Performance and incidence of diarrhea in suckling Jersey calves supplemented with mineral-vitamin complex and Virginiamycin.

The rearing of calves is an essential activity of a dairy system, as it impacts the future production of these animals. This study aims to evaluate the incidence of diarrhea, performance, and blood parameters of suckling calves that received mineral-vitamin supplementation in milk plus virginiamycin that was offered in milk (via the abomasum) or by esophageal tube (via the rumen). Twenty-seven calves were used, from the first week to 60 days of age, submitted to the following treatments: CONTROL, without supplementation; MILK, supplementation of 20 g of a mineral-vitamin complex with 100 mg of virginiamycin, diluted in milk; RUMEN, supplementation of 20 g of a mineral-vitamin complex diluted in milk and 100 mg of virginiamycin in gelatin capsules via an esophageal applicator. MILK and RUMEN calves had lower fecal consistency scoring, fewer days with scores 2 and 3 throughout the experimental period, and lower spending on medication compared to the CONTROL animals. Supplemented calves had higher fat and protein intake and reached feed intake of 600 g earlier than CONTROL animals, but did not differ in performance and hematological parameters. Supplementation with virginiamycin and vitamin-mineral complex for suckling calves reduced the incidence and days of diarrhea, and reduced medication costs, with no difference in performance, but the supplemented animals had higher initial protein and fat intake and reached targeted feed intake earlier to begin the weaning process.

The economic value of sustainability of the integrated crop-livestock system in relation to conventional systems

The objective of this study was to evaluate the potential of improving the economic value of integrated crop-livestock systems (ICLS) compared to conventional systems specialized in monoculture. The experimental area was 16.02 ha, divided into 18 paddocks of 0.89 ha each, organized in a randomized block design, with three replicates and six models of production systems: crop system [corn ( Zea mays ) grain production], livestock system (beef cattle under grazing conditions), and four ICLS, identified as: ICLS-1, corn integrated with Marandu palisadegrass [ Urochloa brizantha (Hoechst. ex A. Rich.) R.D. Webster cv. Marandu (syn. Brachiaria brizantha cv. Marandu] sown simultaneously without herbicide; ICLS-2, corn and Marandu palisadegrass sown simultaneously with herbicide; ICLS-3, corn and Marandu palisadegrass with lagged sowing; and ICLS-4, corn and Marandu palisadegrass sown simultaneously, with herbicide in rows and between-rows of corn. We demonstrated the economic impact analysis combined with the risk optimization and discounted cash flow techniques based on Monte Carlo simulation, considering price and productivity uncertainties. The indicators of added value and return on investment of ICLS had an economic advantage compared with conventional systems. It was also found that ICLS needed a smaller operational area than conventional systems for the economic break-even point. Integrated systems provide lower financial and operational risk levels and greater economic value per hectare compared with conventional systems specialized in monoculture.(AU)

Growth performance, reproductive parameters and fertility measures in young Nellore bulls with divergent feed efficiency.

The growth, sexual maturity and fertility-related parameters related of young Nellore bulls with divergent residual feed intake (RFI) raised on pasture were evaluated. After classification of 48 young males as low and high RFI (more and less efficient, respectively), the animals were evaluated for growth and reproductive parameters at 28-day intervals from 14.3 to 24.6 months of age. The semen was cryopreserved in the last sampling and fresh and post-thaw semen samples were evaluated. Low RFI bulls exhibited higher initial and final body weight (P < 0.05), but feed intake, body condition score and growth measures evaluated by carcass ultrasound were unaffected by RFI (P > 0.05). The scrotal circumference, sperm concentration, defects, and quality of fresh semen, and ultrasonographic testicular characteristics were unaffected by RFI (P > 0.05). However, velocity parameters such as average path and curvilinear velocities determined by computer-assisted sperm analysis of thawed semen submitted to the rapid thermoresistance test were improved (P < 0.05) in low RFI bulls, but this improvement in quality did not enhance in vitro sperm fertilizing ability. Our results demonstrated significant differences in metabolism and growth performance between bulls of divergent RFI. In addition, there was slight improvement in the semen quality of bulls with low RFI bulls, but this did not enhance in vitro fertilizing ability. Selection of beef bulls for RFI can be performed, which will result in economic benefits by improving the growth performance of the animals without affecting reproductive parameters.

Growth performance, reproductive parameters and fertility measures in young Nellore bulls with divergent feed efficiency

The growth, sexual maturity and fertility-related parameters related of young Nellore bulls with divergent residual feed intake (RFI) raised on pasture were evaluated. After classification of 48 young males as low and high RFI (more and less efficient, respectively), the animals were evaluated for growth and reproductive parameters at 28-day intervals from 14.3 to 24.6 months of age. The semen was cryopreserved in the last sampling and fresh and post-thaw semen samples were evaluated. Low RFI bulls exhibited higher initial and final body weight (P < 0.05), but feed intake, body condition score and growth measures evaluated by carcass ultrasound were unaffected by RFI (P > 0.05). The scrotal circumference, sperm concentration, defects, and quality of fresh semen, and ultrasonographic testicular characteristics were unaffected by RFI (P > 0.05). However, velocity parameters such as average path and curvilinear velocities determined by computer-assisted sperm analysis of thawed semen submitted to the rapid thermoresistance test were improved (P < 0.05) in low RFI bulls, but this improvement in quality did not enhance in vitro sperm fertilizing ability. Our results demonstrated significant differences in metabolism and growth performance between bulls of divergent RFI. In addition, there was slight improvement in the semen quality of bulls with low RFI bulls, but this did not enhance in vitro fertilizing ability. Selection of beef bulls for RFI can be performed, which will result in economic benefits by improving the growth performance of the animals without affecting reproductive parameters.(AU)

Economic gains from croplivestock integration in relation to conventional systems

The objective with this study was to calculate the total cost of maize production and beef cattle in permanent pasture activities in separate production systems (conventional) and integrated systems (maize production plus beef cattle), as well as to verify economic gains explained by the economy of scope. The first step for the development of the research was to obtain field experimental data. Six experimental treatments were studied: corn grain production, beef cattle in permanent pasture, and four integrated systems based on different crop and pasture sowings. The second step consisted in the collection, calculation, and allocation of variable and fixed costs to estimate costs of production in the systems. The crop-livestock integration showed economic gains in relation to conventional systems, which can be explained by the dilution of fixed costs and the presence of shareable inputs, resulting in economy of scope. It was also possible to demonstrate that total unit costs of both crop and livestock were lower in crop-livestock integration, showing that integrated systems resulted in economic benefits as compared with conventional ones.(AU)

Performance of Nellore females in tropical pastures during the rainy season when supplemented with molasses blocks / Desempenho de fêmeas nelore em pastagens tropicais, durante a estação chuvosa quando suplementadas com blocos de melaço

The objective of this study was to measure the effect of supplementation with molasses blocks compared with conventional mineral supplementation (with specific formulations for the rainy and dry season) in 92 7-month-old Nellore heifers (Experiment 1) and 40 primiparous 31-month-old Nellore cows (Experiment 2) in Marandu grazing areas. The following measurements were obtained: weight, supplement intake, blood urea and glucose in heifers (Experiment 1), supplement intake, cow weight, body score, calf weight and ruminal temperature and drinking events in primiparous females (Experiment 2). The average molasses block intake was 242 g day-1 per heifer, with an average weight gain of 0.290 kg day-1; the heifers who consumed the molasses blocks were heavier during the rainy season (P < 0.05; Experiment 1). In Experiment 2, molasses block intake varied from 77 to 821 g day-1 per primiparous female, and the average intake in the control group was between 100 and 370 g day-1. The primiparous females given molasses blocks displayed lower weight loss due to calving (P < 0.05) and retained higher body scores at 150 days postpartum (P < 0.05). Ruminal temperature (P < 0.05) and drinking events (P < 0.05) were higher in primiparous Nellore females given molasses blocks. Overall, molasses blocks effectively increased Nellore female performance during the rainy season in Marandu grass pastures.(AU)

Objetivou-se medir o efeito da suplementação utilizando blocos de melaço, em comparação à suplementação mineral convencional, em 92 novilhas Nelore de 7 meses de idade (Experimento 1) e 40 primíparas Nelore de 31 meses de idade (Experimento 2), com formulações específicas para épocas chuvosas ou secas em pastagens de capim Marandu. Também foram realizadas as seguintes medições: peso, consumo do suplemento, ureia e glicose em novilhas (Experimento 1) e consumo de suplemento, peso de vacas primíparas, condição corporal, peso de bezerros, temperatura ruminal e frequência da ingestão hídrica nas primíparas (Experimento 2). O consumo médio dos blocos de melaço, por novilha, foi de 242 g dia-1, com ganho de peso de 0,290 kg dia-1. As novilhas que consumiram os blocos contendo melaço tiveram maiores pesos durante a estação chuvosa (P < 0,05) (Experimento 1). No experimento 2, a ingestão de blocos de melaço variou de 77 a 821 g dia-1 por primípara, e a ingestão média no tratamento controle foi entre 100 e 370 g dia-1. As fêmeas primíparas tratadas com blocos de melaço apresentaram menor perda de peso devido ao parto (P < 0,05), e mantiveram escores corporais mais elevados aos 150 dias pós-parto (P < 0,05). A temperatura ruminal (P < 0,05) e a frequência do consumo de água (P < 0,05) foram maiores nas primíparas Nelore do tratamento com blocos de melaço. O uso de blocos de melaço incrementam o desempenho de fêmeas Nelore durante a estação chuvosa em pastagens de capim Marandu.(AU)

Performance of Nellore females in tropical pastures during the rainy season when supplemented with molasses blocks / Desempenho de fêmeas nelore em pastagens tropicais, durante a estação chuvosa quando suplementadas com blocos de melaço

The objective of this study was to measure the effect of supplementation with molasses blocks compared with conventional mineral supplementation (with specific formulations for the rainy and dry season) in 92 7-month-old Nellore heifers (Experiment 1) and 40 primiparous 31-month-old Nellore cows (Experiment 2) in Marandu grazing areas. The following measurements were obtained: weight, supplement intake, blood urea and glucose in heifers (Experiment 1), supplement intake, cow weight, body score, calf weight and ruminal temperature and drinking events in primiparous females (Experiment 2). The average molasses block intake was 242 g day-1 per heifer, with an average weight gain of 0.290 kg day-1; the heifers who consumed the molasses blocks were heavier during the rainy season (P < 0.05; Experiment 1). In Experiment 2, molasses block intake varied from 77 to 821 g day-1 per primiparous female, and the average intake in the control group was between 100 and 370 g day-1. The primiparous females given molasses blocks displayed lower weight loss due to calving (P < 0.05) and retained higher body scores at 150 days postpartum (P < 0.05). Ruminal temperature (P < 0.05) and drinking events (P < 0.05) were higher in primiparous Nellore females given molasses blocks. Overall, molasses blocks effectively increased Nellore female performance during the rainy season in Marandu grass pastures.

Objetivou-se medir o efeito da suplementação utilizando blocos de melaço, em comparação à suplementação mineral convencional, em 92 novilhas Nelore de 7 meses de idade (Experimento 1) e 40 primíparas Nelore de 31 meses de idade (Experimento 2), com formulações específicas para épocas chuvosas ou secas em pastagens de capim Marandu. Também foram realizadas as seguintes medições: peso, consumo do suplemento, ureia e glicose em novilhas (Experimento 1) e consumo de suplemento, peso de vacas primíparas, condição corporal, peso de bezerros, temperatura ruminal e frequência da ingestão hídrica nas primíparas (Experimento 2). O consumo médio dos blocos de melaço, por novilha, foi de 242 g dia-1, com ganho de peso de 0,290 kg dia-1. As novilhas que consumiram os blocos contendo melaço tiveram maiores pesos durante a estação chuvosa (P < 0,05) (Experimento 1). No experimento 2, a ingestão de blocos de melaço variou de 77 a 821 g dia-1 por primípara, e a ingestão média no tratamento controle foi entre 100 e 370 g dia-1. As fêmeas primíparas tratadas com blocos de melaço apresentaram menor perda de peso devido ao parto (P < 0,05), e mantiveram escores corporais mais elevados aos 150 dias pós-parto (P < 0,05). A temperatura ruminal (P < 0,05) e a frequência do consumo de água (P < 0,05) foram maiores nas primíparas Nelore do tratamento com blocos de melaço. O uso de blocos de melaço incrementam o desempenho de fêmeas Nelore durante a estação chuvosa em pastagens de capim Marandu.

Questões econômicas e gerenciais envolvidas na adoção e manutenção de sistemas de integração lavoura-pecuária / Economic and management issues involved in the adoption and maintenance of integrated crop-livestock systems

Os profissionais envolvidos nas cadeias de produção animal e vegetal se deparam com um cenário atual de contradições. De um lado, o aumento pela demanda de alimentos, de outro, as pressões sociais que questionam o modo como é conduzida a produção. Neste contexto, os sistemas integrados podem ser uma importante estratégia. A integração lavoura-pecuária (ILP) consiste na implantação de diferentes sistemas produtivos para a produção animal e vegetal na mesma área, em plantio consorciado, sequencial ou rotacional. Os benefícios mais divulgados em relação aos sistemas de ILP são os agronômicos ou produtivos, que são consequência da melhoria da qualidade do solo e maior controle de pragas. Contudo, para que os sistemas de ILP sejam adotados em escala comercial, representando de fato uma alternativa para a produção de alimentos, é necessário que a ciência aborde também questões econômicas e gerenciais envolvidas na adoção e manutenção dos sistemas de ILP.

Professionals involved in animal and plant production chains are currently confronted with a scenario of contradictions. There is a growing demand for food, on the other hand, social pressures question how food is produced. Within this context, integrated production systems could be an important strategy. Integrated crop-livestock systems (ICL) consists of the implementation of different systems for animal and agricultural production in the same area, planted concurrently, sequentially or in rotation. The most reported advantages of ICL systems are agronomic or productive benefits, which are the result of improved soil quality and better pest control. However, to implement ICL systems on large scale, representing an actual alternative for food production, scientific research must address the economic and management issues involved in the adoption and maintenance of these systems.

Questões econômicas e gerenciais envolvidas na adoção e manutenção de sistemas de integração lavoura-pecuária / Economic and management issues involved in the adoption and maintenance of integrated crop-livestock systems

Os profissionais envolvidos nas cadeias de produção animal e vegetal se deparam com um cenário atual de contradições. De um lado, o aumento pela demanda de alimentos, de outro, as pressões sociais que questionam o modo como é conduzida a produção. Neste contexto, os sistemas integrados podem ser uma importante estratégia. A integração lavoura-pecuária (ILP) consiste na implantação de diferentes sistemas produtivos para a produção animal e vegetal na mesma área, em plantio consorciado, sequencial ou rotacional. Os benefícios mais divulgados em relação aos sistemas de ILP são os agronômicos ou produtivos, que são consequência da melhoria da qualidade do solo e maior controle de pragas. Contudo, para que os sistemas de ILP sejam adotados em escala comercial, representando de fato uma alternativa para a produção de alimentos, é necessário que a ciência aborde também questões econômicas e gerenciais envolvidas na adoção e manutenção dos sistemas de ILP.(AU)

Professionals involved in animal and plant production chains are currently confronted with a scenario of contradictions. There is a growing demand for food, on the other hand, social pressures question how food is produced. Within this context, integrated production systems could be an important strategy. Integrated crop-livestock systems (ICL) consists of the implementation of different systems for animal and agricultural production in the same area, planted concurrently, sequentially or in rotation. The most reported advantages of ICL systems are agronomic or productive benefits, which are the result of improved soil quality and better pest control. However, to implement ICL systems on large scale, representing an actual alternative for food production, scientific research must address the economic and management issues involved in the adoption and maintenance of these systems.(AU)

Degradabilidade in situ do híbrido de sorgo e do capim-Tanzânia em vacas suplementadas no outono / In situ degrability of sorghum hybrid and Tanzânia guinea-grass in supplented cows during autumn

O experimento foi conduzido na Agência Paulista de Tecnologia dos Agronegócios, em Ribeirão Preto, com objetivo de avaliar o efeito da suplementação concentrada na degradabilidade in situ dos colmos e das folhas do híbrido de sorgo e do capim-tanzânia colhidos no outono com e sem suplementação de concentrado em vacas. Amostras de folhas e colmos das gramíneas colhidas no início do outono foram incubadas em quatro vacas mestiças canuladas no rúmen, avaliando-se a fração solúvel, fração potencialmente degradável, taxa de degradação (kd) e a degradabilidade efetiva (DE), utilizando-se o delineamento em quadrado latino (4x4). Houve diferença (P<0,001) da fração solúvel do colmo entre as gramíneas, e o híbrido de sorgo apresentou maior resultado. Não houve efeito dos tratamentos (P=0,52) na taxa de degradação (kd), mas houve diferença (P<0,0001) entre os tratamentos para as degradações efetivas a 2%/h, 5%/h, e 8%/h, sendo as degradabilidades efetivas do colmo do capim-tanzânia menores que do híbrido de sorgo. Os resultados observados para fração solúvel, fração potencialmente degradável e DE com taxa de passagem de 2%/h para o hibrido de sorgo foram em média 25,12%; 48,78% e 52,5%/h para colmo e 18,6%; 64,54% e 56,9%/h para as folhas, respectivamente. Para o capim-tanzânia as médias obtidas foram de 12,27%; 43,33% e 36,6%/h para colmo e 14,96%; 60,95% e 54,3%/h para as folhas, respectivamente. A fração solúvel do colmo e das folhas é maior no híbrido de sorgo, e a degradabilidade efetiva é maior apenas no colmo do sorgo. O uso de suplementação concentrada não interfere na degradabilidade ruminal quando os animais consomem folhas e colmos de híbrido de sorgo ou capim-tanzânia em sistema de pastejo no outono.

The trial was carried out at Agência Paulista de Tecnologia dos Agronegócios, Ribeirão Preto, to compare in situ degradability of dry matter of hybrid sorghum and Tanzania guinea grass, stem and leaves, on fall with and without concentrate on the diet of the cows. Samples of stem and leaves, harvested on fall, were incubated in four rumen-canulated cows, using a latin square design (4x4). The soluble fraction, the insoluble fraction potentially degradable, degradation rate (kd) and the effective degradation (ED) was estimated. There was difference (P<0.001) between grass species for soluble fraction of the stem and it was higher for hybrid sorghum. No influence of treatments (P=0.52) was met for degradation rate (kd) for stem fraction, but the effective (P<0.0001) degradation rate at 2%/h, 5%/h and 8%/h was higher for stem hybrid sorghum. The degradability of leaves was similar for grasses species. The results for soluble fraction, insoluble fraction potentially degradable and ED with passage rate of 2%/h for hybrid sorghum were 25.12%, 48.78% and 52.5% for stem and 18.6%, 64.54% and 56.9% for leaf, respectively. For Tanzania guinea grass the averages were 12.27%, 43.33% and 36.6% for stem and 14.96%, 60.95% and 54.3% for leaves, respectively. The soluble fraction is higher for stem and leaves of hybrid sorghum but the effective degradability is higher just for stem fraction of hybrid sorghum. The use of concentrate supplementation does not interfere in the rumen when animals consume leaves and stem of the sorghum hybrid or Tanzania grass in grazing systems in the fall.

Degradabilidade in situ do híbrido de sorgo e do capim-Tanzânia em vacas suplementadas no outono / In situ degrability of sorghum hybrid and Tanzânia guinea-grass in supplented cows during autumn

O experimento foi conduzido na Agência Paulista de Tecnologia dos Agronegócios, em Ribeirão Preto, com objetivo de avaliar o efeito da suplementação concentrada na degradabilidade in situ dos colmos e das folhas do híbrido de sorgo e do capim-tanzânia colhidos no outono com e sem suplementação de concentrado em vacas. Amostras de folhas e colmos das gramíneas colhidas no início do outono foram incubadas em quatro vacas mestiças canuladas no rúmen, avaliando-se a fração solúvel, fração potencialmente degradável, taxa de degradação (kd) e a degradabilidade efetiva (DE), utilizando-se o delineamento em quadrado latino (4x4). Houve diferença (P<0,001) da fração solúvel do colmo entre as gramíneas, e o híbrido de sorgo apresentou maior resultado. Não houve efeito dos tratamentos (P=0,52) na taxa de degradação (kd), mas houve diferença (P<0,0001) entre os tratamentos para as degradações efetivas a 2%/h, 5%/h, e 8%/h, sendo as degradabilidades efetivas do colmo do capim-tanzânia menores que do híbrido de sorgo. Os resultados observados para fração solúvel, fração potencialmente degradável e DE com taxa de passagem de 2%/h para o hibrido de sorgo foram em média 25,12%; 48,78% e 52,5%/h para colmo e 18,6%; 64,54% e 56,9%/h para as folhas, respectivamente. Para o capim-tanzânia as médias obtidas foram de 12,27%; 43,33% e 36,6%/h para colmo e 14,96%; 60,95% e 54,3%/h para as folhas, respectivamente. A fração solúvel do colmo e das folhas é maior no híbrido de sorgo, e a degradabilidade efetiva é maior apenas no colmo do sorgo. O uso de suplementação concentrada não interfere na degradabilidade ruminal quando os animais consomem folhas e colmos de híbrido de sorgo ou capim-tanzânia em sistema de pastejo no outono.(AU)

The trial was carried out at Agência Paulista de Tecnologia dos Agronegócios, Ribeirão Preto, to compare in situ degradability of dry matter of hybrid sorghum and Tanzania guinea grass, stem and leaves, on fall with and without concentrate on the diet of the cows. Samples of stem and leaves, harvested on fall, were incubated in four rumen-canulated cows, using a latin square design (4x4). The soluble fraction, the insoluble fraction potentially degradable, degradation rate (kd) and the effective degradation (ED) was estimated. There was difference (P<0.001) between grass species for soluble fraction of the stem and it was higher for hybrid sorghum. No influence of treatments (P=0.52) was met for degradation rate (kd) for stem fraction, but the effective (P<0.0001) degradation rate at 2%/h, 5%/h and 8%/h was higher for stem hybrid sorghum. The degradability of leaves was similar for grasses species. The results for soluble fraction, insoluble fraction potentially degradable and ED with passage rate of 2%/h for hybrid sorghum were 25.12%, 48.78% and 52.5% for stem and 18.6%, 64.54% and 56.9% for leaf, respectively. For Tanzania guinea grass the averages were 12.27%, 43.33% and 36.6% for stem and 14.96%, 60.95% and 54.3% for leaves, respectively. The soluble fraction is higher for stem and leaves of hybrid sorghum but the effective degradability is higher just for stem fraction of hybrid sorghum. The use of concentrate supplementation does not interfere in the rumen when animals consume leaves and stem of the sorghum hybrid or Tanzania grass in grazing systems in the fall.(AU)

Nitrogen and carbohydrate fractions in exclusive Tifton 85 and in pasture oversown with annual winter forage species / Fracionamento do nitrogênio e dos carboidratos de Tifton 85 exclusivo ou sobressemeado com forrageiras anuais

The experiment was undertaken at the Faculty of Agrarian and Veterinary Sciences (FCAV) Jaboticabal, São Paulo State, Brazil, during winter-spring-summer of 2001-2002, to determine the fractionation of nitrogen and carbohydrates in Tifton 85 (Cynodon dactylon Vanderyst x Cynodon nlemfuensis (L.) Pers), exclusively or oversown with winter annual forage species. Treatments comprised bristle oat (Avena strigosa Schreb), yellow oat (Avena byzantina C. Koch), triticale (X Triticosecale Wittmack), bristle oat + yellow oat, bristle oat + triticale, yellow oat + triticale, bristle oat + yellow oat + triticale seeded in Tifton 85 and sole crop (control). Experimental design was composed of completely randomized blocks with three replications. Fodder was cut 20 cm high (presence of winter forage) and 10 cm high (Tifton 85 pasture). Crude protein, total carbohydrate and the fractions of nitrogen compounds and carbohydrates were determined. Decrease was reported in the levels of chemical compounds in winter forage species and in Tifton 85 during the evaluation periods. The content of nitrogen compounds and carbohydrates varied widely during the evaluation period according to the morphological characteristics of grass species and botanical composition of pastures.

O experimento foi conduzido na FCAV ­ Campus de Jaboticabal, no período de invernoprimavera-verão de 2001-2002, com o objetivo de determinar o fracionamento de compostos nitrogenados e de carboidratos do Tifton 85 (Cynodon nlemfuensis Vanderyst x Cynodon dactylon (L.) Pers), exclusivo ou sobressemeado com forrageiras anuais de inverno. Os tratamentos testados foram: aveia preta (Avena strigosa Schreb); aveia amarela (Avena byzantina C. Koch); triticale (X Triticosecale Wittmack); aveia preta + aveia amarela; aveia preta + triticale; aveia amarela + triticale; aveia preta + aveia amarela + triticale, sobressemeados sobre Tifton 85 e, sem consorciação (testemunha). O delineamento experimental utilizado foi o de blocos completos ao acaso, com três repetições. O corte das forrageiras foi realizado a 20 cm de altura (presença de forrageiras de inverno) e 10 cm de altura (ausência das forrageiras de inverno). Foram determinados os teores de proteína bruta, carboidratos totais, e o fracionamento dos compostos nitrogenados e de carboidratos. Houve redução nos teores dos compostos químicos das espécies de forrageiras de inverno e no Tifton 85 ao longo dos períodos de avaliações. Os conteúdos de compostos nitrogenados e de carboidratos apresentaram grande variação durante os períodos avaliados, relacionando com as características morfológicas das espécies de gramineas e com a composição botânica das pastagens.

Respostas do híbrido de sorgo-sudão às adubações nitrogenada e potássica: características estruturais e produtivas / Nitrogen and potassium fertilization effects on a sorghum hybrid: forage production, structural traits

A pesquisa foi instalada no Setor de Forragicultura da FCAV/UNESP-Jaboticabal, para avaliar o híbrido de sorgo-sudão AG 2501C no outono e inverno. O manejo da pastagem foi conduzido, simulando o sistema de lotação intermitente. O experimento foi desenvolvido de março a setembro de 2002. A forrageira foi submetida a nove tratamentos: três doses de N (100, 200 e 300 kg/ha) e três doses de K (0, 80 e 160 kg/ha de K2O), em delineamento experimental de blocos casualizados com três repetições em esquema de parcelas subdivididas. As características estudadas foram massas, secas, inicial de planta inteira, folha e colmo e massa seca residual; relação lâmina/colmo; índice de área foliar (IAF); interceptação da radiação fotossinteticamente ativa (RFA) e coeficiente de extinção luminosa. Os tratamentos não influenciaram a massa seca inicial (MSI) e residual (MSR) da planta inteira, folha e colmo e massa seca residual. Os resultados médios para MSI, MSR, folha e colmo foram 2801,2; 964,7; 1462,8 e 1085,2 kg/ha de MS, por ciclo de pastejo, respectivamente. Houve redução da relação lâmina/colmo e da porcentagem de folhas, enquanto a porcentagem de colmos aumentou. Houve interação entre N e K para IAF, interceptação de luz e coeficiente de extinção.

This research was carried out in the Forage Section of FCAV/UNESP-Jaboticabal, to evaluate hybrid sorghum AG 2501C (Sorghum bicolor x Sorghum sudanense) during autumn/winter. Pasture management was accomplished by a simulation of intermittent stocking. The experiment was developed from March to September of 2002. The forage was submitted to nine treatments: three doses of N (100, 200, and 300 kg/ha) and three doses of K (0, 80, and 160 kg/ha of K2O) in a randomized block design with three replications in a split plot scheme. Characteristics including forage mass before grazing (FMBG), after grazing (residual), leaf and stem, leaf/stem ratio, leaf area index (LAI), interception of light, and light extinction coefficient (LEC) were evaluated. No differences for FMBG, residual, leaf, and stem were found. The averages were 2801.2, 964.7, 1462.8, and 1085.2 kg/ha of DM, per grazing cycle for FMBG, residual, leaf, and stem. There was significant interaction (p<0,01) between N and K for LAI, interception of light, and LEC.

Resposta do híbrido de sorgo-sudão à adubação nitrogenada e potássica: composição química e digestibilidade in vitro da matéria orgânica / Nitrogen and potassium fertilization effects on a sorghum hybrid: chemical composition and in vitro digestibility of organic matter

A pesquisa foi instalada no Setor de Forragicultura da FCAV/UNESP-Jaboticabal, objetivando avaliar a composição química e a digestibilidade in vitro da matéria orgânica (DIVMO) do híbrido de Sorgo-sudão cv. AG 2501C, no outono e inverno. O manejo da pastagem foi conduzido simulando o sistema de lotação intermitente. O experimento foi desenvolvido de março a setembro de 2002. A forrageira foi submetida a nove tratamentos: três níveis de nitrogênio (100, 200 e 300 kg de N/ha) e três níveis de potássio (0, 80 e 160 kg de K2O/ha), em delineamento experimental em blocos casualizados e parcelas subdivididas. A adubação nitrogenada e potássica não foram significativas para a DIVMO. O nitrogênio influenciou a proteína bruta (PB) com valores de 15,1; 16,4 e 15,7 por cento, a fibra em detergente neutro (FDN) com valores de 65,3; 65,8 e 64,5 por cento e fibra em detergente ácido (FDA) com 35,5; 37,8 e 39,6 por cento para 100; 200 e 300 kg N/ha. O potássio aumentou significativamente a lignina das plantas. O melhor nível obtido foi 100 kg/ha de nitrogênio, sem potássio.

The research was carried out in the Forage Section of FCAV/UNESP-Jaboticabal, to evaluate the chemical composition and the in vitro digestibility of organic matter (IVDOM) of the hybrid sorghum cv. AG 2501C (Sorghum bicolor x Sorghum sudanense) during autumn/winter. The management of pasture was conducted by a simulation of a rotational stocking. The experiment was developed from March to September 2002. The forage was submitted to nine treatments: three nitrogen levels (100, 220 and 300 kg/ha) and three potassium levels (0, 80 and 160 kg/ha) in a randomized blocks design and split plot. No effect of nitrogen and potassium fertilization on IVDOM was found. Nitrogen had influence on crude protein with values of 15.1, 16.4 and 15.7 percent of CP and 65.3, 65.8 and 64.5 percent of neutral detergent fiber (NDF) and 35.5, 37.8, 39.6 percent of acid detergent fiber (ADF), for 100, 200 and 300 kg N/ha. The potassium fertilization increased the lignin of plant. We concluded that, the best level was 100 kg/ha of nitrogen fertilization, without potassium.