The aim was to conduct a weighted single‐step genome‐wide association study to detect genomic regions and putative candidate genes related to residual feed intake, dry matter intake, feed efficiency (FE), feed conversion ratio, residual body weight gain, residual intake and weight gain in Nellore cattle. Several protein‐coding genes were identified within the genomic regions that explain more than 0.5% of the additive genetic variance for these traits. These genes were associated with insulin, leptin, glucose, protein and lipid metabolisms; energy balance; heat and oxidative stress; bile secretion; satiety; feed behaviour; salivation; digestion; and nutrient absorption. Enrichment analysis revealed functional pathways (p‐value < .05) such as neuropeptide signalling (GO:0007218), negative regulation of canonical Wingless/Int‐1 (Wnt) signalling (GO:0090090), bitter taste receptor activity (GO:0033038), neuropeptide hormone activity (GO:0005184), bile secretion (bta04976), taste transduction (bta0742) and glucagon signalling pathway (bta04922). The identification of these genes, pathways and their respective functions should contribute to a better understanding of the genetic and physiological mechanisms regulating Nellore FE‐related traits.
Resumen El bovino de raza local brasileiro Curraleiro se encuentra en situación de riesgo. Esto ha motivado a un grupo de investigadores a desarrollar acciones relacionadas con la conservación y utilización de estos animales. Son descendientes de bovinos traídos por los colonos ibéricos, que se han adaptado a los pastos de baja calidad, altas temperaturas, clima seco y otros factores adversos que son característicos en el interior de Brasil. Se realizó un censo poblacional con el objetivo de identificar las características de los criadores de bovinos Curraleiro, en los estados de Goiás y Tocantins: fueron entrevistados 28 ganaderos que respondieron a un cuestionario semiestructurado, con información sobre el ganado, las propiedades y los animales. Se estableció el tipo de sistema productivo utilizado y el nivel de tecnología aplicada en las ganaderías. Fueron localizadas 49 ganaderías en los estados de Goiás, Tocantins, Bahía, Pará y Piauí con un número de 3.692 animales. El sistema de producción de las ganaderías de Curraleiro es extensivo, con un nivel medio de tecnología, bajos costos de producción y poco beneficio económico. El riesgo de la endogamia es evidente pero hay un gran interés de los ganaderos en conservar la raza. El censo nacional es bajo y la raza debe ser considerada vulnerable con riesgo de extinción.
Brazil has the second largest commercial beef cattle herd in the world, occupying a prominent position in the global beef market. Zebu cattle (Bos indicus) comprise more than 80% of the beef cattle in Brazil, and the vast majority of these animals are from Nellore breed, given their tolerance to tropical climate and high resistance to ectoparasites (Baldi et al., 2012). Despite their advantages for production in tropical environments, Zebu cattle tend to produce tougher meat than Bos taurus breeds (Reverter et al., 2003;Thrift & Thrift, 2002). Brazilian beef quality tends to be highly variable, due to a broad diversity of production environments and management systems, and to a large proportion of Zebu animals in
-This study was undertaken to verify major issues present in the discourse of cattle farmers when discussing the use of artificial insemination (AI). Seventy-one beef and dairy cattle farmers in the state of Goiás, Brazil, were interviewed using semi-structured questionnaires during AI training courses in 2010 and 2011. Data analyses were done using the classic method of textual speech content analysis, performing the pre-analytical, analytical and inferential stages. The written questions were separated in elementary context units (ECU) and sorted into similar thematic groups. These groups originated categories and subcategories, which were nominated based on an a posteriori criteria. Overall, personal motivation was the main issue characterizing discourse by farmers about adoption of AI. This motivation stems from the strong points (highlights) and positive expectations AI offers. The positive expectations were mainly related to perceptions of farmers of animal phenotype improvement rather than to the financial features of cattle production. Basic necessity was the second major issue, with emphasis on work force, infrastructure and animal handling, followed by social influence, with eminence of the institutions and people involved with AI and with the everyday life of cattle farmers. The little emphasis on human resource management and on the use of scientific knowledge may have affected the impact of AI over the years, explaining discreet indices of adoption of AI in Brazil.
Context Livestock feed costs have a higher impact on the profitability of beef production systems and are directly related to feed efficiency. However, these traits are hard and have high costs to measure, reducing the availability of phenotypic records and reliability of genetic evaluations. Thus, the use of genomic information can increase the robustness of genetic studies that address them. Aims The aim of the present study was to estimate genetic parameters for feed efficiency, growth, reproductive and carcass traits in Nelore cattle and the correlated response among them, using genomic information. Methods Residual feed intake (RFI), dry-matter intake, feed conversion ratio, feed efficiency (FE), residual average daily gain (RG), residual feed intake and average daily gain (RIG), birthweight, weight at 120, 240, 365 and 450 days of age, scrotal circumference at 365 and 450 days of age, rib-eye area, backfat thickness and rump fat thickness were evaluated. The genetic parameters were estimated using the single-step genomic best linear unbiased prediction approach. Key results The FE-related traits showed low to moderate heritability ranging from 0.07 to 0.23. Feed efficiency-related traits showed low genetic correlations with reproductive (–0.24 to 0.27), carcass (–0.17 to 0.27) and growth (–0.19 to 0.24) traits, except for growth with dry-matter intake (0.32–0.56) and weight at 365 days of age with FE (–0.40). Conclusions The selection to improve growth, reproductive and carcass traits would not change RFI, RG and RIG. The choice of the most adequate selection criterion depends on the production system, that is, RFI might be used for low-input beef cattle systems, and RIG would be used for more intensive and without-any-dietary-restrictions beef cattle systems. Implications The estimates of heritability and genetic correlations suggest that genetic selection for feed efficiency using RFI, RG and RIG in Nellore cattle leads to higher genetic gain than does that using FE and feed conversion ratio without affecting other profitability traits.
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