Resumo Objetivou-se avaliar os efeitos dos manejos do pastejo ponta e repasse combinados a substituição parcial da proteína do suplemento por nitrogênio ureico sobre o consumo e digestibilidade dos nutrientes, composição do leite e balanço de nitrogênio de vacas primíparas da raça Girolanda. As vacas foram alocadas em dois quadrados latinos 4 x 4 compostos de quatro animais cada e quatro tratamentos em um esquema fatorial 2 x 2. Os suplementos foram formulados para um consumo de 0,6% do peso corporal: sem utilização de nitrogênio ureico; ou com 21% de nitrogênio ureico em sua composição. O manejo do pastejo de ponta melhorou o consumo e a digestibilidade dos nutrientes. O suplemento contendo ureia excretou 47% a mais de N urina (g/dia) em comparação ao suplemento sem ureia. A combinação entre o suplemento sem ureia e o manejo de pastejo ponta apresentou maior ingestão e retenção de nitrogênio e maior N retido (%N digerido). A combinação entre o suplemento contendo 21% de nitrogênio ureico e o pastejo de ponta pode ser utilizada sem prejuízos aos parâmetros nutricionais e produtivos das vacas.

Abstract This study aimed to evaluate the effect of the first and last stocking strategies combined with a partial substitution of the protein from the supplement for urea nitrogen on nutrient intake and digestibility, milk composition, and nitrogen balance of primiparous Girolando cows. The cows were allocated to a double 4 × 4 Latin square composed of four animals and four treatments in a 2 × 2 factorial arrangement. Supplements were formulated to provide an intake of 0.6% body weight, with and without the inclusion of 21% urea nitrogen in their composition. The first stocking management method improved nutrient intake and digestibility. Supplementation with urea led to a 47% higher excretion of urine N (g/day) than the urea treatment. The combination of the supplement without urea and the first stocking provided higher intake and retention of nitrogen and higher retained-N levels (%digested N). The combination of a supplement containing 21% urea nitrogen and the first stocking can be used without compromising the nutritional and productive parameters of the cows.

Abstract The purpose of this study was to examine the growth and senescence dynamics of Digitaria eriantha cv. Survenola as a response to several canopy heights (25, 35, 45, and 55 cm) of harvests in two seasons of the year (rainy and dry). The experiment was established at the Federal University of Sergipe, in São Cristóvão - SE, Brazil, from 03/26/2015 to 03/28/2016, under a randomized-complete-block design with four replicates. Plots were irrigated, and upon reaching the pre-established canopy heights, they were cut to a 10 cm-residual height. Increasing canopy heights in the dry season led to lower tiller density, for basal and aerial tillers. However, irrespective of tiller type and season, this variable increased after the rest period. Light interception rose with canopy heights (P<0.05) in the dry period and it showed a quadratic response in the rainy season. Greater canopy heights led to a higher (P<0.05) daily leaf senescence rates and daily stem growth rates. Regardless of the season, the total accumulation and net herbage accumulation rates of basal tillers increased as canopy heights did. The greatest canopy height promoted the daily stem production, whereas the lowest height did not allow the grass to express its production potential. The defoliation-height range of 35 to 45 cm is the most recommended, as it favors the control of stem growth and leaf senescence.

Resumen El objetivo del estudio fue conocer la dinámica del crecimiento y senescencia del forraje de Digitaria eriantha Steud. cultivar Survenola al alcanzar diferentes alturas de corte (25, 35, 45 y 55 cm), en dos épocas del año (lluvias y seca). El experimento se condujo en la Universidad Federal de Sergipe, en San Cristóbal-Sergipe, entre el 26/03/2015 y el 28/03/2016, con un diseño de bloques completos aleatorizados y cuatro repeticiones. Las unidades experimentales fueron irrigadas, y al alcanzar las plantas las alturas preestablecidas, se cortaron a 10 cm sobre el nivel del suelo. Las dos alturas de rebrote mayores redujeron en la época seca la densidad poblacional de tallos basales y aéreos; sin embargo, independientemente del tipo de tallo y la época del año, la densidad de población de tallos aumentó durante el período de descanso. La intercepción de luz en la época seca se incrementó (P<0.05) en las alturas de corte mayores, y en la época de lluvias su comportamiento fue cuadrático. Las alturas de corte mayores aumentaron (P<0.05) la tasa diaria de senescencia de las hojas y la tasa diaria de crecimiento de los tallos basales y aéreos. Las tasas de acumulación total y acumulación neta de forraje de tallos basales, independientemente de las épocas, tuvieron una relación positiva con el incremento en las alturas de corte. La mayor altura de corte produjo la mayor producción diaria de los tallos; además, la menor altura de corte no permitió a la gramínea expresar su potencial productivo. El intervalo de defoliación entre las alturas de 35 a 45 cm es el más indicado, pues favorece el control en el crecimiento del tallo y la senescencia de las hojas.

ABSTRACT. The objective of this study was to verify the activity of invertases in Estilosantes under the influence of cultivation systems and nitrogen fertilization in two seasons. The experiment was conducted in the Xaraés area, where Estilosantes was planted according to a 2 x 2 factorial scheme with two cultivation systems (monoculture and mixed pasture) in the absence or presence of fertilization (75 kg of N ha-1). A randomized block design with four replications was used. The neutral cytosol (Inv-N), vacuole acid (Inv-V) and cell wall acid (Inv-CW) invertase activity and reducing sugar contents in the leaves and stems were evaluated and analyzed by a 5% probability F-test. The interaction between cultivation systems and nitrogen fertilization was significant for Inv-N in the leaves in the summer, such that greater activity occurred in response to the mixed pasture system and nitrogen fertilization. Nitrogen increased the activity of the Inv-N in the stem in both periods, increased the activity of Inv-V in the leaf in the summer, and decreased the activity of Inv-CW in the fall. This cultivation system influenced the activity of Inv-N regardless of the period of the year and did not interfere with the activities of the acid invertases. The invertases did not show regular changes in relation to nitrogen fertilization.

O objetivo deste estudo foi avaliar as correlações existentes entre a ingestão de nutrientes e comportamento ingestivo de novilhos mestiços na fase pós-desmame em pastagem de Brachiaria brizantha cv. Marandu, durante o período chuvoso. Vinte e dois animais foram distribuídos em um delineamento experimental inteiramente casualizado, com dois tipos de suplemento e onze repetições, administrados sob pastejo rotacionado, em uma área de 6,5 ha. A análise de correlação linear de Pearson foi realizado entre as variáveis de comportamento e os valores das variáveis de desempenho. Os coeficientes de correlação foram testados pelo teste de t. O ganho de peso médio diário (GMD) apresentou correlação positiva com os tempos passados em ruminação, comendo no cocho e tempo de mastigação total. Foi observada uma correlação positiva entre o tempo ocioso e conversão alimentar (CA). A taxa de bocados e o número de bocados por dia apresentaram correlações positivas com GMD. Foram encontradas correlações positivas entre as variáveis eficiência ruminação da matéria seca (MS) e da fibra em detergente neutro (FDN) com GMD. O comportamento ingestivo tem uma influência direta sobre o desempenho produtivo de novilhos mestiços desmamados em pasto durante o período chuvoso. A eficiência de ruminação melhorou quando os animais foram alimentados com suplementação proteica, o que levou a uma melhor utilização do alimento ingerido.

The objective of this study was to evaluate the correlations existing between nutrient intake and ingestive behavior of crossbred steers in the post-weaning phase on Brachiaria brizantha cv. Marandu, during the rainy period. Twenty-two steers were distributed into a completely randomized design, with two types of supplement and eleven replications, managed under rotational grazing, in a 6.5 ha area. Pearson's Linear Correlation analysis was performed between the behavior variables and the performance variables values. The correlation coefficients were tested by the t test. The average daily gain (ADG) showed positive correlation with the times spent ruminating and eating at the trough and total chewing time. Positive correlation was observed between the idle time and feed conversion (FC). The bite rate and the number of bites per day presented positive correlations with ADG. Positive correlations were found between the variables rumination efficiency of dry matter (DM) and of neutral detergent fiber (NDF) with ADG. The ingestive behavior has a direct influence on the productive performance of crossbred steers post-weaned on pasture during the rainy period. Rumination efficiency improved when the animals were fed protein supplementation, which led to better utilization the ingested feed.

Objetivou-se avaliar a utilização de suplemento mineral e suplemento mineral proteico na terminação de novilhos Nelore em pastejo de Brachiaria brizantha, no período das águas, e suas implicações sobre o consumo de forragem, o desempenho animal e a digestibilidade aparente dos nutrientes. A parte de campo foi implantada numa área de 26 ha, dividida em quatro piquetes de aproximadamente 6,5 hectares (ha), formados de Brachiaria brizantha cultivar Marandu. Foram utilizados 18 novilhos Nelore, com 28 meses, peso vivo de 400,5 ± 7,5kg e castrados, distribuídos em dois tratamentos: suplementação mineral até a terminação e suplementação mineral proteica de baixo consumo até a terminação. Não houve efeito sobre o consumo de pastagem, da fibra em detergente neutro, proteína bruta, extrato etéreo, carboidratos não fibrosos, cinzas e nutrientes digestíveis totais. O desempenho animal e a conversão alimentar não sofreram efeito da suplementação. Não houve efeito sobre o coeficiente da digestibilidade da matéria seca, matéria orgânica, proteína bruta, extrato etéreo e da fibra em detergente neutro. Houve efeito da suplementação com sal proteinado sobre a digestibilidade dos carboidratos não fibrosos. É desnecessário a suplementação com sal proteinado na época das aguas.

This study aimed to evaluate the use of mineral and mineral supplement protein in finishing Nellore grazing Brachiaria brizantha during the rainy season and its implications for forage intake, animal performance and nutrient digestibility. The fieldwork was located in an area of 26 ha, divided into four paddocks of approximately 6.5 hectares (ha), formed Brachiaria brizantha Marandu. We used 18 Nellore with 28 months live weight of 400.5 ± 7.5kg and castrated in two treatments: mineral supplementation until the termination and mineral supplementation of low protein intake to termination. There was no effect on the consumption of pasture, neutral detergent fiber, crude protein, fat, non-fiber carbohydrates, ash and total digestible nutrients. The animal performance and feed conversion were not affected by supplementation. There was no effect on the coefficient of digestibility of dry matter, organic matter, crude protein, ether extract and neutral detergent fiber. There was an effect of supplementation on the digestibility of non-fiber carbohydrates. In the rainy season the utilization of mineral salt allows the of animals in pastures. It is unnecessary supplementation with protein salt at the time of the waters.