Maria Paz Corrales Marmol

Ruminant production in the Chaco region relies on pastures and native forest foliage, whose nutritional value is poorly characterized and may be influenced by tannins. This study evaluated the in situ digestibility and in vitro ruminal fermentation of foliage from Prosopis affinis (PA), Prosopis nigra (PN), Acacia polyphylla (AP), Phyllostylon rhamnoides (PR), and Tabebuia nodosa (TN), incubated with or without polyethylene glycol (PEG) to assess the effects of tannin on gas production and nitrogen (N) compounds degradability. Foliage contained ≥17% crude protein (CP) and ≥40% fiber-bound N. Tannin concentration was >4% dry matter (DM) in PN and PA and p < 0.05). Gas production was higher in PA, PR, and TN (p < 0.05), with no PEG effect. Methane production was not affected by tree species or PEG (p ≤ 0.277). Both species and PEG affected the effective N compounds degradability (END), with PEG increasing it in PN and AP (p < 0.05). Although foliage is high in CP, its digestibility is low; N is largely fiber-bound, and tannins may further limit END, factors to consider when including them in ruminant diets.

Ruminant production in the Chaco region relies mainly on pastures and naturally available foliage from native forests. However, the nutritional value of this foliage remains poorly characterized and may be affected by tannins. This study evaluated the nutritional value, and tannin effects on in vitro ruminal fermentation of foliage from tree species of the Chaco region: Prosopis affinis (PA), Prosopis nigra (PN), Acacia polyphylla (AP), Phyllostylon rhamnoides (PR), and Tabebuia nodosa (TN). Samples were incubated with or without polyethylene glycol (PEG) to assess tannin effects on gas production and nitrogen (N) degradability. All species were high in crude protein (CP; ≥17% DM). Tannin content was high in PN and PA (>4% DM), and low (<1% DM) in PR, AP, and TN. In situ digestibility was low (≤51%) in all species except PR (73%; p < 0.05). Gas production was higher in PA, PR, and TN (p < 0.05), with no PEG effect. Both species and PEG affected the effective N degradability, with PEG significantly increasing it in PN and AP (p < 0.05). Although foliages are high in CP, their digestibility is generally low, much of the N is fiber-bound, and tannins may further limit N degradability.

The usage of land on small farms in subtropical regions varies with climatic conditions. Agricultural cultivation typically occurs during the spring and summer (of the southern hemisphere), with tobacco being the primary crop on most small farms. During these seasons, livestock graze in pastures and woodlots. After the tobacco harvest (March), farmers plant winter cover crops, and by May, livestock is moved from the pastures to the agricultural areas. This study aimed to examine how grazing influences soil density, water infiltration rates, and animal behavior across different land types (pasture, native forest, eucalyptus reforestation, and agriculture) during the tobacco-growing season, and the off-season when grazing occurs on agricultural lands. It was found that forage availability and climatic conditions determined grazing duration in pastures and forests, under Integrated Crop–Livestock (ICL) systems. Higher forage volume in the agriculture area reduced grazing time and increased resting periods. Eucalyptus reforestation areas had the best soil conditions due to minimal grazing occurring there. An increase in soil bulk density and a decrease in water infiltration rates were observed at the end of the grazing period in both pasture and woodland areas. Year-round ICL systems appear to enhance soil quality through fallow periods, improving forage availability, soil moisture retention, and water infiltration as well.

The use of land on small farms in subtropical regions varies with climatic conditions. Agricultural cultivation typically occurs during the spring and summer (southern hemisphere), with tobacco being the primary crop on most small farms. During these seasons, livestock graze in pastures and forest fragments. After the tobacco harvest (March), farmers plant winter cover crops, and by May, livestock is moved from pastures to agricultural areas. This study aimed to examine how grazing influences soil density and water infiltration rates across different land types (pasture, forest, eucalyptus reforestation, and agriculture) during the tobacco-growing season, and the off-season when grazing occurs on agricultural lands. It was found that forage availability and climatic conditions determined grazing duration in pastures and forests, under integrated crop-livestock (ICL) systems. Higher forage volume reduced grazing time and increased resting periods. Eucalyptus reforestation areas had the best soil conditions due to reduced grazing. Intense off-season grazing increased soil density and reduced water infiltration. Year-round ICL systems appear to enhance soil quality through fallow periods, improving forage availability, soil moisture retention, and water infiltration, as well.

En la producción animal, desde el punto de vista biológico y económico, es importante el análisis de relaciones entre diferentes variables, específicamente, entre el peso vivo y las variables morfométricas, y la estimación del mismo a través de estos rasgos cuantitativos, en distintas especies zootécnicas, incluyendo los recursos locales, en este caso, un grupo aviar localizado en Paraguay. No obstante, la naturaleza de estas características no siempre se ajusta a los supuestos requeridos en los análisis estadísticos clásicos. En ese contexto, el objetivo de este trabajo consistió en explorar y encontrar un modelo plausible para el peso vivo de aves de corral, a partir de variables morfométricas y la edad, teniendo en cuenta la naturaleza intrínseca de los datos del peso. Fueron consideradas 34 aves hembra criadas en una granja de la Facultad de Ciencias Veterinarias de la Universidad Nacional de Asunción, Paraguay. Se analizó la estructura de regresión con enfoque en el modelo aditivo generalizado de ubicación, escala y forma, procediendo a seleccionar el modelo según criterio de información generalizado de Akaike. Los resultados revelaron que, la distribución gaussiana inversa se ajustó mejor a los datos del peso vivo de las aves hembra. Asimismo, la edad, la longitud del cuello y longitud del muslo influyeron en la estimación del peso vivo medio, mientras que, en la dispersión, influyo la longitud del cuello, el ancho del cráneo y la longitud del dedo medio. Fueron establecidas expresiones matemáticas derivadas del modelo para el peso con distribución de probabilidad gaussiana inversa, con sus respectivos parámetros identificados.

In animal characterization research it is essential to establish ranges of typical and fluctuating behaviours of its variables and parameters. For this, the use of robust statistical inferences constitutes a relevant tool. Thus, the study of body traits in a rustic dual-purpose avian population was approached, through correlation and principal component analysis (PCA), contributing to its morphometric characterization and verifying the usefulness of the statistical methods used in a small group. In total, 52 chickens (males and females) were evaluated, classified as adults and older adults, analysing a series of quantitative traits. An association was found between live weight and skull width, middle finger length, wing length (p < 0.01), back length, keel length, breast width, beak length and tarsus length (p<0.05), in adult males, while for older birds calculations are suggested as selection criteria between live weight with keel length and neck length. On the other hand, in adult females, live weight did not show the zootechnical relevance observed in males, while in older females a positive relationship of some body characteristics with live weight was evident. The correlation analysis was useful to provide morphometric links in both sexes and age groups, but not the PCA, which showed good performance in body measurements of males before that of females, in conditions of reduced effective population size (risk) and with native phenotypes.

Algunos subproductos, pueden ser utilizados en alimentación animal dependiendo de sus características nutricionales, con respecto a esto el subproducto de Chía presenta poca información sobre uso del mismo en raciones de vacas lecheras. Con el objetivo de evaluar la inclusión de torta de Chía (Salvia hispanica L.) en la ración de vacas lecheras y su efecto en la producción y composición química de la leche, se llevó a cabo el siguiente experimento. Fueron seleccionadas diez vacas de raza Holstein en primer tercio de lactación, PV 500 ± 50 kg, se utilizó un diseño cruzado con dos tratamientos, en 2 periodos. Un grupo fue alimentado con inclusión de torta de Chía en la ración (Dieta 1) y el otro sin inclusión de torta de Chía en la ración (Dieta 2). Los animales fueron mantenidos en las mismas condiciones de sanitación y manejo, con dos ordeños diarios, a la mañana y tarde. Tras 12 días (d) de adaptación a la dieta, y durante un periodo de mediciones de 5 d, se registraron diariamente la ingesta de alimentos, producción láctea individual y se tomaron muestras para determinar la composición química de la misma. Se presentaron diferencias estadísticas significativas en la producción de leche a favor de la Dieta 2 (P<0,05), siendo de 27,3 ± 3,28 L para Dieta 1 y 28,85 ± 2,46 L para Dieta 2. En cuanto a la composición química de la leche se presentaron diferencias significativas en proteína cruda (3,02 ± 0,21 y 3,25 ± 0,1 %), y solidos no grasos (8,5 ± 1,24 y 8,98 ± 0,28 %); en cuanto a los ácidos grasos detectados las diferencias fueron no significativas (P<0.05). Se presentaron diferencias entre ambas dietas en algunos parámetros, esta diferencia podría deberse al contenido de lípidos de la Dieta 1.