ABSTRACT. - The objective was to evaluate the ingestive behavior of Angus yearling steers grazing natural grasslands of Southern Brazil, submitted or not to the application of fertilizers:NG= natural grassland; FNG= fertilized natural grassland, and FONG= fertilized natural grassland improved with the over sown of temperate forage species. Three Angus yearling steers and a variable number of put-and-take animals were used per experimental unit, to maintain a forage allowance of 13 kg of dry matter/100 kg of body weight.

ABSTRACT:Early detection of fetal distress at lambing is essential to reduce mortality. Practicality and accuracy of pulse oximetry to assess oxygenation status in newborn lambs under field conditions was evaluated. Oximetry was compared with blood gas analyses and included assessment of vitality (Apgar test) and vigour (attempt to and successful standing and suckling) of 135 Finnish by Polwarth lambs.

Resumen: Las deficiencias minerales son un problema de gran impacto productivo a nivel mundial. En el Noroeste argentino la cría extensiva es una de las actividades económicas más importantes y está en franco crecimiento. En esta región los estudios sobre enfermedades carenciales son escasos y parciales. El presente trabajo tiene por objeto describir variaciones estacionales de los niveles séricos de calcio, fósforo, magnesio, cobre y zinc en vacas de cría y sus terneras.

Abstract: Predicting how plants allocate to different anti-herbivore defences in response to elevated carbon dioxide (CO2) concentrations is important for understanding future patterns of crop susceptibility to herbivory. Theories of defence allocation, especially in the context of environmental change, largely overlook the role of silicon (Si), despite it being the major anti-herbivore defence in the Poaceae.

ABSTRACT. - Drought limits crop productivity and reduces yield stability. Drought tolerance as a selection criterion in breeding programs requires the development of high-throughput, precise, and low-cost phenotyping strategies. We developed a mathematical model, based on biological approaches, for evaluating soybean plants? response to drought under controlled growth conditions. The model describes the kinetics of water consumption of a plant pot substrate system (PPS) with low sampling requirements.

ABSTRACT:In semiarid agricultural systems, irrigation may increase soil organic matter (SOM) due to higher biomass production. However, aboveground production tends to increase more than belowground biomass, and in no-till systems SOM responses to irrigation would strongly depend on the fate of crop residues left on the soil surface. Litter decomposition and SOM formation can also be affected by irrigation due to changes in water dynamics, but little is known about the impacts of irrigation on the pathways of SOM formation.

ABSTRACT.- In the Great Plains of central North America, sustainable livestock production is dependent on matching the timing of forage availability and quality with animal intake demands. Advances in remote sensing technology provide accurate information for forage quantity. However, similar efforts for forage quality are lacking. Crude protein (CP) content is one of the most relevant forage quality determinants of individual animal intake, especially below an 8% threshold for growing animals.