Modeling the dynamics of herbage production and intake in complex grasslands

Studies in grassland management and ecology have always been challenging because of the large amount and great variation of the entities representing and affecting the system. Despite that, we were able to progress significantly in range experimentation in the Campos, in Southern Brazil. Along past thirty years, a large amount of data and information was generated, from vegetation production to components of intake. In an attempt to integrate the information available, seeking for a deeper understanding of the functioning of native grasslands, we propose adapting a mechanistic vegetation model, aggregated of a spatialized grazing component to create PampaGraze. This model was developed for temperate perennial grasslands, and was adapted and tested for subtropical, C4-dominated grasslands of the Campos of Southern Brazil (Chapter III). Despite the limited capacity of field data for validating, the model was able to relatively well simulate the trends in vegetation production along the year and seasons, while overpredicting herbage production during peak growing season. The structure of the model as it is did not allow for an accurate simulation slow-growing, tussock-forming species. Further, we developed and integrated a grazing model, based on a hybrid approach of the classical mechanistic equations of the prey model (STEPHENS & KREBS, 1986), and experimental data on foraging behaviour measured on native grasslands (Chapter IV). The model was very successful on predicting the components of intake, and responded well to variation of components in relation to changes in vegetation and to selectivity pressures, compared to available literature. Regardless of the limitations on the vegetation model, we were able to further explore the relationships of components of intake, identifying possible major limitations for herbage consumption, thus animal performance, in native grasslands. A significant progress was achieved with this thesis, but still long ways to go with this project. A list of suggestions for further developments can be found in Chapter V. We identified the emergent needs for field studies on parameters and morphogenesis, for improving predictions of the vegetation model, as well as structural points of the model that could be addressed for better representation of natural phenomena. This thesis is the first step towards a more detailed and reliable tool for studying and predicting the behaviour of vegetation dynamics and animal production in sub-tropical grasslands. This can allow us to explore relationships and scenarios beyond our experimental capacity, and investigate the connectivity of the system, as well as each mechanism separately. The stage has been set, awaiting further developments

Natural genetic diversity of nutritive value traits in the genus Cynodon

The Cynodon spp. collection maintained by United States Department of Agriculture National Plant Germplasm System (USDA-NPGS) has limited information on nutritive value (NV) traits. In this study, crude protein (CP), phosphorous concentration (P), in vitro digestible organic matter (IVDOM), and neutral detergent fiber (NDF) were determined to (i) estimate genetic parameters for NV, (ii) obtain genetic values for the whole population across two harvests, (iii) estimate genotype by harvest interaction (GHI) for NV traits, and (iv) select accessions exhibiting improved NV traits compared to ‘Tifton 850 . The experiment was setup as a row-column design with two replicates and augmented representation of controls: Tifton 85, ‘Jiggs’, and ‘Coastal’. The whole-population was harvested twice, and data were analyzed using linear mixed models with repeated measures. In addition, a selected population of 15 genotypes were evaluated across 11 harvests to determine the extent of GHI. Genetic parameters revealed the presence of significant genetic variability, indicating potential improvements for NV through breeding. Specifically, P and IVDOM presented large variation, while NDF had lower diversity but some accessions exhibited lower NDF than Tifton 85. Low GHI, except for IVDOM, indicated genotypic stability and potential for selecting improved accessions under fewer harvests. Breeding line 240, PI-316510, and PI-3166536 presented superior NV than Tifton 85

Observations on Feral Hog Ecology in South and Southeast Brazil (Abstract)

Feral hog population has been increasing significantly in the past few years in Brazil. Rio Grande do Sul state has the largest sheep herd in Brazil and predation reports had grown exponentially lately. In Santana do Livramento County, 20,000 lambs were reported predated by feral hogs in 2013, resulting on approximately US$700,000 direct losses. Rising domestic pigs free-ranging is still a common practice, which increases the opportunity for breeding and hybridizing with the feral population, resulting in better environmental adaptation and reproductive ability of the offspring. American literature suggests that females can produce 1.6 litters per year with an average of 5.7 piglets per litter. However, reports from feral hog controllers in Santana do Livramento, in the Campos grasslands with short riparian forest, suggest a higher reproduction rate, where pregnant females carry from 3 to 14 fetus, averaging 7.5 piglets per litter (n = 61). According to simulation from data collected in Southern Brazil, feral hog populations could be increasing at a rate of 36% higher than what thought before. Survival rates also seem to be high, with repots of up to 12 piglets per litter at weaning age. This could be attributed to favorable climatic conditions and resources abundance (i.e. water and feed). Data from camera-traps in Itamonte County, Minas Gerais State, identified females farrowing once per year with an average of 2.3±1.6 piglets (n = 55) in continuous fragments of Brazilian Atlantic Forest. The Araucaria angustifolia seeds and local small crops are known to be important resources for feral hog population. Those are preliminary data of investigation being done in Brazil, and several more questions need to be assessed. An estimation of economic losses and potential of population expansion need to be done in both south and southeast of Brazil, where the feral hog invasion are concentrated. Those are key information for warning competent attorneys to the problem and to start a broader and more effective control planning

Observations on Feral Hog Ecology in South and Southeast Brazil (Abstract)

Feral hog population has been increasing significantly in the past few years in Brazil. Rio Grande do Sul state has the largest sheep herd in Brazil and predation reports had grown exponentially lately. In Santana do Livramento County, 20,000 lambs were reported predated by feral hogs in 2013, resulting on approximately US$700,000 direct losses. Rising domestic pigs free-ranging is still a common practice, which increases the opportunity for breeding and hybridizing with the feral population, resulting in better environmental adaptation and reproductive ability of the offspring. American literature suggests that females can produce 1.6 litters per year with an average of 5.7 piglets per litter. However, reports from feral hog controllers in Santana do Livramento, in the Campos grasslands with short riparian forest, suggest a higher reproduction rate, where pregnant females carry from 3 to 14 fetus, averaging 7.5 piglets per litter (n = 61). According to simulation from data collected in Southern Brazil, feral hog populations could be increasing at a rate of 36% higher than what thought before. Survival rates also seem to be high, with repots of up to 12 piglets per litter at weaning age. This could be attributed to favorable climatic conditions and resources abundance (i.e. water and feed). Data from camera-traps in Itamonte County, Minas Gerais State, identified females farrowing once per year with an average of 2.3±1.6 piglets (n = 55) in continuous fragments of Brazilian Atlantic Forest. The Araucaria angustifolia seeds and local small crops are known to be important resources for feral hog population. Those are preliminary data of investigation being done in Brazil, and several more questions need to be assessed. An estimation of economic losses and potential of population expansion need to be done in both south and southeast of Brazil, where the feral hog invasion are concentrated. Those are key information for warning competent attorneys to the problem and to start a broader and more effective control planning

Field selection of native rhizobio for bird’s-foot trefoil

O cornichão (Lotus corniculatus L.) tem sido apontado como uma das forrageiras mais promissoras para o uso no Rio Grande do Sul. No entanto, pouco se conhece a respeito da interação dessas plantas com os rizóbios nativos em condições de campo. Este estudo visou a avaliar a eficiência das interações entre rizóbios e plantas de Lotus corniculatus cv. ‘São Gabriel’ em condições de campo. O experimento foi conduzido na Estação Experimental Agronômica da UFRGS com delineamento de blocos ao acaso com quatro repetições. Os tratamentos estudados foram: dois controles sem inoculação (um com a adição de 80kg ha-1 de nitrogênio na forma de uréia e outro sem a adição de nitrogênio); inoculação com rizóbios: estirpes SEMIA 816, recomendada no Brasil, U510, recomendada no Uruguai, U512, em estudo no Uruguai, e quatro isolados de rizóbios nativos (UFRGS Lc322, UFRGS Lc349, UFRGS Lc269 e Iso 7). O isolado UFRGS Lc322 e a estirpe U510 são mais eficientes do que a estirpe SEMIA 816, recomendada para cornichão no país. Além disso, a produção de forragem das plantas inoculadas com o isolado UFRGS Lc322 e a estirpe U510 superou a obtida com a adição de 80kg ha-1 de nitrogênio.The bird’s-foot trefoil (Lotus corniculatus L.) has been pointed as one of the most promising forage plants for use in Rio Grande do Sul. However, there is lack of information about the interaction of those plants with the native rhizobia in field conditions. This study aimed to evaluate the efficiency of interactions between rhizobia and plants of Lotus corniculatus cv. ‘São Gabriel’ in field conditions. The experiment was carried out in the Agronomic Experimental Station (EEA) of the Federal University of Rio Grande do Sul (UFRGS), using random block design with four replications. The treatments were: two controls without inoculation (one with the addition of urea corresponding to 80kg ha-1 of nitrogen and other without nitrogen addition); inoculation with rhizobia: strain SEMIA 816, recommended in Brazil, U150 recommended in Uruguay and U512, being studied in Uruguay, and four rhizobia isolates (UFRGS Lc322, UFRGS Lc349, UFRGS Lc269 e Iso 7). The rhizobia isolate Lc322 and the strain U510 are more efficient than the strain SEMIA 816, which is recommended for bird’s-foot trefoil in the country. Furthermore, the forage production of plants inoculated with the isolate Lc322 and the strain U510 surpassed that, with the addition of 80kg ha-1 of nitrogen

Seleção a campo de rizóbios nativos para cornichão Field selection of native rhizobio for bird’s-foot trefoil

O cornichão (Lotus corniculatus L.) tem sido apontado como uma das forrageiras mais promissoras para o uso no Rio Grande do Sul. No entanto, pouco se conhece a respeito da interação dessas plantas com os rizóbios nativos em condições de campo. Este estudo visou a avaliar a eficiência das interações entre rizóbios e plantas de Lotus corniculatus cv. 'São Gabriel' em condições de campo. O experimento foi conduzido na Estação Experimental Agronômica da UFRGS com delineamento de blocos ao acaso com quatro repetições. Os tratamentos estudados foram: dois controles sem inoculação (um com a adição de 80kg ha-1 de nitrogênio na forma de uréia e outro sem a adição de nitrogênio); inoculação com rizóbios: estirpes SEMIA 816, recomendada no Brasil, U510, recomendada no Uruguai, U512, em estudo no Uruguai, e quatro isolados de rizóbios nativos (UFRGS Lc322, UFRGS Lc349, UFRGS Lc269 e Iso 7). O isolado UFRGS Lc322 e a estirpe U510 são mais eficientes do que a estirpe SEMIA 816, recomendada para cornichão no país. Além disso, a produção de forragem das plantas inoculadas com o isolado UFRGS Lc322 e a estirpe U510 superou a obtida com a adição de 80kg ha-1 de nitrogênio.The bird's-foot trefoil (Lotus corniculatus L.) has been pointed as one of the most promising forage plants for use in Rio Grande do Sul. However, there is lack of information about the interaction of those plants with the native rhizobia in field conditions. This study aimed to evaluate the efficiency of interactions between rhizobia and plants of Lotus corniculatus cv. 'São Gabriel' in field conditions. The experiment was carried out in the Agronomic Experimental Station (EEA) of the Federal University of Rio Grande do Sul (UFRGS), using random block design with four replications. The treatments were: two controls without inoculation (one with the addition of urea corresponding to 80kg ha-1 of nitrogen and other without nitrogen addition); inoculation with rhizobia: strain SEMIA 816, recommended in Brazil, U150 recommended in Uruguay and U512, being studied in Uruguay, and four rhizobia isolates (UFRGS Lc322, UFRGS Lc349, UFRGS Lc269 e Iso 7). The rhizobia isolate Lc322 and the strain U510 are more efficient than the strain SEMIA 816, which is recommended for bird's-foot trefoil in the country. Furthermore, the forage production of plants inoculated with the isolate Lc322 and the strain U510 surpassed that, with the addition of 80kg ha-1 of nitrogen

Seleção de rizóbios a campo de Lotus corniculatus cv. São Gabriel

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Seleção de rizóbios a campo de Lotus corniculatus cv. São Gabriel

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An Overview on Feral Hog Management in Brazil after Three Years of Control Regulation

Feral hogs are known to be expanding their range in Brazil since late 1980s and reports of damage to crops and livestock predation have become more frequent lately. Just recently, the use of lethal methods for feral hog control was legalized in Brazil, and there are still several restrictions, particularly towards the purchase and transportation of guns and ammunition. Results of questionnaires from feral hog hunters showed that around half of them still act illegally, and hunting with dogs was the main technique used for controlling feral hogs. We believe that to enhance feral hog control in Brazil, legislation needs to be reviewed, and a national control program needs to be created involving researchers, government agencies, and hunters, working together on development and implementation of more efficient techniques for feral hog population control