Soil carbon stock and humification in pastures under different levels of intensification in Brazil

Intensive management of tropical pastures has shown potential for greenhouse gas (GHG) mitigation due to high forage production and C accumulation in the soil. This study aimed to evaluate different pasture management options in relation to their effect on soil C stocks and soil organic matter (SOM) humification. Pastures in four beef cattle production systems were assessed: intensive and irrigated pasture with high stocking rate (IHS); dryland pasture with high stocking rate (DHS); dryland pasture with moderate stocking rate (DMS); degraded pasture (DP). The soil under the native forest was also evaluated and soil carbon stocks from the 0-100 and 0-30 cm layers were assessed. Carbon stocks (0-100 cm) ranged from 99.88 to 142.33 Mg ha1 in DP and DMS, respectively and were, respectively, 14 % and 24 % higher compared to the soil under the forest and indicate the capacity of adequately managed tropical pastures to mitigate GHG emissions from livestock production. Humification indexes indicated the presence of more labile C in pastures with greater C accumulation (DHS and DMS), mainly in the upper soil layers, indicating recent C accumulation resulting from correct management. However, more labile C can be easily lost to the atmosphere as CO2, depending on pasture management. Low C stocks associated with high humification indexes are characteristics of DP in which significant amounts of SOM are lost. It is necessary to develop technologies to improve C sequestration in IHS and results indicate the importance of quantifying C stocks in association with C stability.

Soil carbon stock and humification in pastures under different levels of intensification in Brazil

Intensive management of tropical pastures has shown potential for greenhouse gas (GHG) mitigation due to high forage production and C accumulation in the soil. This study aimed to evaluate different pasture management options in relation to their effect on soil C stocks and soil organic matter (SOM) humification. Pastures in four beef cattle production systems were assessed: intensive and irrigated pasture with high stocking rate (IHS); dryland pasture with high stocking rate (DHS); dryland pasture with moderate stocking rate (DMS); degraded pasture (DP). The soil under the native forest was also evaluated and soil carbon stocks from the 0-100 and 0-30 cm layers were assessed. Carbon stocks (0-100 cm) ranged from 99.88 to 142.33 Mg ha1 in DP and DMS, respectively and were, respectively, 14 % and 24 % higher compared to the soil under the forest and indicate the capacity of adequately managed tropical pastures to mitigate GHG emissions from livestock production. Humification indexes indicated the presence of more labile C in pastures with greater C accumulation (DHS and DMS), mainly in the upper soil layers, indicating recent C accumulation resulting from correct management. However, more labile C can be easily lost to the atmosphere as CO2, depending on pasture management. Low C stocks associated with high humification indexes are characteristics of DP in which significant amounts of SOM are lost. It is necessary to develop technologies to improve C sequestration in IHS and results indicate the importance of quantifying C stocks in association with C stability.(AU)

Biogas production: litter from broilers receiving direct-fed microbials and an enzyme blend

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 d1 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 kg1) when compared to NC (0.88 and 1:02 106 mL kg1), DFM (0.80 and 1:40 106 mL kg1) and DFM + E (0.88 1:25 and 106 mL kg1). 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.

Biogas production: litter from broilers receiving direct-fed microbials and an enzyme blend

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 d1 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 kg1) when compared to NC (0.88 and 1:02 106 mL kg1), DFM (0.80 and 1:40 106 mL kg1) and DFM + E (0.88 1:25 and 106 mL kg1). 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.(AU)

Digestible valine requirements for broilers from 22 and 42 days old / Exigências em valina digestível para frangos de corte de 22 a 42 dias de idade

Current experiment established different criteria to evaluate the requirements of digestible valine for broilers from 22 and 42 days of age, by different regression models (quadratic, exponential and Linear Response Plateau) and, in the case of statistical significance, the comparison of means by Duncantest at 5% probability. A total of 1,920 Cobb 500 male broilers were used and distributed in an entirely randomized experimental design, with 6 treatments (6 digestible valine levels: 0.7192, 0.7729, 0.8265, 0.8802, 0.9339 and 0.9876%) and 8 replications, with 40 broilers each. Data on performance and carcass characteristics were evaluated. The level of 0.8265% digestible valine was considered standard. The inclusion of 0.816, 0.848 and 0.903% of digestible valine levels, corresponding to digestible valine:lysine ratios of approximately 76.00%, 79.00% and 84.12%, provided best feed intake, weight gain and feed conversion ratio, respectively for broiler from 22 to 42 days of age.(AU)

Um experimento foi realizado com o objetivo de estabelecer critérios de avaliação das exigências de valina digestível para frangos de corte de 22 a 42 dias de idade utilizando-se diferentes modelos de regressão (quadrático, exponencial e de retas segmentadas ou Linear Response Plateau). Foram utilizados 1.920 frangos de corte machos com 22 dias de idade, distribuídos em delineamento inteiramente ao acaso, com seis tratamentos (6 níveis de valina digestível: 0,7192; 0,7729; 0,8265; 0,8802; 0,9339 e 0,9876) e oito repetições de 40 aves. Utilizou-se como padrão o nível de 0,8265% de valina digestível. A inclusão dos níveis 0,8160; 0,8484 e 0,9031% de valina digestível proporcionou os melhores resultados de consumo de ração, ganho de peso e conversão alimentar respectivamente.(AU)

Digestible valine requirements for broilers from 22 and 42 days old / Exigências em valina digestível para frangos de corte de 22 a 42 dias de idade

Current experiment established different criteria to evaluate the requirements of digestible valine for broilers from 22 and 42 days of age, by different regression models (quadratic, exponential and Linear Response Plateau) and, in the case of statistical significance, the comparison of means by Duncantest at 5% probability. A total of 1,920 Cobb 500 male broilers were used and distributed in an entirely randomized experimental design, with 6 treatments (6 digestible valine levels: 0.7192, 0.7729, 0.8265, 0.8802, 0.9339 and 0.9876%) and 8 replications, with 40 broilers each. Data on performance and carcass characteristics were evaluated. The level of 0.8265% digestible valine was considered standard. The inclusion of 0.816, 0.848 and 0.903% of digestible valine levels, corresponding to digestible valine:lysine ratios of approximately 76.00%, 79.00% and 84.12%, provided best feed intake, weight gain and feed conversion ratio, respectively for broiler from 22 to 42 days of age.

Um experimento foi realizado com o objetivo de estabelecer critérios de avaliação das exigências de valina digestível para frangos de corte de 22 a 42 dias de idade utilizando-se diferentes modelos de regressão (quadrático, exponencial e de retas segmentadas ou Linear Response Plateau). Foram utilizados 1.920 frangos de corte machos com 22 dias de idade, distribuídos em delineamento inteiramente ao acaso, com seis tratamentos (6 níveis de valina digestível: 0,7192; 0,7729; 0,8265; 0,8802; 0,9339 e 0,9876) e oito repetições de 40 aves. Utilizou-se como padrão o nível de 0,8265% de valina digestível. A inclusão dos níveis 0,8160; 0,8484 e 0,9031% de valina digestível proporcionou os melhores resultados de consumo de ração, ganho de peso e conversão alimentar respectivamente.

Effect of sodium gluconate on performance, carcass characteristics, and intestinal morphometry of broilers from 22 to 42 days of age / Efeito do gluconato de sódio sobre o desempenho, rendimento de carcaça e morfometria da mucosa intestinal de frangos de corte de 22 a 42 dias de idade

The objective of this experiment was to evaluate the effect of the sodium gluconate addition on performance (feed intake, body weight, weight gain, feed conversion, livability and productive efficiency), carcass characteristics (carcass, breast, thigh and drumstick, wing and back yield), and morphometry of duodenum, jejunal and ileum of broilers from 22 to 42 days of age. A total of 1,200 Cobb male broilers were distributed in a completely randomized design with five treatments (0.00, 0.10, 0.20, 0.30 and 0.40% sodium gluconate), and eight replications of 30 broilers each. The inclusion of sodium gluconate did not affect the broiler performance and carcass characteristics. However, the morphometry of duodenum and jejunal mucosa showed beneficial effects.

O presente estudo teve por objetivo avaliar o efeito da utilização de níveis crescentes do gluconato de sódio sobre o desempenho, o rendimento de carcaça e de partes e a morfometria da mucosa intestinal de frangos de corte de 22 a 42 dias de idade. Foram utilizados 1200 frangos de corte da linhagem Cobb, distribuídos em um delineamento inteiramente casualizado, envolvendo cinco tratamentos (0,00; 0,10; 0,20; 0,30 e 0,40% de gluconato de sódio) com oito repetições de 30 aves cada parcela. As variáveis foram submetidas à análise de variância e em caso de significância estatística foram realizadas análises de regressão pelos modelos polinomial e quadrático. A inclusão do gluconato de sódio não afetou o desempenho e o rendimento de carcaça e de partes. Entretanto, exerceu efeito benéfico sobre a morfometria da mucosa intestinal do duodeno e do jejuno.

Effect of phytase supplementation on performance, bone densitometry and carcass yield in broilers chicks / Efeito da adição da enzima fitase sobre o desempenho, densitometria óssea e rendimento de carcaça de frangos de corte

An experiment was conducted to evaluate the performance, bone densitometry and carcass yield of broilers chicks, using different levels of phytase enzyme. Nine hundred and sixty male one-day-old broiler chicks were used. The birds were distributed in a completely randomized experimental design, involving five treatments and six replications of 32 chicks each. The treatments consisted of a control diet for each phase, and four other diets were formulated adding growing levels of the phytase enzyme (250, 500, 750 and 1,000 FTU of phytase kg-1 feed). When adding the phytase enzyme, the nutritional matrix was valued to guarantee the same nutritional levels as the control diet. In general, the addition of phytase enzyme determined a linear decrease on the performance of the birds. However, the performance obtained with the level of 250 FTU phytase kg-1 feed were no different from the control treatment. The best bone density results were observed in the control treatment with no phytase, and the highest leg and thigh yield were obtained at the level of 514 FTU phytase kg-1.

Um experimento foi realizado com o objetivo de avaliar a inclusão de diferentes níveis da enzima fitase, sobre o desempenho, a densitometria óssea e o rendimento de carcaça e partes de frangos de corte nas diferentes fases de criação. Foram utilizados 960 pintainhos de corte com um dia de idade, da marca comercial Ross, distribuídos em um delineamento inteiramente casualizado, com quatro tratamentos mais uma testemunha (quatro níveis da enzima fitase - 250, 500, 750 e 1.000 FTU de fitase kg-1 de ração + testemunha) e seis repetições de 32 aves cada. Ao adicionar a enzima fitase, a matriz nutricional da mesma foi valorizada para garantir os mesmos níveis nutricionais da dieta testemunha. Foram avaliados os índices de desempenho, de densitometria óssea e o rendimento de carcaça e de partes nas diferentes fases de criação. De maneira geral o aumento na inclusão da enzima fitase determinou declínio linear sobre o desempenho das aves. Entretanto, até o nível de 250 FTU de fitase kg-1 de ração não foram observadas diferenças expressivas em relação ao tratamento isento de fitase. Os melhores resultados de densitometria óssea foram observados no tratamento controle sem a adição da enzima fitase e o maior rendimento de coxa+sobrecoxa foi obtido com o nível de 514 FTU de fitase kg-1 de ração.