La yerba carnicera o conyza (Conyza sumatrensis) es una maleza de elevada capacidad adaptativa a los sistemas productivos uruguayos, en especial por presentar fallas de control después de la aplicación de los herbicidas glifosato e inhibidores de la acetolactato sintasa (I-ALS). El objetivo del trabajo fue confirmar la presencia y nivel de resistencia de C. sumatrensis a glifosato (GLI), diclosulam (DIC) y clorimuron (CLO), a partir de ensayos de curvas de dosis respuesta e investigar la ocurrencia de mutaciones en el gen ALS como mecanismo de resistencia asociado a los I-ALS.

ABSTRACT.- A comprehensive understanding of how native grasslands (rangelands) respond to chronic nutrient addition requires considering interactions with climate variability, water availability in particular, and with stocking rate management. We assessed animal production responses to phosphorus plus nitrogen fertilization sustained over a decade on a highly diverse subtropical grassland.
©2024 The Society for Range Management. Published by Elsevier Inc.

ABSTRACT.- Random-regression models (RRM) are used for dairy cattle genetic evaluations in many countries. The output of a genetic evaluation with RRM is an estimated breeding value (EBV) for a specific function of the additive genetic random regression coefficients, say, 305-d milk yield and its corresponding reliability. The reliability of an EBV in RRM is calculated from the inverse of the coefficient matrix of mixed model equations (MME). The objective of this study was to develop an efficient method to approximate reliabilities for RRM with ssGBLUP.

ABSTRACT.- Determining the optimal defoliation frequency is essential to increase the productivity of pasture-based dairy systems. An experiment was carried out to study the effect of the defoliation regimen around flowering time on the evolution of chemical composition and nutritional value of orchardgrass. The experiment was conducted on a 4-year-old orchardgrass (Dactylis glomerata cv 'INIA Perseo') pasture at the experimental station "La Estanzuela" (INIA, Uruguay).

ABSTRACT.- In the context of ever-growing demand for food and associated concerns regarding the environmental impacts of high-input agricultural systems, there is growing interest in mixed farm enterprises to deliver greater sustainability compared with mono-enterprise production systems. However, assessments of such systems are complex and require high-resolution data to determine the true value and interconnectivity across enterprises.

ABSTRACT.- Alligator weed, Alternanthera philoxeroides (Mart.) Griseb. (Amaranthaceae) is an aggressive invader in waterways and pastures throughout most of the southeastern U.S.A., and California. Three insect biological control agents have provided substantial control of aquatic A. philoxeroides in the warmer parts of its range in the U.S.A. However, these insects are less effective against A. philoxeroides in riparian-terrestrial habitats.

ABSTRACT.- Efficient pasture-based animal production systems require optimisation of forage production with the highest nutritive value. Increasing the defoliation regimen of pastures allows to improve the nutritive value of forage for ruminants but it can be detrimental for total biomass production. An experiment was carried out to study the effect of the defoliation regimen around flowering time on productivity, chemical composition and nutritional value of tall fescue.

ABSTRACT.- The aim of this study was to evaluate two levels of forage allowance (FA) during the prepartum period on metabolic, hormonal, productive, and reproductive variables in primiparous (P) and multiparous (M) beef cows. Six weeks before calving, 40 P and 42 M cows were assigned to two FA (native pastures) treatments until calving (day 0):High (15 kg DM/100 BW; H) and Low (5 kg DM/100 BW; L). After calving all cows were managed together. High FA cows presented greater intake than L cows, while M tended to have greater intake than P cows.