Yield, chemical composition, and efficiency of use of nitrogen by Marandu grass

The objective of this study was to evaluate the effect of five nitrogen doses on the productive and quality characteristics and the use efficiency of Brachiaria brizantha cv. Marandu grass. The treatments consisted of four doses of nitrogen (0, 60, 120, 180 and 240 kg ha-1), distributed through a completely randomized design with four replicates. Samples of the material were collected to analyze productivity variables, concentrations of neutral detergent fiber, crude protein and neutral detergent insoluble nitrogen, and in vitro dry matter digestibility. The nitrogen use efficiency, recovery of the applied nitrogen (RAN) and agronomic efficiency of the applied nitrogen (AE) were calculated. Dry mass production increased by 1,624.67 (kg/ha) as the nitrogen doses were increased. The doses of nitrogen affected the concentrations of neutral detergent fiber (from 294.6 to 381.4 g.kg-1, in the leaf), crude protein (from 86.1 to 99.6 g.kg-1, in the leaf) and neutral detergent insoluble protein (from 402.9 to 396.2 g.kg-1 CP, in the leaf). Nitrogen use efficiency increased, whereas RAN and AE were not affected by the nitrogen doses. Nitrogen fertilization promotes improvement in productivity and chemical composition of Marandu grass, also improving the efficiency with which the grass utilizes the nitrogen

Avaliação biométrica e nutrientes das culturas de milho, milheto e sorgo

The objective of this work was to evaluate the biometric measurements and nutrient contents of the corn, sorghum, and pearl millet crops from 30 days after sowing up to ensiling time. The experiment was conducted in a randomized complete block design, in which the three crops were evaluated with eight replicates. Stem height and diameter and leaf length and width were measured to determine plant growth. In addition, samples were collected to evaluate plant chemical composition. For the characterization of nutrient accumulation and biometric evaluation, linear and nonlinear models were used. Dry matter accumulation did not differ between corn and sorghum, but decreased in pearl millet from the fiftieth day up to ensiling. Crude protein, ashes, and neutral detergent fiber tend to reduce over time. The biometric variables do not differ between corn, pearl millet, and sorghum from 30 days after sowing until ensiling time.O objetivo deste trabalho foi avaliar as medidas biométricas e o conteúdo de nutrientes das culturas de milho, sorgo e milheto desde 30 dias após a semeadura até o momento da ensilagem. O experimento foi conduzido em delineamento de blocos ao acaso, tendo-se avaliado as três culturas, com oito repetições. A altura e o diâmetro do caule e a largura e o comprimento das folhas foram medidos para determinar o crescimento das plantas. Além disso, foram coletadas amostras para avaliar a composição química das plantas. Para a caracterização do acúmulo de nutrientes e a avaliação biométrica, foram utilizados modelos lineares e não lineares. O acúmulo de matéria seca não diferiu entre o milho e o sorgo, mas diminuiu no milheto do quinquagésimo dia até a ensilagem. Proteína bruta, cinzas e fibras em detergente neutro tendem a diminuir com o tempo. As variáveis biométricas não diferem entre o milho, o milheto e o sorgo desde 30 dias após a semeadura até o momento da ensilagem

Evaluation of the availability of mass of forage: morphological responses and chemical composition of Tanzania grass subjected to two pasture-management strategies

The objective of this study was to evaluate the morphogenetic traits and chemical composition of Tanzania grass using a fixed rest period or according to light interception at 95%. The treatments consisted of evaluations of two Tanzania-grass pasture-management strategies: (1) LI95 - animals entered the paddocks when the pasture reached 95% of light interception (LI), with three days of paddock occupation; and (2) FR - the pasture was managed with a defoliation interval (DI) of 30 days, and three days of paddock occupation. The experimental area consisted of 4 ha, with 22 paddocks per treatments. Ten recently-calved cows were used per treatment in year 1, and eight cows were used per treatment in year 2. Sward height, forage mass, and morphological components and their chemical composition were evaluated. The management strategies used on the Tanzania grass pasture did not affect pasture mass or height in the pre- and post-grazing conditions, or the proportion of stems. However, the proportion of leaves was greater in the paddocks with 95% light interception. The crude protein content was higher in the paddocks with 95% light interception; the other nutrients were not affected. In conclusion, management adopting 95% light interception does not influence morphogenetic traits. Nevertheless, it promotes an increase in the crude protein content of grasses

Factors affecting feed efficiency in dairy goats

The objective of this study was to present some factors affecting feed efficiency in dairy goats. To develop our work, individual and average data from performance experiments with lactating goats were used. The following variables were evaluated: gross feed efficiency, adjusted feed efficiency, dry matter intake, milk-yield, 3.5% fat-corrected milk yield, dry matter digestibility, dietary neutral detergent fiber content, different roughage-to-concentrate ratios and body weight. The statistical analyses involved the application of descriptive and dispersion measures besides Pearson's correlation coefficient and linear regression analysis. The analyzed variables were highly correlated with feed efficiency. The feed efficiency of lactating goats was affected by the milk fat correction, dry matter digestibility, dietary fiber content, proportion of roughage in the diet and body weight. Among these factors, standardization of the milk fat appeared to be the most efficient in correcting the feed efficiency in lactating goats. Correction of some of these factors implies greater precision in the measurement of feed efficiency

Milk production of crossbred holstein × zebu on different pasture-management strategies

The objective of this study was to evaluate nutrient intake and digestibility, yield and components of milk from Holstein × Zebu cows on Tanzania grass pastures using a fixed-rest period or 95% light interception. The treatments consisted of evaluations of two Tanzania-grass pasture-management strategies: LI95 - when the pasture reached 95% light interception (LI), with 3 paddock-occupation days; and FR - the pasture was managed with a 30-days defoliation interval (DI) and 3 paddock-occupation days. Ten recently calved cows per treatment in year 1 and eight cows per treatment in year 2 were used, i.e. five cows per replicate in year 2 and four cows per replicate in year 2. Intake and digestibility of pasture nutrients, milk yield and milk composition were evaluated. The management strategies imposed on the Tanzania-grass pasture did not affect nutrient intake or digestibility. Milk yield and milk components were not affected by the management strategies, but milk yield per area unit was affected by the use of 95% light interception. The management strategy applying 95% light interception implies greater efficiency in the use of area, which translates to a higher milk yield per unit area, and thus it can be recommended to increase milk yield per area

Chromium yeast and ractopamine in diets for finishing pigs

Para avaliar o efeito do cromo levedura (CrL) e ractopamina (RAC) em rações sobre o desempenho, características da carcaça, qualidade de carne e variáveis sanguíneas, foi realizado um experimento com 96 suínos machos castrados híbridos comerciais com peso corporal médio inicial de 75,07 ± 3,9 kg, distribuídos em delineamento experimental em blocos casualizados, com seis tratamentos, oito blocos e dois animais por baia. Os tratamentos foram constituídos de planos nutricionais (PN) em dois períodos consecutivos: período 1 de 0 a 14 dias e o período 2 de 14 a 42 dias, respectivamente, compostos pelas rações: Controle/Ração Controle (RC/RC); Cromo levedura/Aminoácidos (CrL/AA); Cromo Levedura/Aminoácidos + Ractopamina (CrL/AA+RAC); Controle/Cromo Levedura (RC/CrL); Ração Controle/Aminoácidos + Cromo Levedura (RC/AA+CrL) e Cromo Levedura/Aminoácidos+Ractopamina+Cromo Levedura (CrL/AA+RAC+CrL). Maior peso final (PF) e ganho de peso diário (GPD) (P 0,05) o consumo diário de ração. Os melhores resultados de conversão alimentar (P0,05). O uso de cromo levedura e ractopamina promoveram alterações positivas sobre o desenvolvimento de células musculares nos suínos e na qualidade da carne que devem ser consideradas quando da utilização do mineral e o uso em associação a ractopamina revelou melhorias sobre o desempenho dos animais.To evaluate the effect of chromium yeast (CY) and ractopamine (RAC) on performance, carcass characteristics, meat quality, and blood, an experiment was conducted with 96 commercial castrated crossbred pigs with an average initial body weight of 75.07 ± 3.9 kg. Animals were distributed in a randomized-block experimental design with six treatments, eight blocks and two animals per stall. The treatments consisted of feeding plans (FP) in two phases: from 0 to 14 days; and from 14 to 42 days of age, respectively, composed of diets: Control/Control (CD/CD); Chromium yeast/Amino acids (CY/AA); Chromium yeast/Amino acids + Ractopamine (CY/AA+RAC); Control /Chromium yeast (CD/CY); Control/Amino acids + Chromium Yeast (CD/AA+CY); and Chromium Yeast/Amino Acids + Ractopamine + Chromium Yeast (CY/AA+RAC/CY). The greatest final weight and daily weight gain (P0.05) daily feed intake. The best feed-conversion results (P0.05). The use of chromium yeast and ractopamine or alone promoted positive alterations in the development of muscle cells in the pigs and in the meat quality, which should be considered when this mineral is used. The association of chromium yeast with ractopamine revealed improvements in the animal performance.Conselho Nacional de Desenvolvimento Científico e Tecnológic

Características das pastagens e desempenho produtivo de vacas leiteiras sob duas estratégias de manejo de pastejo

The objective of this work was to evaluate the supply, morphological and chemical composition of forage, performance and milk composition of crossbred cows managed in Megathyrsus maximus cv. Tanzania in intermittent grazing system with fixed and variable defoliation intervals according to the interception of 95% of photosynthetically active radiation by the canopy. The experimental design was a randomized complete block design with two treatments and two area replications. In each grazing cycle the supply, morphological composition, forage nutritive value, dry matter intake, milk production and composition were determined. The experimental area was 4.0 hectares, divided into two blocks of 2 hectares. Each block was subdivided into 22 pickets (11 for each treatment) totaling 44 pickets with an area of 909 m2 each. Significant differences (P < 0.05) were observed for leaf blade content, in vitro digestibility of dry matter and forage crude protein, dry matter intake, individual and area milk production and lactose content milk, being the highest values found in the pastures managed with variable defoliation interval. Thus, the defoliation interval defined by the 95% interception of the photosynthetically luminosity leads to higher leaf blade proportions in the forage canopy, resulting in higher individual milk yield and per unit area, but with a loss of protein and total solids contents of milk.Objetivou-se com esse trabalho avaliar a oferta, composições morfológica e química da forragem, o desempenho animal e a composição do leite de vacas mestiças manejadas em pastagens de Megathyrsus maximus cv. Tanzania em sistema intermitente de pastejo com intervalos de desfolhação fixos e variáveis de acordo com a interceptação de 95% da radiação fotossinteticamente ativa pelo dossel. O delineamento experimental utilizado foi de blocos ao acaso, com dois tratamentos e duas repetições de área, em cada ciclo de pastejo foi determinado a oferta, composição morfológica, valor nutritivo da forragem, consumo de matéria seca, produção e a composição do leite. A área experimental foi de 4,0 hectare, dividida em dois blocos de 2 hectare cada. Cada bloco foi subdividido em 22 piquetes (11 para cada tratamento) totalizando 44 piquetes com uma área de 909 m2 cada. Foram observadas diferenças significativas (P < 0,05) para a proporção de lâminas foliares, digestibilidade in vitro da matéria seca e proteína bruta da forragem, no consumo de matéria seca, na produção de leite individual e por área e no teor de lactose do leite, sendo os maiores valores encontrados nos pastos manejados com intervalo de desfolha variável. Sendo assim, o intervalo de desfolha definido pela interceptação de 95% da luminosidade fotossinteticamente ativa leva a maiores proporções de lâmina foliar no dossel forrageiro, resulta em maior produção de leite individual e por unidade de área, porém com prejuízo aos teores de proteína e sólidos totais do leite