Van Der Walt J G, Briel B J
Onderstepoort J Vet Res. 1976 Mar;43(1):11-21.
Changes in the total concentration of the volatile fatty acid (VFA) pool in the rumen were followed over a 24 hour period in 2 groups of sheep, 1 fed at 08h00 and the other twice daily at 08h00 and 20h00. Although similar maximum (143 and 147 meq/1) and average (100, 3 and 102, 1 meq/1) levels were found in the 12 and 24 h groups respectively, the twice daily feeding regimen resulted in a lower variation (S.D.=17, 0 meq/1 and 28, 9 meq/1 respectively). It was concluded from changes in the percentage molar composition of the VFA pool over the same period that the other of VFA absorption from the rumen was propionate greater than acetate greater than butyrate for both groups, but that the differences were less marked for the twice daily fed sheep. Long term infusions of 14C labelled acetic, propionic and butyric acids into the rumen of sheep fed a total of 1 600 g lucerne hay twice daily (08h00 and 20h00), gave an average net total VFA production rate of 4,52+/-1,01 moles/800 g/12 hours irrespective of the acid infused. The net individual turnover rates for acetic (2,81 moles/12 h), propionic acid (0,82 moles/12 h) and butyric acid (0,55 moles/12 h), derived by the subtraction of the inter-conversion factors from the gross production rates of the acids, and expressed as the percentage contribution of each acid to the total net VFA turnover (acetic=62%, propionic=18% and butyric=12%) closely resembled the percentage molar composition of the VFA pool in the rumen (acetic=60%, propionic=23% and butyric=12%). The total net VFA production was found to be directly proportional to the total VFA concentration in the rumen (correlation coefficient=0,83), and the relationships can be described by the equation y=0,034 x + 0,16 where y=VFA production in moles/12 hour and x=VFA concentration in meq/1. A specific VFA production rate of 0,85 moles per 100 g digestible organic matter was calculated from the average daily VFA production rate and the composition of the lucerne hay.
在两组绵羊中，对瘤胃挥发性脂肪酸（VFA）池总浓度在24小时内的变化进行了跟踪。一组在08:00喂食，另一组每天在08:00和20:00各喂食一次。尽管分别在12小时组和24小时组中发现了相似的最高水平（143和147 meq/1）和平均水平（100.3和102.1 meq/1），但每日两次喂食方案导致的变化较小（标准差分别为17.0 meq/1和28.9 meq/1）。从同一时期VFA池摩尔组成百分比的变化得出结论，两组瘤胃中VFA的吸收顺序均为丙酸＞乙酸＞丁酸，但每日两次喂食的绵羊中差异不太明显。对每天在08:00和20:00共喂食1600克苜蓿干草的绵羊瘤胃进行14C标记的乙酸、丙酸和丁酸的长期输注，无论输注何种酸，平均净VFA总产生率为4.52±1.01摩尔/800克/12小时。通过从酸的总产生率中减去相互转化因子得出乙酸（2.81摩尔/12小时）、丙酸（0.82摩尔/12小时）和丁酸（0.55摩尔/12小时）的净个体周转率，并表示为每种酸对总净VFA周转率的贡献百分比（乙酸=62%，丙酸=18%，丁酸=12%），这与瘤胃中VFA池的摩尔组成百分比（乙酸=60%，丙酸=23%，丁酸=12%）非常相似。发现总净VFA产生与瘤胃中VFA总浓度成正比（相关系数=0.83），并且这种关系可以用方程y = 0.034x + 0.16来描述，其中y = 12小时内VFA产生量（摩尔），x = VFA浓度（meq/1）。根据平均每日VFA产生率和苜蓿干草的组成计算出每100克可消化有机物的特定VFA产生率为0.85摩尔。
