Digestibility of DNA in selected prey species was estimated by an in vivo feeding trial using six test diets. Each diet contained one of the following: (a) goldfish, (b) goldfish + citric acid, (c) goldfish + CaCO3, (d) shrimp, (e) snail, and (f) goldfish + shrimp + snail. The diets were fed to rainbow trout and fecal samples were collected. Mitochondrial DNA was extracted from both diet and fecal samples and quantified by qPCR using two sets of species-specific primers for each prey species. The first set of primers amplified a short stretch of DNA (51-80 bp), whereas another set amplified a longer stretch (126-162 bp). DNA digestibility was estimated based on the ratio between short and long amplicons using the following formula: Digestibility () = log(((Mt-S)/(Mt-L))) (S/L)/(0.01 x Mt), where Mt: 16,000 (bp), S: length of short amplicon (bp), L: length of long amplicon (bp), S: relative quantity of short amplicon, L: relative quantity of long amplicon. Calculated fecal digestibility of goldfish DNA ranged from -1.05 (f) to 2.07 (a). Digestibility of shrimp DNA was 10.79 (d) and 12.61 (f). Digestibility of snail DNA was 1.88 (e) and 2.06 (f). These results suggest that the digestibility of dietary DNA can be estimated based on the ratio between long and short fragments
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机译：通过使用六种测试饮食的体内喂养试验来估计所选猎物物种中DNA的消化率。每种饮食都含有以下一种：（a）金鱼，（b）金鱼+柠檬酸，（c）金鱼+CaCO3，（d）虾，（e）蜗牛，（f）金鱼+虾+蜗牛。将日粮喂给虹鳟鱼并收集粪便样本。从饮食和粪便样本中提取线粒体DNA，并使用每种猎物的两组物种特异性引物通过qPCR进行定量。第一组引物扩增了一小段DNA（51-80 bp），而另一组引物扩增了较长的一段（126-162 bp）。根据短扩增子和长扩增子之间的比率，使用以下公式估计 DNA 消化率：消化率 （%） = log（（（Mt-S）/（Mt-L））） （[S]/[L]）/（0.01 x Mt），其中 Mt：16,000 （bp），S：短扩增子的长度 （bp），L：长扩增子的长度 （bp），[S]：短扩增子的相对数量，[L]：长扩增子的相对数量。计算出的金鱼DNA粪便消化率范围为-1.05%（f）至2.07%（a）。虾DNA的消化率分别为10.79%（d）和12.61%（f）。蜗牛DNA的消化率分别为1.88%（e）和2.06%（f）。这些结果表明，膳食DNA的消化率可以根据长片段和短片段之间的比例来估计
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Department of Bio-resources Management, School of Environmental Sciences, The University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga, 522-8533, Japan;
