Izraely H, Choshniak I, Stevens C E, Demment M W, Shkolnik A
Department of Zoology, George S. Wise Center for Life Sciences, Tel Aviv University, Ramat Aviv, Israel.
Q J Exp Physiol. 1989 Jan;74(1):1-6. doi: 10.1113/expphysiol.1989.sp003234.
Factors determining the digestive efficiency of donkeys were studied in animals fed either a low quality roughage (wheat straw: 77.1% neutral detergent fibre, 2.8% crude protein) or a high quality forage (alfalfa hay: 47.5% neutral detergent fibre, 22.7% crude protein). The neutral detergent fibre (NDF) intake when fed wheat straw was 1693 +/- 268 g animal-1 day-1, 10% higher than when fed alfalfa hay. Digestive coefficient of NDF and acid detergent fibre (ADF) when fed wheat straw amounted to 50.9 +/- 4.9 and 42.0 +/- 4.1% respectively. NDF and ADF apparent digestibilities and mean retention times (37.7 +/- 1.7 and 36.4 +/- 3.2 h respectively) were not significantly different (P greater than 0.05) between the two diets. The donkey appears to digest cell wall constituents as efficiently as the Bedouin goat when on low quality roughage, but less efficiently when fed alfalfa hay. Its energy digestibility is, however, as high as that reported for the Bedouin goat. The donkey's high energy digestibility is related to its capacity to digest soluble food components more efficiently than the ruminant. The mean retention time in the donkey is shorter than in the Bedouin goat and is consistent with its capacity to compensate for a lower quality diet by increasing its intake rate. Recycling of urea in donkeys maintained on wheat straw amounted to 75.5 +/- 13.0% of the entry rate. A decrease in the rate of renal urea filtration, coupled with an increase in the fraction reabsorbed, increased the retention of nitrogenous waste and permitted recycling of nitrogen into the gut.
在以低质量粗饲料（小麦秸秆：中性洗涤纤维含量77.1%，粗蛋白含量2.8%）或高质量草料（苜蓿干草：中性洗涤纤维含量47.5%，粗蛋白含量22.7%）喂养的动物中，研究了决定驴消化效率的因素。喂食小麦秸秆时，中性洗涤纤维（NDF）摄入量为1693±268克/动物-1/天-1，比喂食苜蓿干草时高10%。喂食小麦秸秆时，NDF和酸性洗涤纤维（ADF）的消化系数分别为50.9±4.9%和42.0±4.1%。两种日粮之间，NDF和ADF的表观消化率以及平均停留时间（分别为37.7±1.7小时和36.4±3.2小时）无显著差异（P>0.05）。在食用低质量粗饲料时，驴消化细胞壁成分的效率似乎与贝都因山羊相同，但喂食苜蓿干草时效率较低。然而，其能量消化率与报道的贝都因山羊的能量消化率一样高。驴的高能量消化率与其比反刍动物更有效地消化可溶性食物成分的能力有关。驴的平均停留时间比贝都因山羊短，这与其通过提高采食率来补偿低质量日粮的能力相一致。以小麦秸秆为食的驴中，尿素的再循环量占进入率的75.5±13.0%。肾尿素滤过率降低，再吸收部分增加，增加了含氮废物的潴留，并使氮能够再循环到肠道中。
