RESUMEN. Los resultados de las primeras evaluaciones del Proyecto Ovejas Prolíficas de INIA (2008-2011) muestran que la cruza Frisona Milchschaf x Corriedale o Finnish Landrace x Corriedale desteta 60 % más corderos que la Corriedale pura y, por otro lado, la cruza Finnish Landrace x Frisona Milchschaf desteta 85 % más que la Corriedale pura. Sin embargo y bajo las mismas condiciones productivas, no se conoce el comportamiento al parto y la producción de calostro de estos nuevos biotipos.

Potential consequences of climate change on crop production can be studied using mechanistic crop simulation models. While a broad variety of maize simulation models exist, it is not known whether different models diverge on grain yield responses to changes in climatic factors, or whether they agree in their general trends related to phenology, growth, and yield.

The productivity and profitability of the use of maize silage (MS) within pasture-based beef production systems was evaluated using the Farmax Pro® model. Farm systems were simulated based on an intensive oneyear-old steer production system with two pasture growth patterns (Waikato and Hawkes Bay), three different proportions of the farm in MS production (0%, 5% or 10%) and MS fed either during winter (W) or summer (S). MS cost 13.5 and 16.1 c/kg dry matter (DM) for Waikato and Hawkes Bay respectively. This price included the cost of growing, harvesting, ensiling and feeding.

In native campos of Uruguay, overseeding legumes coupled with phosphorus (P) fertilization is a technology used to increase animal production. Short-termimprovements in both forage productivity and quality are repeatedly reported. However, some evidence suggests that this management may at times lead to the collapse of the native community and invasions by exotic species. Indeed, it is yet unclear to what extent overseeding legumes into native grasslands affects its long-term integrity.

In native campos of Uruguay, overseeding legumes coupled with phosphorus (P) fertilization is a technology used to increase animal production. Short-termimprovements in both forage productivity and quality are repeatedly reported. However, some evidence suggests that this management may at times lead to the collapse of the native community and invasions by exotic species. Indeed, it is yet unclear to what extent overseeding legumes into native grasslands affects its long-term integrity.

Water management impacts both methane (CH4) and nitrous oxide (N2O) emissions from rice paddy fields. Although controlled irrigation is one of the most important tools for reducing CH4emission in rice production systems it can also increase N2O emissions and reduce crop yields.

RESUMEN. En Sudamérica ocurrieron, en las últimas décadas, grandes transformaciones del paisaje. Como consecuencias de mejoras tecnológicas, nuevas condiciones en el mercado y precios internacionales, tanto pastizales como bosques o arbustales fueron transformados, principalmente para la producción de soja con fines de exportación.