Metabolizable protein supply according to the nrc (2001) for dairy cows grazing elephant grass

Abstract

Tropical pastures fertilized with nitrogen may have high crude protein (CP) contents with high rumen degradability. High crude protein concentrates offered to cows grazing these pastures may increase feed costs without positive effects on their performance. The objectives of this trial were to evaluate the effects of increasing metabolizable protein (MP) supply beyond the NRC (2001) recommendations for mid lactating dairy cows grazing elephant grass pasture (Pennisetum purpureum Schum. cv. Napier) managed with high stocking rates. Three concentrates (6.3 kg DM -1 cow -1 day -1 ) were evaluated: control (17%CP) was adjusted in relation to MP according to the NRC (2001); the other two contained extra soybean meal, to increase the CP content to 21.2% (CP) and 25.0% (CP). Twelve multiparous Holstein cows, averaging 150 days of milk production at a rate of 19.5 kg of milk day -1 , were used in a 3 × 3 latin square design, replicated four times. Forage consumption was 11,270 kg DM ha -1 with 34% of green leaves and 12% CP. Milk production, corrected to 3.5% fat, milk fat, protein, lactose and total solids contents were not affected by treatments (P > 0.05). Milk urea nitrogen and plasma urea nitrogen increased linearly (P < 0.05) as the MP supply increased. Treatments did not affect (P > 0.05) body weight gain, body condition score, grazing time, ruminating time, resting time, rectal temperature and respiratory rate. Crude protein content in the concentrate formulated according to NRC (2001) , arranjadas em QL 3 × 3 com quatro replicatas. A massa de forragem disponível era de 11.270 kg MS dia -1 com 34% de folhas verdes e 12% de PB. A produção de leite, produção de leite corrigida para 3,5%, teores de gordura, proteína, lactose e sólidos totais não foram afetados (P > 0,05) pelos tratamentos. O nitrogênio uréico do leite e o nitrogênio uréico do plasma aumentaram linearmente (P < 0,05) com o aumento do suprimento de proteína metabolizável. Os tratamentos não afetaram (P > 0,05) o ganho de peso, condição corporal, tempo de pastejo, tempo de ruminação, tempo em ócio, temperatura retal e a freqüência respiratória dos animais. O teor de PB no concentrado para suprir proteína metabolizável de acordo com o NRC (2001), é adequado para vacas em terço médio de lactação, mantidas em pastagens tropicais. Palavras-chave: concentrados, produção de leite, teor de proteína, pastagens tropicais NRC (2001) for dairy cows

Características produtivas e qualitativas do capim-elefante pastejado em intervalo fixo ou variável de acordo com a interceptação da radiação fotossinteticamente ativa

“…Os valores de massa de forragem em pré-pastejo desse estudo foram menores que os obtidos por Voltolini et al (2008), na mesma área experimental. Esses autores relataram valores de 8.000 a 16.000 kg MS/ha por ciclo de pastejo.…”

Santa Inês sheep supplementation on urochloa grass pasture during the dry season: intake, nutrient digestibility and performance

“…Voltolini et al (2009) observed that the addition of concentrate supplementation was insufficient to promote greater intake of total dry matter, which may evidence, in these cases, the occurrence of rumen acidosis. The values of dry matter intake and forage dry matter intake-to-concentrate supplement treatments observed in this study are higher than those reported by Voltolini et al (2009), who worked with Santa Inês × UB (undefined breed) crossbred sheep on irrigated Tifton 85 pastures receiving 180 g/day of concentrate supplement. According to the authors, the dry matter intake and mean forage intake were 0.595 and 0.417 kg/day, respectively; but when comparing the dry matter intake and forage intake of animals grazing only on pasture, the results obtained by these authors are higher: 0.628 kg/day.…”

“…This effect, in turn, can be used in the production system as a tool to increase the stocking rate of pastures (Voltolini et al, 2009).…”

“…The exclusive use of pastures cannot meet the nutritional requirements of animals, especially in relation to the categories of higher nutritional requirement. In turn, the use of supplement concentrate for grazing animals should comply with basic conditions, such as the genetic potential of the livestock, the quality and quantity of forage available, the price of the concentrate and the price of livestock products generated (Voltolini et al, 2008).…”

“…The evaluation of grazing sheep with supplements has received growing attention of researchers in the last ten years (Barbosa et al, 2003;Frescura et al, 2005;Voltolini et al, 2009).…”