The objective of this experiment was to study the effect of substitution of corn by beet pulp on energy partitioning, substrate oxidation, nitrogen and carbon balance and milk performance in dairy goats during late lactation. Twelve multiparous lactating Murciano-Granadina goats were fed two diets. Six goats were fed a mixed ration with 310 g/kg DM of ground corn (diet CORN) and in the other diet the corn was substituted with 302 g/kg DM of beet pulp (diet BP) in a cross-over design. No significant differences between diets were observed for milk production (1.36 kg/day, on average) and differences were found for milk fat (5.39 and 4.21% for BP and CORN, respectively). The metabolisable energy intake was higher (P < 0.05) in the CORN diet than BP (1320 vs 1044 kJ/kg0.75 BW, respectively). The difference in methane emissions between treatments was significant (P < 0.05) with values of 92 vs 61 kJ/kg0.75 BW for BP and CORN, respectively, indicating that greater levels of starch in diet reduce methane production. Replacing corn with BP reduced significantly the energy body fat deposition (300 vs 44 kJ/kg0.75 BW for CORN and BP diets, respectively). This reduction in energy retention for the BP diet did not compromise milk yield and milk energy output.

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 <1% DM in PR, AP, and TN. In situ digestibility was ≤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. 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.

El objetivo de este experimento fue valorar el coeficientes de digestibilidad in vitro y la composición química de residuos post selección y hojas secas para extracción de steviósidos de Stevia rebaudiana Bertoni (Ka´á He´é). Para la digestibilidad in vitro fueron utilizadas dos ovejas mestizas canuladas en el rumen, que tuvieron un periodo de adaptación a la dieta de 12 días previo a la extracción de líquido ruminal, las muestras para composición química fueron recogidas de una industria extractora de steviósidos. Los análisis bromatológicos y digestibilidad in vitro se realizaron siguiendo los métodos de la AOAC (2000) y Tilley y Terry (1963) respectivamente. Los resultados obtenidos en cuanto a la composición química en base parcialmente seca para Materia Seca a 105°C (MS) de Residuos 89,99 y 91,71%; para hojas y en base seca para Proteína Bruta (PB): 15,49 y 15,47%; FND 29,96 y 24,63%; Extracto Etéreo (EE) 10,15 y 6,39%, Energía Bruta (EB) 4,3 y 4,1 Mcal/kg para residuos post selección y hojas, respectivamente. En cuanto a los coeficientes de digestibilidad in vitro de la Materia Seca (%DMSIV) y de la Materia Orgánica (%DMOIV) fueron de 51,22 y 53,34% y 52 y 54,57% para residuos post selección y hojas respectivamente.

The effect of Guarania genre music on productive performance and animal well- being (milk production and serum cortisol) was evaluated. In total, 17 animals of various breeds and in different stages of lactation were used, with a crossover design, where each animal received both treatments in each period (inclusion and non-inclusion of music in the milking process). Each period was two weeks. Daily controls of milk production were carried out (two milkings per day) and blood samples were obtained weekly to determine serum cortisol concentrations. The average milk production of the group of cows without music application was 19.7 L/day and in the group of cows with music application it was 20.4 L (p=0.008). 96% of cortisol concentrations had a level less than 1 µg/dl, considered within the reference range, and without significant difference between treatments.

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.