Forage quality and performance of sheep in Massai grass pastures managed at pre-grazing canopy heights

The objective of this study was to evaluate the effects of pasture height at pre-grazing of Massai grass on the quality of available forage, forage intake and the performance of lambs raised for meat production. The treatments consisted of four pre-grazing canopy heights (35, 40, 45 and 50 cm). Pastures were managed by the intermittent stocking method and 32 sheep were used. Dry matter intake (DMI) was estimated by Lipe® indicator. Green forage allowance was not affected by pre-grazing heights. There was no effect of heights on the chemical composition of the stem or the leaf blades, except for crude protein content of leaf blades, which showed an inverse linear effect. Grazing time had a quadratic response in function of canopy height. The minimum point was at 42.6 cm, with 502.9 min/day. DMI increased linearly with increasing pasture height. Average daily weight gain (ADG) and stocking rate (SR) responded linearly to pre-grazing heights. Weight gain per hectare was not affected by height as a result of the compensation between SR and ADG. The increase from 35 to 50 cm in Massai grass canopy height reduces its nutritional value and individual performance and increases DMI of sheep intended for meat production.Keywords: Panicum maximum, tropical pasture, voluntary intak

Canopy structure, ingestive behavior and displacement patterns of beef heifers grazing warm-season pastures

Analyses in a data set of six experiments (n=436) was performed with the aim of characterizing canopy structure and forage intake patterns of beef heifers grazing on Pearl millet (Pennisetum americanum), Alexandergrass (Urochloa plantaginea) and Coastcross (Cynodon dactylon). Forage and leaf lamina mass were similar among species, 3001.4 and 668.1kg of DM/ha, respectively, while leaf:stem ratio of canopy vertical strata was different. Intake rate (12g DM/minute), bite mass (0.343g DM/bite) and bite rate (36.6bites per minute) were similar in Pearl millet and Alexandergrass. In Pearl millet, neutral detergent fiber content (56.1%) in forage as grazed, grazing time (518.9 minutes/day) and displacement rate (8.8 steps/minute) were lower. Increased grazing time (639 minutes/day) represented the main compensatory mechanism for smaller bite masses (0.234g DM/bite) and reduced intake rates (8.8 grams of DM/minutes) in Coastcross. Bite rate variations happened as a response to constraints imposed by canopy structure. Surface utilization on Alexandergrass and Coastcross was increased by greater number of feeding stations visited and displacement rate. Ingestive behavior components of beef heifers are affected by differences in the canopy structure of Pearl millet, Alexandergrass and Coastcross

Disponibilidade e valor nutritivo de gramíneas tropicais sob pastejo com ovinos

Objetivou-se avaliar a disponibilidade e valor nutritivo de três forrageiras Panicum maximum 'Aruana', Panicum maximum Jacq. 'Massai' e Brachiaria hibrida 'Mulato', com ovinos em pastejo contínuo. A qualidade do Massai foi inferior em relação às outras duas gramíneas, com baixo teor de PB, alto de FDN, alto de FDA e baixa DIVMO. Já o Mulato foi semelhante ao Aruana e diferentes estatisticamente ao Massai para todos os parâmetros avaliados. Conclui-se que o cultivar Massai apresenta valor nutricional inferior ao cultivares Mulato e Aruana, enquanto estes últi- mos mantiveram bons níveis nutricionais, inclusi- ve durante o período seco.The objective was to evaluate three forage Panicum maximum 'Aruana', Panicum maximum Jacq. 'Massai' and Brachiaria hybrid 'Mulato'. The quality of the Massai proved to be lower, with low crude protein, high NDF, ADF high and low digestibility. Mulato has already had results similar Aruana and different statistically Massai to all the parameters of quality assessed. It was concluded that the cultivar Massai presents nutritional value lower than the cultivars Aruana and Mulato, while the latter maintained good nutritional levels, even during the dry season

Dynamic of a papuã pasture under two grazing intensities and two nitrogen levels Dinâmica de uma pastagem de capim-papuã sob duas intensidades de pastejo e dois níveis de nitrogênio

This work aimed to evaluate the effects of grazing intensities and nitrogen fertilization levels on the dynamics of a Brachiaria plantaginea pasture. The experiment was laid out as a random block design, in a 3 × 2 factorial scheme, composed of three nitrogen levels (0, 200 and 400 kg/ha nitrogen in urea form) and two grazing intensities termed low mass (LM; forage mass of 1500 kg of DM/ha) and high mass (HM; forage mass of 3000 kg of DM/ha) in a continuously stocked swards with two replications. Animals used were half-blood Boer goats averaging five months old and 21 kg body weight (BW) for adjustment of the target forage mass. Real forage mass, average height of the plants and animal stocking rates were of 2,567 and 3,862 kg DM/ha; 23.6 and 31.2 cm and 2,804 and 2,089 kg BW/ha respectively for low and high mass. Accumulation rate was of 100, 147 and 132 kg DM/ha/day and total production 13,659; 19,834 and 17,820 kg DM/ha, respectively to the 0, 200 and 400 kg N/ha. There were no differences on pasture yield among grazing intensities suggesting that higher stocking rates can be used. The level of 200 kg N/ha promotes the best response on papuã grass pastures. Papuã grass shows high yield, good production distribution during the plant cycle and excellent nutritional value.<br>Objetivou-se avaliar a influência da intensidade de pastejo e dos níveis de abubação nitrogenada sobre a dinâmica de uma pastagem de Brachiaria plantaginea. O delineamento experimental adotado foi o de blocos ao acaso, em esquema fatorial 3 × 2, composto de três níveis de adubação nitrogenada (0, 200 e 400 kg/ha de nitrogênio na forma de ureia) e duas intensidades de pastejo (1.500 e 3.000 kg de MS/ha, respectivamente, para as massas baixa e alta em pastejo com lotação contínua e taxa de lotação variável), totalizando seis tratamentos, cada um com duas repetições. Foram utilizados caprinos meio-sangue Boer com 5 meses de idade e peso médio de 21 kg de peso vivo (PV) para ajuste das massas de forragem preconizadas. A massa de forragem real, a altura média das plantas e a carga animal foram de 2.567 e 3.862 kg de MS/ha; 23,6 e 31,2 cm; e 2.804 e 2.089 kg de PV/ha respectivamente para as massas baixa e alta. A taxa de acúmulo foi de 100, 147 e 132 kg de MS/ha/dia e a produção total, de 13.659, 19.834 e 17.820 kg de MS/ha, respectivamente para as doses de 0, 200 e 400 kg de N/ha. Não houve diferença na produtividade da pastagem entre as intensidades de pastejo, logo maior carga animal pode ser utilizada. O nível de 200 kg de N/ha promove a melhor resposta em pastagens de capim-papuã. O capimpapuã tem alta produtividade, boa distribuição da produção ao longo do ciclo e excelente valor nutricional