ABSTRACT.- Background: Likelihood-based inferences such as variance components estimation and hypothesis testing need logarithms of the determinant (log-determinant) of high dimensional matrices. Calculating the log-determinant is memory and time-consuming, making it impossible to perform likelihood-based inferences for large datasets. Conclusions: The method presented in this study allows to approximate the log-determinant of positive semi-definite matrices and, therefore, the likelihood for datasets of any size.

ABSTRACT.- Pregnancy rates following embryo transfer (ET) in cattle may be influenced by transient inflammatory responses triggered during the procedure. The objective of this study was to evaluate the effect of tolfenamic acid (TA), a nonsteroidal anti-inflammatory drug (NSAID), on pregnancy rates in embryo-recipient females. A total of 1431 recipients (367 heifers and 1064 cows) were enrolled in 34 ET programs conducted on 24 commercial farms in Uruguay, using either in vivo-derived or in vitro-produced embryos, fresh or frozen.

ABSTRACT.- Fusarium graminearum sensu stricto (F. graminearum s.s) and Fusarium proliferatum are species frequently isolated from sorghum grains. However, ecophysiology studies of these Fusarium species have not been carried out on sorghum grains. For this reason, the aim of this work was to evaluate the effects of different water activity levels (0.95, 0.98, 0.995) and temperatures (15 ◦C, 25 ◦C, 30 ◦C) on the mycelial growth and mycotoxin production of these species on a sorghum grain substrate.

ABSTRACT.- A simple and fast analytical method was developed and applied to assess the effect of two forms of zinc fertilization on a pecan tree cultivar in Uruguay: fertigation and foliar application with a specially formulated fertilizer. Zinc content was determined in 36 leaf samples from two crop cycles: 2020-2021 and 2021-2022. Fresh samples were dried, ground, and sieved. Analytical determinations were performed by flame atomic absorption spectrometry (FAAS, considered a standard method) and energy dispersive X-ray spectrometry (EDXRF, the proposed method). © 2025 by the authors.

ABSTRACT.- Livestock production, in particular sheep farming, faces the challenge of increasing food production in the context of limited resources, with less access to arable land and sup-plements. In addition, explained by variability and climate change, access to high-quality and quantity pastures and water would be soon restricted. Furthermore, sheep will be more frequently and for longer periods exposed to higher temperatures, to changes in the rainfall pattern and to a scenario of pests and diseases different from the current one.

ABSTRACT.- Genetic selection is an effective tool to improve sustainability of livestock production and contribute to greenhouse gases mitigation, particularly of enteric methane (CH4) emissions, in accordance with international agreements. Feed efficiency (FE) and CH4 emissions have been postulated as potential selection objectives to achieve mitigation goals and support sustainability. Uruguay has had genetic evaluation systems for three decades and new intensive phenotyping platforms are in place for measuring FE and CH4 in beef cattle and sheep.

ABSTRACT.- Uruguay's livestock methane is a mayor source of greenhouse gas (GHG) emissions, despite the country's low overall emissions. A case study was conducted on Forestal Caja Bancaria (FCB), a commercial farm in Uruguay's central region, with an integrated production system covering 5,802 hectares. The study aimed to estimate GHG emissions from livestock, crops and forestry, CO2 captured by eucalypt and pine plantations, and soil organic carbon for all land uses. -------------------------

While agriculture is crucial to feeding people, it is strongly impacted by climate change and variability, and also contributes to it. Agriculture and land use change are responsible for around ¼ of greenhouse gas emissions from human activities(1). Climate change already impacts the quantity, quality and geographic distribution of food production from agriculture. In this special issue, entitled "Climate change and variability impacts on agriculture", the selected articles address different issues.

ABSTRACT.- Leaf rust (LR) of bread wheat (Triticum aestivumL.), caused by the fungus Puccinia triticina Eriks, is one of the most important diseases in Paraguay, the Southern Cone of America and worldwide. The economic importance of the disease is clear considering that two or more fungicide applications are necessary to control the disease in susceptible cultivars. The best strategy for the management of this disease is through genetic resistance.

ABSTRACT. - Zygote microinjection is considered the most suitable technique to introduce CRISPR/Cas9 reagents for efficient genome editing in livestock. In this study, zygote electroporation was evaluated as an alternative to microinjection for CRISPR/Cas9-mediated genome editing in sheep. Four experiments were conducted on 3548 cumulusoocyte complexes. Acid Tyrode's solution (AT) was used to partially degrade the zona pellucida (ZP) to improve reagent entry, resulting in ZP thinning with longer AT exposure (P < 0.05).