Estimation of Organic Matter Digestibility and Intake from Faecal Organic Matter and Daily N Excretion and Concentration

This study was performed with grazing sheep, to establish: a) if the amount of total faecal N (C; in g 100g-1 of organic matter intake (OMI)) remains constant at three feeding levels, in four utilisation periods of deferred Panicum coloratum cv. Verde; b) the relationship between C and faecal N fractions, and c) the relationship between faecal daily excretion of OM and N, and OMI. Intake increased (P\u3c 0.01) with utilisation period, and was related (r = - 0.82; P\u3c 0.01) to the protein content of food, the insoluble N fraction (r = -0.49; P\u3c 0.01) and the soluble:insoluble N ratio (r = 0.41; P\u3c 0.01) in faeces. No relation with total N concentration (r = -0.22; P\u3e 0.05) or soluble N fraction (r = -0.02; P\u3e 0.05) in faeces could be found. Daily excretion of OM and N were positively related (R2 = 0.93 and 0.96, respectively; P\u3c 0.01) to OMI. The slopes of regression lines, but not the intercepts, were different (P\u3c 0.01) between evaluation periods. The digestibility can be estimated from OMI and faecal N whenever time of the year is taken into consideration

Intake Estimation of Rams under Grazing Condition in a Deferred Pastures of \u3ci\u3ePanicum coloratum\u3c/i\u3e by Two Techniques

The goal of this study was to quantify the organic matter intake (OMI) of Pampinta rams grazing in a Panicum coloratum cv Verde differed pasture. The OMI was compared by two methods: a) the difference between the forage measured in pre and post-grazing condition, and b) the faecal production:digestibility ratio of the diet, estimated by total faecal gathering, and from the quantity of total faecal N in g per 100 g-1 of OMI and the concentration of total faecal N, respectively. The OMI estimated by difference between the forage measured in pre and post-grazing was 9 % higher (P\u3c 0,05) than the one estimated from total faecal gathering and OMD. Interaction was not detected (P\u3e 0,10) between treatments (length of the deferment period) and estimation method. The use of the faecal N can be utilized, considering the time of the year, to estimate the OMD and OMI in grazing condition in P. coloratum deferred pastures

Slowly and non-digestible tissues in Elytrigia scabrifolia y E. Scabriglumis

The estimation of the percentages of slowly and non-digestible tissues allows the prediction 01the nutritive value of forages. In this study, the percentages of tissues in sheaths and blades of two species natives of the Salado Basin and abundant in the Pampas range pastures (Elytrigia scabrifolia y E. scabriglumis) were determined as a primary evaluation of their forage qualily. The estimations were done in the vegetative and reproductive stages. A split-plots design in space and time, with species as main plot, plant part (sheath or blade) as secondary plots, and three replications was used. Percentages of all leaf tissues were estimated by microscopic analysis of cross section and were grouped in rapidly and slowly plus non-digestible tissues. The variation of all leaf tissues between species, plant parts and growth stage, and the percentages variation of slowly and non-digestible tissues were analysed by principal components and by ANOVA, respectively. In all cases, the percentages of sclerenchyma were lower than 10% and those of slowly plus non-digestible tissues were lower than 45%. The percentages of slowly and non-digestible tissues did not differ (P<0.05) either between species (P<0.05) or plant parts, but increased 34% with the advancement of growth from the vegetativa to the reproductive stage. Although the percentage of slowly and nondigestible tissues suggest that both species have an acceptable nutritive value, this rating could be altered by the degree of forage lignification.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.) Publicado en Archivos latinoamericanos de producción animal, 5(Supl. 1): 118-121, 1997

Slowly and non-digestible tissues in Elytrigia scabrifolia y E. Scabriglumis

The estimation of the percentages of slowly and non-digestible tissues allows the prediction 01the nutritive value of forages. In this study, the percentages of tissues in sheaths and blades of two species natives of the Salado Basin and abundant in the Pampas range pastures (Elytrigia scabrifolia y E. scabriglumis) were determined as a primary evaluation of their forage qualily. The estimations were done in the vegetative and reproductive stages. A split-plots design in space and time, with species as main plot, plant part (sheath or blade) as secondary plots, and three replications was used. Percentages of all leaf tissues were estimated by microscopic analysis of cross section and were grouped in rapidly and slowly plus non-digestible tissues. The variation of all leaf tissues between species, plant parts and growth stage, and the percentages variation of slowly and non-digestible tissues were analysed by principal components and by ANOVA, respectively. In all cases, the percentages of sclerenchyma were lower than 10% and those of slowly plus non-digestible tissues were lower than 45%. The percentages of slowly and non-digestible tissues did not differ (P<0.05) either between species (P<0.05) or plant parts, but increased 34% with the advancement of growth from the vegetativa to the reproductive stage. Although the percentage of slowly and nondigestible tissues suggest that both species have an acceptable nutritive value, this rating could be altered by the degree of forage lignification.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.) Publicado en Archivos latinoamericanos de producción animal, 5(Supl. 1): 118-121, 1997

Estimation of intake and digestibility of kleingrass from in situ parameters measured in sheep

The voluntary intake and digestibility of kleingrass (Panicum coloratum cv. Verde) were measured in seven periods, comprising one full year. The forage was offered twice a day ad Iibitum to .seven rams, frtted with faces collection bags; each experimental period was composed of 8 days for adaptation and 8 days for collection of data. The dry matter (DM) Intake (DMI) varied from 36.1 to 64.9 glkg MO.75, the digestible dry-matter Intake (DDMI), from 17.4 to 41.9 glkg MO.75 and the in vivo dry matter apparent digestibility (DMD), from 0.471 to 0.667. Daily samples of offered forage were taken and pooled subsamples from each of the seven periods were incubated in nylon bags in the rumen of three Hereford steers. The data were fitted to the exponential equation: p= a + b (1-e~) to estimate p (the proportionate loss of DM at time t of incubation); effective degradability (ED) and lag time (L) were also estimated. The parameters obtained in situ were related to the in vivo results by simple and multiple regression. The correlation coefficients of the rate of degradation {9 and ED with DMI, DDMI and DMD were, respectively, 0.96 and 0.97; 0.97 and 0.96; 0.86 and 0.88. By including, Q, Q and k into a multiple regression analysis, the coefficients of determination (R2) were: DMI: 0.99; DDMI: 0.99 and DMD: 0.91. Within the conditions of this study, the parameters obtained in situ were reasonable estimators of voluntary intake and digestibility.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.) Publicado en Animal Science, 67: 535-540, 1998

Comportamiento de verdeos invernales en Santa Rosa, La Pampa. II. Estimación de la degradabilidad ruminal in sacco

The objetive of this study was to evaluate dry matter (DM) rumen degradation kinetics of cultivars (cvs) of small grain pastures. Cultivars were: avena (Avena sativa L.) cv Don Victor, avena (Avena byzantina C. Koch) cv Millauquén, cebada (Hordeum vulgare L.) cv Ullaiché, centeno (Secale cereale L.) cvs Choiqué y Naicó, tricepiro (Triticum x Secale x Thinopyron) unea 3/40 y triticale (x Triticosecale Witt.) cvs Don Norman y Tehuelche. Each plot was cuftour times, on the followingdates: June r-, August 12th, September 30th and November 30th The harvested forage, dried and milled, was incubated in the rumens into suspended nylon bags. Three Holstein-Freisian steers, titted with permanent rumen canulae were used in the experiment. Animals were fed on ad libitum alfalfa hay and water. Ruminal degradability was estimated using DM rate of disappearance, through an exponential model p = a + b(1- exp(-ct)). Data were compared by ANOVA, under a split-plot design Treatment mean were separated using Tukey's test (α= 0.05). Most differences between cultivars in effective degradability were given by differences in the soluble:insoluble potentially degradable fractions ratio, and due to different fractional rates of degradation. Non-degradable fraction was similar (p>0.05) between cultivars.El objetivo de este estudio fue evaluar la cinética de la degradación ruminal de la materia seca (MS) en cultivares (cvs) de verdeos invernales. Estos fueron: avena (Avena sativa L.) cv Don Víctor, avena (Avena byzantina C. Koch) cv Millauquén, Cebada (Hordeum vulgare L.) cv Ullaiché, centeno (Secale cereale L.) cvs Choiqué y Naicó, tricepiro (Triticum x Secale x Thinopyrum) Unea3/40 y tritícale (x Triticosecale Witt.) cvs Don Norman y Tehuelche. Se realizaron cuatro cortes, sobre una misma parcela en las fechas 07-06, 12-08, 30-09 Y 30-11. El forraje secado y molido, fue incubado en bolsitas de nylon suspendidas en rumen. Se utilizaron 3 novillos Holando-argentino con fístula ruminal, alimentados con heno de alfalfa y agua a voluntad. La tasa de desaparición de la MS fue el criterio utilizado para calcular la degradabilidad, a través de un modelo exponencial p = a + b(1-exp-Ct).Los datos fueron analizados mediante ANOVA, utilizando un diseño de parcelas divididas, y Test de Tukey  (α=0,05).En general, las diferencias en degradabilidad efectiva entre cvs se correspondieron a diferencias en la relación entre la fracción soluble y la fracción insoluble potencialmente degradable, y a diferencias en la tasa fraccional de degradación. La fracción indegradable resultó similar (p>0,05) entre cultivares

Comparación de modelos utilizados para estimar la materia seca in sacco y la degradabilidad

El objetivo del presente estudio fue comparar algunos de los modelos disponibles, utilizados para estimar la dinámica de la desaparici6n y la degradabilidad de la materia seca (MS) en rumen, en dos grupos de gramíneas: Verdeos invernales (VI) y perennes de crecimiento estival (GrE). Las muestras (n = 327) fueron incubadas en bolsas de nylon en el rumen de tres novillos Holando-Argentino, con fistula ruminal. Los datos experimentales obtenidos, fueron tratados matemáticamente utilizando distintos modelos para estimar tasa de degradación y degradaci6n efectiva de la MS. La tasa de desaparici6n fue estimada a partir de dos modelos no lineales similares, con y sin tiempo de retardo y con una ecuación de primer orden. Las degradabílidades efectivas se calcularon utilizando las constantes estimadas por los dos modelos no lineales con y sin tiempo de retardo, por sumatoria de las degradaciones entre perlados sucesivos y por estimación de la relación entre la tasa de pasaje de la MS no degradada para las primeras horas de incubación y la de la MS insoluble. La degradabilidad máxima se estimó a través de la predicción de la asíntota de la hipérbola, determinando la intercepción de la doble reciproca de tiempo y materia seca no degradada. Los parámetros equivalentes entre modelos fueron comparados como observaciones apareadas dentro de cada recurso forrajero. La asociación entre parámetros y entre valores de degradabilidad se evaluó por análisis de correlación. Las diferencias entre parámetros comparables en VI y GrE fueron significativas (P < 0,01), la asociación fluctuó entre 0,72 y 0,96. Las correlaciones entre degradabilidades efectivas y máxima obtenidas mediante los distintos modelos fueron estrechas (r > 0,97). Todos los modelos estimaron con similar precisión la degradabilidad efectiva de la MS del alimento, independientemente del valor nutritivo del mismo. Por lo tanto, cualquiera de los modelos estudiados puede utilizarse para estimar la degradabilidad de la MS. Sin embargo, a partir de un trabajo experimental similar, puede obtenerse mayor información si ésta se procesa utilizando el modelo no lineal con tiempo de retardo.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.), Publicado en Revista argentina de producción animal, 17(4): 353- 364, 199

Dry matter production and nutritive value of forage of Digitaria eriantha cv. Irene in two locations oft be central semi-arid region of Argentina

The aim of this experiment was to compare dry matter (DM) production rates and nutritive value of a warm-season grass, Digitaria erisntha ev. Irene, in two locations of Central Argentina, Santa Rosa (SR) and Villa Mercedes (VM). The plants were established in two identical groups of plots, within a randomized block design DM rates were calculated from serial, out of phase clippings, and in vitro dry matter digestibility (IVDMD) and crude protein (CP) content analyzed on subsamples. The study lasted for three consecutive growing seasons. Results showed that DM production rates were generally higher (P<0.05) in SR than in VM, but IVDMD and CP content showed no clear trends between both locations. DM production tended to lower from year 1 to 3, related to processes of N depletion from soils (VM) and diminishing rainfall (SR). It is concluded that D. eriantha is a very promising warm-season grass to Central Argentina. Data of nutritive value obtained in one location can be used in others, but results of DM production rates should be taken under the conditions where they will be used.Resúmenes de Trabajos presentados en otras publicaciones (por docentes de la UNLPam.)  Publicado en Proceedings of the XVIII international grassland congress. Forage and Management, Session 22: 101-102, 1997

Contenido de Iignina como estimador de la degradabilidad ruminal en gramíneas

The objective of this study was to establish the relationship between lignin content and the degradable fraction of warm-season grasses. The 120 samples used came from plots of the following species, Eragrostis curvula ev. Tanganyka (Ee), Panicum virgatum ev. Pathfinder (Pv), Panicum coIoratum ev. Selection 75 (Pe) and Tetrachne dregeí (Td). The samples were obtained during two consecutive winters, in 1990/91. The forage obtained was divided into its fractions, blade and stem+sheath, on which Iignin content (L) was determined. Each fraction was incubated within nylon bags, in the rumen of three fístulated steers. The Information obtained from incubations was mathematically processed to estimate the asymptote of the hyperbole (Dmax), and, through a non-linear model, the rapidly (a) and slowly (b) degradable dry malter values were determined. The contents of L were related to the values obtained by rumen incubation y, = (a+b) and Y2 = Dmax. Pseudovarlables were used to discriminate between grass species: Ee (Pv, Pe and Td=0); Pv (Pv = 1; Pe and Td=0); Pe (Pe = 1; Pv and Td=0);Td (Td=1; Pv and Pe=0). The equations obtained were, y, = 102.6 - 6.97L + 21.57Pv + 7.70Pe - 1.82L*Pe; R2 = 0.68(P<0.01), SE = 7.8; Y2 = 73.10 - 3.72L + 43.72Pv - 5.55L*Pv + 26.76Pe - 2.85L*Pc + 25.69Td - 3.44L*Td; R2 = 0.77(P<0.01), SE = 5.8. The results demonstrate that, the degradable fraction of warm-season grasses can be estimated by the Iignin content of the forage source.El objetivo de este estudio fue establecer la relación existente entre el contenido de lignina con la fracción degradable en gramíneas perennes de crecimiento estival. Se tomaron 120 muestras provenientes de parcelas implantadas con Eragrostis curvula ev Tanganyka (Ec), Panicum virgatum ev Pathfinder (Pv), Panicum coloratum ev Selection 75 (Pc) y Tetrachne dregel (Td) cortadas durante dos inviernos, en 1990/91. En las muestras, previa división en las fracciones lámina y tallo+vaina, se determinó el contenido de Iignina (L) y fueron incubadas en bolsitas en el rumen de tres novillos. A partir de la información obtenida en la incubación se estimó la asíntota de la hipérbola (Cmax) y, a través de un modelo no lineal, los valores de materia seca rápida (a) y lentamente (b) degradable. Los contenidos de L fueron relacionados con v,=(a+b) e VI=Cmax. Para diferenciar entre gramlneas se utilizaron pseudovariables, Ee (Pv, Pe V Td=0); Pv (Pv=1; Pe y Td=0); Pe (Pc=1; Pv Y Td=0); Td (Td=1; Pv Y Pc=0). Las ecuaciones obtenidas fueron, V, = 102,6 - 6,97L + 21,57Pv + 7,70Pc - 1,82L*Pe; R2 = 0,68(P<0,01); EE = 7,8; VI = 73,10 - 3,72L + 43,72Pv - 5,55L*Pv + 26,76Pc - 2,85L*Pe + 5,69Td· 3,44L*Td; R2 = 0,77(P<0,01);EE = 5,8. Se concluye que conociendo el contenido en lignina, para gramíneas perennes de crecimiento estival, puede estimarse la fracción degradable

Efecto de la suplementación con jugos de fruta sobre el ambiente y la digestión de forrajes en rumen

The use of fruit juice as energy supplement to beef cows have been increasing in La Pampa Province during the last years. The aim of the present study was to measure the effect of the addition of fruit juice to an alfalfa hay diet, on rumen environment and forage digestion. Six rumen fistulated steers were used within a cross-over design, with two treatments and two perlods. The animals were fed ad libitum on alfalfa hay. This diet was supplemented with 4.47 mi Kg LWO·7S.d" of distilled water (To) or fruit juice (T,), via rumen cannulae twice a day (8:00 and 16:00 h). After seven days of adaptation to the diets, samples of rumen liquid were taken at 8:00, 10:00 and 14:00 h (16, 2 and 6 h after supplementation of water or juice) during tour consecutive days. Concentration of ammonia nitrogen (NH)-N), volatile fatty acids NFA) and pH were determined on the rumen samples. The rumen digestion of DM and CP of leaves of alfalfa hay and DM of deferred weeping lovegrass hay was measured through the in sacco technique. The results were analyzed by ANOVA. The pH values were different (To= 6.60; T1 = 6.35; P = 0.051) after 2 h of supplementation, but no differences were found after 6 h (To= 6.50; T1 = 6.40; P = 0.130) or 16 h (To= 6.33 T1 = 6.17; P = 0.169). The VFA concentrations showed a trend to signification (in mM) (To= 76.3 T1 = 71.3; P = 0.094) at 6 h, although no treatment effect could be detected at 2 h (To= 74.8; T1 = 80.7; P = 0.293) or 16 h (To= 85.7; T1 =  84.6; P = 0.866). The supplementation with fruit Juice had no effect on rumen ammonia concentration (in mg.l-1 of NH3-N): 2 h: To= 237.0; ; T1 = 230.6; P = 0.522; 6 h To= 210.0; ; T1 =197.2; P = 0.356; 16 h: TD = 215.8; ; T1 = 196.7; P = 0.154. The addition of fruit juice to the diet To= 67.8;  T1 =  67.6; P = 0.831 and deferred weeping lovegrass hay: T0 = 23.1; T1 = 22.2; p". 0.421. The ED of CP of Ieaves of alfalfa hay showed a trend to be higher when only distilled water was added (To = 47.4; T1 = 45.6; P = 0.107). In the conditions of this assay, the supplementation of fruit juice to fibrous diets did not produce clear effects on rumen environment and digestion that could affect the nutritional status.La utilización de Jugos de fruta como suplemento energético en vacas de cria ha tomado gran importancia en la Provincia de La Pampa, durante los últimos años. El objetivo del presente estudio fue determinar el efecto de la adición de Jugo de fruta a una dieta de heno de alfalfa sobre el ambiente ruminal y la digestión ruminal. Se utilizaron seis novillos fistulados en el rumen, en un diseño cross-over de dos tratamientos y dos periodos. Los animales recibieron, sd libitum, heno de alfalfa, a esta dieta se adicionaron 4,47 mi Kg. PV0.75.d-1 de agua destilada (To) o jugo de fruta (T1), ambos fueron suministrados a través de cánula ruminal dos veces al día (8:00 y 16:00 h). Después de 7 días de acostumbramiento a los tratamientos se extrajeron muestras de líquido ruminal a las 2, 6 Y 16 h posteriores al suministro del agua o jugo, durante cuatro días consecutivos en cada periodo. Sobre las muestras extraídas se determinó pH, concentración de nitrógeno amoniacal (N-NH3 y ácidos grasos volátiles (AGV). La degradación de la materia seca (MS) y proteína bruta (pe) en el rumen fue medida sobre hojas de heno de alfalfa y sobre MS de heno de pasto llorón diferido, a través de la técnica in sacco. Los resultados fueron analizados mediante ANOVA. El pH difirió (To :1 6,60; T1 = 6,35; P = 0,051) luego de dos horas de la adición de jugo, mientras que no fue distinto a las 6 h (To = 6,50; T1 = 6,40; p= 0,130) ni a las 16 h (To = 6,33; T1=6,17; p= 0,169). En AGV (en mM) se observó una tendencia a la significación (To= 76,3; T1= 71,3; P :1 0,094) a las 6 h, mientras que no hubo efecto de tratamiento a las 2 h (To= 74,8; T1= 80,7; P = 0,293) ni a las 16 h (To= 85,7; T1 = 84,6; P= 0,866). No se detectó efecto alguno de la suplementación con jugo sobre la concentración de amoniaco ruminal (en mg l-1, de N-NH3): 2 h: Te = 237,0; T, = 230,6; P = 0,522; 6 h: To= 210,0; T1= 197,2; P= 0,356; 16 h: To = 215,8; T1= 196,7; P= 0,154. La adición de Jugo no influyó sobre la degradabilidad efectiva (DE) in sacco de la materia seca de hojas de alfalfa (DE: To= 67,8; T1= 67,6; p =0,831) Y de heno de pasto llorón diferido (DE: Te = 23,1; T, = 22,2; P = 0,421). La DE de la PB de hojas de heno de alfalfa presentó una tendencia a ser mayor cuando se agregó agua destilada (To = 47,4; T1= 45,6; P = 0,107). En las condiciones del ensayo, la suplementaci6n con Jugos de fruta sobre una dieta fibrosa no produjo efectos claros sobre el ambiente ruminal que afecten el status nutricional.Trabajo presentado en el 20° Congreso Argentino de Producción Animal, junio de 1996, Río Hondo, Santiago del Estero