Association of rainfall pattern with the disappearance of mineral mixtures fed cattle managed on tropical pastures.

The objective of the present study was to evaluate the association between rainfall and the disappearance of mineral mixtures in the supplementation of cattle on pasture. Supplement consumption and rainfall data were obtained from five experiments carried out between 2016 and 2022. The experiments lasted from 84 to 126 days and had 12 to 18 paddocks formed by Brachiaria spp. under grazing by beef cattle (n = 544), receiving mineral supplementation. Supplement disappearance (SD), difference between the amount offered and leftovers (considering intake and losses) and precipitation (PR), was measured over periods of 14 to 21 days. The periods (n = 565) were classified as very dry, dry, normal, rainy, and very rainy, using the Quantis method. The number of rainy days (RD) and the average precipitation per RD (APRD) per period and the average body weight (BW) of the animals in the periods were also determined. Linear regression analyses assessed the association between BW, PR, RD, and APRD. The average PR in the periods studied was 68.5 mm, ranging from 0.00 to 160.3 mm. Each period had up to six RD, with up to 129.5 mm precipitated. The average BW was 270 kg, ranging from 208 to 335 kg and the average SD was 82.2 g/animal/day, ranging from 0.52 to 176.7 g/animal/day. Differences in RD and APRD are consistent across precipitation classes. In the regression analysis, the model with the highest coefficient of determination was the one that contained the linear and quadratic terms for the RD variable. Including linear and quadratic terms of all variables in a multiple regression represented more than half of the variation in the disappearance of the supplement (R2 = 0.5823). There is no clear relationship between the intensity of precipitation, reflected in the form of classes, and the disappearance of supplements offered to cattle on pasture since dry and very rainy periods can be equivalent. However, variables that characterize the precipitation pattern are more relevant than animal live weight to explain existing variations in supplement disappearance. Among them, the frequency with which precipitation occurs (number of rainy days in the period) seems to be more important than the precipitation rate itself, probably because it is related to the volume of precipitation accumulated in the period.

Strategies of virginiamycin supplementation in the postweaning phase on growth performance and carcass quality of beef cattle.

The present study evaluated the effects of supplementing VM in grazing cattle during the rearing phase on performance and carcass quality of beef cattle in the finishing phase. Two experiments with a randomized block design were conducted in consecutive years to contrast two post-weaning supplementation strategies using VM at 45 mg/100 kg body weight (BW). In the first year, treatments were protein supplement in the dry season and mineral supplement in the rainy season versus the addition of VM both in the protein and mineral supplements. In the second year, was contrasted with protein supplement in the dry season and protein-energy supplement in the rainy season. Performance, carcass traits, and carcass quality were evaluated at the end of both phases. In Year 1, adding VM in mineral supplement increased final backfat thickness (P=0.05), backfat gain (P=0.06), final rump fat thickness (P=0.02), and rump fat gain (P=0.01). In the finishing phase, VM-treated cattle had a greater dry matter intake (P=0.03) and tended to show a greater backfat thickness than non-treated cattle (P=0.07). In Year 2, no VM effects were observed on post-weaning phase performance and carcass traits. However, cattle-fed VM during the post-weaning phase tended to show a lower feed conversion ratio (P=0.09) and had a significantly higher gross feed efficiency (P=0.03) than non-treated cattle at slaughter. Virginiamycin supplementation during rearing on pasture improves performance and carcass fattening in the growth phase and has a residual effect in the finishing phase that may reflect greater backfat thickness and gross feed efficiency.

Biological and economic responses to increasing nitrogen rates in Mombaça guinea grass pastures.

Nitrogen fertilization has been recognized as an essential tool towards the establishment of sustainable intensification of pasture-based livestock systems using tropical perennial grasses if, for a given ecosystem it is capable of increasing forage growth, stocking rates and animal performance. This study assessed pasture growth traits, nutritive value, animal and economic responses of Panicum maximum cv. Mombaça guinea grass pastures subjected to different levels of N fertilization (100 (N100), 200 (N200), and 300 (N300) kg N ha-1 yr-1). Pastures were managed under rotational stocking to maintain similar pre (80-90 cm) and post-grazing (45 cm) canopy heights. A partial budget and a Benefit-Cost Analysis were used to assess the economic returns on increasing N fertilization. N300 resulted in greater post-grazing herbage mass. A slightly higher neutral fiber and acid lignin detergent was observed at N100 (P < 0.05); crude protein increased linearly, and in vitro digestible organic matter reached maximum value at 265.4 kg N ha-1 yr-1. Annual averages of animal weight gain were 515, 590 and 660 g d-1, respectively, for N100, N200 and N300. There was a decrease from 3.7 to 1.9 kg of body weight gain per kg of additional N applied when increasing N rates from 100 to 200 and from 100 to 300 kg ha-1. The net profit improved with increasing N levels, but at reducing rates, reaching its maximum at the N300 level. The change from 100 to 200 kg N ha-1 presented the best return, with USD 3.73 for each additional dollar invested, while the change from 200 kg N ha-1 to 300 kg N ha-1 was economically less than optimal, recouping only USD 1.60 for each dollar. The N300 rate presented the highest net profit per hectare (accounting profit), even in a pessimist scenario (25% reduction in production). Despite being profitable, the N300 rate was less than optimal from an economic standpoint, since an additional 100 kg of Nitrogen ha-1 to change from N200 to N300 level reduced both the net returns and the Benefit-Cost ratio. Our results suggest that the economically optimal level of N fertilization for Mombaça guinea grass pasture should be between 200 and 300 kg ha-1.

Effect of supplementation of ewes in the final third of gestation on the development of their lambs

This study examined the effect of different supplementation strategies for ewes in the last third of gestation, kept on a deferred Brachiaria brizantha cv. Marandu pasture, on their performance and the growth curve of their lambs. A total of 54 ewes, of no defined breed, with an average weight of 41.10±3.10 kg, were used in a completely randomized design, divided into three groups (18 ewes per treatment). In total, 61 lambs were born, 28 females and 33 males, with 3.70±0.55 and 3.68±0.69 kg birth weight, respectively. Treatments were as follows: multiple mixture ad libitum, concentrate supplement at 0.4% live weight (LW), and concentrate supplement at 0.8% LW. Average daily weight gain (ADG, g/animal/day) and total weight gain (TWG, kg/animal) were evaluated in ewes and lambs. Reproductive efficiency indices were measured in the ewes and biometric variables in the lambs. The ADG and TWG of ewes in the last third of gestation were higher in animals supplemented at 0.8% LW. Reproductive efficiency results were superior in ewes supplemented at 0.4% LW. The effect of ewe supplementation on lamb growth curve as estimated by the Gompertz model did not reveal differences between the curves of lambs born to ewes that received supplementation at 0.4 and 0.8% LW. However, supplementing ewes with a multiple mixture induced a reduction in the growth curve parameters of their lambs. The use of concentrated supplementation, at levels of 0.4 and 0.8% of LW, provides greater productive and reproductive performance for ewes and lambs.(AU)

Morphogenetic and structural traits of Ipyporã grass subjected to nitrogen fertilization rates under intermittent grazing / Características morfogênicas e estruturais do capim-ipyporã submetido a doses de adubação nitrogenada sob pastejo intermitente

This study examined the effects of annual nitrogen (N) rates of 100 and 200 kg ha-¹ on the morphogenetic and structural traits of Ipyporã grass (Brachiaria brizantha × Brachiaria ruziziensis) under intermittent grazing during the seasons of the year. The experiment was laid out in a randomized-block design with two treatments and three area replicates. Ipyporã grass pastures were grazed by beef cattle. Morphogenetic and structural traits of the forage canopy were evaluated using the marked-tiller technique. Forage accumulation and tiller density (TD) were also evaluated. Significant interaction effects (P < 0.05) between N rates and seasons were observed for the rest period, leaf lifespan (LLS), phyllochron, stem elongation rate (SER) and final leaf length (FLL). During winter, the rest period was shorter (40 vs. 50 days) in the pastures fertilized with 200 kg ha-¹ N. Conversely, in winter, the pastures fertilized with 100 kg ha-¹ N showed higher LLS, SER and phyllochron values, but lower FLL values. There was no isolated effect of N rates (P > 0.05) on forage accumulation rate; leaf appearance, elongation or senescence rates; leaf:stem ratio; or TD. However, the effect of seasons was significant for these variables, with the highest values occurring during spring and summer. The use of 200 kg ha-¹ N in Ipyporã grass pastures reduces the seasonality of forage production.

O objetivo foi avaliar os efeitos das doses anuais de 100 e 200 kg ha-¹ de nitrogênio (N) sobre as características morfogênicas e estruturais do capim-ipyporã, em lotação intermitente durante as estações do ano. O delineamento experimental foi em blocos ao acaso, com dois tratamentos e três repetições de área. Os pastos de capim-ipyporã foram submetidos ao pastejo por bovinos de corte. Foram avaliadas as características morfogênicas e estruturais do dossel forrageiro por meio da técnica de perfilhos marcados. Também foi avaliado o acúmulo de forragem e a densidade populacional de perfilhos (DPP). Foi observada interação significativa (P < 0,05) das doses de N e estações do ano para o período de descanso (PD), duração de vida das folhas (DVF), filocrono, taxa de alongamento de colmos (TAlC) e comprimento final das folhas (CFF). Durante o inverno, o PD foi menor (40 vs 50 dias) nos pastos adubados com 200 kg ha-¹ de N. Em contra partida, no inverno, os pastos adubados com 100 kg ha-¹ de N apresentaram maiores valores para DVF, filocrono e TAlC, e menores para o CFF. Não foi observado efeito isolado de doses de N (P > 0,05) para as taxas de acúmulo de forragem; de aparecimento, alongamento e de senescência de folhas, relação folha:colmo e para a DPP. No entanto, o efeito das estações foi significativo para estas variáveis, com os maiores valores observados durante a primavera e verão. O uso de 200 kg ha-¹ de N para pastos de capim-ipyporã promove redução da estacionalidade de produção da forrageira.

Morphogenic and structural characteristics of Panicum cultivars during the establishment period in the Brazilian Northeast

This study aimed to evaluate the morphogenic and structural characteristics of six Panicum maximum cultivars during the establishment period. A completely randomized block design with four replicates and six treatments (Tamani, Mombaça, Massai, Tanzania, Aruana and Zuri cultivars) was used. Morphogenic (leaf appearance rate, leaf elongation rate e stem elongation rate), structural (final leaf length, tiller population density e number of leaves per tiller) and productive (forage mass, leaf blade mass, stem mass, senescent material mass and leaf:stem ratio) characteristics were evaluated. There was no difference (p > 0.05) between the cultivars in terms of the number of live leaves per tiller (2.95 leaves/tiller). Mombaça cultivar had (p 0.05) between cultivars. However, leaf appearance rate was higher (p < 0.05) in Tanzania (0.07 leaves tiller day-1) than in Aruana cultivar (0.05 leaves tiller day-1). Leaf blade mass was higher (p < 0.05) in Mombaça cultivar (1518.31 kg DM ha-1), whereas Massai showed higher (p < 0.05) leaf:stem ratio (9.25). Panicum cultivars Tamani, Tanzania and Massai establishment after 75 days, while the other cultivars establish at 105 days of sowing in the Brazilian Northeast.

Morphogenic and structural characteristics of Panicum cultivars during the establishment period in the Brazilian Northeast

This study aimed to evaluate the morphogenic and structural characteristics of six Panicum maximum cultivars during the establishment period. A completely randomized block design with four replicates and six treatments (Tamani, Mombaça, Massai, Tanzania, Aruana and Zuri cultivars) was used. Morphogenic (leaf appearance rate, leaf elongation rate e stem elongation rate), structural (final leaf length, tiller population density e number of leaves per tiller) and productive (forage mass, leaf blade mass, stem mass, senescent material mass and leaf:stem ratio) characteristics were evaluated. There was no difference (p > 0.05) between the cultivars in terms of the number of live leaves per tiller (2.95 leaves/tiller). Mombaça cultivar had (p < 0.05) higher canopy height (50.64 cm) compared with other cultivars. The highest (p < 0.05) tiller population density was observed in Tamani (235.90 tillers m-2) and Massai (201.60 tillers m-2) cultivars. Leaf lifespan (54.18 days), phyllochron (17.40 days/leaf) and leaf senescence rate (0.87 cm tiller day-1) were not different (p > 0.05) between cultivars. However, leaf appearance rate was higher (p < 0.05) in Tanzania (0.07 leaves tiller day-1) than in Aruana cultivar (0.05 leaves tiller day-1). Leaf blade mass was higher (p < 0.05) in Mombaça cultivar (1518.31 kg DM ha-1), whereas Massai showed higher (p < 0.05) leaf:stem ratio (9.25). Panicum cultivars Tamani, Tanzania and Massai establishment after 75 days, while the other cultivars establish at 105 days of sowing in the Brazilian Northeast.(AU)

Principal component analysis of steers performance and structural and nutritional characteristics of Mombasa grass / Análise de componentes principais entre o desempenho de novilhos de corte e as características estruturais e nutricionais do capim-mombaça

There is little information about whether the increased secondary productivity observed in pastures fertilized with high nitrogen rates is attributable to fluctuations in the nutritional value or pasture structural characteristics, or both. This study aimed to identify a set of factors (structural and nutritional characteristics) that best explain the performance of beef steers grazing Mombasa grass pastures under residual effects of nitrogen fertilizer. The data were collected in Mombasa grass pastures fertilized with increasing rates of nitrogen (N) (100, 200 and 300 kg ha-1) from 2015 to 2017. In 2018, nitrogen fertilization was not used in order to characterize a residual effect of the nutrient. Variables related to pasture structural characteristics such as forage accumulation rate (FAR), canopy height, forage mass (FM) and morphological components were evaluated. The study also evaluated the nutritional value of leaf blades and the performance of beef steers based on average daily gain (ADG) and stocking rate. Principal component analysis was performed using the dataset available. Most of the variance (99.6%) was explained by only two principal components (PCs), of which 90.0% corresponded to PC1. The most influential parameters for PC1, in order of priority, were: FAR, FM, leaf blade and stem masses. These variables were positively associated with stocking rate. Conversely, ADG was not associated with any variable. ADG was the most relevant variable for the second PC; however, this PC explained less variance (9.6%). The structural characteristics of the pasture (FAR, FM and morphological components mass) better explain the fluctuations in the performance of cattle on pastures of Mombasa grass under residual effects of nitrogen fertilizer. The stocking rate is an efficient parameter to support decision-making in managed pastures with variable stocking.(AU)

Há pouca informação sobre se o aumento da produtividade secundária observada em pastagens fertilizadas com altas taxas de nitrogênio é atribuível a flutuações no valor nutricional ou nas características estruturais das pastagens, ou em ambas. Objetivou-se identificar grupos de caraterísticas (estruturais e nutricionais) que melhor explicassem o desempenho de novilhos de corte em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. Os dados foram coletados em pastos de capim-mombaça que receberam três doses anuais de nitrogênio (N) (100, 200 e 300 kg ha-1) de 2015 a 2017. No ano de 2018 não foi utilizada adubação nitrogenada, para caracterizar o efeito residual do nutriente. As variáveis avaliadas foram relacionadas às características estruturais, taxa de acúmulo de forragem (TAF), altura do dossel, massa de forragem (MF) e dos componentes morfológicos. Também foi avaliado o valor nutritivo da lâmina foliar e o desempenho dos novilhos através do ganho médio diário (GMD) e da taxa de lotação. A partir do banco de dados foi realizada a análise de componentes principais. Os resultados demonstraram que 99,6% da variação no conjunto de dados foram explicados por apenas dois componentes principais (CPs), e 90,0% desse valor corresponde ao CP1. As características de maior magnitude para a diferenciação dos tratamentos no CP1, em ordem de prioridade foram: TAF, MF, massas de lâmina foliar e de colmo. Essas variáveis estiveram positivamente associadas com a taxa de lotação. Já o GMD não se relacionou com nenhuma variável. O GMD foi a variável de maior importância para o segundo CP, entretanto, esse CP teve pouca contribuição (9,6%) para a elucidação do resultados. As características estruturais (TAF e MF e compondes morfológicos) do pasto explicam melhor as oscilações em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. A taxa de lotação é um parâmetro eficiente para apoiar a tomada de decisão em pastos manejados com lotação variável.(AU)

Principal component analysis of steers performance and structural and nutritional characteristics of Mombasa grass / Análise de componentes principais entre o desempenho de novilhos de corte e as características estruturais e nutricionais do capim-mombaça

ABSTRACT: There is little information about whether the increased secondary productivity observed in pastures fertilized with high nitrogen rates is attributable to fluctuations in the nutritional value or pasture structural characteristics, or both. This study aimed to identify a set of factors (structural and nutritional characteristics) that best explain the performance of beef steers grazing Mombasa grass pastures under residual effects of nitrogen fertilizer. The data were collected in Mombasa grass pastures fertilized with increasing rates of nitrogen (N) (100, 200 and 300 kg ha-1) from 2015 to 2017. In 2018, nitrogen fertilization was not used in order to characterize a residual effect of the nutrient. Variables related to pasture structural characteristics such as forage accumulation rate (FAR), canopy height, forage mass (FM) and morphological components were evaluated. The study also evaluated the nutritional value of leaf blades and the performance of beef steers based on average daily gain (ADG) and stocking rate. Principal component analysis was performed using the dataset available. Most of the variance (99.6%) was explained by only two principal components (PCs), of which 90.0% corresponded to PC1. The most influential parameters for PC1, in order of priority, were: FAR, FM, leaf blade and stem masses. These variables were positively associated with stocking rate. Conversely, ADG was not associated with any variable. ADG was the most relevant variable for the second PC; however, this PC explained less variance (9.6%). The structural characteristics of the pasture (FAR, FM and morphological components mass) better explain the fluctuations in the performance of cattle on pastures of Mombasa grass under residual effects of nitrogen fertilizer. The stocking rate is an efficient parameter to support decision-making in managed pastures with variable stocking.

RESUMO: Há pouca informação sobre se o aumento da produtividade secundária observada em pastagens fertilizadas com altas taxas de nitrogênio é atribuível a flutuações no valor nutricional ou nas características estruturais das pastagens, ou em ambas. Objetivou-se identificar grupos de caraterísticas (estruturais e nutricionais) que melhor explicassem o desempenho de novilhos de corte em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. Os dados foram coletados em pastos de capim-mombaça que receberam três doses anuais de nitrogênio (N) (100, 200 e 300 kg ha-1) de 2015 a 2017. No ano de 2018 não foi utilizada adubação nitrogenada, para caracterizar o efeito residual do nutriente. As variáveis avaliadas foram relacionadas às características estruturais, taxa de acúmulo de forragem (TAF), altura do dossel, massa de forragem (MF) e dos componentes morfológicos. Também foi avaliado o valor nutritivo da lâmina foliar e o desempenho dos novilhos através do ganho médio diário (GMD) e da taxa de lotação. A partir do banco de dados foi realizada a análise de componentes principais. Os resultados demonstraram que 99,6% da variação no conjunto de dados foram explicados por apenas dois componentes principais (CPs), e 90,0% desse valor corresponde ao CP1. As características de maior magnitude para a diferenciação dos tratamentos no CP1, em ordem de prioridade foram: TAF, MF, massas de lâmina foliar e de colmo. Essas variáveis estiveram positivamente associadas com a taxa de lotação. Já o GMD não se relacionou com nenhuma variável. O GMD foi a variável de maior importância para o segundo CP, entretanto, esse CP teve pouca contribuição (9,6%) para a elucidação do resultados. As características estruturais (TAF e MF e compondes morfológicos) do pasto explicam melhor as oscilações em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. A taxa de lotação é um parâmetro eficiente para apoiar a tomada de decisão em pastos manejados com lotação variável.

Biological and economic performance of genetic groups under different diets / Desempenho biológico e econômico de grupos genéticos sob diferentes dietas

A grazing trial to evaluate biological and economic efficiencies for rearing young animals exclusively on pasture from weaning at 7 months of age, with average initial weight of 220 ± 12 kg, to slaughter was conducted from May 2006 to October 2007. Two levels of combined supplementation during the first dry period and four genetic groups (F1 Angus-Nellore; ½Braford-»Angus-»Nellore; ½Brahman-»Angus-»Nellore; and ⅝Charolais-⅜Nellore) were used following a 4 by 2 factorial arrangement and eight replications in a completely randomized design. During both dry periods, eight paddocks of deferredBrachiaria brizantha were utilized. During the first dry period, concentrated mix (CM) and protein-mineral mixture (PMM) were provided in quantities of 0.8% and 0.2% of body weight (BW), respectively, for 142 days. During the subsequent rainy period, the animals were transferred to eight guinea grass paddocks for 197 days. During the second dry period, the animals were allocated to the same eight palisade grass paddocks used during the previous dry season. Steers had received supplementary diet with the same CM used before at 0.8% of BW. Animals supplemented with CM gained more BW than those supplemented with PMM; however, during the rainy season, steers supplemented with PMM performed better than those receiving CM during the preceding dry period. Using concentrate since the first dry season is a risky option in economic terms, as only the Angus-Nellore group showed a positive but small gain.(AU)

O experimento foi conduzido de maio de 2016 a outubro de 2017 com o objetivo de avaliar as eficiências biológica e econômica de animais exclusivamente em pastos, da desmama ao abate. Foram avaliados dois níveis de suplementação alimentar combinados com quatro grupos genéticos durante o período seco: F1 Angus-Nelore; ½Braford-»Angus-»Nelore; ½Brahman-»Angus-»Nelore; e⅝Charolais-⅜Nelore, seguindo-se um arranjo fatorial 4 x 2 com oito repetições em delineamento completamente ao acaso. Durante os dois períodos secos avaliados, oito piquetes de Brachiaria brizantha diferida foram utilizados. No primeiro período seco, mistura concentrada (MC) e mistura mineral múltipla (MMM) foram fornecidas nas quantidades de 0,8 e 0,2% do peso vivo (PV), respectivamente, durante 142 dias. Durante a estação das águas subsequente, todos os animais foram transferidos para oito piquetes de Panicum maximum, por 197 dias. No segundo período seco, os animais foram alocados nos mesmos oito piquetes de braquiária utilizados no período seco anterior e receberam suplementação alimentar MC, no mesmo nível, 0,8% PV utilizado anteriormente. Animais suplementados com MC apresentaram maior ganho de peso que animais recebendo MMM; entretanto, durante o período chuvoso, estes animais apresentaram melhor desempenho que àqueles que receberam MC durante o período seco. Animais Angus-Nelore apresentaram desempenho superior aos demais cruzamentos, destacando-se a precocidade da raça em alcançar o ponto de abate. A utilização de suplemento concentrado desde a primeira seca após desmama é uma opção de risco econômico, uma vez que apenas o grupo genético Angus-Nelore apresentou pequeno incremento positivo de ganho.(AU)

Beef cattle performance in response to Ipyporã and Marandu brachiariagrass cultivars under rotational stocking management

The objective of this two-year study was to evaluate live weight gain per animal and per area and their relationships with the characteristics of BRS Ipyporã (Brachiaria ruziziensis × Brachiaria brizantha) and Marandu (Brachiaria brizantha) pastures. A completely randomized block design was used with two treatments and four replicates. The grazing method was rotational stocking, with variable stocking rate. Stocking rate was adjusted twice a week during the grazing period (six or seven days) and post-grazing canopy height target of 15 cm. Animals were weighed every 28 days. Pastures were evaluated pre-grazing to estimate forage accumulation rate, forage mass (FM), leaf (LP) and stem (SP) percentages, and nutritive value. In the post-grazing, FM, LP, and SP were evaluated. Marandu palisadegrass pastures had greater FAR, pre-grazing FM, and hence, a greater SR when compared with BRS Ipyporã. However, compared with Marandu, BRS Ipyporã showed greater LP, leaf:stem ratio, crude protein, and in vitro organic matter digestibility, resulting in greater individual live weight gain. The lesser stocking rate in Ipyporã pastures was compensated, providing a greater individual live weight gain of steers, resulting in a similar live weight gain per area for the two cultivars. Thus, BRS Ipyporã is a good alternative for the diversification of pastures in the Cerrado region.(AU)

Canopy structure and tillering of piatã and marandu grasses under two grazing intensities with sheep / Estrutura do dossel e perfilhamento dos capins-piatã e marandu sob intensidades de pastejo com ovinos

This study aimed to evaluate productive and structural parameters of Piatã and Marandu cultivars submitted to two grazing intensities. The experimental design was in randomized blocks with treatments in a 2 x 2 factorial arrangement (Marandu and Piatã palisadegrass x 25 and 30 cm residual heights). Intermittent stocking grazing method was used. Non-defined breed sheep were used as defoliation agents. Interaction between cultivars and height was not significant for any of the variables. In pastures managed at 25 cm post-grazing, a greater regrowth period was observed. Forage mass was on average 27% higher in Marandu palisadegrass in relation to Piatã palisadegrass, regardless of height. Dead material accumulation was higher in the Marandu cultivar. There was no difference in mass between the cultivars and heights for leaf blade or stem before and after grazing. The highest population density of tillers was observed in pastures lowered to 25 cm post-grazing height, with no difference between cultivars. In the third generation the appearance of tillers was higher in pastures managed at 25 cm. Post-grazing heights of 25 and 30 cm do not change pasture structure in Piatã and Marandu cultivars in pre-grazing; however, it is possible to obtain a shorter regrowth period if managed at 30 cm.

Objetivou-se avaliar parâmetros produtivos e estruturais das cultivares Piatã e Marandu submetidas a duas intensidades de pastejo. O delineamento experimental foi em blocos ao acaso, com os tratamentos em arranjo fatorial 2 x 2 (Marandu e Piatã x 25 e 30 cm de alturas de resíduo). O método de pastejo empregado foi o de lotação intermitente. Como agentes de desfolhação foram utilizados ovinos sem padrão racial definido. A interação entre cultivar e altura não foi significativa para nenhuma das variáveis. Nos pastos manejados a 25 cm de altura no pós-pastejo foi observado maior período de rebrotação. A massa de forragem foi em média, 27% maior no capim-Marandu em relação ao capim-piatã, independentemente da altura. O acúmulo de material morto foi maior na cultivar Marandu. Não houve diferença nas massas entre as cultivares e alturas para de lâmina foliar e colmo no pré e pós-pastejo. A maior densidade populacional de perfilhos foi observada em pastos rebaixados a 25 cm de altura pós-pastejo, sem diferença entre as cultivares. Na terceira geração o aparecimento de perfilhos foi superior nos pastos manejados a 25 cm. As alturas de pós-pastejo de 25 e 30 cm não modificam a estrutura dos pasto das cultivares de Piatã e Marandu no pré-pastejo, porém manejados a 30 cm é possível obter menor tempo de rebrotação.

Steer performance on deferred pastures of Brachiaria brizantha and Brachiaria decumbens / Desempenho de novilhos de corte em pastos diferidos de Brachiaria brizantha e Brachiaria decumbens

ABSTRACT: The objective of this study was to compare structural, morphological and bromatological characteristics of forage as well as performance of Caracu beef cattle (200 ± 9 kg of initial body weight) supplemented with a multi-mineral mixture (0.25% of body weight) on deferred pastures of Brachiaria brizantha 'Marandu' and Brachiaria decumbens 'Basilisk' under continuous grazing. After the pasture was grazed to 10 cm of height, in March 2014, both grasses were left to rest and subjected to a 126-day deferment period. The experimental period lasted from July to October 2014; the sward characteristics and the animal's weight were evaluated every 28 days. The highest forage mass was recorded in 'Marandu' grass, whereas the highest leaves percentage and lowest dead material percentage were observed in 'Basilisk' pastures. Similarly, the highest crude protein content (8.1 vs. 7.0 ± 0.2%), in vitro organic matter digestibility (57.7 vs. 53.9 ± 0.4%), lowest neutral detergent fiber content (69.2 vs. 72.7 ± 0.4%), and; consequently, the highest average daily gain (680 vs. 530 ± 0.04g animal-1) were recorded for 'Basilisk' pastures. 'Marandu' and 'Basilisk' deferment was associated with a multi-mineral mixture supplementation as a management alternative for rearing beef cattle during the drought periods. Because of the duration of the pasture recovery period in this study, B. decumbens pastures were more likely to achieve the highest animal performance.

RESUMO: O objetivo deste trabalho foi comparar as características estruturais, morfológicas e bromatológicas da forragem e o desempenho de bovinos de corte, da raça Caracu (200±9kg de peso inicial), suplementados com mistura mineral múltipla (0,25% do peso corporal) em pastos diferidos de Brachiaria brizantha , cv. 'Marandu', e Brachiaria decumbens , cv. 'Basilisk', sob pastejo contínuo. Após o rebaixamento dos pastos a 10cm de altura, realizado em março de 2014 por meio de pastejo, ambas as espécies foram vedadas e diferidas por 126 dias. O período experimental foi de julho a outubro de 2014, e as avaliações das características do pasto e as pesagens dos animais foram realizadas a cada 28 dias. A maior massa de forragem foi registrada em pastos de 'Marandu'. A maior porcentagem de folhas e a menor de material morto foram observadas para a 'Basilisk'. Os maiores teores de proteína bruta (8,1 vs 7,0 ± 0,2%), digestibilidade in vitro da matéria orgânica (57,7 vs 53, 9 ± 0,4%), os menores teores de fibra em detergente neutro (69,2 vs 72,7 ± 0,4%) e, consequentemente, o maior ganho médio diário (680 vs 530 ± 0,04g animal-1) foram registrados para a cv. 'Basilisk'. O diferimento de pastagens de 'Marandu' ou 'Basilisk' associado à suplementação com mistura mineral múltipla figura como alternativa de manejo para recria de bovinos de corte durante o período seco. Para a duração do período de vedação utilizada, pastos de B. decumbens são mais indicados para alcançar o maior desempenho animal.

Tillering dynamic and structural characteristics of tropical grasses under cutting management / Dinâmica de perfilhamento e características estruturais de gramíneas tropicais sob corte

This paper aimed to evaluate the dynamics of tillering, tiller density and structural characteristics of Brachiaria brizantha, Panicum maximum and Cenchrus ciliaris under a cutting regime. The utilized design was randomized blocks with six treatments (cultivars) and three replications. The evaluations were conducted from May to September 2011, with the data grouped into two periods, rainy season and beginning of the dry season. The greatest tiller population density was observed in the Massai cultivar, averaging 1,019 tillers.m-2. The tiller mortality rate was higher for Mombaça and less for Piatã cultivars. The highest values for forage mass, percentage of leaf blades and relations between green mass:dead mass were observed in Brachiaria brizantha and Panicum maximum cultivars. Panicum and Brachiaria cultivars have shown to be promising for cultivation in the transition areas between the Atlantic Forest and Caatinga biomes in Northeastern Brazil. Cenchrus cultivars are less productive in environments without restriction of abiotic factors.

Objetivou-se avaliar a dinâmica de perfilhamento, a densidade populacional de perfilhos e as características estruturais de cultivares de Brachiaria brizantha, Panicum maximum e Cenchrus ciliaris em regime de corte. O delineamento utilizado foi em blocos ao acaso com seis tratamentos (cultivares) e três repetições. As avaliações foram realizadas de maio a setembro de 2011, sendo os dados agrupados em dois períodos, águas e início da seca. A maior densidade populacional de perfilhos foi observada na cultivar Massai com média de 1019 perfilhos/m2. A taxa de mortalidade de perfilhos foi maior na cultivar Mombaça e menor na Piatã. Os maiores valores para massa de forragem, percentual de lâminas foliares e relações entre massa verde:massa morta foram observados nas cultivares de Brachiaria brizantha e Panicum maximum. As cultivares de Panicum e Brachiaria se mostraram promissoras à utilização em áreas de transição entre os biomas de Mata Atlântica e Caatinga na Região Nordeste do Brasil. As cultivares de Cenchrus são menos produtivas em ambientes sem restrição de fatores abióticos.

Características morfogênicas e acúmulo de forragem de gramíneas forrageiras sob corte / Accumulation of forage and morphogenic responses in forage grass by cutting

Objetivou-se avaliar e as características morfogênicas e o acúmulo de forragem de três gêneros de gramíneas, Brachiaria, Panicum e Cenchrus em regime de corte. O delineamento utilizado foi em blocos ao acaso com parcelas subdivididas. Houve efeito de interação entre cultivar e época de avaliação para a taxa de aparecimento de folhas, alongamento de colmos, duração de vida das folhas e senescência de folhas. As cultivares Áridus e Biloela (Cenchrus) apresentaram os menores Filocronos, seguidos da cultivar Piatã (B. brizantha). A taxa de alongamento de folhas e seu comprimento final foram maiores no período das chuvas, para todas as cultivares. As cultivares Massai e Mombaça apresentaram os maiores comprimentos de folha, mas os menores números de folhas vivas por perfilho. As cultivares Áridus e Biloela as menores taxas de acúmulo de lâminas foliares em relação ás demais. O maior fluxo de tecidos observado no gênero Cenchrus, não foi suficiente para superar a maior de produtividade das cultivares dos gêneros Panicum e Brachiaria.

This study aimed to evaluate the accumulation of forage and the morphogenesis of three genera Brachiaria, Cenchrus and Panicum in cutting regime. The experimental design was a randomized block with three replicates and six treatments. After each cut were evaluated for forage production, appearance and elongation rates of leaves and stem final leaf length, number of green leaves, leaf life span, rate of senescence of leaves. For herbage accumulation rate was higher in the cv. Xaraes, which is more than double the cumulative cv. Aridus, the lowest rate among cultivars. As for leaf appearance rate and leaf elongation was higher in the rainy season only for cultivars Aridus Biloela and the other showed no difference between the evaluation periods. Cultivars Aridus, Biloela and Piata obtained the highest number of leaves per tiller, differing from Mombaça, Massai and Xaraes that showed the lowest values. The lower values of leaf life span were found in the rainy season to cultivate Aridus, Biloela and Mombaça. Except Aridus, which showed a higher rate of senescence of leaves in the rainy season, others grasses did not differ between the evaluation periods. We conclude that the highest rates of leaf appearance and number of green leaves found on the cultivars of the genus Cenchrus, were not enough to overcome the greatest potential for producing forage cultivars of the genera Panicum and Brachiaria. The grasses tested showed potential for use in the Northeast, but were influenced by seasons, mainly due to a decrease in rainfall.

Características estruturais do dossel e acúmulo de forragem em gramíneas tropicais, sob lotação intermitente e pastejada por ovinos / Canopy plants and forage accumulation in tropical grasses, under intermittent stocking and pastured by sheep

Objetivou-se com este estudo avaliar o acúmulo de forragem e as características estruturais do dossel de gramíneas forrageiras tropicais sob lotação intermitente na época das águas. Os tratamentos constituíram de quatro cultivares de gramíneas: Aruana, Marandu, Massai e Piatã pastejadas por ovinos sob lotação intermitente. Foram avaliadas as massas e os componentes da forragem no pré-pastejo em dois estratos, de 0-25 e de 25-50 cm, e no pós-pastejo; e o acúmulo de forragem. Não houve diferença entre os períodos de ocupação e de descanso entre as cultivares, para as variáveis avaliadas. A cv. Massai obteve a maior massa seca de forragem (MSF) nos dois estratos, além da maior densidade volumétrica (DV) e massa de material morto (MMM) no estrato 0 a 25 cm. No pós-pastejo dos pastos de Massai foram observadas as maiores MSF, DV e MMM. Os maiores acúmulos e taxa de acúmulo de lâminas foliares foram observados nos pasto de Massai. O pré-pastejo a 50 cm para as cultivares avaliadas, resulta em valores elevados para massa e proporção dos componentes de colmo e/ou material morto no dossel, além de excesso de forragens no pós-pastejo. As cultivares avaliadas são produtivas e adequadas para cultivo na região Nordeste, apresentando resultados de taxas de acúmulos de forragem e de lâminas foliares próximos a produção em outras regiões do Brasil.

The objective of this study was to evaluate the structural characteristics of canopy and herbage accumulation of tropical forage under intermittent stocking in the rainy season. Treatments consisted of four cultivars of grasses: Aruana, Marandu, Massai and Piata grazed by growing sheep. The masses and the grass components were evaluated on the pre-grazing in two layers, 0-25 and 25-50 cm, on the residual herbage; and forage accumulation. There was no difference between the periods of occupation and rest among cultivars. The cv. Maasai had the highest herbage dry matter (MSF) in two strata, the highest density (HD) and mass of dead material (MMM) in 0-25 cm. In the residual mass of Massai were observed the biggest MSF, DV and MMM. The highest accumulation rate and leaf accumulation was observed in Massai guineagrass. The pre-grazing height of 50 cm resulting in high mass components and proportions of stem and/or dead material in the canopy, and high forage mass in the residue. The cultivars are productive and suitable for cultivation in the Northeast region, showing good results for rates of accumulation of forage and leaf blades.

Acúmulo de forragem, características morfogênicas e estruturais do capim-marandu sob alturas de pastejo / Herbage accumulation, morphogenetic and structural characteristics in marandu palisadegrass under grazing heights

Os objetivos deste estudo foram avaliar as características morfogênicas e estruturais e o acúmulo de forragem do capim-marandu, submetido a três alturas de pastejo, sob lotação contínua. O delineamento experimental foi de blocos completos casualizados, com duas repetições e três alturas: 15; 30 e 45cm. O pasto manejado com 15cm de altura apresentou as maiores taxa de aparecimento de folhas e densidade de perfilhos basilares. O acúmulo de forragem foi semelhante entre as alturas de pastejo. Com base nas características da planta, o capim-marandu pode ser utilizado entre 15 e 45cm de altura do dossel.

The objectives of this study were to evaluate the morphological and structural characteristics and the herbage accumulation, in (Brachiaria brizantha cv. 'Marandu') marandu palisadegrass pastures subjected to three grazing heights under continuous stocking. It was used a randomized block design, with two replicates and three sward heights 15, 30 and 45cm. The biggest leaf appearance and the smallest basal tiller densities decreased were found in 15cm pasture The herbage accumulation was similar among the pastures managed with different grazing intensities. The marandu palisadegrass presents high management flexibility, and may be utilized between 15 and 45cm sward height.

Ingestão de matéria seca por novilhas de corte em pastagem de milheto / Dry matter intake by beef heifers in a Pearl Millet pasture

Em pastagem de milheto (Pennisetum americanun (L.) Leeke), foram avaliadas a ingestão de matéria seca (MS) da forragem por novilhas de corte e a massa de bocado. Utilizou-se o delineamento inteiramente casualizado com medidas repetidas no tempo, com dois tratamentos de massas de lâmina foliar (600 e 1.000kg ha-1 de MS), mantidos por lotação contínua e com ajuste de carga, e três repetições de área. A ingestão de matéria seca foi estimada por meio do uso de óxido de cromo (Cr2O3) como indicador da produção fecal e da fibra em detergente ácido indigestível como indicador interno. Os parâmetros qualitativos avaliados na forragem foram a fibra em detergente neutro, a digestibilidade in vitro da matéria orgânica e o teor de proteína bruta. Bocados mais pesados foram observados quando o milheto foi manejado com 1.000kg ha-1 de MS de lâminas foliares, mesmo que as novilhas tenham ingerido a mesma quantidade de matéria seca, 1,8 por cento do peso corporal, nas duas massas de lâminas foliares. A pastagem de milheto manejada com massas de lâminas foliares de 600 ou 1.000kg ha-1 de MS proporciona aos animais em pastejo oportunidade semelhante de consumo de forragem.

It was evaluate the dry matter (DM) herbage intake by beef heifers and the bite mass on a Pearl Millet (Pennisetum americanun (L.) Leeke) pasture. The experimental design was completely randomized with repeated measures in time, two leaf blade mass (600 and 1,000kg ha-1 of DM), which were maintained by continuous stocking with variable stocking rate, and three replicate areas. The herbage intake was evaluated using chromic oxide (Cr2O3) as a faecal production indicator and the acid detergent indigestible fiber as an internal indicator. The qualitative parameters evaluated in the forage were the neutral detergent fiber, in vitro organic mater digestibility and the crude protein content. The heavier bites were achieved in a Pearl Millet pasture managed with 1,000kg ha-1 of leaf blade dry matter (DM) even though the steers have eaten the same dry matter amount, 1.8 percent of live weight, in the two leaf blade mass. The Pearl Millet pasture managed with leaf blade herbage mass of 600 or 1,000kg ha-1 of DM provides to the grazing animals similar opportunity of herbage intake.

Manejo da pastagem de milheto para recria novilhas de corte / Pearl Millet pasture management for rearing of beef heifers

Neste trabalho foram avaliados o desempenho de novilhas de corte e o retorno econômico da pastagem de milheto (Pennisetum americanum (L.) Leeke) manejada em duas massas de lâminas foliares (MLF). As MLF observadas foram de 642 e 1.024kg ha-1 de matéria seca (MS) e denominadas de '600' e '1.000'. Os valores de ganho de peso diário, carga animal, ganho de peso por área e escore de condição corporal foram semelhantes (P>0,05) nas massas de lâminas foliares avaliadas. A utilização de milheto, com massa de lâminas foliares com valores entre 600 e 1.000kg ha-1 MS, promove ganhos individuais satisfatórios em novilhas de corte, que permitem o seu adequado desenvolvimento para acasalamento aos 18-20 meses, e o retorno financeiro direto médio de R$2,9 para cada real investido.

A study was conducted to evaluate the influence of Pearl Millet pasture (Pennisetum americanum (L.) Leeke) leaf lamina mass (LLM) on beef heifers performance and financial return. The observed LLM were 642 and 1.024kg ha-1 of dry matter (DM) and identified as '600' and '1000'. Daily weight gain, stocking rate, gain per area and body condition score averages were not affected (P>0.05) by changes on LLM. Pearl millet pasture managed between 600 and 1000kg ha-1 of LLM promotes satisfactory beef heifers individuals gains, which allows their mating at 18/20 months of age and average direct financial return of 2.9 for each real invested.