Degradable intake protein supplementation through the inclusion of urea in finishing diets containing distillers grains: effects on feedlot cattle performance, ruminal fermentation, and feed digestibility

Tesis para obtener el grado de Philosophical Doctor (PhD), Major: Animal sciences, de la University of Minnesota, en mayo de 2014Degradable intake protein (DIP) represents the proportion of protein that is potentially fermented in the rumen. Ruminal DIP balance is calculated by the difference between DIP supply and requirements. The former is a function of dry matter intake and dietary DIP, and represents nitrogen (N) available for synthesis of microbial crude protein (MCP), which is used as a measurement of microbial growth or production of new microbial cells. Synthesis of MCP basically requires ammonia-N (NH3-N), carbon skeletons, and energy. While the last two are mainly derived from fermentation of dietary carbohydrates, dietary N represents the main NH3-N source. Consequently, DIP requirements represent rumen-degradable N needs for MCP synthesis, and are a function of available fermentable carbohydrates. High dietary inclusion of grain as well as more extensive grain processing methods can result in increased ruminal availability of rapidly-fermentable carbohydrates, which in turn may result in increased DIP requirements. In addition, corn-based diets may not supply adequate amounts of DIP because corn protein is considered to be approximately 60% undegradable. Despite great protein content and because of great undegradable protein concentration, small to moderate dietary inclusion of corn distillers grains (DG) may also result in DIP deficit. Experiments 1 and 2 described in Chapter 2 evaluated the effect of adding urea, a highly rumen-degradable N source, to a high-concentrate, moderate-DG-containing diet on feedlot cattle performance, ruminal fermentation, and feed digestibility. Results from both experiments indicate that due to a DIP deficit generated by the un-supplemented diet, the addition of urea resulted in enhanced ruminal fermentation and feed digestibility, and consequently improved animal performance. Because rates of degradation of carbohydrates and conventional urea do not match, beneficial effects may arise from the use of slow-release urea (SRU) sources over conventional urea when added to DIP-deficient diets. Therefore, experiments 1 and 2 described in Chapter 3 evaluated the effect of increasing DIP concentration through the inclusion of one of two SRU sources in comparison with the inclusion of conventional urea in DG-containing feedlot diets on ruminal fermentation and feed digestibility. Likely due to lack of DIP deficit with the un-supplemented diet, results from these experiments do not demonstrate potential beneficial effects of SRU sources over conventional urea. Several confluent factors are discussed that may explain lack of need of urea supplementation in Chapter 3 experiments. Because previous studies have demonstrated improved ruminal fermentation, feed digestibility, and animal performance when supplementing conventional urea to rapidly-fermentable, moderate-DG-containing diets, more research is warranted to evaluate the use of SRU in diets for which a DIP deficit is expressed.EEA General VillegasFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; Argentin

Degradable intake protein supplementation through the inclusion of urea in finishing diets containing distillers grains: effects on feedlot cattle performance, ruminal fermentation, and feed digestibility

Tesis para obtener el grado de Philosophical Doctor (PhD), Major: Animal sciences, de la University of Minnesota, en mayo de 2014Degradable intake protein (DIP) represents the proportion of protein that is potentially fermented in the rumen. Ruminal DIP balance is calculated by the difference between DIP supply and requirements. The former is a function of dry matter intake and dietary DIP, and represents nitrogen (N) available for synthesis of microbial crude protein (MCP), which is used as a measurement of microbial growth or production of new microbial cells. Synthesis of MCP basically requires ammonia-N (NH3-N), carbon skeletons, and energy. While the last two are mainly derived from fermentation of dietary carbohydrates, dietary N represents the main NH3-N source. Consequently, DIP requirements represent rumen-degradable N needs for MCP synthesis, and are a function of available fermentable carbohydrates. High dietary inclusion of grain as well as more extensive grain processing methods can result in increased ruminal availability of rapidly-fermentable carbohydrates, which in turn may result in increased DIP requirements. In addition, corn-based diets may not supply adequate amounts of DIP because corn protein is considered to be approximately 60% undegradable. Despite great protein content and because of great undegradable protein concentration, small to moderate dietary inclusion of corn distillers grains (DG) may also result in DIP deficit. Experiments 1 and 2 described in Chapter 2 evaluated the effect of adding urea, a highly rumen-degradable N source, to a high-concentrate, moderate-DG-containing diet on feedlot cattle performance, ruminal fermentation, and feed digestibility. Results from both experiments indicate that due to a DIP deficit generated by the un-supplemented diet, the addition of urea resulted in enhanced ruminal fermentation and feed digestibility, and consequently improved animal performance. Because rates of degradation of carbohydrates and conventional urea do not match, beneficial effects may arise from the use of slow-release urea (SRU) sources over conventional urea when added to DIP-deficient diets. Therefore, experiments 1 and 2 described in Chapter 3 evaluated the effect of increasing DIP concentration through the inclusion of one of two SRU sources in comparison with the inclusion of conventional urea in DG-containing feedlot diets on ruminal fermentation and feed digestibility. Likely due to lack of DIP deficit with the un-supplemented diet, results from these experiments do not demonstrate potential beneficial effects of SRU sources over conventional urea. Several confluent factors are discussed that may explain lack of need of urea supplementation in Chapter 3 experiments. Because previous studies have demonstrated improved ruminal fermentation, feed digestibility, and animal performance when supplementing conventional urea to rapidly-fermentable, moderate-DG-containing diets, more research is warranted to evaluate the use of SRU in diets for which a DIP deficit is expressed.EEA General VillegasFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; Argentin

Evaluación de un planteo intensivo de recría y engorde a corral de novillos Limousin y Angus

El objetivo del ensayo fue comparar la respuesta productiva y las características de la res resultantes de un ciclo de recría y terminación a corral de animales de raza continental respecto de animales de raza británica.EEA General VillegasFil: Elizalde, J. Actividad privada; ArgentinaFil: Riffel, Sebastián L. Actividad privada; ArgentinaFil: Castrillon, L. Martínez Arenaza e hijos S.A.; ArgentinaFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; Argentin

Combined use of monensin and virginiamycin to improve rumen and liver health and performance of feedlot-finished steers

Monensin and virginiamycin are included in beef cattle finishing diets as prophylaxis to minimize the incidence of ruminal acidosis and liver abscesses. Due to different and probably complementary modes of action, this study aimed to determine the effects of a combination of monensin and virginiamycin, both included in the diet at recommended doses, on ruminal health, the occurrence of liver abscesses, and growth performance of feedlot-finished cattle. One hundred and forty-four steers (6 animals/pen) were fed 1 of 3 corn-based finishing diets containing 30 mg of monensin (MN), 25 mg of virginiamycin (VM), or 30 and 25 mg of monensin and virginiamycin (MN + VM), respectively, per kilogram of dry matter. Ruminal pH probes were inserted into two animals per pen and set to record pH every 10 min. On d 100, animals were slaughtered, and rumens and livers were recovered, on which occurrence and degree of ruminal damage, prevalence and number of liver abscesses, and liver scores (A−: livers with no more than two small abscesses; A+: livers with at least one large abscess or more than four medium abscesses; A: any other abscessed liver) were determined. Simultaneous inclusion of monensin and virginiamycin resulted in a 4.3% decrease (P 0.13) average daily body weight gain (ADG; 1.49 ± 0.021 kg/d) and hot carcass weight (HCW; 269 ± 1.7 kg), compared with feeding diets containing one additive or the other. Therefore, in terms of ADG, a 9.4% improvement (P < 0.01) in feed efficiency was observed in MN + VM-fed animals. Backfat thickness (5.6 ± 0.08 mm) and ribeye area (69.9 ± 0.53 cm2) remained unaffected (P ≥ 0.74), as well as the minimum (4.98 ± 0.047), mean (6.11 ± 0.037), and maximum ruminal pH (7.23 ± 0.033) values and the time (125 ± 22.3 min/d), area (57.67 ± 12.383 pH × h), and episodes (22 ± 3.8 bouts) of pH below 5.6 (P ≥ 0.12). Overall, prevalence (24 ± 3.4%) and the number of liver abscesses (1.6 ± 0.14 abscesses/abscessed liver), liver scores (20 ± 3.1% of A− and 4 ± 1.8% of A livers), and prevalence (67 ± 3.5%) and degree of damage to the ruminal epithelium (2.5 ± 0.22% affected surface) were similar (P ≥ 0.18) across treatments; however, the occurrence of ruminal lesions tended (P ≤ 0.07) to be associated with that of liver abscesses and reduced ADG when feeding monensin alone.EEA General VillegasFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Viano, Sergio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Méndez, Daniel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: González, Lucas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Davies, Patricio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Elizalde, J. C. Actividad privada; ArgentinaFil: Bressan, Elbio. Phibro Animal Health; ArgentinaFil: Grandini, Danilo. Phibro Animal Health; BrasilFil: Nagaraja, T.G. Kansas State University. Department of Diagnostic Medicine/Pathobiology; Estados UnidosFil: Tedeschi, Luis O. Texas A&M University. Department of Animal Science; Estados Unido

El nivel de engrasamiento inicial y la ganancia de peso durante la recría a corral afectan los resultados físicos y económicos del proceso de invernada

La recría de terneros a corral es una estrategia que se ha incorporado a los sistemas de producción en los últimos seis o siete años. El manejo durante la fase de recría a corral puede afectar el resultado físico de todo el proceso de invernada. El objetivo de este trabajo fue evaluar el efecto del nivel de engrasamiento inicial y la ganancia de peso (GDP) durante la recría a corral sobre los resultados físicos y económicos del ciclo total de invernada: recría a corral, engorde a pasto y terminación a pasto o a corral. Se utilizaron terneros británicos de menor (Men) y mayor (May) nivel de engrasamiento y peso inicial. Las GDP objetivo en cada grupo fueron: Rápida (R), Intermedia (I) y Lenta (L). Durante la etapa de recría a corral los terneros Men consumieron menos kilos de alimento y fueron más eficientes en convertir ese alimento en carne. El menor nivel de engrasamiento al ingresar al corral y una GDP I o L durante la recría determinaron un menor nivel de engrasamiento a la salida del corral de recría y esto resultó en una mayor GDP y en una mayor producción por animal durante la fase subsiguiente de engorde a pasto. Asimismo, esa combinación permitió reducir el peso medio y por lo tanto incrementar la carga del sistema, afectando positivamente la producción por unidad de superficie. A su vez, el ingreso de categorías menos engrasadas y livianas redujo significativamente el monto de las compras, siendo éste uno de los rubros más representativos de los gastos directos. La mejor performance productiva durante las etapas de recría a corral y engorde a pasto de los terneros MenI y MenL permitió obtener el mejor resultado económico, a pesar de que una mayor proporción de estos animales debió ser encerrada a corral para lograr las condiciones de terminación.In Argentina, backgrounding calves in pens is a practice that has been used in beef production systems during the last six or seven years. Management practices during this pen growing period can affect the results of the whole wintering process. The objective of this study was to evaluate the effect of initial backfat depth and average daily weight gain (ADG) during a pen growing period on technical and economic results of the whole wintering process: a growing period in pen, a fattening period on pasture and a finishing period on pasture or in pen. British calves with lower (Men) or higher (May) initial backfat depth and weight were used. Predicted ADGs in each group were: Fast (R), Intermediate (I) and Slow (L). Men calves consumed less feed and were more efficient in turning this feed into gain. Lower initial backfat depth and I or L ADG during the pen growing period resulted in lower backfat depth at the end of the pen growing period, thus resulting in higher ADG and individual production during the following grazing stage. In addition, this management led to a lower average body weight. This resulted in a higher stocking rate and, as a consequence, animal production per hectare was increased. Besides, entering a lighter (and thinner) calve to the system implied a lower amount of kilograms to be bought, that being one of the most significant component of the cots. The best performance of MenI and MenL during the pen growing period and the grazing phase allowed to obtain the best economic result, in spite of the fact that a higher proportion of animals in these treatments was finished in a feedlot.EEA General VillegasFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Davies, Patricio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Mendez, Daniel Gustavo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Elizalde, J. C. Actividad privada; ArgentinaFil: Buffarini, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; Argentina

La utilización de alfalfa en verano con mayor frecuencia de defoliación generó incrementos en la producción animal

Alturas pre-pastoreo en alfalfa (Medicago sativa) menores a 35 cm generan, respecto a mayores alturas, cubiertas con mejor calidad nutritiva (ejemplo mayor proporción de hoja) y una mayor respuesta animal individual (Berone et al., 2020). Sin embargo, este aspecto nunca fue evaluado para mitigar la caída en ganancia de peso observada entre la primavera y el verano (Méndez et al., 2020). El objetivo del presente trabajo fue evaluar, durante el período estival, la producción de forraje, la ganancia de peso, y la producción de carne en pasturas de alfalfa con alturas pre-pastoreo contrastantes (ejemplo menores y mayores a 35 cm de altura).Estación Experimental Agropecuaria General VillegasFil: Méndez, Daniel Gustavo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Sardiña, María Cecilia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; Argentina.Fil: Diez, Marianela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Viano, Sergio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Berone, German Dario. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentin

Effect of slaughter handling conditions and animal temperament on bovine meat quality markers = Efecto del manejo y del temperamento animal sobre indicadores de calidad de la carne bovina

The aim of this research was to study the effect of different handling conditions on physiological stress indicators and meat quality of beef cattle by studying animals with different temperaments. Forty animals classified by their temperament (calm and disturbed) were used. They were fed on pastures and finished with a mixed diet of corn grain and pasture. Biochemical indicators of animal stress were measured at slaughter (packed cell volume -PCV-, proteins, glucose, creatinine, alkaline phosphatase -APactivity, cortisol, insulin, glycogen). Also, ultimate pH and instrumental colour were chosen as meat quality markers. Animal temperament showed a significantly increase (p<0.05) on PCV levels and a significantly (p<0.05) decrease on muscle glycogen. Besides, levels of plasma glucose and total proteins showed significant (p<0.05) differences associated to management applied. Meat quality markers (pH and colour) did not show significant differences according to handling conditions or temperament. Mean cortisol levels at the exsanguination time were significantly higher (p<0.05) than the values obtained one week prior to slaughter, which suggests an important effect of stress associated to slaughter procedures. It would be interesting to focus attention on theassessment of acute stress at abattoir, in order to improve handling protocols, and therefore to assure meat quality in Argentinean beef production systems.El objetivo del presente trabajo fue estudiar el efecto de diferentes condiciones de manejo sobre indicadores fisiológicos de estrés y de calidad de carne en bovinos con temperamentos contrastantes. Se utilizaron cuarenta animales clasificados como calmos y excitables. Los mismos fueron alimentados inicialmente a base de pasturas y terminados con una dieta mixta de grano de maíz y pasturas. Se dosaron indicadores bioquímicos de estrés (hematocrito, proteínas plasmáticas, glucosa, creatinina, actividad fosfatasa alcalina, cortisol, insulina, contenido muscular de glucó- geno). Como indicadores de calidad de carne se midieron el pH de 24 h y color instrumental. El temperamento animal demostró un incremento significativo (p<0,05) en los niveles de hematocrito y con una disminución significativa (p<0,05) del glucógeno muscular. Los niveles de glucemia y de proteínas totales mostraron modificaciones significativas (p<0,05) asociadas con el manejo. El incremento (p<0,05) en los niveles plasmáticos de cortisol durante la faena, independientemente del tratamiento o el temperamento animal, sugiere un importante efecto estresor por parte del proceso de faena. Sería interesante centrar la atención en el estudio del estrés agudo, a fin de mejorar protocolos de manejo animal, y consecuentemente, optimizar la calidad de la carne asociada en los sistemas de producción de Argentina.Fil: Pighin, Darí­o Gabriel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Morón. Facultad de Agronomía y Ciencias Agroalimentarias; ArgentinaFil: Davies, Patricio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Grigioni, Gabriela Maria Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Morón. Facultad de Agronomía y Ciencias Agroalimentarias; ArgentinaFil: Pazos, Adriana Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Universidad de Morón. Facultad de Agronomía y Ciencias Agroalimentarias; ArgentinaFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Mendez, Daniel Gustavo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Buffarini, Miguel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Sancho, Ana Maria Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Universidad de Morón. Facultad de Agronomía y Ciencias Agroalimentarias; ArgentinaFil: Gonzalez, Claudia Beatriz Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. San Martín. Escuela de Ciencia y Tecnología; Argentin

Requerimientos de nitrógeno degradable en rumen en novillos alimentados a corral con dietas a base de grano de maíz seco partido

Los rumiantes se distinguen del resto de los herbívoros por la adaptación morfofisiológica que presenta la parte anterior de su tracto gastrointestinal. Son animales policavitarios con la presencia de un rumen-retículo que aloja un complejo microbioma y funciona como una gran cuba de fermentación (Trinchero et al, 2013). Esto les permite convertir alimentos fibrosos y proteínas de baja calidad, incluso el nitrógeno no proteico (NNP; urea, ácidos nucleicos, nitrógeno amoniacal, nitratos, etc.), en nutrientes de alto valor biológico para el animal (Dewhurst et al., 2000). Para crecer y multiplicarse, los microorganismos degradan y transforman los tejidos vegetales en aminoácidos, esqueletos carbonados, NH3 y energía en forma de ATP para sintetizar proteína microbiana (PMic), ácidos grasos volátiles (AGV), vitaminas y, a su vez, mantener funciones vitales de las células (NASEM, 2016; Russell, 2002) Sin embargo, el ganado de carne es relativamente ineficiente utilizando el N dietario, ya que no más del 20% del mismo es utilizado para su propio crecimiento (NASEM, 2016). Esta ineficiencia en parte es debida a la rápida degradación ruminal de las proteínas dietarias que resulta en una mayor absorción de amoníaco (NH3) a través del epitelio ruminal, que finalmente se excreta en forma de urea en la orina (Kennedy & Milligan, 1980). Otra parte de la urea sintetizada en el hígado se recicla de regreso al rumen a través de la saliva o de la sangre. Este mecanismo de reciclaje es muy beneficioso para el animal porque brinda la oportunidad de sobrevivir y reproducirse en una amplia gama de condiciones ambientales, incluidos los casos en los que la ingesta de N es muy baja (NASEM, 2016). A su vez, los AGV y la PMic resultantes de la fermentación ruminal del alimento y del crecimiento microbiano, entre otros, son esenciales para proveer al animal de fuentes energéticas y de precursores de ácidos grasos de cadena larga (acetato, butirato) y de glucosa (propionato), así como de péptidos y aminoácidos para la síntesis de proteína animal. Consecuentemente, un adecuado suministro de N, de carbohidratos y otros factores para promover el crecimiento microbiano son centrales para eficientizar la producción de bovinos de carne tanto desde una perspectiva de suministro de fuentes energéticas como proteicas (Ceconi et al., 2013).Estación Experimental Agropecuaria General VillegasFil: González, Lucas. Universidad Nacional de Buenos Aires. Facultad de Agronomía; ArgentinaFil: González, Lucas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: González, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Viano, Sergio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Davies, Patricio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; Argentina.Fil: Méndez, Daniel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; ArgentinaFil: Jaurena, Gustavo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Arroquy, Jose Ignacio. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santiago del Estero; ArgentinaFil: Elizalde, Juan. Actividad privada; ArgentinaFil: Ceconi, Irene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria General Villegas; Argentin