Fontes protéicas e energéticas com diferentes degradabilidades ruminais para vacas em lacta o = Protein (raw or rosted soybeans) and energy (coursely ground or steamflaked corn) sources with varying ruminal degradabilities for lactating cows

O objetivo deste trabalho foi avaliar a combina o de fontes de energia e proteína com diferentes degradabilidades ruminais. Foram utilizadas quatro vacas multíparas (23 kg leite dia-1) em Quadrado Latino 4 x 4 com arranjo fatorial 2 x 2: duas fontes de proteína (soja crua ou tostada) e duas de energia (milho moído, grosso oufloculado). O tratamento com milho moído grosso e soja tostada resultou em maior consumo de matéria seca (p < 0,11). O fornecimento de milho floculado apresentou tendência (p = 0,12) de aumento da produ o e diminui o do teor de gordura no leite. A tostagem do gr o de soja n o melhorou (p > 0,05) o desempenho lactacional. A tostagem da soja e a flocula o do milho diminuíram (p < 0,01) as concentra es ruminais de Namoniacal. Animais que receberam milho floculado apresentaram maiores concentra es totais de AGV (p = 0,10), mas n o houve efeito no pH ruminal. Observou-se maiordigestibilidade ruminal (p = 0,06) quando se forneceu soja crua. The objective of this trial was the evaluation of ruminal degradation synchrony of protein and energy sources. Four Holstein cows (23 kg day-1) were used in a 4 x 4 Latin Square design and 2 x 2 factorial arrangement: two protein (raw vs. roasted soybeans) with two energy sources (coarsely ground vs. steam-flaked corn). Dry matter intake was higher for cows fed coarsely ground corn with roasted soybean (p < 0.11). Flaking of corn tended (p = 0.12) to increase milk yield and to decrease milk fat content. Roasted soybean did not improve lactational performance of mid lactating cows (p > 0.05). Rumen pH was not affected by treatments (p > 0.05). Both roasted soybeans and flaking of corn decreased rumen ammonia nitrogen (p < 0.01). Animal fed steamflaked corn tended showed higher total VFA molar concentrations (p = 0.10), but there were no treatments effect on ruminal pH. A higher (p = 0.06) ruminal starch digestibility was observed for raw soybean treatment.