage in increasing the backslop proportion above 0.20. However, the exclusion of coliform bacteria required the pH to remain below 4.0 for at a minimum of 24 h. The results of these studies indicate that fermentation of wheat has the potential to reduce the risk of feed-borne colibacillosis and provides a practical alternative to producers that cannot ferment multiple diets or have limited fermentation capacity.

Influence of supplemental endoglucanase or xylanase on volatile fatty acid production from ruminant feed by ruminal in vitro cultures.

This study employed two commercial enzyme preparations to examine the effects of endoglucanase, xylanase or their combination on in vitro volatile fatty acid (VFA) production by ruminal microbial populations. Batch ruminal cultures were established with one of various feedstuffs or with a fescue hay-based diet and ruminal fluid from a heifer fed a 40% forage:60% concentrate diet. Addition of xylanase at 135 xylanase units (XU) per ml increased total VFA production from the fescue hay-based diet (44.3 vs. 57.2 mM, p < 0.05) without changing the acetate to propionate (A:P) ratio. Addition of endoglucanase at 2, 3, 4, and 5 carboxymethyl cellulase units (CMCU) per ml increased total VFA production from the fescue hay-based diet on average by 36% (p < 0.05). Addition of 3, 4 and 5 CMCU/ml also decreased (p < 0.05) the A:P ratio. The combined addition of xylanase (135 XU/ml) and endoglucanase (5 CMCU/ml) increased total VFA production from the fescue hay-based diet (40.9 vs. 61.5 mM, p < 0.05) and reduced the A:P ratio (3.4 vs. 1.5, p < 0.05). The effects of endoglucanase and xylanase supplementation on in vitro VFA production varied across the various substrates used. However, endoglucanase supplementation consistently reduced the A:P ratio with all substrates tested. The effects of the enzyme combination were generally greater than either enzyme alone. We conclude that endoglucanase and xylanase activities differ in their ability to affect ruminal VFA production, and endoglucanase but not xylanase, may improve fermentation efficiency by reducing the A:P ratio.