Tafaj M, Junck B, Maulbetsch Anja, Steingass H, Piepho H P, Drochner W
Institute of Animal Nutrition, University of Hohenheim, Stuttgart, Germany.
Arch Anim Nutr. 2004 Aug;58(4):325-42. doi: 10.1080/00039420412331273259.
The influence of fibre content of hay (H) and concentrate level (C) on local differences in the composition of ruminal digesta (ratio of solid to fluid digesta, DM, NDF, ADF and ADL content), particle size (MPL), specific gravity (SG) and fermentation (pH and concentrations of SCFA and bicarbonate) have been tested on two ruminally cannulated Friesian cows (520 kg BW) which were fed restricted, using individual cows as experimental units. Digesta samples were collected via cannula from three rumen layers: 5 to 10 cm (top) and 25-35 cm beneath the top of the particle mat (middle) and 5-10 cm above the rumen floor (bottom). For a main plot treatment (H x C), repeated samples were collected at four time intervals (1 h before and 2, 5 and 10 h after morning feeding) on each of two days. From top to bottom rumen the share of solid digesta mass (SM), DM and NDF contents of squeezed digesta fluid (SRF) and concentration of SCFA decreased (P < 0.05); pH and bicarbonate concentration increased (P < 0.05), while DM, NDF, ADF and ADL contents in SM, MPL and SG did not differ. Higher NDF content of hay (from 47-62%) increased SM, fibre fractions in SM, MPL, pH and concentration of bicarbonate in ruminal digesta, especially when 50% concentrate was given, while SG decreased. When the concentrate level was enhanced from 20 to 50%, digesta SM, MPL and the content of DM and NDF in SRF increased, while pH, concentrations of SCFA and acetate decreased when low-fibre hay was given. With longer time after feeding the digesta SM was reduced and fibre content in SM increased. The increase of the fibre content of hay reduced the possible negative effect of high concentrate level on the stratification of ruminal digesta. The decrease of the fibre content of hay promised better conditions for fibre digestion in the rumen when concentrate availability is limited.
以两头装有瘤胃瘘管的弗里生奶牛（体重520千克）为实验单位，采用个体限饲的方式，研究了干草纤维含量（H）和精料水平（C）对瘤胃消化物组成的局部差异（固体与液体消化物比例、干物质、中性洗涤纤维、酸性洗涤纤维和酸性洗涤木质素含量）、颗粒大小（平均颗粒长度）、比重和发酵（pH值、挥发性脂肪酸和碳酸氢盐浓度）的影响。通过瘘管从瘤胃的三个层面采集消化物样本：颗粒垫顶部以下5至10厘米（顶部）、颗粒垫顶部以下25 - 35厘米（中部）和瘤胃底部以上5至10厘米（底部）。对于主区处理（H×C），在两天中的每一天，于四个时间点（晨饲前1小时以及晨饲后2、5和10小时）重复采集样本。从瘤胃顶部到底部，固体消化物质量（SM）、压榨后消化液（SRF）的干物质和中性洗涤纤维含量以及挥发性脂肪酸浓度均降低（P<0.05）；pH值和碳酸氢盐浓度升高（P<0.05），而SM中的干物质、中性洗涤纤维、酸性洗涤纤维和酸性洗涤木质素含量、平均颗粒长度和比重无差异。干草较高的中性洗涤纤维含量（47% - 62%）增加了SM、SM中的纤维组分、平均颗粒长度、瘤胃消化物的pH值和碳酸氢盐浓度，尤其是在给予50%精料时，而比重降低。当精料水平从20%提高到50%时，消化物SM、平均颗粒长度以及SRF中的干物质和中性洗涤纤维含量增加，而在给予低纤维干草时，pH值、挥发性脂肪酸和乙酸浓度降低。随着采食后时间延长，消化物SM减少，SM中的纤维含量增加。干草纤维含量的增加减轻了高精料水平对瘤胃消化物分层的可能负面影响。当精料供应有限时，干草纤维含量的降低有望为瘤胃中的纤维消化创造更好的条件。
