Hugo Imaizumi

Produção e composição do leite de vacas mantidas em pastagens de capim-elefante submetidas a duas frequências de pastejo

Objetivou-se avaliar duas frequencias de pastejo em pastagens de capim-elefante (Pennisetum purpureum Schum. cv. Cameroon): uma variavel, determinada pela entrada dos animais na area a ser pastejada, quando o dossel atingisse 95% de interceptacao da radiacao fotossinteticamente ativa; e uma frequencia fixa, de 26 dias. Utilizaram-se oito vacas com media de 124 dias em lactacao, 516 kg de peso corporal e 17,5 kg de leite no inicio do experimento. O periodo experimental foi de 80 dias, divididos em quatro subperiodos de 20 dias. O delineamento experimental utilizado foi o cross-over. As frequencias de pastejo nao influenciaram a producao e composicao do leite, o nitrogenio ureico no plasma, o escore de condicao corporal e a variacao de peso corporal. Entretanto, a taxa de lotacao e a producao de leite por unidade de area foram maiores nas pastagens com intervalo de pastejo determinado pela interceptacao de 95% da radiacao fotossinteticamente ativa. Assim, a frequencia de pastejo definida em intervalos variaveis por meio da interceptacao da radiacao fotossinteticamente ativa resulta em maior producao de leite por unidade de area.

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

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) 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) is adequate for mid lactating cows grazing tropical pastures.

Diet crude protein content and sources for lactating dairy cattle

O fornecimento de dietas com maior teor de proteina para aumentar o fluxo de aminoacidos para o intestino pode aumentar o desempenho lactacional. Compararam-se dietas para vacas em lactacao contendo 16% de proteina bruta (PB), adequada em proteina degradavel no rumen (PDR) e proteina metabolizavel (PM) (NRC, 2001) com dietas com maiores teores de PB (17,5%) . Quarenta e duas vacas (27 primiparas e 15 multiparas, com 172 dias em lactacao) foram utilizadas em um delineamento do tipo Quadrado Latino 3 ´ 3, com 14 repeticoes. A dieta controle continha 16% de PB e era adequada em PDR e PM de acordo com o NRC (2001). O teor de PB das dietas foi aumentado para 17,5% atraves do aumento no fornecimento de farelo de soja e de algodao (SBCS-17,5) para aumentar a PM, ou ureia (U-17,5) para aumentar a PDR. O experimento teve duracao de 60 dias com tres subperiodos. Os animais foram alimentados em grupo com racao completa e ordenhados duas vezes ao dia. O consumo de materia seca foi maior para a dieta U-17,5 (p 0,05) pelos tratamentos. O teor de proteina foi reduzido (p < 0,01) pelo maior fornecimento de ureia (U-17,5); enquanto maior producao de proteina do leite (p < 0,01) foi observada para o tratamento SBCS-17,5. Para vacas produzindo em torno de 29 kg d-1, aumentar o teor de PB para 17,5%, por meio do maior fornecimento de farelo de soja e de algodao, acima das recomendacoes do NRC (2001) para PDR e PM, resultou em aumentos na producao de leite, leite corrigido para gordura e de proteina do leite.

Estimativa de energia metabolizável de rações com polpa cítrica em substituição ao milho para tourinhos em terminação

Seventy-two finishing Canchim bulls averaging 318 kg of initial body weight and 18 months of age were assigned to a completely randomized block design to evaluate the effects of replacing ground corn (GC) with dried citrus pulp (CP) on average daily weight gain, dry matter intake, feed efficiency, carcass yield, and Longissimus dorsi fat thickness. Diets contained forage (sugarcane silage) to concentrate ratio of 30:70 and the following levels of CP and GC: 100% GC (CP0), 50% GC + 50% CP (CP50), 25% GC + 75% CP (CP75), or 100% CP (CP100). The experiment lasted 130 days with 14 days for diet adaptation and 116 days for data and sample collection. Feed efficiency and net energy for maintenance and gain were all greatest on CP50 than on CP0 diet. Daily weight gain and DM intake were lower on CP100 and CP75 compared to CP50. No significant differences were observed for fat thickness and carcass yield across treatments. Based on the actual data, both the NRC (1996) and NRC (2001) models underestimated the energy value of CP compared to GC.

Fontes protéicas e de amido com diferentes degradabilidades ruminais para alimentar vacas leiteiras

The objective of this work was to evaluate starch sources (fine ground x popped corn) and protein sources (soybean meal x fish meal x urea) varying in rumen degradability in order to feed dairy cows. Fifty-six Holstein cows averaging 112 days in milk were used. The treatments were: MFS (fine ground corn + soybean meal); PFS (popped corn + soybean meal); PFP (popped corn + soybean meal + fishmeal) and PU (popped corn + soybean meal + urea). The treatment PFS did not affect milk yield, but it decreased milk fat content, milk fat yield and milk protein content, compared to MFS. Milk yield was higher for PFS than for PFP or PU. Treatment with fishmeal (PFP) decreased milk fat content, milk fat yield and 3.5% FCM yield, but increased milk protein content.