Firkins J L, Berger L L, Merchen N R, Fahey G C
J Anim Sci. 1986 Apr;62(4):1081-94. doi: 10.2527/jas1986.6241081x.
A 2(3) factorial arrangement of treatments was used to study main effects and interactions between particle size of prairie hay (chopped vs ground), two levels of feed intake (60 and 90% of ad libitum) and ruminal degradability of protein sources [dry corn gluten feed (DCGF) vs dry distillers grains (DDG)] on ruminal and total tract digestion in eight ruminal- and duodenal-cannulated steers. Steers were fed every 2 h to approach steady-state feeding conditions. Steers fed ground hay diets digested higher (P less than .05) percentages of total digestible organic matter (OM) and neutral detergent fiber (NDF) in the rumen and had lower (P less than .05) nonammonia-nonbacterial N (NANBN) flows to the duodenum than did those fed chopped hay, probably because greater surface area of ground hay allowed more extensive ruminal fermentation. Protein source X intake interactions were noted for ruminal OM and NDF digestion when expressed as percentages of total digestion. At low intakes, steers fed DCGF had higher (P less than .05) percentages of total digestible OM and NDF disappearing in the rumen than did those fed DDG. Steers fed DCGF had lower total N, NANBN and total amino acid (AA) flows at the duodenum than did those fed DDG, indicating that less DCGF protein escaped ruminal degradation. Steers fed DDG had greater (P less than .05) total tract NDF digestion, suggesting that escape protein from DDG may stimulate hindgut fermentation and thereby affect site and extent of nutrient digestion. Regression analysis indicated that extent of ruminal fermentation and efficiency of microbial growth in vivo are associated with ruminal rates of passage within individual animals. When steers were fed at high-intake levels (1.6% of body weight), ruminal dilution rates were not increased (P less than .05) due to forage particle size or level of intake treatments, accounting, in part, for the lack of expected treatment differences in efficiency of bacterial growth and duodenal N flow, and for the low number of interactions between main effects.
采用2（3）析因试验设计，研究了草原干草粒度（切碎与粉碎）、两个采食量水平（随意采食量的60%和90%）以及蛋白质来源（干玉米蛋白粉与干酒糟）的瘤胃降解率对8头安装了瘤胃和十二指肠瘘管的阉牛瘤胃消化和全消化道消化的主效应及相互作用。每隔2小时给阉牛投喂一次，以接近稳态采食条件。采食粉碎干草日粮的阉牛在瘤胃中对总可消化有机物（OM）和中性洗涤纤维（NDF）的消化率更高（P<0.05），且与采食切碎干草的阉牛相比，其十二指肠非氨非细菌氮（NANBN）流量更低（P<0.05），这可能是因为粉碎干草的表面积更大，瘤胃发酵更充分。当以总消化率的百分比表示时，蛋白质来源与采食量之间存在瘤胃OM和NDF消化的相互作用。在低采食量时，采食干玉米蛋白粉的阉牛瘤胃中总可消化OM和NDF消失的百分比高于采食干酒糟的阉牛（P<0.05）。采食干玉米蛋白粉的阉牛十二指肠总氮、NANBN和总氨基酸（AA）流量低于采食干酒糟的阉牛，表明干玉米蛋白粉蛋白质瘤胃降解较少。采食干酒糟的阉牛全消化道NDF消化率更高（P<0.05），这表明干酒糟中的过瘤胃蛋白可能刺激后肠发酵，从而影响养分消化的部位和程度。回归分析表明，瘤胃发酵程度和体内微生物生长效率与个体动物瘤胃流通速率有关。当阉牛以高采食量水平（体重的1.6%）采食时，瘤胃稀释率并未因饲草粒度或采食量处理水平而增加（P<0.05），这部分解释了细菌生长效率和十二指肠氮流量缺乏预期的处理差异，以及主效应之间相互作用较少的原因。
