RESUMO -Para avaliação da influência da estrutura do dossel de pastagens tropicais sobre o processo de ingestão de forragem por bovinos, cinco alturas de dossel (60, 80, 100, 120 e 140 cm) de uma pastagem de capim-mombaça (Panicum maximum, Jacq.) foram estabelecidas, em um delineamento inteiramente casualizado, com duas repetições. Quatro novilhas da raça Holandês Preto e Branco com coletores de fezes e urina foram utilizadas em testes de pastejo de 45 minutos. O número de bocados e o tempo de alimentação foram registrados com o uso de contadores e cronômetros. A massa de forragem total consumida foi obtida pela técnica de dupla pesagem. Com o aumento na altura do dossel, observou-se aumento linear na massa de bocado. O aumento do comprimento das lâminas foliares expandidas e em expansão resultou em consumo quase que individual de folhas, refletindo em aumento linear no tempo por bocado e em redução linear na taxa de bocados. Uma vez que o aumento no tempo por bocado foi proporcionalmente maior que o aumento da massa de bocado, a massa de forragem total consumida e a taxa de ingestão estabilizaram-se nas maiores alturas da pastagem. As limitações físicas impostas pela estrutura do dossel levaram a menor eficiência de captura de forragem pelos animais nas maiores alturas do dossel. O consumo de forragem foi maximizado à altura de 109,3 cm. Palavras-chave: bovinos, estrutura do dossel, massa de bocado, pastagem tropical Forage intake characteristics on mombaçagrass pastures grazed by Holstein heifersABSTRACT -In order to evaluate the influence of tropical grass sward structure on the intake of grazing cattle, five sward heights (60, 80, 100, 120, and 140 cm) of Panicum maximum Jacq. were established, in a completely randomized design with two replications. Four black-and-white coat Holstein heifers, carrying feces and urine bags, were used in grazing tests of 45 minutes each. Number of bites and feeding time were registered by counters and chronometers. Total herbage mass consumed was obtained by double sampling technique. Increasing sward height increased bite mass, followed by an increase in chewing number. The increase in the length of both expanded leaves and expanding leaves, resulted in individual bite per leaf, leading to an increase in biting time, and consequent linear decrease in bite rate. Since increases in time per bite was proportionally greater than that for bite mass, total herbage mass consumed and intake rate stabilized at the highest sward heights. Under these conditions, the physical limitation imposed by sward structure led to a lower efficiency of foraging by the animals, even at high forage allowance situation. Intake rate was maximized at pasture height of 109.3 cm.
-The effect of nitrogen (N) fertilization (0, 50, 100 and 200 kg N ha -1 ) on forage yield and morphogenesis of Axonopus aureus was evaluated in the savannas of Roraima State, Brazil. The experimental design was in randomized blocks with three replicates. The grass showed high responsiveness to N fertilization. Dry weight (DW) yield, morphogenetic and structural traits and forage quality were positively affected by N fertilization. The effects of N fertilization on DW yield, N content, leaf appearance rate, leaf elongation rate, number of live leaves/tiller, final leaf length and leaf area index were quadratic and maximum values were estimated with application of 168.8 (2,181 kg ha -1 ); 124.8 (21.1 g/kg); 158.5 (0.163 leaf/day per tiller); 172.3 (2.75 cm/tiller per day); 155.5 (17.23 cm); 185.5 (7.55 leaves/tiller) and 185.3 (2.22) kg N ha -1 , respectively. Tiller population density and leaf senescence rate are directly proportional to increase in N rates, and the opposite occurs for N utilization efficiency and apparent N recovery.
Meat sheep production on four different production systems ABSTRACT -The potential performance of lambs and ewes from the Suffolk breed in pasture of Tifton grass 85 (Cynodon spp.) and ryegrass (Lolium multiflorum) was evaluated in different production systems: lambs weaned with 60 days and kept in pasture; lambs with ewes and kept in pasture; lambs with ewes and kept in pasture with creep feeding; feedlot confined lambs with alfalfa hay + balanced ration. The treatments were applied when the lambs reached 60 days of age until slaughter time, at 32 kg, and were allocated in a completely randomized experimental design, with three replications. A continuous grazing system, with variable stocking rate, was used in pasture treatments. Important effect of the treatments on performance of the lambs was observed. Feedlot confined lambs showed higher daily weight and at lower age at slaughter time. Creep feeding supplementation at 1% LW, did not have effect in lambs with more than 60 days of age kept with the ewes in Tifton 85 grass pasture. The presence of the ewe in the pasture showed important and positive effect in the individual performance of lambs as compared to lambs weaned at 60 days of age.
RESUMO -Com objetivo de avaliar o comportamento de pastejo de novilhos de corte, foi desenvolvido um experimento em pastagem de azevém anual (Lolium multiflorum Lam) e aveia-preta (Avena strigosa Schreb) submetida a quatro alturas de manejo (10, 20, 30
RESUMO -Os objetivos neste trabalho foram analisar a viabilidade econômica de sistemas de produção de cordeiros e identificar os componentes de maior influência no custo de produção. O estudo foi realizado em duas etapas. Na etapa 1, realizouse a comparação de quatro sistemas de terminação de cordeiros: 1) desmame aos 60 dias e terminação em pasto; 2) cordeiro com mãe em pasto; 3) cordeiro com mãe em pasto e concentrado (1% PC/dia) em creep feeding; e 4) desmame aos 60 dias e confinamento. Na etapa 2, um módulo de 150 ovelhas em 9 ha de pasto cultivado nos sistemas em pastagem e 7 ha no confinamento foi proposto a partir do experimento para avaliações econômicas, considerando a venda de cordeiro vivo terminado ou abate e venda de carne, além da venda de matrizes. Foram realizados cálculos de custo fixo (depreciação), variável (materiais, mão-de-obra, transporte, abate, juros, conservação, despesas gerais) e total (fixo+variável), lucratividade e rentabilidade, valor presente líquido, taxa interna de retorno e custo/benefício. O maior custo total foi observado no confinamento e o menor, no sistema de cordeiro terminado com a mãe em pasto. A margem líquida na venda de cordeiros foi negativa em todos os sistemas. A venda de carne apresentou margem líquida negativa apenas para terminação em confinamento.A taxa interna de retorno para venda de carne foi: 1,4% no desmamado em pasto; 4,3% no de cordeiro com mãe em pasto; 2,1% no creep feeding; e -2,3% no confinamento. Os componentes do custo operacional total com maior influência sobre o custo de produção nos sistemas a pasto, em ordem decrescente, foram mão-de-obra e alimentação; no confinamento, foram alimentação e mão-de-obra. A venda da carne apresentou lucratividade maior que a venda de cordeiro vivo, com maior valor no sistema sem desmame terminado na pastagem.Palavras-chave: custo de produção de ovinos, lucratividade da criação de ovinos, margem da venda de cordeiro, resultado econômico da criação ovina, venda de carne ovina Economic return of sheep production on pasture and in feedlotABSTRACT -The objectives of this study were to analyze the economic viability of meat lamb production systems and identify the components with greatest influence on production cost. The study was carried out in two stages. Stage 1: comparison of finishing lamb production systems: (1) lambs weaned at 60 days and finished on pasture; (2) lambs with mother on pasture; (3) lambs with mother on pasture plus concentrate (1% BW/day) in creep feeding; and (4) lambs weaned at 60 days and feedlot.Stage 2: a module of 150 ewes on 9 ha of pasture cropped in the pasture systems and 7 ha in feedlot was proposed after the economic assessment experiment, considering the sale of finished lamb or slaughter and sale of meat, and the sale of animals for reproduction.The fixed cost (depreciation), variable cost (materials, labour, transport, slaughter, interest, conservation, general expenses), total cost (fixed+variable), profitability, economic return, present net worth, intern return rate and benefi...
The aim of this study was to evaluate the effects of concentrate supplementation on the performance and ingestive behaviour of lambs grazing tropical grasslands of Panicum maximum cv. IZ-5 and its effect on pasture characteristics. Different levels of daily supplementation with concentrate were compared: no supplementation; or supplemented at 1.5% and 2.5% of lamb liveweight. The grazing simulation technique was used for qualitative assessment of the pasture every 28 days. Herbage mass, pasture growth rate, sward height as well as botanical and morphological composition of the pasture were evaluated. Average daily gain, gain per hectare and ingestive behaviour were measured on the lambs. The forage supply was 4% of green leaves (4 kg dry matter per 100 kg of liveweight) in all treatments. Six 3–4-month-old Texel and Corriedale lambs were used per paddock. The design was a randomised block design with three replications. Concentrate supplementation had a direct effect on pasture structure, especially height (significant interaction treatment vs period – P = 0.0373). In the treatment without supplementation, the animals grazed for a longer period than the others. Idle time was higher in the treatment with the highest level of supplementation, and rumination time was similar among the treatments. Supplementation with 2.5% significantly increased the average daily gain (0.143 g vs 0.026 g for no supplementation) and gain per hectare (30 kg vs 258 kg for no supplementation vs supplementation at 2.5% of lamb liveweight, respectively). The results show the potential increase in production and productivity with the use of concentrate supplementation at 2.5% lamb bodyweight. Notwithstanding the increase in production, supplementation with concentrate provided a strong negative impact on pasture structure and behaviour of animals that should be considered when using concentrate supplementation for finishing lambs in tropical regions.
RESUMO -Para avaliar as estratégias de alimentação de bovinos em pastejo, quatro novilhas da raça Holandês Preto e Branco foram mantidas em uma pastage m de capim-mombaça ( Panicum maximum Jacq.) com cinco alturas de dossel, em um delineamento inteiramente casualizado, com duas repetições, durante os meses de fevereiro a abril de 2002. Os animais experimentais foram avaliados por meio de testes de pastejo de 45 minutos, durante os quais foram determinados o número de bocados, o número de estações alimentares, o número de passos e o tempo de alimentação utilizando-se cronômetros e contadores. Com o aumento da altura do dossel, o número de estações alimentares diminuiu de forma quadrática ( Ŷ = 16,3199 -0,2424 x + 0,000996 x 2 , R 2 = 0,9328, P = 0,0031), como resultado da maior disponibilidade de forragem, que reduziu a procura por melhores sítios de pastejo. O número de passos entre as estações alimentares aumentou ( Ŷ = 0,7247 + 0,01603 x, R 2 = 0,6172, P = 0,0043), ampliando a exploração do ambiente de pastejo. Quando a massa de forragem aumentou, os animais reduziram as distâncias totais percorridas ( Ŷ = 513,998287 -2,659875 x, R 2 = 0,728076, P = 0,0016), a taxa média de deslocamento ( Ŷ = 11,567445 -0,058396 x, R 2 = 0,724633, P = 0,0013) e, conseqüentemente, a intensidade de utilização da área ( Ŷ = 9,533139 -0,051351 x, R 2 = 0,7708, P = 0,0005), como resultado da elevação da altura do dossel, que garantiu elevado consumo de forragem. Os animais ajustam seus padrões de deslocamento e procura de forragem em resposta à estrutura do dossel forrageiro.Palavras-chave: comportamento de pastejo, estrutura da pastagem, novilhas holandesas, Panicum maximum Displacement and forage searching patterns of Holstein heifers in mombaçagrass pastureABSTRACT -To evaluate grazing strategies of cattle on pastures, four Holstein black and white coating heifers were submitted to five sward heights of mombaçagrass (Panicum maximum Jacq.) pasture, in a completely randomized design, with two replications, between February and April, 2002. The experimental animals were evaluated during 45 minutes tests. Number of bites, number of feeding stations, number of steps and feeding time were measured, using chronometers and counters. The number of feeding stations per minute decreased quadratically (Ŷ = 16.3199 -0.2424 x + 0.000996 x 2 , R 2 = 0.9328, P = 0.0031), from low to tall sward, as a result of the greater available mass present in the highest sward heights, that reduced the searching for other feeding stations. The number of steps between feeding stations increased (Ŷ = 0.7247 + 0.01603 x, R 2 = 0.6172, P = 0.0043) increasing the exploration of pasture environment. With the increase in available forage dry matter, the animals reduced total number of steps (Ŷ = 513.998287 -2.659875 x, R 2 = 0.728076, P = 0.0016), steps by minute ( Ŷ = 11.567445 -0.058396 x, R 2 = 0.724633, P = 0.0013) and, consequently, the intensity of area utilization ( Ŷ = 9.533139 -0.051351 x, R 2 = 0.7708, P = 0.0005), as the greater sward height assured hi...
RESUMO -O trabalho foi realizado no Setor de Ovinocultura da Universidade de Marília, objetivando estudar os efeitos de três níveis de energia (2,6; 2,8 e 3,0 Mcal EM/kg MS) na ração de cordeiros inteiros Suffolk criados em creep feeding, sobre o desempenho e características de carcaça. Na parição numerava-se e registravam-se o peso ao nascer dos cordeiros que, posteriormente, foram distribuídos aleatoriamente, compondo doze repetições por tratamento. As rações foram isoprotéicas (18,46% PB) fornecidas ad libitum duas vezes ao dia, pesandose as respectivas sobras. Os cordeiros foram pesados a cada 14 dias, permanecendo com as ovelhas até atingirem o peso vivo final, preestabelecido em 31 kg. Em seguida, os cordeiros permaneceram em jejum alimentar por 16 horas, até o momento do abate, obtendo-se o peso vivo ao abate. Após o abate, registraram-se o s pesos da carcaça quente e do conteúdo digestivo, para o cálculo do peso de corpo vazio. As carcaças permanecerem por 24 horas na câmara de refrigeração em temperatura de 5 º C, obtendo-se o peso da carcaça fria. Para o ganho médio diário ocorreu diferença significativa entre os tratamentos, utilizando-se como covariável a idade de abate, com melhor desempenho para os cordeiros que receberam a ração com 3,0 Mcal EM. Para as características da carcaça não houve efeito dos tratamentos. Concluiuse que o nível 3,0 Mcal EM foi o mais indicado para a ração de cordeiros Suffolk alimentados e terminados em creep feeding. Palavras-chave: comedouro seletivo, crescimento dos ovinos, suplementação Performance and Carcass Traits of Lambs Fed Diets with Different Energy Levels Grown in Creep FeedingABSTRACT -The experiment was carried out at Sheep Production Department, Universidade de Marília-SP, to evaluate the effect of rations with three energy levels fed to Suffolk lambs grown in creep feeding, on performance and carcass traits. At birth, lambs were identified, weighed and, then, randomly allotted to the treatments, with 12 replications for different energy levels. Lambs fed isoproteins rations ad libitum, twice a day, and orts were daily recorded. Lambs were weighed at each 14 days and stayed with their dams until final live weight, 31 kg. After, lambs were fasted for 16 h until slaughter, when slaughter live weight was recoded. Hot carcass weight and digestive content were recorded to estimate empty live weight. Then, carcasses were maintained 24 h at 5ºC, and was recorded cold carcass weight. Average daily live weight gain was affected by treatments, with slaughter age as covariable. Higher performance values were observed for lambs fed rations with 3.0 Mcal ME. Considering carcasses traits, there was no effect of treatments. It was concluded that 3.0 Mcal ME was the most indicated for rations of Suffolk lambs fed and finished in creep feeding.
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