Fecal N excretion as an approach to estimate forage intake by sheep and cattle.

This study was carried out to evaluate the reliability of using faecal N as a predictor of organic matter (OM) intake by sheep and cattle fed a natural pasture hay

Production Per Animal and Use of Intake Estimatives to Predicted Animal Productivity in \u3cem\u3ePennisetum Purpureum\u3c/em\u3e cv. Mott and \u3cem\u3eCynodon\u3c/em\u3e spp cv. Tifton 85 Pastures

Dairy production is a very important activity in southern Brazil, being an essential source of income to small household farms. Milk production from pastures is an alternative to reduce costs in dairy systems. Some C4 grasses, such as dwarf elephant grass (DEG) and Tifton 85, have presented high animal production per animal and per area. Although studies evaluating milk production from these pastures are rare in south Brazil, in vitro studies have demonstrated that the nutritional value of these forages is higher than production registered in grazing. So, it is possible that, in spite of a high intrinsic nutritional value, limitation on cows’ productivity is linked to the food’s capacity of conversion to milk and/or management conditions that limit forage intake. Leaf mass in pastures is a factor that determinates forage intake, as cows prefer leaf to other parts of plants. In this context, adequate animal performance may be possible if offered enough leaf biomass at pasture. The aim of this experiment was to evaluate the potential of milk production with these two forage species

Membrane Potential-Dependent Modulation of Recurrent Inhibition in Rat Neocortex

Dynamic balance of excitation and inhibition is crucial for network stability and cortical processing, but it is unclear how this balance is achieved at different membrane potentials (Vm) of cortical neurons, as found during persistent activity or slow Vm oscillation. Here we report that a Vm-dependent modulation of recurrent inhibition between pyramidal cells (PCs) contributes to the excitation-inhibition balance. Whole-cell recording from paired layer-5 PCs in rat somatosensory cortical slices revealed that both the slow and the fast disynaptic IPSPs, presumably mediated by low-threshold spiking and fast spiking interneurons, respectively, were modulated by changes in presynaptic Vm. Somatic depolarization (>5 mV) of the presynaptic PC substantially increased the amplitude and shortened the onset latency of the slow disynaptic IPSPs in neighboring PCs, leading to a narrowed time window for EPSP integration. A similar increase in the amplitude of the fast disynaptic IPSPs in response to presynaptic depolarization was also observed. Further paired recording from PCs and interneurons revealed that PC depolarization increases EPSP amplitude and thus elevates interneuronal firing and inhibition of neighboring PCs, a reflection of the analog mode of excitatory synaptic transmission between PCs and interneurons. Together, these results revealed an immediate Vm-dependent modulation of cortical inhibition, a key strategy through which the cortex dynamically maintains the balance of excitation and inhibition at different states of cortical activity

Avanços metodológicos na determinação do consumo de ruminantes em pastejo.

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