ABSTRACT.- The aim of this study was to evaluate the effect of different factors on maternal protective behavior (MPB) of Nellore cows. A total of 3629 cows were evaluated around 24 h after calving, while their newborns were handled for navel care, ear tattoo and weighing. MPB was assessed by observing each cow reactions when its calf was caught in a corral pen. MPB score consisted of 5 levels, going from 1 (the cow paid no attention to the calf and remained indifferent to the procedure) to 5 (the cow showed aggressive behaviors toward the handler, trying to attack).

Red-banded stink bug Piezodorus guildinii (P. guildinii) has been described as the most damaging stink bug regarding soybean crops, leading to seed injury, low germination percentages and foliar retention, even at low population densities. In this work the first P. guildinii transcriptome from a pool of all developmental stages was assembled, annotated and RNAi components were analyzed.

This study provides insights into N losses in hybrid dairy systems, emphasizing the importance of tailored strategies to minimize environmental impacts, considering the diverse spatiotemporal responses across different farmland uses and covers.

ABSTRACT.- Random regression models (RRM) with ssGBLUP are used worldwide for dairy cattle genetic evaluations. This study aimed to improve the efficiency of implementing RRM with ssGBLUP for national dairy evaluations using the BLUPF90 software suite and to test a method to approximate reliabilities with genomic information.

ABSTRACT.- With the algorithm for proven and young (APY), the computing cost of ssGBLUP is linear with the number of noncore animals and cubic with the number of core, which is less than 20K for single breed and 50k for multibreed evaluations.

ABSTRACT.- Knowledge of the factors that influence the composition of grass is essential for its proper management in pasture-based dairy systems, thus increasing its productivity. An experiment was carried out to study the evolution of chemical composition and nutritional value of a regrowth of tall fescue as affected by the defoliation regimen around flowering time.

ABSTRACT.- Ramularia collo-cygni (Rcc) is the causal agent of Ramularia leaf spot (RLS). The main management tool is the use of foliar fungicides, the impact of which on cereal safety is unknown. Therefore, the aim of this thesis was to optimise the management of ramulariosis in barley and to minimise fungicide residues in grain. -- RESUMEN.- Ramularia collo-cygni (Rcc) es el agente causal de ramulariosis. La principal medida para su manejo es la utilización de fungicidas foliares cuyo impacto en la inocuidad del grano es desconocido.

ABSTRACT.- In the natural grasslands of the Río de la Plata, where livestock production can coexist with biodiversity, effective pasture management practices play a critical role. This study combines two approaches to shed light on the relationship between livestock management and bird species. ------- RESUMEN.- En los pastizales naturales del Río de la Plata, donde la producción ganadera puede coexistir con la biodiversidad, las prácticas efectivas de manejo de pastizales desempeñan un papel crítico.