Multiple supplements containing spineless cactus enriched with urea forcattle/Suplementos multiplos contendo palma forrageira enriquecida com ureia para bovinos

This study was realized to evaluate the effect of the 'multiple supplements' containing spineless cactus enriched with urea (0, 1, 2 and 3% on dry matter basis--DM) as a replacement to a traditional supplement (control) on ruminal parameters and microbial protein synthesis in crossbred steers. Five steers(1/2 Holstein x Zebu) can nulated in the rumen, with an average initial body weight of 240 [+ or -] 22.1 kg were used in a 5 X 5 Latin square. A quadratic effect was observed for DM intake and N retention, with maximum values of 6.97 kg [d.sup.-1] and 50.9 g[d.sup.-1] with the inclusion of 1.8 and 2.1% urea, respectively. Maximum concentrations of 16.2, 23.2 and 24.3 mg [dL.sup.-1] of N-N[H.sub.3] were recorded in animals fed spineless cactus enriched with 1, 2, and 3% of urea. There was a quadratic effect on ruminal pH, with a value of 6.45 at 4.08 hours after feeding. Microbial synthesis efficiency of 103 g CP[kg.sup.-1] TDN was obtained with the inclusion of 1.6% urea. Multiple supplements containing spineless cactus enriched with 1.6 up to 1.8% urea in replacement of a traditional supplement is recommended for cattle. Keywords: intake, rumen pH, supplementation, volatile fatty acids. Este trabalho foi realizado para avaliar o efeito de suplementos multiplos contendo palma forrageira enriquecida com ureia (0, 1, 2 e 3% na materia seca--MS) em substituicao a um suplemento tradicional (controle) sobre os parametros ruminais e sintese de proteina microbiana em novilhos mesticos. Cinco novilhos canulados no rumen (1/2 Holandes x Zebu), com peso corporal inicial de 240 [+ or -] 22,1 kg foram utilizados em um Quadrado Latino 5 X 5. Efeito quadratico foi observado para o consumo de MS e retencao de N, com valores maximos de 6,97 kg [d.sup.-1]e 50,9 g [d.sup.-1]com a inclusao de 1,8 e 2,1% de ureia, respectivamente. Concentracoes maximas de 16,2; 23,2 e 24,3 mg [dL.sup.-1] de N-N[H.sub.3] foram registradas nos animais alimentados com palma forrageira enriquecida com 1, 2 de 3% de ureia. Houve efeito quadratico sobre o pH ruminal, com valor de 6,45 as 4,08 horas apos alimentacao. Sintese de proteina microbiana de 103 g de proteina bruta [kg.sup.-1] de nutrientes digestiveis totais foi obtida com a inclusao de 1,6% de ureia. Recomenda-se a utilizacao de suplementos multiplos contendo palma forrageira enriquecida com 1,6 a 1,8% de ureia em substituicao ao suplemento tradicional para bovinos. Palavras-chave: consumo, pH ruminal, suplementacao, acidos graxos volatei