RESUMO: O objetivo foi avaliar o efeito dos níveis de fertilização nitrogenada na produtividade e no valor nutritivo do BRS Kurumi quando manejado em diferentes alturas de resíduos durante os períodos seco e chuvoso do ano. O capim foi manejado em três alturas de resíduos (20, 35 e 50 cm) em associação com três níveis de fertilização com nitrogênio (0, 100 e 200 kg N/ha/ ano), durante o período seco e chuvoso do ano. Quando a altura do capim de cada parcela atingiu 80 cm, o Kurumi foi cortado nas alturas de resíduos pré-estabelecidas. Cerca de 89% da produção de MS foi observada durante o período chuvoso. A altura do resíduo de 35 cm juntamente com doses de 100 ou 200 kg N/ha/ ano, e a altura do resíduo de 20 cm, com dose de 100 kg N/ha/ ano foram os tratamentos que apresentaram maior produção de MS durante o período chuvoso. Não foram observadas diferenças na produção de MS entre os tratamentos testados durante o período da seca. O Kurumi cultivado no período da seca apresentou maior teor de fibra em detergente neutro e menor digestibilidade. O Kurumi manejado com alturas de resíduo de 20 e 35 cm e fertilizado com 100 kg N/ha apresentou os maiores valores de eficiência de utilização do nitrogênio aplicado. Recomenda-se a utilização de 20 ou 35 cm de altura do resíduo e 100 kg de N/ha/ ano para obter maior produção de biomassa e nutrientes, qualidade nutricional e eficiência no uso do nitrogênio.

ABSTRACT: The objective was to evaluate the effect of nitrogen fertilization levels on productivity, and nutritional value of BRS Kurumi managed at different residue heights during rainy and dry periods of the year. The pasture was managed in three residue heights (20, 35, and 50 cm) and three nitrogen fertilization levels (0, 100, and 200 kg N/ha/year) during the rainy and dry seasons. When the height of the grass of each plot reached 80 cm, the Kurumi was cut manually at the pre-established residue heights. Around 89% of the dry matter (DM) production was observed during the rainy season. The residue height of 35 cm together with doses of 100 or 200 kg N/ha/year, and the residue height of 20 cm, with a dose of 100 kg N/ha/year were the treatments that had the highest DM production during the rainy period. No differences in DM production were observed between tested treatments during the dry period. The Kurumi cultivated during the dry period had the highest content of neutral detergent fiber and lowest digestibility. The Kurumi managed with residue heights of 20 and 35 cm and fertilized with 100 kg N/ha had the highest values of efficiency of utilization applied nitrogen. The use of 20 or 35 cm of residue height and 100 kg of N/ha/year is recommended to obtain greater biomass production and nutrients, nutritional quality, and nitrogen use efficiency.

RESUMO: A co-digestão dos dejetos suínos associados a resíduos vegetais é uma alternativa que pode elevar as produções de biogás e metano alcançadas pela digestão isolada do dejeto. No entanto, recomendações que se baseiem na melhor proporção entre dejeto e forragem, assim como na idade de colheita ainda são escassas na literatura. O objetivo do trabalho foi avaliar inclusões crescentes (0, 25, 50, 75 e 100% dos sólidos totais (ST) de capim elefante (Pennisetum purpureum Schum.) colhido em duas idades de corte mediana (MA) aos 45 dias de crescimento e avançada (AA) aos 90 dias, empregado em co-digestão com o dejeto suíno, adotando-se delineamento inteiramente ao acaso, em esquema fatorial 5x2. Foram utilizados biodigestores batelada de bancada, sendo as produções de biogás acompanhadas durante 12 semanas. Houve influência da idade da forragem (P<0,05) na degradação de sólidos e fibra em detergente neutro, com maiores valores para os substratos que continham a forragem MA. Os maiores rendimentos de CH4 foram alcançados pelos substratos que continham forragem MA na inclusão de 27,7 e 31,6 %, sendo de 253,7 e 222,2 L de CH4 por Kg de ST ou sólido volátil adicionado. A idade das forragens influenciou o início e a persistência das produções de biogás ao longo do período de digestão, sendo vantajosa apenas na inclusão de 25% de forragem com MA.

ABSTRACT: The co-digestion of swine manure with vegetable waste is an alternative that can increase the production of biogas and methane generated by the isolated digestion of manure. However, recommendations that are based on the best ratio between manure and forage, as well as the age of harvest, are still scarce in the literature. This study was conducted to evaluate inclusions (0, 25, 50, 75 and 100%) of the total solids (TS) of Elephant grass (Pennisetum purpureum Schum) harvested at two ages medium age (MA) at 45 days of growth and advanced age (AA) at 90 days in co-digestion with swine manure, using an entirely randomized design in a 5x2 factorial scheme. Batch digesters were used and biogas production was monitored for 12 weeks. There was influence of forage age (P <0.05) on the degradation of solids and neutral detergent fiber, with higher values for the substrates containing MA forage. The highest CH4 yields were obtained by the substrates containing MA forage in the inclusion of 27.7 and 31.6%, being 253.7 and 222.2 L of CH4 per Kg of total or volatile solids. The age of the forages influenced the onset and persistence of biogas production, being advantageous only in the inclusion of 25% of MA forage. The AA forage inclusion is not recommended for co-digestion with swine manure.

RESUMO: Esta pesquisa foi realizada com o objetivo de se avaliar a produtividade da biomassa e valor nutricional da silagem e do feno provenientes do consórcio entre o capim-Tamani e diferentes espécies de leguminosas. Para as características produtivas das diferentes culturas consorciadas, adotamos o delineamento de blocos ao acaso, para avaliação da interação dos consórcios com técnicas de conservação usamos esquema fatorial 5 x 2 (cinco consórcios e duas técnicas de conservação). Os tratamentos foram o capim-Tamani em monocultura, e o consórcio de capim-Tamni associado a crotalária, soja, feijão-caupi ou feijão-guandu. As plantas foram semeadas em fileiras alternadas, com espaçamento de 45 cm. As técnicas de conservação foram silagem pré-secada (520 g / kg de MS) e feno (870 g / kg de MS). Avaliamos a produção de biomassa de gramínea e leguminosa, a altura do dossel, a composição química e a digestibilidade in vitro da matéria seca (ivDMD). Não houve diferenças na produção total de biomassa entre os consórcios e o monocultivo de capim-Tamani. Os tratamentos consorciados com feijão-caupi e soja tiveram maior participação de leguminosas na mistura, promovendo aumento no teor de proteína bruta e ivDMD da silagem pré-secada e feno. A silagem pré-secada e o feno tinham a mesma composição química, embora a silagem pré-secada apresentou maior ivDMD do que o feno. Concluímos que o consórcio de capim-Tamani com soja ou feijão-caupi manteve a produtividade da biomassa total e melhorou o valor nutricional da silagem pré-secada e do feno.

ABSTRACT: This research evaluated the biomass productivity and nutritional value of the haylage and hay from intercropping between Tamani grass and different legume species. For the productive characteristics of the different intercrops, we adopted a randomized block design, for evaluation of the combination of intercropping and conservation technic we used 5 x 2 factorial scheme (five intercrops and two types of conservation techniques). The treatments were Tamani grass as monoculture, and the intercrops of Tamani grass with crotalaria, soybean, cowpea, or pigeon pea. The conservation techniques were haylage (520 g/kg of DM) and hay (870 g/kg of DM). Plants were sown in alternate rows, with 45 cm of spacing between the rows. The parameters evaluated were grass and legume biomass production, canopy height, and haylage and hay chemical composition, and in vitro dry matter digestibility (ivDMD). There were no differences in the total biomass production between the intercrops and TA grass monoculture. The treatments intercropped with cowpea and soybean had the highest legume participation in the mixture, promoting an increase in crude protein and ivDMD content of haylage and hay. Haylage and hay had the same chemical composition, although haylage had higher ivDMD than hay. We concluded that intercropping Tamani grass with soybeans or cowpea maintained total biomass productivity and improved the nutritional value of haylage and hay.

ABSTRACT We aimed to evaluate the effects of crude glycerine purity and levels of glycerol on the fermentative profile, microorganisms counting, and nutritional value of Piatã grass silage. The experiment was carried out in a 3×3+1 completely randomized factorial design using three different types of crude glycerine [low purity (40% of glycerol), medium purity (60% glycerol), and high purity (80% glycerol)], three doses of glycerol (20, 40, and 60 g/kg DM), and a control (no crude glycerine added) as an additional treatment, which were stored for 80 days. Statistical differences were not observed on fermentative losses of the treatments tested. The increase of glycerol doses resulted in higher levels of non-fibrous carbohydrates and lower levels of fibre components. The addition of low-purity crude glycerine increased the levels of fat and in vitro digestibility of silages. The highest levels of lactic acid and acetic acid occurred in the treatments with 60 g/kg of glycerol when using crude glycerine with a low purity. The lowest lactic acid content was observed in the control treatment and in the lowest dose of glycerol. The highest glycerol dose (60 g/kg), associated with the lowest degree of crude glycerine purity (40%) resulted in the greatest nutritional value and provided the best silage conservation.

Resumo: O objetivo deste trabalho foi avaliar o desempenho produtivo e as características da carcaça de cordeiros alimentados com silagens de diferentes tipos de sorgo e milho. Foram utilizados 32 cordeiros machos, da raça Suffolk. O delineamento experimental foi inteiramente casualizado, com quatro tratamentos (silagens) e oito repetições (animais). Foram testadas silagens de sorgo forrageiro GrandSilo, sorgo sacarino BRS 506, sorgo sacarino BRS 511 e milho híbrido duplo BRS 2223. Os cordeiros alimentados com silagens de sorgo apresentaram menor consumo diário de matéria seca que os alimentados com silagem de milho. A dieta contendo silagem de milho proporcionou ganho de peso 27% superior ao dos tratamentos com as demais silagens. A digestibilidade in vivo não diferiu entre as diferentes silagens. Os cordeiros alimentados com silagem de milho apresentaram os menores rendimentos de carcaça quente e fria, de 44,71 e 42,62%, respectivamente, enquanto os que consumiram silagem de sorgo BRS 506 apresentaram os maiores rendimentos de carcaça quente e fria, de 46,90 e 44,78%. O maior consumo e o melhor desempenho dos animais alimentados com silagem de milho não foi suficiente para incrementar a produção e o rendimento de carcaça. Os cordeiros alimentados com silagem de sorgo sacarino BRS 506 apresentam maior eficiência de conversão da silagem em carcaça.

Abstract: The objective of this work was to evaluate the productive performance and carcass traits of lambs fed silages of different types of sorghum and corn. Thirty-two uncastrated male Suffolk lambs were used. The experimental design was completely randomized, with four treatments (silages) and eight replicates (animals). Silages of the GrandSilo forage sorghum, BRS 506 saccharine sorghum, BRS 511 saccharine sorghum, and the BRS 2223 double-grain corn hybrid were tested. The lambs fed sorghum silages had a lower daily dry matter intake than those fed corn silage. The diet containing corn silage led to 27% greater weight gain, when compared with the treatments with the other silages. In vivo digestibility did not differ among the different silages. Lambs fed corn silage showed the lowest hot and cold carcass yields of 44.71 and 42.62%, respectively, whereas those that consumed BRS 506 sorghum silage showed the highest hot and cold carcass yields of 46.90 and 44.78%. The greater intake by and the better performance of the animals fed corn silage was not enough to enhance production and carcass yield. Lambs fed BRS 506 saccharine sorghum silage have higher efficiency in the conversion of silage into carcass.

ABSTRACT: The composting of laying hen manure is an efficient way of treating waste and producing an organic fertilizer with excellent characteristics; however, the high N losses reduce its concentration in the resulting fertilizer. Associating this residue with crude glycerin (CG) promotes a better C:N ratio and contributes to higher N retention during composting, with improvements in solids reduction and production of organic fertilizer with higher concentration of this nutrient. We carried out this research considering the hypothesis that adding CG – a byproduct of biodiesel production – to laying hen waste composting provides better N retention in the fertilizer generated. Increasing CG doses (0, 3, 6, 9, and 12 % in relation to the fresh mass in the windrows) were added to the laying hen manure with windrows composted for 70 days. A reduction by 100 % in total and thermotolerant coliforms occurred at all levels of CG addition. The maximum reductions in total (TS) and volatile (VS) solids were 64 and 76 %, respectively, and occurred with the addition of 6 % CG. The windrows that did not receive CG had higher N losses during the process (32 %) while the highest N concentration in the compost was 5 % at 6 % CG. We identified that adding 6 % CG to the laying hen manure in co-composting increases the reductions in TS and VS and provides higher N retention, which improves the quality of the organic fertilizer.

RESUMO: Objetivou-se encontrar a melhor dose de inclusão de óleo residual durante a co-digestão de substratos preparados com dejetos de bovinos leiteiros e suínos, com o intuito de maximizar as reduções de sólidos e as produções de biogás. Foram realizadas no abastecimento e desabastecimento dos biodigestores as análises de sólidos totais (ST), sólidos voláteis (SV) e fibra em detergente neutro (FDN), enquanto as mensurações de biogás duas vezes por semana. A máxima redução de SV (51,4%) foi possibilitada pela inclusão de até 54,6g de óleo de descarte kg dejetos-1, já as máximas degradações de FDN ocorreram com adições de até 69,4g de óleo de descarte kg dejetos-1. As inclusões de até 64g de óleo de descarte kg dejetos-1 possibilitaram produções específicas de biogás de 291,4 e 251,0 L de biogás.kg SV-1 adicionado, para substratos contendo dejetos de suínos e bovinos respectivamente. A adição de óleo em doses entre 45,1 e 69,4g.kg-1 a substratos contendo dejetos de bovinos ou suínos maximiza as reduções dos constituintes sólidos e fibrosos bem como potencializa as produções específicas de biogás, sendo que o dejeto de suíno ainda suporta maiores doses de inclusão de óleo residual.

ABSTRACT: This study aimed to obtain the best dose of waste cooking oil inclusion for the co-digestion of substrates prepared with dairy cattle and swine manure in order to maximize solids reductions and biogas yield. Analyses of total solids (TS), volatile solids (VS), and neutral detergent fiber (NDF) were performed during the loading and unloading of digesters, while biogas yield was measured twice a week. The maximum reduction in VS (51.4%) was reached with the inclusion of up to 54.6g waste cooking oil.kg manure-1. Maximum NDF degradation occurred with inclusions of up to 69.4g waste cooking oil.kg manure-1. Inclusions of up to 64g of waste cooking oil.kg manure-1 provided specific biogas yield of 291.4 and 251.0L biogas.kg VS-1 added to substrates with swine and cattle manure, respectively. Adding oil at doses between 45.1 and 69.4g waste cooking oil kg manure-1 to substrates composed of cattle or swine manure maximizes reductions of solids and fibrous constituents and enhances specific biogas yield. Furthermore, swine manure supports higher doses of waste cooking oil.

ABSTRACT The objective of this study was to evaluate fermentation losses and the nutritional value of silage of Brachiaria brizantha cv BRS Piatã ensiled with different levels of crude glycerin. The experiment followed a 4 × 2 completely randomized factorial design with four doses of crude glycerin (0, 100, 200, and 300 g kg–1 of DM silage) and two cutting ages (45 and 60 days) with four replicates per treatment (silos). The parameters of dry matter losses, effluents losses, gas losses, pH, microbial population, and nutritional value of the silage were evaluated. There was no difference in pH among the tested doses of crude glycerin. However, reductions in dry matter and gas losses were observed as a function of crude glycerin doses. Bacterial populations of lactic acid and facultative mesophilic anaerobes also increased as a function of crude glycerin inclusion. Crude glycerin increased ether extract levels and reduced neutral detergent fiber and acid detergent fiber concentrations (dilution effect), improving chemical composition of the silage. Crude glycerin can be used in the ensiling of Piatã grass and the dose of 300 g kg–1 of DM yields the best results.

ABSTRACT Anaerobic digestion of crude glycerin (CG) along with animal waste has been an excellent option for increasing the production of biogas and methane to achieve efficiency in the treatment of both residues. This study aimed to evaluate improvements in specific productions of biogas and methane, reductions in solid and fibrous components in substrates prepared with dairy cattle manure and CG (containing 14 % glycerol). With these residues, experimental substrates were prepared and placed in 25 batch digesters. Initial content of the TS in the influent was 4 % and CG was added in increasing doses (0, 5, 10, 15 and 20 % relative to total solids (TS) of the influent). Results were submitted to ANOVA and orthogonal contrasts to assess the effects of linear and quadratic order and thereby estimate the optimal CG doses through the adjusted models. The highest values for specific production of methane (0.19 and 0.26 L g−1 of TS and volatile solids (VS) added, respectively) were reached with the CG inclusions of 6 and 8 %, respectively. Total production of biogas with the inclusion of 6 % CG was 11 % higher when compared to the control treatment. The largest reduction in VS (48 %) was achieved with the addition of 4 % CG. Addition of CG at levels between 3 and 8 % improved the efficiency of the process of anaerobic digestion with dairy cattle manure.

ABSTRACT The beef production depends basically on the production of pastures, thus the main goal of this research was to evaluate the dossal height and dry matter production of leaf blades and grass stalk Urochloa brizantha cv. Piatana depending on cutoff frequency, seasons and irrigation. The experimental design used was completely randomized in factorial scheme (4x2x3) with four cutoff frequencies (21, 28, 35 and 42 days between cuts) irrigated and non-irrigated, and three seasons (fall, winter and spring) with six repetitions per treatment (experimental plots). The parameters evaluated were: dossal height and total dry mass production of leaf blades and stem. The results showed: in spring season, the highest of the dossal were observed in pastures cut to 28 days with 39.6 cm. The dry mass production of leaf blades was higher at 42 days cutting, with the largest production (1.364 kg ha-1) in autumn with irrigation. In spring season without irrigation was the best dry matter production of stalks with 0.141 kg ha-1 at 42 days. The dossal height increases with irrigation in winter. This information may be recommended in the feeding of ruminant animals.

RESUMO A produção de carne bovina depende basicamente da produção de pastagens, assim, o objetivo dessa pesquisa foi avaliar a altura do dossel e as produções de matéria seca de lâminas foliares e colmo do capim Urochloa brizantha cv. Piatã em função das frequências de cortes, estações do ano com e sem irrigação. O delineamento foi inteiramente casualizado em esquema fatorial 4x2x3, sendo quatro idades de corte (21, 28, 35 e 42 dias entre cortes), irrigado e não irrigado, e três estações do ano (outono, inverno e primavera) com seis repetições por tratamento (canteiros experimentais). Os parâmetros avaliados foram: altura de dossel e as produções de massa seca total de lâminas foliares e colmo. Os resultados indicaram que na primavera, as maiores alturas do dossel foram registradas em pastos cortados aos 28 dias com 39,6 cm de altura. As produções de massa seca de lâminas foliares foram maiores no intervalo de corte de 42dias, sendo as maiores produções durante o Outono com 1,364 kg ha-1 com irrigação. A primavera foi à estação que apresentou as melhores produções de massa seca de colmos com 0,141 kg ha-1 de MS aos 42 dias sem irrigação. A irrigação aumenta a altura do dossel durante o inverno. Estas informações podem ser recomendadas na alimentação de animais ruminantes.

RESUMO O objetivo foi avaliar o desempenho da co-digestão anaeróbia de dejetos de suínos associados com crescentes doses de glicerina bruta, adotando-se diferentes tempos de retenção hidráulica (TRH). O delineamento utilizado foi inteiramente casualizado em esquema fatorial 3x4, três TRH (10; 17 e 24 dias) e quatro doses de glicerina bruta (0; 5; 10 e 15% dos sólidos totais), com quatro repetições por tratamento. Os parâmetros avaliados foram produção e potencial de produção de biogás, reduções de sólidos totais (ST), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA). A produção de biogás e potencial de produção apresentaram efeito quadrático nos TRH de 17 e 24 dias, evidenciando como doses ideais 4,09 e 5,63% de glicerina bruta, respectivamente, para produção e 4,52 e 5,42% de glicerina bruta para potencial de produção. Não houve diferença entre as doses de glicerina bruta dentro do TRH de 10 dias para as reduções de ST. No entanto, foi observado diferença entre as doses nos TRH 17 e 24, com a maior redução observada de 54,9% ao incluir 5% de glicerina bruta no maior TRH. As reduções de FDN e FDA aumentaram de acordo com a adição de glicerina bruta nos TRHs de 10 e 17 dias. A inclusão de 4 a 6% de glicerina bruta no TRH 24 mostrou-se mais eficiente na produção de biogás e reduções de ST e FDN. Já visando maior redução de FDA pode-se utilizar doses mais altas de glicerina a partir da co-digestão com dejetos suínos.

ABSTRACT The aim of this study was to evaluate the performance of the anaerobic co-digestion of pig manure associated with increasing doses of crude glycerine, adopting different periods of hydraulic retention time (HRT). A completely randomised design was used in a 3 x 4 factorial scheme, three HRT (10, 17 and 24 days) and four doses of crude glycerine (0, 5, 10 and 15% of the total solids), with four replications per treatment. The parameters to be evaluated were biogas production and potential production, reduction in total solids (TS), neutral detergent fibre (NDF) and acid detergent fibre (ADF). Biogas production and potential production displayed a quadratic effect for an HRT of 17 and 24 days, showing the doses of 4.09% and 5.63% crude glycerine to be respectively optimal for production, and 4.52% and 5.42% crude glycerine for production potential. There was no difference between the doses of crude glycerine at the HRT of 10 days for reductions in TS. However, a difference was seen between doses at HRT 17 and 24, with the greatest reduction of 54.9% being found when including 5% of crude glycerine at the greatest HRT. The reductions in NDF and ADF were greater with the addition of crude glycerine for an HRT of 10 and 17 days. The inclusion of 4% - 6% crude glycerine at HRT 24 was more efficient in the production of biogas and reducing TS and NDF. With a view to a greater reduction in ADF, higher doses of glycerine can be used in the co-digestion of pig manure.

ABSTRACT The effect of additives used in the feed of broilers on anaerobic bio-digestion of poultry litter was evaluated. Four diets were used: NC: negative control; DFM: NC + 500 ppm direct-fed microbials (DFM) containing Bacillus subtilis and Bacillus licheniformis; ENZ: diet formulated with an enzyme blend (20 ppm phytase, 200 ppm protease and 200 ppm xylanase); DFM+E: ENZ + DFM. Substrates for the anaerobic bio-digestion were prepared with litter from each treatment, containing 4 % total solids (TS). These were used in 16 continuous bio-digesters with a 2 kg d−1 load, to determine the production and potential biogas production and composition during an 85-day period. Influent and effluent samples were collected for the amounts of TS and volatile solids (VS), fiber fraction (neutral detergent fiber [NDF], acid detergent fiber [ADF] and lignin), nutrients (N, P and K), and total and thermotolerant coliforms to be determined. For all treatments a reduction in the following effluents was observed as follows: TS (49, 48, 48 and 50 %) VS (70, 54, 55 and 62 %) NDF (91, 90, 95 and 96 %) ADF (89, 88, 93 and 94 %) and lignin (80, 76, 89 and 88 %). The efficiency of the treatment for coliforms in bio-digesters was higher than 90 % in the 85-day period in all treatment groups. There was a reduction in biogas and methane production when DFM (5500 and 4000 mL) and DFM + E (5800 and 4100 mL) were used, compared to treatments NC (6300 mL and 4400) and ENZ (6400 and 4500 mL). The potential production of reduced TS and VS was higher in ENZ (1:00 and 1.74 106 mL kg−1) when compared to NC (0.88 and 1:02 106 mL kg−1), DFM (0.80 and 1:40 106 mL kg−1) and DFM + E (0.88 1:25 and 106 mL kg−1). The additives did not affect the percentage of methane production, and all treatments showed values higher than 70 %. Adding enzymes to the diet of broilers influences the litter characteristics and, as a consequence, increases biogas production. The addition of DFM and DFM + E to broiler diets reduced biogas and methane production.

ABSTRACT The objective of this research was to evaluate the performance of anaerobic co-digestion of swine excreta associated with increasing doses of crude glycerin and different hydraulic retention times (HRT). A completely randomized design was adopted in a 3 × 4 factorial arrangement composed of three HRT (10, 17, and 24 days) and four crude glycerin doses (0, 5, 10, and 15 g/100 g of total solids [TS]), with four replications per treatment. The assessed parameters were: biogas production potential, reductions of volatile solids (VS), chemical oxygen demand (COD), and most probable number of total and thermotolerant coliforms. The biogas production per added VS presented quadratic effect at 17 and 24 days of HRT, with ideal doses of 5.5 and 5.9 g of crude glycerin/100 g TS, respectively. There was no difference among glycerin doses at 10-day HRT for VS reductions; however, at HRT of 17 and 24 days, there were differences, with greater reduction of 61.1% for 5 g of crude glycerin/100 g TS at 24-day HRT. The COD reduction values showed an effect among retention times, in which the 24-day HRT provided the best results. Reductions in coliforms were greater than 99%, with no difference among treatments. Addition of 5 to 6 g of crude glycerin/100 g TS with a 24-day HRT is more effective in biogas production and reduction of VS, COD, and coliforms from co-digestion of swine excreta.

Resumo: O objetivo deste trabalho foi avaliar quatro variedades de sorgo sacarino (Sorghum bicolor)quanto à produtividade, à composição química das partes da planta e à qualidade do processo de ensilagem. As variedades de sorgo sacarino utilizadas foram BRS 506, BRS 508, BRS 509 e BRS 511. O experimento foi dividido em dois ensaios, que avaliaram: produção, composição morfológica e qualidade nutricional das variedades sacarinas; e qualidade do processo fermentativo e valor nutricional das silagens das variedades sacarinas. Das variedades testadas, a BRS 509 e a BRS 511 foram as que apresentaram maiores produções de matéria seca (MS) total. A variedade BRS 508 apresentou o maior coeficiente de digestibilidade in vitro da planta inteira (70,65% da MS). Durante a ensilagem, a variedade BRS 509 foi a que apresentou menor perda de MS (8,87%). A maior produção de efluentes foi observada para BRS 506 e BRS 508, com produção de 521,87 e 393,16 kg Mg-1 de MS ensilada, respectivamente. A variedade BRS 511 é a mais indicada em razão dos melhores resultados de produção e de qualidade nutricional da planta. Em relação ao processo de ensilagem, a BRS 509 apresenta as menores perdas fermentativas e o maior valor nutritivo da silagem.

Abstract: The objective of this work was to evaluate four cultivars of saccharine sorghum (Sorghum bicolor) regarding productivity, chemical composition of plant parts, and quality of the ensiling process. The tested varieties of saccharine sorghum were BRS 506, BRS 508, BRS 509, and BRS 511. The experiment was divided into two trials, which assessed: production, morphological composition, and nutritional quality of the saccharine varieties; and fermentation quality and nutritional value of the silage produced from the saccharine varieties. Of the tested varieties, BRS 509 and BRS 511 showed the highest total dry matter (DM) production. The BRS 508 variety presented the highest in vitro digestibility of the whole plant (70.65% DM). During ensiling, the BRS 509 variety showed the lowest DM loss (8.87%). The highest effluent production was observed for BRS 506 and BRS 508, with yields of 521.87 and 393.16 kg Mg-1 ensiled DM, respectively. The BRS 511 variety is the most recommended because of the best results for plant production and nutritional quality. Regarding the ensiling process, BRS 509 presents the lowest fermentation losses and the highest nutritional value of silage.

RESUMO A suinocultura resulta na produção de grandes quantidades de resíduos, os quais, quando manuseados incorretamente, podem causar graves problemas ambientais. Este estudo objetivou testar modelos matemáticos para estimar os parâmetros de biodigestão anaeróbia em biodigestores, em função da variação da composição de efluentes de suinocultura com e sem separação da fração sólida e dos tempos de retenção hidráulica (TRH). Foram utilizados biodigestores semicontínuos, abastecidos com efluentes de suinocultura com e sem separação da fração sólida, manejados por 15, 22, 29 e 36 dias de retenção hidráulica. Foram avaliados os potenciais de produção de biogás e metano e as reduções de sólidos totais, sólidos voláteis e demandas químicas de oxigênio, em função da composição dos efluentes. O TRH foi a variável que teve maior influência na variação dos modelos, seguido dos teores de sólidos totais e voláteis. Os modelos uni e multivariados apresentaram elevados índices de confiança, sendo classificados como ótimos para predizer os potenciais de produção de biogás e metano e como bons para predizer as reduções de sólidos totais, sólidos voláteis e demanda química de oxigênio. Os modelos deste estudo podem ser utilizados para predizer com segurança os parâmetros do processo de biodigestão anaeróbia de efluentes de suinocultura, em biodigestores semicontínuos tubulares.

ABSTRACT Pig breeding results in the production of large amounts of waste, which can cause serious environmental problems, when handled incorrectly. This study aimed at testing mathematical models to estimate the parameters of anaerobic biodigestion in biodigesters as a function of the composition of swine effluents with and without separation of the solid fraction and hydraulic retention times (HRT). Semi-continuous biodigesters fed with swine effluents with and without separation of the solid fraction and managed for 15, 22, 29 and 36 days of hydraulic retention were used. The potential of biogas and methane production, as well as the reduction of total solids, volatile solids and chemical oxygen demand, were assessed as a function of the effluents composition. HRT was the variable that most influenced the variation of the models, followed by the contents of total and volatile solids. Uni and multivariate models presented high confidence indices, being classified as “great” at predicting the potentials of biogas and methane production and “good” at predicting the reductions of total solids, volatile solids and chemical oxygen demand. The models obtained in this study can be used to reliably predict the parameters of the anaerobic biodigestion process of swine effluents in semi-continuous tubular biodigesters.