Monitoring Kinetics of Readily Available Fermentable Components by Means of In-Vitro Gas Production

In vitro rumen incubations were used for measuring substrate disappearance and gas production dynamics. Samples were neutral detergent extracts of alfalfa and orchardgrass with or without added glucose. A logistic multi-pool model was used for describing feed fractions with distinct kinetic parameters, namely pools A, B1, B2 and C that represent fractions of increasing refractoriness. This technique based on gas measurement allowed to monitor early fermentation kinetics of readily available substrates thus overcoming the limitations encountered in traditional in vitro substrate disappearance. Pools A, B1 and B2 showed specific rates near 0.14 , 0.08 and 0.02 and lags of zero, 3 to 6 and 10 to 18 respectively. These results are very consistent with the expected nutritional behavior of the chemical entities included in each fraction

\u3ci\u3eIn Vitro\u3c/i\u3e Gas Production Technique to Predict DMD of Ensiled Forage Ruminant Based Diets

The in vitro gas production technique was used as a tool to develop an improved prediction model of dry matter digestibility of ensiled forage based diets. Eleven diets were tested through conventional experiments of in vivo dry matter digestibility (DMD). The same diets were evaluated by the in vitro gas production technique using a gas pressure transducer . The parameters of the model y = A - B Qt Z√t were calculated with data from the accumulated gas curves, i.e. y=cumulative gas production (ml), Q=e-b, Z=e-c, B=ebT+c√T , being A the value for gas pool size (ml), plus lag time, minimum lag time, time for 50% gas production and time for 95% gas production. A stepwise linear regression procedure was used to obtain a model with the best fit. The higher adjusted R2 (0.85) was obtained for a model with: 1. accumulated gas, 2. lag time, 3. Q, 4. B, 5. time for 50% gas production and 6. minimum lag time were included in the model

Ensilaje de forraje de vegas naturales en Tierra del Fuego, Argentina

722-728Livestock activity in the Argentinian «Tierra del Fuego» island is based on highly variable natural grasslands (NG). The conservation of fodder, despite the unfavorable environment, is restricted to hay; conservation as silage could be constrained by fodder quality and low temperatures. The objective was to assess the quality of NG silages fermented under contrasting storing conditions. Typical meadow forage was ensiled in minisilos and stored under shelter (Shelter) or in the field (Field) in a complete block design with repeated measures in time (t). Forage was chopped and inoculated with lactic acid bacteria plus enzymes, and harvested with 420 g dry matter (DM) kg-1 fresh matter, 111 g crude protein kg-1 DM, 665 g ash-free neutral detergent fibre kg-1 DM, and 64 g water soluble carbohydrates kg-1 DM. Shelter minisilos had higher metabolizable energy concentration at 236 d (PTrat×t = 0.03; Shelter = 10.2 ; Field = 9.6 MJ kg-1 DM, P = 0.01), and lower DM losses (Shelter = -0.2; Campo = 22 percent, P = 0.02) and values of pH and N-NH3/total N (Field: 5.6 and 12 percent and Shelter: 4.4 and 6.8 percent, P = 0.01). Fermentation acids concentration was similar for both treatments with preponderance of lactic acid, but acetic acid concentration increased over time (Pt = 0.01). It was concluded that in «Tierra del Fuego», natural meadow forage quality is compatible with ensiling, but environmental conditions can limit the fermentation process. Additional key words: forage conservation, natural grasslands, Patagonia, silage

Ensilaje de forraje de vegas naturales en Tierra del Fuego, Argentina

722-728Livestock activity in the Argentinian «Tierra del Fuego» island is based on highly variable natural grasslands (NG). The conservation of fodder, despite the unfavorable environment, is restricted to hay; conservation as silage could be constrained by fodder quality and low temperatures. The objective was to assess the quality of NG silages fermented under contrasting storing conditions. Typical meadow forage was ensiled in minisilos and stored under shelter (Shelter) or in the field (Field) in a complete block design with repeated measures in time (t). Forage was chopped and inoculated with lactic acid bacteria plus enzymes, and harvested with 420 g dry matter (DM) kg-1 fresh matter, 111 g crude protein kg-1 DM, 665 g ash-free neutral detergent fibre kg-1 DM, and 64 g water soluble carbohydrates kg-1 DM. Shelter minisilos had higher metabolizable energy concentration at 236 d (PTrat×t = 0.03; Shelter = 10.2 ; Field = 9.6 MJ kg-1 DM, P = 0.01), and lower DM losses (Shelter = -0.2; Campo = 22 percent, P = 0.02) and values of pH and N-NH3/total N (Field: 5.6 and 12 percent and Shelter: 4.4 and 6.8 percent, P = 0.01). Fermentation acids concentration was similar for both treatments with preponderance of lactic acid, but acetic acid concentration increased over time (Pt = 0.01). It was concluded that in «Tierra del Fuego», natural meadow forage quality is compatible with ensiling, but environmental conditions can limit the fermentation process. Additional key words: forage conservation, natural grasslands, Patagonia, silage

Microbial populations and ruminal fermentation of sheep and llamas fed low quality forages

The objective of this study was to assess the ruminal microbial population and fermentation of sheep and llamas fed low quality forages. Two llamas and three sheep with permanent ruminal cannula were fed ad libitum with a low quality fescue hay (Festuca arundinacea Schreb). The animals were adapted to forage feeding for 21 days, followed by one day of collection of the ruminal fluid (RF), during 2 experimental periods separated by 7 days. The RF was extracted before morning feeding. The llama forestomach content showed higher degree of fermentative activity than the sheep one, as indicated by NH3-N and VFA values (P 0.050). However, the forestomach of llamas contained higher density of total protozoa and Eudiplodinium (P < 0.050), whereas holotrich protozoa were undetectable. In conclusion, the llama forestomach had higher fermentative activity than sheep rumen, different protozoa population, but no differences in bacterial population densities.Fil: Ortiz Chura, Abimael. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación En Ciencias Veterinarias y Agronómicas. Instituto de Patobiología Veterinaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Patobiología Veterinaria; ArgentinaFil: Fernández Pepi, María Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal; ArgentinaFil: Wawrzkiewicz, Marisa. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal; ArgentinaFil: Cerón Cucchi, María Esperanza. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación En Ciencias Veterinarias y Agronómicas. Instituto de Patobiología Veterinaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Patobiología Veterinaria; ArgentinaFil: Cravero, S.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación En Ciencias Veterinarias y Agronómicas. Instituto de Patobiología Veterinaria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Patobiología Veterinaria; ArgentinaFil: Jaurena, G.. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal; Argentin

Efectos de corto plazo de la interacción riego-fertilización en la producción y composición de un campo natural de basalto en Uruguay

Supplementary irrigation is a strategic option to ensure the forage production in a scenario of high climate variability. Nevertheless, Uruguay lacks of information to be able to generate technical coefficients about responses. An experiment was performed with the objective to evaluate the effects of irrigation and N-P fertilization on forage yield and botanical composition in a basaltic natural grassland. In the period October 2011 to June 2012 was carried out an experiment to determine the effect of supplemental irrigation and fertilization N-P in a split plot design. Supplementary irrigation and rainfed were located in the big plots, while the fertilizer ones were established at smaller plots. Fertilizer treatments consisted on one unfertilized control and seven fertilization treatments: one with phosphorus only (80 kg P2O5.ha-1), three nitrogen rates (50, 100 and 200 kg N.ha-1) and three N-P combinations (80 P2O5-50 N, 80 P2O5-100 N, P2O5 and 80-200 N). The interaction of irrigation with nitrogen fertilization explained the short-term variations in productivity and botanical composition. Irrigation improved the response to nitrogen fertilization doubling forage production, and allowed conditions to increase the contribution of the most valuable forage productive types.El riego suplementario es una opción estratégica para asegurar la producción de forraje en un escenario de alta variabilidad climática, pero en Uruguay falta información para generar coeficientes técnicos de respuesta. Se realizó un experimento con el objetivo de evaluar los efectos del riego y la fertilización N-P en la producción de forraje y composición botánica de un campo natural de basalto. En el período octubre de 2011 a Junio 2012 se desarrolló un ensayo con un diseño de parcelas divididas. En las parcelas mayores se ubicaron el riego suplementario y el secano, mientras que en las parcelas menores se ubicaron un testigo sin fertilizar y siete tratamientos de fertilización: una dosis de fósforo (80kg P2O5.ha-1), tres dosis de nitrógeno (50, 100 y 200 kg N.ha-1) y tres combinaciones N-P (80 P2O5-50 N; 80 P2O5-100 N; y 80 P2O5-200 N). La interacción del riego con la fertilización nitrogenada explicó las variaciones a corto plazo de la productividad y composición botánica de la vegetación. El riego incrementó la respuesta a la fertilización nitrogenada duplicando la producción de forraje del campo natural y generando condiciones para el aumento de la contribución de los tipos productivos más valiosos desde el punto de vista forrajero

Degradabilidad in sacco de Festuca arundinacea (Poaceae) en ovejas ( Ovis aries ) y llamas ( Lama glama )

Fernández Pepi, María G.; Abimael Ortiz Chura; Alejandro F. Zucol; Gusta- vo Jaurena. 2016. “Degradabilidad in sacco de Festuca arundinacea (Poaceae) en ovejas ( Ovis aries ) y llamas ( Lama glama )”. Lilloa 53 (2) . La degradabilidad del forraje está asociada a la composición química de la pared celular, la lignificación de los distintos tejidos (característico para cada especie) y de la accesibilidad de los microorganismos del rumen a esos polisacári- dos. En este trabajo se evaluó en forma comparativa la degradación de los tejidos de lámina y vaina foliar de Festuca arundinacea , en el rumen de camélidos y ovinos. Se tomaron mues- tras de láminas y vainas, las cuales fueron sometidas a distintos tiempos de degradación mediante el método in sacco . La degradación ruminal no fue diferente entre las especies (lla- mas y ovejas, p>0,05). La anatomía de la lámina y la vaina influyeron en la degradación di- ferencial de los tejidos, aunque sólo se encontraron diferencias significativas para el tejido esclerenquimático y tejido xilemático de ambas fracciones a las 24 hs de incubación. A las 48 de incubación en el rumen, sólo se encontraron restos de tejido no digerible, correspon- dientes al sistema vascular. La accesibilidad a los carbohidratos estructurales de la pared celular por los microorganismos ruminales está determinada por la disposición de los elemen- tos de cada tipo de tejido y por la composición química de la pared

Measuring or estimating greenhouse gas emissions techniques

La disponibilidad de técnicas objetivas para medir o predecir las emisiones de gases de efecto invernadero (GEI) es fundamental para el desarrollo de trabajos de investigación y de gestión de las emisiones de GEI en los sistemas agropecuarios. Existe una variada disponibilidad de técnicas e instrumentos que permiten abordar estudios a nivel ruminal, tales como las técnicas in vitro, o a escala de animal o incluso de rodeo (e.g. cámaras de respiración, torres micrometeorologicas). En este capítulo se describen diferentes técnicas utilizadas para obtener indicadores de las emisiones de GEI, y se explica brevemente la estrategia de cálculo de los inventarios nacionales.Fil: Jaurena, Gustavo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Juliarena, María Paula. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Errecart, Pedro. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Producción y Sanidad Animal; ArgentinaFil: Arroquy, Jose Ignacio. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Buenos Aires Sur. Estacion Experimental Agropecuaria Cesareo Naredo.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Berone, Germán Darío. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Producción y Sanidad Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Posse, G.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Ricci, Patricia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Producción y Sanidad Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Enteric methane mitigation strategies for ruminant livestock systems in the Latin America and Caribbean region: a meta-analysis.

Latin America and Caribbean (LAC) is a developing region characterized for its importance for global food security, producing 23 and 11% of the global beef and milk production, respectively. The region?s ruminant livestock sector however, is under scrutiny on environmental grounds due to its large contribution to enteric methane (CH4) emissions and influence on global climate change. Thus, the identification of effective CH4 mitigation strategies which do not compromise animal performance is urgently needed, especially in context of the Sustainable Development Goals (SDG) defined in the Paris Agreement of the United Nations. Therefore, the objectives of the current study were to: 1) collate a database of individual sheep, beef and dairy cattle records from enteric CH4 emission studies conducted in the LAC region, and 2) perform a meta-analysis to identify feasible enteric CH4 mitigation strategies, which do not compromise animal performance. After outlier?s removal, 2745 animal records (65% of the original data) from 103 studies were retained (from 2011 to 2021) in the LAC database. Potential mitigation strategies were classified into three main categories (i.e., animal breeding, dietary, and rumen manipulation) and up to three subcategories, totaling 34 evaluated strategies. A random effects model weighted by inverse variance was used (Comprehensive Meta-Analysis V3.3.070). Six strategies decreased at least one enteric CH4 metric and simultaneously increased milk yield (MY; dairy cattle) or average daily gain (ADG; beef cattle and sheep). The breed composition F1 Holstein × Gyr decreased CH4 emission per MY (CH4IMilk) while increasing MY by 99%. Adequate strategies of grazing management under continuous and rotational stocking decreased CH4 emission per ADG (CH4IGain) by 22 and 35%, while increasing ADG by 22 and 71%, respectively. Increased dietary protein concentration, and increased concentrate level through cottonseed meal inclusion, decreased CH4IMilk and CH4IGain by 10 and 20% and increased MY and ADG by 12 and 31%, respectively. Lastly, increased feeding level decreased CH4IGain by 37%, while increasing ADG by 171%. The identified effective mitigation strategies can be adopted by livestock producers according to their specific needs and aid LAC countries in achieving SDG as defined in the Paris Agreement