Influence of Feeding Enzymatically Hydrolyzed Yeast Cell Wall on Growth Performance and Digestive Function of Feedlot Cattle during Periods of Elevated Ambient Temperature.

In experiment 1, eighty crossbred steers (239±15 kg) were used in a 229-d experiment to evaluate the effects of increasing levels of enzymatically hydrolyzed yeast (EHY) cell wall in diets on growth performance feedlot cattle during periods of elevated ambient temperature. Treatments consisted of steam-flaked corn-based diets supplemented to provide 0, 1, 2, or 3 g EHY/hd/d. There were no effects on growth performance during the initial 139-d period. However, from d 139 to harvest, when 24-h temperature humidity index averaged 80, EHY increased dry matter intake (DMI) (linear effect, p<0.01) and average daily gain (ADG) (linear effect, p = 0.01). There were no treatment effects (p>0.10) on carcass characteristics. In experiment 2, four Holstein steers (292±5 kg) with cannulas in the rumen and proximal duodenum were used in a 4×4 Latin Square design experiment to evaluate treatments effects on characteristics of ruminal and total tract digestion in steers. There were no treatment effects (p>0.10) on ruminal pH, total volatile fatty acid, molar proportions of acetate, butyrate, or estimated methane production. Supplemental EHY decreased ruminal molar proportion of acetate (p = 0.08), increased molar proportion of propionate (p = 0.09), and decreased acetate:propionate molar ratio (p = 0.07) and estimated ruminal methane production (p = 0.09). It is concluded that supplemental EHY may enhance DMI and ADG of feedlot steers during periods of high ambient temperature. Supplemental EHY may also enhance ruminal fiber digestion and decrease ruminal acetate:propionate molar ratios in feedlot steers fed steam-flaked corn-based finishing diets

Evaluación preliminar de patrones fisiológicos de semillas de seis especies frutales promisorias del piedemonte amazónico

Entre febrero y octubre de 2004 se evaluaron los patrones germinativos de seis especies frutales promisorias amazónicas bajo las condiciones de Florencia (Caquetá): Pouroma cecropiifolia (uva caimarona), Annona muricata (guanábana amazónica), Annona sp. (guanábana cimarrona), Pouteria caimito (caimo), Solanum sessiliflorum (cocona) y Eugenia stipitata (arazá). Los aspectos fundamentales abordados durante este estudio fueron: las respuestas de las semillas a diversas condiciones de luz y de escarificación, hábitos de imbibición y longevidad de las semillas. Se encontró que la exposición de semillas a diferentes componentes de luz, como el rojo corto, el azul y el rojo lejano, influenció la velocidad y los porcentajes de geminación de varias especies; sin embargo, las condiciones normales de luz (foto período normal) ofrecen condiciones óptimas de germinación en la mayoría de los casos. La uva caimarona y el caimo mejoraron los porcentajes de germinación tras un proceso de escarificación química, y la semilla de arazá presenta fuertes daños por exposición al brillo solar directo, desarrollando además latencia cuando es sometida a la oscuridad. Si bien el presente estudio tuvo una orientación descriptiva, los resultados tienen el peso suficiente para hacer un acercamiento a la fisiología y ecología de las especies amazónicas

Calorimetric and acoustic study of binary mixtures containing an isomeric chlorobutane and butyl ethyl ether or methyl tert-butyl ether

Densities and speeds of sound in the temperature range 283.15-313.15 K have been measured for the binary mixtures formed by an isomeric chlorobutane (1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, or 2-chloro-2-methylpropane) and butyl ethyl ether or methyl tert-butyl ether. Excess isentropic compressibilities were calculated from the experimental data. Excess enthalpies at T = 298.15 K are also included for the same binary mixtures. All these properties provide an insight into the nature of interactions operating on the present systems. Finally, the Prigogine-Flory-Patterson theory has been used to analyze the H E results and to estimate the isentropic compressibility values of the mixtures at T = 298.15 K